visual interest in my house , has standard roof trusses 24″ oc. I am wondering how to insulate the roof without covering the framing that i am trying to expose. any thoughts would be greatly appreciated .
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I think you have asked this before.
I can't speak for others but I didn't answer because IMO, it is a gaummy idea and there is no good answer. You are t5rying to do something ugly and to add insulation in a space where there is no space if you intend to keep the trusses exposed. Additionally you can creat a lot of problems with wiring, ventilation, moisture control eetc.
If exposed framing is what you really want, build a timbre framed house and get it designed to accomodeat your aethetic desires.
But what you are asking for now is the equivaalent of saying, "I have a car but I always wanted a motorcycle. Is there any way I can take two wheels off and drive around in leathers?"
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i am new to this site and this my first venture into seeking advice on a project so i dont know if your critical and sarcastic response is a typical one or not or its just your way of responding. It might be ugly to you but maybe not to me besides i was looking for advice on if it can be done and how to do it, not what it would look like. Your comment on building a timber frame house is a rather odvious solution. if i could afford to do that I would.
I realize you don't know me and I don't know you.But take it from the top that there was not one drop of sarcasm in that post. It was all honest opinion straight from th e heart and from 35 years or so of experience. Sure, you can do something like this, but you wil spend thousands and in the meantime reduce the value of the house by as much as you spend trying to do it, meanwhile causing yourself problems with condensation and maintanence.I was doing you two favors.One is giving you honest opinion.The other was to bump your post to be seen for coment from others who might have other opinions and not fall away ignored like the other one a few days ago.You may have interpreted my close as sarcasm, but liek any good teacher or public speaker trys to find mental images to drive a point home, I made mine vivid to try and help you understand just how foolish this idea is.Now then, if you are still headstrong and homnor bond to go ahead with it, tear off the shingles, add SIPs and roof it over again, then start the interior work.
and that was not sarcasm either. It is the only way to get this accomplished without ruining the house.
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
The people at Fine Homebuilding must not share your opinion that this is a foolish idea, check out July 04 issue Dramatic Skylight. But the article doesnt give any detail on insulating or venting, cant tell if SIPs were used or not i see rigid insulation in the middle of the skylight and fiberglass insulation elsewhere. Also dont see how this would negatively affect the value of the home it looks pretty sharp to me.
I think you have a great idea ickabod. I've seen it in a mag several years ago; may have been HB, not sure. It looked great!
I can't answer your question, just thought I'd lend my support. I don't think it will look gaummy at all, but then I only have 25 years experience, so what do I know. By the way... what exactly does "gaummy" mean?
I think it was Mrs. Gump who said "If you don't have anything constructive to say, then don't waste the bandwidth"
Hey Ick... post some pics when your project is done.
Edited 5/6/2007 9:15 pm ET by bobditch
thanks for the support, JULY 04 issue of FH,"Dramatic Skylight".I dont know what Gaummy means either, just sure that it isnt a good thing. And to top it all off i dont have any pro experience, just a serious DIYer, if there is such a thing. will gladly and proudly post pics if i can run down the author of the article and do the job right.
I've done just what you suggest in a retail store. The same shopping center now has 4 or 5 stores with exposed trusses so apparently someone likes the look. It looks great in these stores but is a lot of work. We nailed two by fours to the sides of the trusses flush with the top plate and tapering to about 18 inches below the ridge. We insulated as usual and then drywalled between the trusses. The real pain was filling in the drywall between the truss chords. We taped and finished with 90 minute mud and painted everything white. It is a lot of work but is a unique look.
1) Actually, If you are new to the board you should get used to the idea we all say what we think. If you don't like a response ignore it, but don't act offended. This is all free advice.
2) I agree with Piffin, go look at the unlit under-roof spaces in some of the quick food establishments. While they are serviceable for a commerciable establishment, They would not add resale value to your home. Use timbers & purlins if you want to look at them.
if you have your mind made up, do it. Sure it can be done. Is it worth it? You'll have to answer that one. I'm not even sure you are capable of doing it or if you would hire out.But it would probably pay to consider contrary advice. Piffen, like most everyone on this board is sometimes full of crap and sometimes there's good advise sprinkled among the manure. and sometimes the advice is given because it's always been done that way.the trick is to either have the wisdom to know which is which, pick the one that smells the the least like manure, pick and choose among the answers or go your own way.
