I just read “Removing a Bearing Wall” #152 pgs 80-85. To my astonishment the author left out a critical detail. Since the ceiling joists are components in the roof system care must be taken when cutting them. The joists not only support ceiling and attic loads but more importantly form a truss system with the roof rafters keeping the roof from “squatting ” and exterior walls from “bowing” outwards. When compromising these members care must be taken to:
1) Provide temporary support during construction. I recommend 1/2 threaded rod spanned from both top sillplates and thru bolted with a big washer. I place these every 4 feet O.C. The objective here is to transfer the tensional forces from the ceiling joists to the rod. Once the temps are in place the joists may be cut.
2) Reconnect the cut ends of the joists with minimum 24 gauge sheetmetal straps. I recommend the strap laps a full 24″ on each side of the beam and fasten with 8p nails every 4 inches. I do not use truss nails as they tend to split the 2x joists.
3) All temps may be removed however if there is little interference with attic space, they can be left in place.
Edited 11/29/2002 2:39:08 PM ET by KWILBE
Edited 11/30/2002 10:31:30 AM ET by KWILBE
Replies
I agree with the point you make but never noticed the lack in the article. Guess I was asleep.
but for a small house with no snow on it while the work is happening that much threaded rood might be overkill.
Here's another method that I use;
I have some large eye bolts with large custom 1/4" plate for washers. The eyebolts are 5/16" so I drill a 3/8" hole through the wall near the plate and feed the bolt and thread the nut over the washer. Then I run a cable with comalong from one side to the other. I can control how much tension I have and pull thgings together if I need to - which is about nine times out of eight on these old houses. This cable would get in the way when lifting the beam the way he shows but I usually work it down from above instead of up from below anyway.
I ty ribbons to the cable so every one stays aware of where it is. It can cause a lot of pain to walk into it and if anyone ever cut one with a sawsall accidentally, I shudder to think about the flapping steel.
Excellence is its own reward!
"The first rule is to keep an untroubled spirit.
The second is to look things in the face and know them for what they are."
--Marcus Aurelius
KWILBE:
I think your point of considering the tension forces in the joists is good, especially in the final installation. It appears that little attention was paid to pullout in the joist hangers, so strapping as you suggested seems appropriate.
I guess I'm less concerned, in this specific instance, about the tension forces DURING installation. Just ran a few numbers. Assuming 30' span w/ 6/12 pitch, 7 PSF roof dead load and rafters at 24", looks like 420# tension force in ea. rafter (w/o considering live loads), or about 210 PLF outward force at exterior plates from temporary working loads. While this isn't insignificant, there IS a huge horizontal diaphram at the ceiling to resist these forces, aided by top plates, collar ties, _some_ ridge beam effect, and adjacent ceiling joists that aren't cut.
Obviously, every situation is different and should be analyzed carefully, and I would always encourage a builder to consult with an engineer for this type of work, just suggesting that redundancies in construction MIGHT make tension rods overkill if it's just bracing for a day or two. (And how do you avoid the rod's conflict with a flush beam, anyway?)
Richard
Guess in engineering school, they didn't teach you that the ones under the roof are RAFTERS and the ones that hold up the ceiling are CEILING JOISTS.
When you shut the door on a refridgerator, how do you know that little light inside really goes off?
But, Boss, with no load bearing bridge beam, the ceiling joist act in combination with the rafters. What was the point?.
Excellence is its own reward!
"The first rule is to keep an untroubled spirit.
The second is to look things in the face and know them for what they are."
--Marcus Aurelius
I guess my point was that the guy was coming acroos as a know-it-all, but didn't know the difference between a joist and a rafter.
Just didn't like his tone.Veni, vidi, velcro: I came, I saw, I stuck around.
That could be. I had to re-read it all to pick that up. Let 'm have a little wiggle room, it's his first time. Newbies get one one the house.
;).
Excellence is its own reward!
"The first rule is to keep an untroubled spirit.
The second is to look things in the face and know them for what they are."
--Marcus Aurelius
I noticed that too, but I assumed that there were (collar ties?) higher up on the rafters that never got mentioned. I read this thread pretty quickly, but I think that is what is in question, right? The other thing I noticed (and was mentioned here) was the roof pitch was pretty shallow . . . Steelkilt Lives!
But then he is an engineer...
LOL.
Excellence is its own reward!
"The first rule is to keep an untroubled spirit.
The second is to look things in the face and know them for what they are."
--Marcus Aurelius
I suppose I should have proofed my message more completely- I did re-edit for clearity sake. From time to time I have confused rafters with joists and pitch with slope and nailers with blocking- haven't you? I take it you are not fond of engineers?
No, tone is everything, titles are targets, if the tone isn't right. These guys almost always reccommend getting engineering support for many projects that are brought here for discussion.
Welcome aboard.
Dave
Thanks for your support- I feel like I have a new friend. I assumed this would be a good format to discuss issues amongst professionals. I could have responded to the article with a letter to the editor but I think there is an urgency for readers be aware the risks of compromising the structure before they attempt this project.
Edited 11/30/2002 4:43:39 PM ET by KWILBE
I confuse left & right from time to time, but I also noticed he'd cut the walls loose & wondered if anything was holding it from spreading. Don't recall any collar ties in the pics. If there are ties, they're too high to matter. Joe H
Hi all. Just my 2 cents, As I'm Canadien 1,53 cents.
Have a look on page 83, just above the mans butt, is that not a collar tie? As well at the bottom of the page it looks like the piece of wood in front of the comealong is also a collar tie.
I think the point is that this is really not a DIY job. Although an engineer may not be required in all cases, at least a pro who has done several other similar jobs with referances.
Be good all and let's be nice to the engineers, They know not of the practical applications of the jew bolt or the giggling pin next to the laughing chain. ;-0
I don't dislike engineers, just didn't like the tone of your post.
I'm actually an engineer of sorts, and am used to delivering news that people don't want to hear. But I try to be a lot more delicate than you were.
But - Piffin is right - Newbies to the forum should get a break.
So what I'd ask you to consider is that your concern can't be implied in a post - It has to be in black and white. The reader of your posts doesn't know why you're posting unless you explain that. Does that make sense? Good intentions can't be implied - They have to be in black and white.Bumpersticker: My child was inmate of the month at the county jail
Sorry, My off hand comment about engineers is founded in the fact that generically, practitioners of your vocation are known for being extremely specific, to a fault, and sometimes lacking in the common sense to drive a car from the street to the garage, so to speak.
Then here you were, criticizing a specific while making a general error.
Hope you can laugh it off. Some engineers are also known for not having a sense of humour.
.
Excellence is its own reward!
"The first rule is to keep an untroubled spirit.
The second is to look things in the face and know them for what they are."
--Marcus Aurelius
Edited 11/30/2002 2:53:42 PM ET by piffin
I just finished a similar job.
What I did was to build my beaam ON TOP of the cieling joists, long enough to sit on a stud that would stay on both ends.
I added blocking under the ends and some doublers for the rough opening.
Then I put in four pieces of 1/2" threaded rod through the beam and though the top plates with double nuts and BIG warshers on both ends.
Then I was able to remove just enough of the studs to put in a flat header and not disturb the top of the wall (with grass wallpaper).
The cieling joists and the wall finish on one side were barely left intact, and the 1x8 T&G Maple paneling on the other side was saved and put back.
I didn't even need to get out my taping tools, always a good thing!
Mr TDo not try this at home!
I am a trained professional!
Mr T
It sounds like you left the top portion of the wall. How would you do it if it had to be a flat ceiling? I have a similar project and wanted to build up a beam in the attic instead of cutting all the joists. Are there hangers available or would I need to get them fabricated? As for the article I wondered why he did not do the beam from above, it looks like there is plenty of room. Also what do you guys think the price for that job should have been?
J.
There are hurricane straps available that are just a flat strap with a 90º twist in the middle, (boy I love making that º symbol! ººººº ...simple pleasures....)
TDo not try this at home!
I am a trained professional!
hey, can you teach me to do that too?
i can never find it (the degree symbol) on my keyboard.
degree symbol = alt + 0 1 7 6 on the numeric keypad.
Excellence is its own reward!
"The first rule is to keep an untroubled spirit.
The second is to look things in the face and know them for what they are."
--Marcus Aurelius
PIFFIN!!!!
Now that you told him, we have to kill him!!!
Ok Who's got 00 status?
Agent T Do not try this at home!
I am a trained professional!
> Are there hangers available or ....
Look at http://www.strongtie.com, there are lots to choose from. Ask your inspector or building department if they accept the particular model numbers that seem to fit your application.
-- J.S.
I've done wall removal similar to T's, we called the beam (made them L shaped,or T shaped) a strongback. Ours were not engineered, not that I have any thing against those of that persuasion, well, except for the ones that stamped plans for houses that we had to crawl under after they were built and then put in the load bearing piers and beams...but hey, the engineers stayed clean and didn't break a sweat;-)
But, kidding aside, I didn't see anything wrong the tone of the question that started this post. Taunton should have mentioned that shotgun houses are not very wide, and that whacking the joists in a larger house without proper provisions could result in a lotta s h i t a poppin' or worse. I think it was a pretty good call, even for an engineer<G>
I hope you keep an eye out... It's okay, I can fix it!
Gotta agree with you, we missed that detail. Even so, I think that was a pretty good article. Just the ideas of using a chain hoist and a ventilator were worth the cost of admission. In the opinion of FHB's executive editor, anyway <G>.
Andy Engel, The Former Accidental Moderator
As an engineer and as someone who has spent significant time working in the construction field (pre-engineering school), I feel like I am qualified to say this:
SOME tradesmen, craftsmen and ALL of the wood butchers who want to use leftover 2x4s as a beam spanning 20some odd feet or whatever) simply do not understand basic engineering principles. Conversely, SOME engineers do not understand the practical applications that these craftsmen encounter daily in spite of the fact that engineering school is extremely challenging. (As far as personality goes? We are all over the map, from the humorless nerd stereotype to some of the nicest, funniest people you will ever meet.)
When I read these forums, I am scared to see the number of people who post who have no idea what they are doing AND are reluctant to call in an engineer for a structural problem or an electrician for a wiring issue. One of the reasons why Norm and Tom Silva of TOH are such professionals is in spite of their vast experience as GCs both remodelling and building homes, they always use/recommend an engineer for non-standard applications for structural issues. Most amateurs have never dealt with an engineer and perhaps there is an intimidation factor in consulting with one for the first time. We all are used to seeing doctors and dentists for those types of problems but lawyers and engineers are off the beaten path. They may also be afraid of "opening up a can of worms" regarding getting a construction permit, etc. Who knows...
Finally, Some tradesfolk like to denigrate engineer's ability in various "practical" areas, as if this disqualifies their more analytical abilities. This is short sighted and ignorant on their part, NO engineer can possibly have every practical "trick" or technique that a Tommy Silva has in his toolbelt, just like it would not be a good idea to have Tommy calculate the post-tension cable layout and structural steel design (with 20 foot cantilevered balconies) for that Frank Lloyd Wright inspired home. We all have our areas of expertise and smart pros know this!
Together we can design and build some beautiful things!
Since you posted that very well written bit of apologetics to me, I take it that you may have thought that I needed a little correction on this issue. I'm well aware of what you had to say and have used an engineer about every eighteen months - no barrier here - I was only explaining a percetion expressed. I think it has some basis in fact. engineers are practical mathematicians. People who deal in numbers. They have to be specific. If not, they fail. Some of them are a little short on the human side though. I remember writing English term papers for an engineering student in college who could barely put a complete sentence together but who could solve quadratics in his mind's eye.
Artists and musicians who rely more strongly on the other side of their brain have different attributes, and thank God for the mix and the variety.
Thanks for bringing clarification to the thread.
Now, let's go farther. You percieve a mental barrier to people attempting to access good engineering. I think you are right. In the past couple years, I've probably told twenty people here to go get in touch with an engineer for the solution to their structural issues. You've made a good and thorough point for the two or three hundred people who will read this thread. How about writing an article to submit to FHB on the subject, "When do you need engineering assistance" and "How to get in touch with your local ..." I bet it would find some ink..
Excellence is its own reward!
"The first rule is to keep an untroubled spirit.
The second is to look things in the face and know them for what they are."
--Marcus Aurelius
Great post Haole27. Could you draw us a diagram of how you got that soap box in your cubicle?
WAHD
Edited 12/3/2002 8:41:07 AM ET by WAHD
Sure I could diagram the soapbox in cubicle process for you, do you have someone in your outhouse that could help you follow it?
I was hopeing you would have a sence of humor and draw us a diagram. I guess not.
OK, I'm ignorant about both engineering and building, so maybe you can explain something to me. We had an architect/structural engineer partnership draw up the plans for our addition. To meet the original house, we had 9 3/4" to work with for the floor system - this was very clear in the original specs. The joists only had to go 11 ft, easy enough for TJIs, but one end had to hang off a beam with a 23 foot span. The engineer called for a 16+ inch beam in accompanying paperwork, but this wasn't indicated on the drawings for either a notch in the foundation or a step up to the addition - so we had nowhere to put that extra 7 inches. So here is finally the question for engineers and builders. His suggested solution was to notch the beam on either end and sit it directly on the concrete (cut away the sill to gain an extra 1 1/2"). To non-cogniscenti like me, putting non-pressure treated wood directly on concrete doesn't sound too bright, or is this just more of my ignorance? Also, to a non-engineer, it seems like cutting the beam makes it less of a beam and wouldn't bear the weight anyway. Or is this one of those non-intuitive engineering/math things that cutting it on the ends is OK? Our solution (that he approved) was to use 9 1/4" LVLs bolted together and move a closet to the other side of the room so we could have a load bearing wall in the middle of the span. Luckily we saw the problem early enough that we could put in a footing for the load bearing wall. This seemed like a much better solution to us - we don't lose so much headroom in the basement and we don't have a tripper on the main floor. How much simpler it would have been though, if the engineer and architect (partners, mind you) actually worked together. Although, perhaps my rejection of the engineer's suggestion was merely ignorance and it all would have worked anyway? I know I sleep better (I sleep under this same floor system) with what we have.