Barry E-Remodeler
You give good advice in saying I should pick and choose from the responses. Figuring Piffen was a pro and me a measly DIYer I could only think to myself what you expressed about his comments. I admire the trades, and the skills that go with being in them and was looking forward to getting advice from any and all that would be willing to share. What I didnt expect was the negative and sarcastic responses.
Nah. . .Piffin wasn't trying to be the least sarcastic. He only bluntly giving you his true opinion. Sometimes we have only a small bit of time to read and answer.
Right now, I have a bit more than Piffin did then. Sometimes he writes long thought out responses. Knowing Piffin, I would recommend that you at least consider what he said the blunt truth as he sees it.
I on the other hand, am getting excited about your project. I can see how it can be very esthetical and how you can DIY. Trusses painted either a subtle or a drastic contrast to the ceiling, globe lights above the bottom chord.
Or face the trusses and connectors with door skin making faux wood beams.
Combining some of the ideas alread given, insert a mid chord far enough below the top chord for ventilation, (2",) Insulation, (2" foam?) and a nailer, (3/4",) on top of the Mid Chord. Set double foil sided foam on top of the nailers and hang your foil backed drywall on the bottoms.
If you wanted a large beam look, wrap the tops and sides of the 2x4s with rigid foam and wood veneer, (door skins.) Leave the webs at 2x4 and have a unique and interesting look up there.SamT
Praise the Corporation, for the Corporations' highest concern is the well being of the public.
but he says pretty clearly in his first post that he does not want to cover the framing.And in the post before that a few days back he was even more cleaar about liing and wanting the look of the truss just the way it comes.My repsonse was quite well thought out. As a matter of fact, I spent several minutes the other day staring att he screen and conceptualising whether it was possible to do what he wanted with any reasonable method.
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
just wondering if you have had a chance to dig through your back issues to see the project, and if so do you still consider this unattractive.
No, I haven't - I doubt I would find it. I am not that organized with back issues.Besides, I already know what it would look like. I have worked around this kind of thing before. I even have some old photos someplace from a house I designed an addition for. I know what you will be dealing with.
All I am doing is offering you an opionion based on my own experience. If you don't like that opinion, that is fine, I can live with different opinions, but don't bother wasting time trying to convince me it will be great. Notice that even those who think here that it can be done and who have a suggestion or two about how are trying to point out how to cover them up and they are afgreeing with me that the cost in time will be atrocious.Now you already said that money is a consideration, so think on that.another think to consider is that you don't know how many of these guys are pulling your leg...;)
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Your mood has changed since your first response to me. I would like to clear a few things up and then put the issue to bed as far as you and I are concerned. It is very clear to me that you think it is a bad,costly ,ugly,foolish idea,I get it. I was only trying to steer you to the back issue to give you an actual visual of the kind of thing I was trying to do, because of your previous responses it was clear to me that if a client had approached you with this idea you would have ran the other way without having actually seen a project like this completed. Or you would have offered to build them a whole new timber frame home, which brings me to another clarification. I have several thousand dollars I could dedicate to this project, not several HUNDRED thousand that it would take to build a timber frame home as you suggested to me in your first response. So there really is no money issue here. And I only asked for opinions on how to do it, not how it would look, but i realize it is hard to give one without the other.I'm still surprised at the volume of negative and or discouraging responses on this posting, since the idea came from my favorite how-to magazine FineHomebuilding. I am certain you are a deep well of how-to techniques and hope that if I am in over my head I can come here and you will throw me your advice, as long as its not about exposing roof trusses. Now if you would be kind enough to let go of my leg I can go to bed.
Sleep well.Maybe there is a carreer for you as an interior designer
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
very funny, you might want to switch to a career where satire is more appreciated. over and out
I, like Piffin, imagined a nasty looking mess, but the look is very nice to me after seeing the pictures. You may find thet your trusses are not so attractive though. I've seen some pretty ugly ones.
AGREED! That's the ONLY reason I went ahead with doing it. I was VERY fortunate to have some good stock used for trusses.Ickabod, you'll want to know what you're getting into BEFORE you commit.Mark
Sorry about not responding earlier. Now I have forgotten what we were talking about.My computor always sends me to a secure site to log in and says I don't exist anymore.I'm, on a friends box right now, so will have to keep this veddy short.