Notching beams is generally a bad idea. But it can work,in some cases. It needs to be reviewed by the people who manufacture the beams, not an engineer.
Putting a beam in direct contact with concrete is also a bad idea.
Having a 16" deep beam span 23' is also a bad idea. If you only knew the power of the Dark Side. [Darth Vader]
Piffin, here's an illustration of your point (and yes, I'm and engineer)
Two gentlemen were in a hot air balloon; after several hours of fog, they came to a clear spot. Below them, in a field, they saw a man. So they lowered the balloon, and shouted out, "Hey, can you help us? Where are we?" The fella in the field looked around, puzzled, and then hollered up to them "Well, you're in a hot air balloon, about 20 feet above this field."
At which point, one of the balloonists called down "You must be an engineer!" The fella in the field looked surprised, and replied "Why, yes I am. How did you know?"
"Well, everything you've told us is factually correct, but also completely useless! What do you expect us to do now?"
So the engineer looks up and says, "You guys must be Managers!"
The balloonists look down, and one says, "Yes, we are. How did you know?"
The engineer replied, "Well, you don't know where you are; you don't know where your're going, and you've just found a way to put the blame on the first person you've met!"
I've wondered which came first the homebulider or the engineer? It seems the builder 'does" something and the engineer "tells" him what he did wrong. If you ask first the engineer shows you how to over build to cover himself. For Petesake there is no "black magic " in building , if you need an engineer in residentual construction you need to go to work for somebody else and not be in business for yourself.
>if you need an engineer in residentual construction
Or it could mean you're doing something different than was done before. Any time you take spans to the limits or cantilevers or such, rules of thumb and common sense just aren't gonna be good enough--for either the owners or the inspectors. Take my staircase in the Photo Gallery. You wanna try the engineering on that one? Guess at the rebar schedule and concrete thickness, and I'll tell ya if it matches the engineer's specs. Hint: better study up on twisting torsion.
###
I think y'all are jumping on the engineers too much. Maybe they didn't word everything with the humility that all you posting-police woulda preferred, but maybe you could guide them rather than jump on them. The one way will encourage more and better participation, while the other way makes people hesitant to post.
these guys ain't real enganears
i can tell cause the way they spelled enganear.
you know the saying
i couldn't spell enganear, now i are one!bobl Volo Non Voleo Joe's cheat sheet
C.H. "posting Police". Since when can you guide a prima dona , the very title of the post " thats why I went to engineering school" infers , while the rest of you beat hell out of yourself and don't know anything. Venting...thats whats happening here, the frustration of doing something without knowing why . The engineer has a perfect oppurtinuity to teach all us "heathens" but prefers to drive the train.
It looks like the builder came first, and learning from mistakes in building is where engineering came from. Note in the following that the collapse of one pyramid may have led to engineering changes in another:
http://www.crystalinks.com/bentpyr.html
-- J.S.
J.S. Haven't seen many residentual pyramids lately, :)...I understand your point and my comment was venting the current trend to not think on your own and the inability not to be able to converse with the engineer on possible ways that our experience tells us that will work if his numbers will work for the inspectors.
>>I've wondered which came first the homebulider or the engineer? It seems the builder 'does" something and the engineer "tells" him what he did wrong. If you ask first the engineer shows you how to over build to cover himself. For Petesake there is no "black magic " in building , if you need an engineer in residentual construction you need to go to work for somebody else and not be in business for yourself.<<
Nails,
Check out the current issue of FH, the tiltup stone/concrete wall system for a single family home. Would you like to design the structural steel for that one yourself and then live in it? I didn't think so!
No black magic there , just engineering principles...and by the way, we overdesign to give a factor of safety against possible inferior materials, the guy who wants to put a kingsize waterbed, 100 gallon whirlpool and his new Pacific Fitness gym system in the master suite, etc...
H27 ..Thank you, Thank You .....in 30+ years of hammer swinging this is the first time an engineer ever responded to anything I said .Don"t you go anywhere please stay right here at breaktime and give everybody hell.
thanks Nails, I wont! I think FH is not only the best building mag out there but its my favorite mag period! Its not just the choice homes but the little things, like for instance the article about how to repair drywall...
they found THE GUY (i think he was from RI) who is a true expert on drywall to show how to repair and hang, etc not some NY writer-type who doesnt know drywall from a walnut who is merely quoting a couple of tradesmen.
Why do engineers overdesign? The "factor of safety" is one thing, since not all materials (especially wood) are homogenous.
However, what about the legal issues involved? I'm surprised that no one has brought this up yet. If some sort of structrual failure occurs, guess whose butt is on the line? So what exactly is an engineer's motivation for cutting things close? There is none. Why expose yourself to ridiculous lawsuits and excessive settlements? It's much better to just tell the builder to use a 6x12 instead of a 2x6.
I think the problem of overdesign lies less with engineers and more with our legal system. But that's my opinion. ;)
Ragnar
As my late Dad (40 years as a GC) said:
"concrete and steel are cheap so why skimp?"
concrete and steel are cheap so why skimp?
Well, in general I agree with your Dad. For example, why not make hardware nice and heavy so that it will last pretty much forever? In that instance, you're talking a difference of a few pennies on the dollar.
However, in wood framing, things can just get downright wasteful. For instance, most of the roofs on houses I work on were framed with 2x4s at 24" centers. The last project I was working on had a 8' deep covered porch with a hip roof, and the architect's drawings (allegedly spec'd by the engineer) instructed us to use 2x6s and 4x8s at the hips. This is just plain overkill which results in unnecessary cost to the homeowner, and unnecessary waste of a valuable building material.
the 2x6s req sounds right but the 4x8 may be overkill, next time, ask to see the engineer's work sheet calculations (or computer aided modelling program results).
this applies to any engineered job, ask him to go over the calcs and show you the stresses, deflections, loads, etc
ask him what factor of safety he applied, most engineers/architects will be happy to share these things with you, if not find another one who will!
"ask him what factor of safety he applied"
Engineers don't apply the safety factors. Lumber and beam design values have the safety factors built into them already.
An engineer can upgrade something that looks like it works on paper, if he thinks it isn't a good idea for some reason. Like a beam that works O.K. on paper, but will have enough deflection that it will look bad.Who could be serious with men? What I really wanna do is to date a lot of pigs. Tell 'em to line up outside... and bring lots of emeralds. [Judy Tenuta]
Boss,
Incorrect. Engineers use a database for the strength of various materials. Loads are applied to a modeled system resulting in the internal stresses and deflections of the various members. Factors of safety are applied to the final result to give a safe design.
You are probably confused by the beam spanning tables (and similar tables) that have ALREADY applied the factor of safety to the results.
Haole
Sounds like you learned a different way than I have.
I design wood beams, headers, and I-beams all the time. Every one I've ever seen already has design values applied to it.
How do you come up with your "database"? You have to have some values to start with.........He loves me, we have great sex, and he fixes my car. [Amy Fisher]
Boss are you an engineer? Just curious.
Materials are tested for modulus of elasticity(E), yield strength(PSI) , ultimate tensile strength (PSI), associated values of strain(in/in). These values are contained in materials handbooks for wood, concrete, steels, aluminum, etc
Engineers use this material data in their strength calculations to derive span tables for different kinds of dimensional lumber, beams, etc. It sounds like you use these tables to "size" various structural members. If this is the case, the engineering has been done for you., as it was intended.
The design values typically do have a factor of safety applied to it, typically 2 for building construction. This means for a given load, it is twice as strong or twice as stiff as the case may be to preclude outright failure or a given amount of deflection as for a beam.
If you would like, I can fax you some examples of this from my engineering textbooks, what is your fax #?
I like to tell people I'm a "P.E."
That stands for "Pretend Engineer"............(-:
Actually, I'm a truss designer. Been in the truss business for about 18 years.
I wonder if we're just using different terminology or something. Maybe an example would help.
If I were to hand calc a beam made out of 2X10 #2 SYP, the published design value I have for bending (Fb)on this lumber is 1050. The safety factor has already been considered in assigning the bending value.
Don't know what you have that you would fax, but I would be interested in seeing it. My fax # is (217) 324-6658When the Buddha was asked to explain why he did not respond to a verbal attack, he said, "If someone declined to accept a present, it would belong to the one who offered it. In the same way, I decline to accept the abuse."
Engineers do use safety factors. For example, machinery for lifting people (elevators, mine cages), must be designed with a safety factor of 10. I think what was intended was that IF YOU USE THE PUBLISHED TABLES, they already have a safety factor built into them. But that doesn't mean that engineers don't use safety factors. they also use experience and gut feel, just like everyone else.
Incidentally, in Canada, if you decide to run around calling yourself an "engineer", you have to be a Registered Professional Engineer, or else you risk a fine. This has gotten Microsoft into some trouble, because they have decided to use a term Microsoft Certified Systems Engineers, which is illegal in Canada. And Microsoft being Microsoft, they have refused to stop using the term, despite being notified. So, all of their MCSE graduates in Canada risk being taken to court if they use the term.
Incidentally, in Canada, if you decide to run around calling yourself an "engineer", you have to be a Registered Professional Engineer, or else you risk a fine.
That is technically the case in the US also, though I usually see disciplinary action only against those selling such services without credentials, or working outside of their area of expertise, not against those using internal company titles, like "Sales Engineer". It's similar to needing a CPA to offer accounting services to the general public, Licensed Land Surveyor registration, MD, DDS, whatever. Sealing drawings and calcs shifts liability from the contractor and authority to someone else (the Engineer), hence the tendency toward robust design. That's really what you're paying for.Be seeing you...
My "favorite" misuses of engineering titles include "domestic engineer" (aka housewife) and "sanitation engineer" (aka janitor). Microsoft seems especially adept at creating fancy titles for otherwise mundane job activities.
Hey Boss,
Do you have numbers for "Fv" for Doug Fir #1 and #2, and possibly for hemlock/spruce as well?
Ragnar
Fv is 180 psi for all grades of doug fir. I wanted to post the following as a table, but no matter what, Perspiro won't let me change the font to courier. If you can, it might make more sense.
Lumber Grading marks for Doug Fir:
Grade Fb Ft Fc Par E
Sel Str 1500 1000 1700 1.9 1 & Btr 1200 800 1550 1.8 1 1000 675 1500 1.7 Const 1000 650 1650 1.5
2 900 575 1350 1.6
Stud 700 450 850 1.4
Stand 575 375 1400 1.4 3 525 325 775 1.4 Util 275 175 900 1.3
Fb = Extreme fiber bending stress Ft = Tension stress Fc par = Compression parallel to grain E = Modulus of Elasticity
Fv = Horizontal shear = 180 for all Fc perp = Compression perpendicular to grain = 625 for all
-- J.S.
John,
Thanks a million for the table! I was having a discussion with Boss Hog about some of these values before Thanksgiving. I have some engineering texts which are great for metals, but don't have much in the way of wood values.
To make sure I'm interpreting things correctly, Ft (tension stress) would really only occur in truss situations where a member is in axial tension, right? All units are in psi with the exception of E (elastic modulus), which would be in units of 1x10^6 psi (1,000,000 psi), correct?
I'm not sure how to interpret Fc_par and Fc_perp. I can think of three different ways to load wood grain, but maybe I should just wait for some clarification before I cloud the waters with my speculations! ;)
In case you were curious, my text includes some values for Douglas Fir (unspecified grade, unless "timber" means anything specifically). Under "ultimate strength", it lists 7.2 ksi for compression, and 1.1 ksi for shear. I'm assuming "ultimate strength" is the point at which failure occurs.
Regards,
Ragnar
> To make sure I'm interpreting things correctly, Ft (tension stress) would really only occur in truss situations where a member is in axial tension, right? All units are in psi with the exception of E (elastic modulus), which would be in units of 1x10^6 psi (1,000,000 psi), correct?
Yes and yes.
> I'm not sure how to interpret Fc_par and Fc_perp. I can think of three different ways to load wood grain, but maybe I should just wait for some clarification before I cloud the waters with my speculations! ;)
My understanding is that Fc_par is what you have in studs, and Fc_perp is what you have in plates and the ends of joists and headers, and blocking between joists side to side and bearing walls above and below, stuff like that. I can see that you could consider the direction of the growth rings and get additional ways to classify loading, but that seems not to be done.
> I'm assuming "ultimate strength" is the point at which failure occurs.
Yes, ultimate strength is where the wood fails. The values in the tables are the safe limits. Those safe limits are subject to adjustment factors for different applications, like temporary loads, snow, wind, earthquake, impact, etc. For permanent dead loads, the factor is 0.9, which is the strongest option in the Parker/Ambrose book I'm looking at.
Also, I've found that the grade stamps have to be tempered with common sense. I was sorting through some "Std&Btr" 2x4's (supposed to be the same as Standard in the table), and one of them had a knot in the middle so big that it broke in half when I picked it up. In that case, it looks like Fb at the knot was significantly less than advertised..... ;-)
-- J.S.