SamT
Praise the Corporation, for the Corporations' highest concern is the well being of the public.
Be honest now -- Piffin doesn't know how to NOT be sarcastic. Of course the same could be said for most of us here. It's an occupational hazard.
So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
I agree that Piffin didn't exactly sugar-coat his answer, but I think the advice was sound and in your best interests. Have you walked through a building being built after the trusses are up and the roof is on, but before it's been drywalled? You want that look? Okay, but--won't all those pieces of rough wood and so on get awfully dusty, full of bugs and cobwebs? How would you keep the space clean? I guess I'm just not seeing the beauty in that. But, it's your house and if that is what you've decided to do, go for it!
Sure, this can be done. I've insulated and drywalled to leave the bottom 2/3rds of the trusses exposed on existing construction. Warning -- the drywalling will be very time consuming - lots of extra blocking to install and small triangles to cut, and lots of extra taping and sanding.
This was on the second floor of a heated carriage house, so the exposed trusses overhead looked nice, and it increased the visual head room from 8 feet to over 10. It fit the type of construction. This was for a workshop over a garage. It allowed the lights to be installed much higher than normal.
It has been a few years...let me think. The wiring was routed along the top 1/3 of the trusses. The top cords were probably 2x8s, so there was enough room for the fiberglass insulation and air channels for the eave-to-ridge venting. The roof rise and run was 12x12. I ran the drywall from the top of the wall to about 2/3rds up the truss, and then over horizontally and back down.
We sanded the trusses lightly to get off the dirt and drywall mud drips, and then put on one or two coats of satin varnish without worrying too much about how it looked. We left the connecting plates alone; they're just part of the building. I suppose a light brown rustoleum paint on the plates would work if you had the time and inclination.
Don't think I have any pictures; this was about 11 years ago.
Dusty and Lefty
Interesting idea...but I can't help but repeat an earlier comment regarding the bracing. Since the trusses are existing, you will need some engineering to remove the ceiling since the sheetrock serves as the bottom chord bracing. The alternative to sheetrock is usually to brace the bottom chords with lateral 2x4 braces (which will not do anything for the asthetics of your idea) Adding additional load to the top chord to accomplish the insulation will also alter the truss design and require an engineer.
I hope my 2 cents helps...I hope you are able to find solution!
"But what you are asking for now is the equivaalent of saying, "I have a car but I always wanted a motorcycle. Is there any way I can take two wheels off and drive around in leathers?"LOL! I guess one could buy those little imitation victorian add-ons sold at Home Cheapo to dress up each truss along the chords. :)
You know why we love this site!
;)There might have been a wee bit of sarcasm in that line now!
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
I think Piffin makes some valid points. Perhaps you could keep the trusses hidden, but add false beams or a coffer ceiling or something like that to add interest. Exposed trusses so close together would look awfully busy I would think, not to mention the problems Piffin pointed out. Trusses aren't that pretty either, in my opinion, with the pressed on metal plates at every connection and the wood used isn't that nice either. Lastly, most trusses have bracing which cannot (should not) be removed and those braces certainly wouldn't add anything to the esthetics.
Thanks for your input. i didnt appreciate piffins sarcastic response. maybe i just have thin skin,anyway i would paint all the components to blend in the connectors and dont think they would be that noticeable. I am aware of the importance of the truss to remain intact and would not alter any of its components.
I would think rigid insulation would work fine. They sell insulation with OSB attached to one side, but I don't know what it's called.
Is the house already built? Your post implies that.
If it isn't, there are things you can do that would make the trusses more attractive. I'll go over them if you want.
thanks for the response, i havent come across the OSB you refer to at any of the home centers ive been to where would i install this OSB to keep the framing exposed?
The most straightforward way would be to remove the roofing material, add rigid insulation to the desired R-value, cover the insulation with sheathing,then replace the roofing material. Also one could put sips on the roof, a little overkill if you already have sound roof sheathing.A medium to large guy named Alan, not an ambiguous female....
NOT that there is anything wrong with that.