My understanding is that Fc_par is what you have in studs, and Fc_perp is what you have in plates and the ends of joists and headers.....I can see that you could consider the direction of the growth rings and get additional ways to classify loading, but that seems not to be done.
Thanks for the info, John, that's pretty much what I figured. However, it seemed a bit counterintuitive to me that wood could bear more weight when loaded parallel to the grain than perpendicular. This is due to the fact that parallel loading (i.e. a column) would naturally present shear planes along each and every growth ring.
For example, if I was using a 12" cube of wood on which to rest a house jack, I would orient the grain perpendicular to the jack because I'd be afraid of the block splitting if oriented parallel. What's your gut feeling on that?
Regards,
Ragnar
PS: What sort of work do you do?
> parallel loading (i.e. a column) would naturally present shear planes along each and every growth ring.
In order for it to shear between the growth rings, there would have to be a shear force present there. In theoretical parallel loading that doesn't happen. To get the results that the theory predicts, practical applications have to be designed and installed so that you don't get significant shear.
> For example, if I was using a 12" cube of wood on which to rest a house jack, I would orient the grain perpendicular to the jack because I'd be afraid of the block splitting if oriented parallel. What's your gut feeling on that?
If all the vertical fibers are uniformly loaded, that doesn't happen. Perhaps you could take a scrap of 2x4 and cut off some 1 1/2" pieces from it. Crush these pieces to death in a big vise, some parallel to the grain, and some perpendicular. That should give you a good gut feeling for what the difference is. I think you'd find the wood to be significantly stronger parallel to the grain. But the other difference is that perpendicular to the grain you'll get a gentle gradual crushing, and parallel the failure will be more sudden and complete. My gut feeling on this comes mostly from using scrap blocks under hammers and crowbars when pulling nails. That doesn't really give you uniform loading, so perhaps my guts are pointing in the wrong direction. ;-)
> PS: What sort of work do you do?
My day gig is Director of Technology for Television at Paramount, and nights and weekends I'm converting a four unit 1926 apartment building into a single family house.
-- J.S.
Thanks for your thoughts, John. I'm sure I'll crush some pieces of 2x in my vice sometime over the next several days.. ;)
Glad to hear you're converting a multiple unit into a single one!!!!! I'm very tired of seeing all those beautiful houses from the 1910s and 1920s bulldozed and turned into condos, etc.
I'm very fond of the 1920s. I'd say 49% of my work is on 1920s houses (49% is pre-1920s, and the remainding 2% is new work!). I even like playing music from the 20s when I'm at the job site. Someday, I'd like to get a flatbed truck from the time period, just for fun. I'm sure it would make for great advertising.
Good luck on your project and post some pictures!
Ragnar
> I'd say 49% of my work is on 1920s houses (49% is pre-1920s, and the remainding 2% is new work!). I even like playing music from the 20s when I'm at the job site.
I also love the old buildings and the music of the period, roughly mid 1910's through late 1940's. Being a DIY, of course I play the music on a clarinet rather than just running a tape. ;-) ...... (Actually it's been quite a while since I've had time to pick up the clarinet.)
> Someday, I'd like to get a flatbed truck from the time period, just for fun. I'm sure it would make for great advertising.
My grandfather had a REO Speedwagon when he was in the millwork business in Chicago in the 1920's - 40's. I even have some of his tools from that period, I'm using the combination square, framing square, an old hand saw, brace and bits, and the Unisaw.
> Good luck on your project and post some pictures!
Thanks. I've already posted in the gallery on doing a new footing in the middle of the house, and on home made tooling. I just went there and bumped those threads to the top.
-- J.S.
John,
I'll go look for the threads. Let me know if you ever need any advice on the remodel - I've got lots of sources up here in Seattle.
Regards,
Ragnar
> Let me know if you ever need any advice on the remodel -
Thanks! Actually I do have a problem I'm pondering now. I have big time termite damage in both top plates on an outside wall, so I'm looking for a strategy to replace them. This wall supports the rafters for a 7 in 12 Spanish clay tile roof, but no ceiling load, the ceiling joists are parallel to it. I'm figuring that the only way to go is to build up a temp wall parallel to the outside wall, poke holes thru the ceiling to get support up to the underside of the rafters, and tie the rafters on this side to those on the other side with cable and turnbuckles -- a really big megillah. In fact, this should probably start a new thread.....
-- J.S.
john.. shore it, cut it , replace it.. and quit cher dam whininMike Smith Rhode Island : Design / Build / Repair / Restore
I liked the article and I thought Mr. Davis did a fine job. I guess it is a matter of perspective but, since I ain't no engineer, the most interesting thing to me was the use of the chainsaw on the job, not to mention the boss's skill with it. Structurally speaking, I had no problem with the technique. With all of that board sheathing, the collar ties, and the fact that from what I could see the beam only spans half the house. Sorry bud, but those ceiling joists ain't goin' nowhere. Did anyone also note that this is a common remodel down on the Bayou?
John,
I'm assuming you're going to replace the top plates along the entire length of the gable wall.
What is the length of the gable wall? How much projection do you have at the rake?
Here are my initial thoughts:
Get into the attic and screw a 2x12 across the face of the gable studs, just a couple of inches above the damaged wall plates. The 2x12 will act as a header to add some stiffness to the section. Fasten the ends of the gable rafters to this "header", too, and you'll keep the roof section at the gable from splaying when the plates are eventually cut out.
Build some temporary shoring on the exterior. My preference would be to mirror the 2x12 on the interior with one on the exterior. Fasten it to the sheathing and screw through the sheathing into the gable studs. Of course, this would require some removal of the siding, and I don't know what sort of siding you have, or how easy it would be to replace it. Alternatively, I suppose you could bear against the barge rafter (aka fly rafter).
In any event, the exterior shoring, together with the first rafter pair inboard of the gable wall, would support the roof load over the damaged plates and enable you to proceed to your main objective.
Ragnar
Thanks for the thoughts, but alas this is about 26 feet up with a tree in the way, so shoring from the interior will probably be better. Like Mike said, I'll stop looking for an easier way and just get going on it.
-- J.S.
26 feet up? Oh well! Back to the drawing board. ;)
I saw the pictures you have posted here regarding the foundation work. Any others that show the exterior, or some of the interior details?
Ragnar
> I saw the pictures you have posted here regarding the foundation work. Any others that show the exterior, or some of the interior details?
Not yet, except that I posted my jigs for some of the window work in answer to a question on home made tooling, it's in the photo gallery. So far I have a little framing done, but it's all very ordinary stuff, not worth a picture.
-- J.S.
I'd like to get a flatbed truck from the time period."........a 2ton.....with side racks ........could be canvased covered bed .......two story cab.....split windshield that opens from the bottom.....dual wheels.......headlights the size of a bushel basket .....a whinney side loading transmission.......smells like 30 weight oil and rear end lube .....Ohhhh man we could go see Boss Hog in the spring , whatta road trip!
Hey John -
Where did you get that table from? And what size of lumber is it for? My lumber tables don't agree with yours. The only value I have which seems to match up with yours is "Fc perp".
Are you maybe using a table from pre-1990? Back then the tables had the same design values for all sizes of lumber.
I don't know how to make a table either. Anyone know if use can set "tabs" in html? (Like setting tabs in MS word)And you thought punctuation didn't count:Woman, without her man, is nothing.Woman. Without her, man is nothing.
Boss,
I don't know how to put a tab within a line, but this is how you put a tab at the beginning of a line...
<p style='text-indent:.5in'>
That will give you a tab of a half inch.
Cahnge the .5 to a 1, for a one inch tab. Or .25 for a quarter inch. Etc.
Don't bogart the Ghost
Quittin' Time
Thanks fer the info. I'll give it a try here. If it works, I should get some columns here. If this works, I shoule get a column of "ABCD" over a column of "1234".
ABCD
1234The best way to make your dreams come true is to wake up.
Interesting effect, but not at all what I was looking for. This is the text I used to try to create the columns:
A<p style='text-indent:.5in'>B<p style='text-indent:1in'>C<p style='text-indent:1.5in'>D<br>
1<p style='text-indent:.5in'>2<p style='text-indent:1in'>3<p style='text-indent:1.5in'>4The earliest Chinese ideograph for "male" was also a synonym for "selfish".
Boss,
what software do you have? Microcrap Office?bobl Volo Non Voleo Joe's cheat sheet
A B C D
1 2 3 4
4 5 6 7
WYSIWYG cut and pasted from word.bobl Volo Non Voleo Joe's cheat sheet
Great -
Doesn't work in Netscape. Here's what I get:
A B C D
1 2 3 4
4 5 6 7Why is it that our memory is good enough to retain the least triviality that happens to us, and yet not good enough to recollect how often we have told it to the same person?
How about a screen shot?Be seeing you...
If I shot my screen, I wouldn't be able to see anything here............
.
O.K., seriously - What do you want a screen shot of? Are you saying we should input the table we want into word or excel, then do a screen shot of that? I guess that would work, but it seems like making a table in a post would be easier..........
Or maybe a screen shot could be done like in the attachment.Writing is easy. All you do is stare at a blank sheet of paper until drops of blood form on your forehead. [Gene Fowler]
Too bad we can't get that to work inside of a line. Let me look around and see if I can find something to make spaces with.Don't bogart the Ghost
Quittin' Time
> Where did you get that table from? And what size of lumber is it for? My lumber tables don't agree with yours. The only value I have which seems to match up with yours is "Fc perp".
This is for two by doug fir. It was about a year and a half or two years ago that I was doing the design for my remodel, and IIRC, what I did was Google around looking at web sites for the various west coast lumber companies and trade organizations. I think that SelStr, #1&Btr, #1, #2, and #3 were from one table, and Const, Stud, Stand, and Util were from another, but both on the same page. Having found it, I stashed it in my subdirectory for useful building data, and just pulled it out when the question arose.
-- J.S.
"This is for two by doug fir. "
That was kinda my point - Ther are different values for every size of 2X lumber now. ie: 2X4 and 2X6 have different design values within the same grade and species. They changed that back around 1990 or 1991 after the imperical/full sized testing that they did. If at first you don't succeed, it could that you're just not be very good at it.
Sorry for the delay, I lurk from here at work. We take lumps of black coal and turn it into the sparks that escape from the ends of screwdrivers when working on outlets that have been denergized. <g> I do very little actual engineering any more, mostly just SWAG estimates on manhours, $'s, and time to do repairs. I've been through the whole package of power plant engineering jobs from calculating turbine efficiencies to pump performance, etc. Now I spend my time as an outage coordinator. My ME degree gets very little use. I took the EIT exam many moons ago and passed but there was little incentive to get the PE so I never attempted it but heard horror stories from those who did.
Lefty - Lurker without an attitude or a clue
>- Ther are different values for every size of 2X lumber now.
Can you post the current values here?
Thanks --
-- J.S.
Post all the lumber tables ??? I've got like 12 pages or so, with about 80 values on each page. (And no scanner)
Maybe tomorrow I could come up with some tables on the web somewhere..........The main reason Santa is so jolly is because he knows where all the bad girls live.
Hey fella -
I have all kinds of tables for lumber - About 10 pages worth. I'll be glad to fax them to you if ya like. It's no accident that stressed spelled backwards is desserts.
>if you decide to run around calling yourself an "engineer", you have to be a Registered Professional Engineer, or else you risk a fine.
As a friendly comment, you might want to heed this warning and not mention "engineer" or "engineer of sorts" even in jest. It has all kinds of liability and other implications in the legal code of most states. I got a good warning from my atty about using this term and "architect" when I started designing buildings. Even when a client introduces me to another as "my architect" I correct them and make it clear I am neither archy nor engineer, and that we require them to use an licensed structural engineer on our jobs, or whatever is required in their state.
A second reason is that engineers/archys work hard to attain that designation, and I wouldn't want to minimize that by using the title, even in jest, if I hadn't the same training they had.
Amen Cloud!
I understand your concern - You may be right that I might possibly offend an engineer by saying that I'm "an engineer of sorts". But I don't see how saying I'm a "pretend engineer" could offend anyone.
Seems to me that the term engineer gets thrown around far too easily. Even people who run amplifiers at concerts call themselves "sound engineers", or something like that. So what exactly Is an engineer?
Actually, I wouldn't have a problem calling what I do engineering. An engineer recieves training, then works under supervision, then works on his own. That's basically what I've done. The only difference is that I don't have a degree. I feel like I know more about trusses and my job than any engineer I've ever met. (That wasn't directly involved in the truss industry as an occupation) But I still refrain from referring to myself as an engineer, since everyone seems to be hung up on that piece of paper.
I'm curious what engineers think about this subject - We have a couple around.........If you want to sacrifice the admiration of many men for the criticism of one, go ahead, get married. [Katharine Hepburn]
From my perspective, BSME '81, the term engineer doesn't require a degree, a lot of the people I work with have no degree and are better engineers than I will ever dream of being. Hands on experience and a good reference source can give all the knowledge that a degree involves. The bigest difference is that the education may involve a good understanding of the theory and background but the experience will get you to the same point. Some of the dumbest people I have ever met were engineers and couldn't build a toothpick if you gave them all the materials and a drawing. But these same people understood how a radioactive rock could create electric power and could explain it in plain english. On the other hand. a PE is a state issued title and entails a large amount of training, sweat, tears and blood and an ever larger amount of responsibility. The PE stamp is deserving of respect and I would not want it tossed around as domestic PE, sanition PE, etc. Just my humble thoughts.
Lefty - Lurker without an attitude or a clue
Here's a little bit of HTML I scabbed together to make a table. I found several sets of values for Doug Fir, this is just one. Design Values for visually graded 5"x5" or larger Douglas Fir-Larch
Bending (Fb)
Tension Par to Grain (Ft)
Shear Par to Grain (Fv)
Compression Perp to Grain (Fc-Perp)
Comp Par to Grain(Fc-Par)
Dense Select Struct
1900
1100
85
730
1300
Select Struct
1600
950
85
625
1100
Dense No. 1
1550
775
85
730
1100
No. 1
1350
675
85
625
925
"Listen, strange women lying in ponds distributing swords is no basis for a system of government."Jon
Edited 12/5/2002 4:20:11 PM ET by JJSHAW
BSEA Michigan State '79. (we used to use punch cards in computer lab)
I second the motion on the concept that some people think better in different environments. In my Industrial engineering life i was always awestruck by the Functional Rube Goldberg contraptions that the farm boys created. In fact that was a hidden attribute they asked in the General Motors plant interviews. MSOE in Milwaukee turns out some of the finest nerds in the nation as they focus on the rubber meeting the road form of engineering. lots of hands on workplace training. The common mistake is thinking that the financial, emotional, and marketing environments bend to the same rules as physical laws)
The Professional engineer moniker is a tested quantified value of a type of engineer. State issued liscense is given only when all of the testing elements are passed adequatey in state run tests. I tried and was unable to do it. Too much time passed for me to roll thru the thermal fluid phenomonon & other quantitative tests for Industrial engineering. If you don't use it you lose it. It is a good filter and I do respect the title if for nothing more than it increases the engineers liability and that rolls into the check and ballance of competence.
Theory is important if you want to avoid lots of trial and error testing. I think it gets to a deeper level of understanding of the way things work. The degree helps but the PE suffix should be held in some higher regard, in its field of competence.
Theory is important if you want to avoid lots of trial and error testing
Booch,
I agree -- in fact, one of my professors used to define engineering as "the ability to accurately predict outcomes". That is, anyone with common sense can go through trial and error and eventually come up with a workable design. An engineer is supposed to be able to do it the first try. Of course, a second (or third!) iteration is often required, especially as complexity increases. But understanding how theory applies to the real world is still the shortest path to success.
By the way, I'm familiar with ME, CE, EE, IE, and maybe a few others.... but what exactly is BSEA?
Regards,
Ragnar
Engineering Arts. BS degree with minor in a variety of business related fields. Among them are Marketing, Writing, & Management. Purdue, Michigan State and another eastern University offered this as a cirrucula that would provide more of a different direction for engineering types that didn't want to design Nuclear power plants or electronic circuits, etc. Lots of us end up in industry and not in the design field.
I've taken a lot of ribbing over the years but in my mind it was the best direction for me. Out of 180 credits required 150 are core engineering, 1 yr each Physics, Chemistry, Calculus, and the general college requirements (Accounting, ATL, Humanities, Social studies) The list goes on and on. Same stuff as an EE, ME or the like. The difference is the math track stops after 1 year of Calc. and the pursuit of higher level mathematical definitions of Thermal fluid, and a few other classes were spared so that additional classes could be taken in the selected area.
Marketing for people interested in sales and product to market applications, Writing for the people who should be writing the instructions you read to put stuff together, and Management for the people who would like to apply their efforts to improving the corporate design.
Truely Engineering Arts it is what you make it. Like engineering courses in college this gives you the lattitude to maintain a BS degree (which I valued) but it also got me out of stupid (to me) theoretical issues on the decay of an atom or the growth of a population by the application of Thompson's law (if that is indeed a Theorem of calculus) I didn't want to go there, yet I wanted most of the engineering banquet. This gave me the chance to look at those other programs and not choke on excessive detail (again my opinion).
Funny, My eldest applied to Universities this fall and we heard a pitch on the Honors college and found it is similar but less restrictive still. If you have the grades that is the way to go.
Long explaination, and I think it is still too short. But the main points are there.
Gotta say the "Arts" part tends to counterpoint the engineering. Maybe that is why that name stuck. Engineering is Defined as Truth with a "V", carved in stone (thus the V) Art is more transient and not really defined as clearly.
It worked for me.
Booch,
Thanks for the explanation. Yeah, the words "engineering" and "arts" seem somewhat contradictory at face value! ;)
But it sounds like a good program to get you well-rounded. A common criticism of engineers is that they lack just that. But there's so many core requirements to get an engineering degree that there's hardly any room at all for GE classes. Your degree got around that restriction somewhat.
I'm BSME, and also minored in a language, nearly minored in math, and took a lot of music classes as well. I think it helped keep me grounded, although it definitely added a significant amount of time to the college experience. ;)
Regards,
Ragnar
Yep I got thru in 4 years and 1 class over the summer semester. It was pretty concise.
I still am awed by the high level stuff done in the numerical representation of the real world. It is great some people thrive on calculus. I found it beat on a part of my brain that wasn't going to pay attention no matter what. It was either a frontal lobotomy or a bottle in front of me if Calc. needed to continue.
Math Language Music & Mech E classes. Did you have to wear hats in order to keep the thinking straight? The music, unless you were a Bach afficionado, would have been the greatest stretch. Bach's permutations on a theme probably fit into your sense of order.
Speaking of that have you played with the new music programs for PC'S? A buddy who is into classical guitar uses a program that allows you to write note for note with all the usual musical measures. This allows you to write a song for one "voice" Say guitar, then overlay another score with another voice. Up to 16 deep! He sent a CD he burned and it is pretty incredible. As his skill diminishes over time the fact he can still write the music and hear it played is pretty inspiring.
Voicing is determined by the quality of your sound card. He used ancient drums, marimba, flute, oboe, and the list goes on. The program is called Finale 2002 with Midi2Wave software. If you have the talent to write it is all there for you.
Edited 12/6/2002 9:35:20 AM ET by Booch
I was wondering about the degree also.
I have almost the exact oposite degree.
I have a BEE, Batchors of Electical Engineering. Not a BS.
I went to Speed Scientic School, University of Louisville. But really I went to Speed, not UofL. Speed was on the other side of the parkway and we where on a different schedule and had our own classes for everything. Thus we were very, very limited in anything outside of engineering classes. Usualy had stuff like tech writing and American Government.
The first 2 years where core classes for branches of engineering. Our 2nd year math booth was the same one that the math majors where using for their senior class.
For the 3 or 4 years we went to school for 3 months alternated with 3 months of coop work.
Then 9 months for the 5 year.
Later when the state took over UofL then changed the program and integrated Speed into the rest of the school. They offered retro masters for people that had gone through the old program.
In any program it should be possible to follow your muse. The only way i found the program was by going Nonpreference for 2 years and shopping the classes I took and tried to see what fit.
Some are better set with definitive engineering courses some with a mixture. The concept of pure BA style courses, (Humanities, Philosophy, and whatever other courses) that are the basis of a liberal arts degree weren't appealing. I was just fortunate to find a program that fit my needs. I hope yours fit you as well. The goal ought to be like the military, "be all you can be"
"But understanding how theory applies to the real world is still the shortest path to success."
That's the diference between a good engineer and a great engineer, IMHO.
"Thanks for the explanation. Yeah, the words "engineering" and "arts" seem somewhat contradictory at face value!"
I think good engineering can be like art. After all, art is supposed to be about creating, thinking outside the box, etc. isn't it? I think engineering can be the same.
hey lefty, what kind of engineering do you do?
Cloud,
After reading your post, I would consider you a truss designer, and you sound like a good one too!
To put this into perspective, we (BSME) spent about two weeks in Statics learing about basic planar (two dimensional) truss design. Taking the loads applied and calculating the internal stresses in the members. We also touched upon this in later courses during Strength of Materials I. So all in all probably about 3 or 4 weeks total out of a 5 year program we spent studying this one small aspect of engineering! BSCEs took these sames classes along with one more specialty class, so they probably spent around 6 weeks on this out of a 5 year program.
Note: ABET (national engineering school accreditation) has driven E schools to become extremely rigorous in every way, packing material into the degree reqs, this increase in course content and class number has resulted in a 5 year program for most.
On top of 3 years of math, 1 year of chemistry, 2 years of physics; The ME program consisted of statics, dynamics, thermodynamics, fluid mechanics, design of machinery, of physical systems, material science, electrical circuits, various lab classes, technical electives, and senior thesis. 5 years of Hell! Most people cant take it and dont make it.
Not sure why you called me "Cloud". But I've been called worse............(-: (Cloud Hidden is a dome home builder)
Thanks for the kinds words, anyway.
I don't envy you all that college that you took. I never did particularly well in school - I learn things better by doing rather than studying.
When you say you would consider me a "truss Designer", you're basically correct. Some say we're only "truss detailers", since the computer does most of the engineering work.
Which indirectly brings up an interesting point - Should truss designers be required to have a minumum amount of training, and be certified/licensed?
Actually - Maybe that's a subject worth starting a thread over. Maybe I'll do that in a few minutes.........If bankers can count, how come they have eight windows and only four tellers?
>Not sure why you called me "Cloud". But I've been called worse............(-: (Cloud Hidden is a dome home builder)
Right back at you, Boss. Though I'm a dome designer. Built just one. Building is too damn hard for me to try to make a living at it. I'm trying to stay within my limits. :)
Sorry - I thought you built them. Guess I just haven't paid enough attention..............(-:Better not take a dog on the next space shuttle flight, because if he sticks his head outside the window, his face might burn up. [Jack Handey]
I got some great reactions last time I posted this, so..
BS Bull Sh.t
MS More Sh.t
PHD Piled Higher and Deeperbobl Volo Non Voleo Joe's cheat sheet
From building the first, learned I don't have the body type to haul a 2" concrete hose, nor to be a rod buster. Just beat the crap out of me. I do get to job sites whenever I can though, to see how a project is going, and sometimes to show someone not used to compound curves some of the techniques that might make it go smoother, and sometimes to learn some of the techniques they know.
BScEng (80). (Bachelor of Science in Engineering).
Engineering is a combination of ART and SCIENCE. The art is the application of the science. You don't need a degree to be an engineer, but around here, you'd better be a registered professional engineer, unless you are a locomotive engineer, or a stationary engineer (running a steam boiler, which also requires a license). You really need a knowledge of the science involved, plus the ability to apply it. And yes, there is a liability involved. If, for instance, my neighbor says to me, "Hey, you're an engineer; is this deck ok?", and I quaff a few more of the frothing ales, and reply "Sure", then when it falls down and kills Fluffy the Rat Terrier, I can be sued. I may not know anything about decks at all, but if I give an "engineer's opinion", even if it's out of my area of expertise (as if I have one, anyway), then I am deemed liable. Because if it is my area of expertise, then I should know what I'm talking about. And if it isn't I shouldn't give someone an opinion that they might take as an expert's.
Or something like that.
But then again, you could just go work for a railroad and drive choo-choo trains.
-Peter
Nah, never liked licorice.
(Choo-Choo Charlie and Good-n-Plenty, get it? ar-ar-ar.)
>Engineers don't apply the safety factors.
Sure they do. I hear all the time how they apply their own safety factors. And I hear, too, about liability concerns. Whether with doctors, designers, engineers, whomever.....liability is a huge issue.
"Why do engineers overdesign?"
I think you're partly correedct in saying that "...the problem of overdesign lies less with engineers and more with our legal system." As I understand it, there is no statute of limitations on engineering. So anything on a project that an engineer is involved in can be held against him as long as the structure exists.
Sometimes the idea of what's "overdesigned" can be subjective. Often when I recommend something, I get a lot of crap because "That's not the way we've always done it" or something like that.
And there's room for disagreement on how things should be designed. (If you laid all the engineers in the world end to end, they wouldn't reach a conclusion)Good things come to those who wait. Crap arrives the fastest. [Rich Hall]
Now that you`ve edited your original post, may I suggest you return to the article in question and inspect the pictures a little more closely. There are several visible collar ties in a few of the pics and the roof does not apear to be a simple "A" frame. From what I can see it apears there are both hip and valley rafters surrounding the area being worked on. I`m no engineer, but I imagine that has much to do with how the walls remain tied together and how "squatting" and "bowing" might be avoided.
J. D. Reynolds
Home Improvements
"DO IT RIGHT, DO IT ONCE"
Waitaminnit, waitaminnit.
Let me get this straight...
"That's why I went to engineering school"
You went to engineering school so that you could pick apart magazine articles ?
: )
Don't bogart the Ghost
Quittin' Time
I went to engineering school to drink lots of beer. Which I did. And the magazines we criticized sure weren't about homebuilding....
I went to engineering school because all the adults who knew better said that I'd make a good engineer.
After working one summer in an engineering dept I knew better....
Excellence is its own reward!
"The first rule is to keep an untroubled spirit.
The second is to look things in the face and know them for what they are."
--Marcus Aurelius
I'm glad that someone realized that I had posted that from the great state of Sensayuma. (Mike Smith has lived on the border of that state, apparently for most of his life.)
If I'd thought that it would cause some to use it as the opening shot to a volley of insults, I'da thought twice about hitting that post button.
Hmmmm, you think that if I went to engineering school I might come across some of that reading material you mention ?
Don't bogart the Ghost
Quittin' Time
Luka,
The engineering school I went to was it the state of Sensemilla!
What a coincidence!
TDo not try this at home!
I am a trained professional!
Well doooooh... Good catch, I missed it too but your post brought me back to it and you are right. A bearing wall may also be a tie wall or plate that holds the whole darn house together. I guess measure twice and cut once prevails again.