The OSB/insulation assembly I was referring to isn't something you'll find at home centers. You'd likely have to ask around for a commercial building supplier, unless someone on the board knows what it's called. You still didn't mention if this house is already framed or still in the planning stages, unless I missed it.
it is an existing home about 25 yrs old. FHB article you refered me to shows me alot but not what i was looking for as far as trying to insulate and vent the spaces inbetween the trusses. do you have any insight on this thanks in advance
Like I said, you'd need to create dummy top chords on the trusses (if you don't it'll look like carp and fitting your ceiling around them will be a royal pain). Leave a foot or so above and use the same ventillation techniques used for a roof with scissor trusses or the like.
Of course, consider that all the wiring in the area will have to be moved.
So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
do u have access to back issues the july 04 issue shows a project like what i want to do but doesnt say anything about insulation or ventilation, and also doesnt say anything about bummy top chords or the like, were they not needed or what
Don't have access.The dummy top chord is the way I'd do it, because I hate cutting and mudding around odd shapes. I suppose it can be done differently, but I don't think it would look as good.
So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
Yeah, if it's not framed yet then there are a lot more options. First, make it a hot roof. Then add purlins if necessary and spread the trusses out to 3-4 feet. Yeah, you'll need heavier, more expensive trusses, but the improvement in appearance will be substantial.
So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
If you want visual interest, perhaps the trusses aren't your solution. If they're not designed to be exposed, chances are you won't want to see them.
Maybe skylights between the trusses would be a better option for providing some additional oomph to the space.
It can be done, but a lot of work for very little payback. You'd have to dummy up fake top chords a foot or so below the roof deck, insulate above, and then install whatever ceiling, working in narrow 2-foot "slits". The trusses themselves are not great lookers, so you'd likely want to box them in somehow, which is even more work.
look through back issues of fine homebuilding there was a article a year or two ago about doing somewhat what your suggesting as part of a large skylight in a existing house
the trusses where smoothed and painted and it was interesting looking
as a recall it was two or three exposed trusses so you could get the effect
you can see how he handled it
here you go
jun / jul '04
building a splayed skylight pg 92
http://www.taunton.com/store/pages/fh_toc_164.asp
Edited 5/6/2007 1:33 pm ET by skip555
Edited 5/6/2007 1:43 pm ET by skip555
Edited 5/6/2007 1:44 pm ET by skip555
thanks skip, i thought i had seen it done in fine homebuilding but couldnt be sure, i go through alot of mags
Would it be possible to add a couple of pix from the article for us non-members?“The richest genius, like the most fertile soil, when uncultivated, shoots up into the rankest weeds..” – Hume
sorry I'm not a member , try your local library see if they have back issues .or you can get a one month membership for 6.00 or so I recall being impressed with the look of the final result and Its something I'd like to do in our bedroom someday . I have the magazine around somewhere I kept it because I liked the look
if you want to see if your local library has the back issue the article can be found in the JULY 04 issue.
build fakey box "beams"
-worth exactly 2 cents!
I do recall seeing a house in FHB, maybe a Houses issue, that had a wide open top floor with exposed trusses. IIRC they sandwiched the bottom chord with the next size up of 2x stock to hide the nail plates. Everything painted white. Not my idea of attractively exposed structure, but it looked better than I would have imagined.
I forget if you said this is already built. If it is, you could install "nail base" insulation on top of the roof sheathing--it's foam adhered to osb. If there is no roof sheathing you could just use SIPs. If you're going to use SIPs anyway though you might as well get rid of the trusses though.
I have attached a picture to show what I did. Generally, most of the suggestions in this thread are a better way to go (such as adding the insulation over the roof, etc.) but if the structure is in place (as was mine) here is a solution.
As you can see by looking at the skylight, the top chords of the truss were built down by adding two layers of 2x material, This creates 3 inches of space in addition to the 3.5 inches of the truss for a total of 6.5 inches. Fiberglass batting fits made for 2x6 walls, 24 inches on center, fits in the space perfectly. You should add the pink rigid foam stuff (I don't know the formal name) that creates an airflow space against the bottem of the roof sheathing.
I smeared some painters caulk into the metal truss joiners to soften their look, primed all of the wood with BIN shellac based primer to insure the knots would not show through, and painted the trusses and drywall flat white. The trim around the skylights is a satin finish.
Overall, we like the appearance, and it does open up the room. The skylights are nice, but the overall look without them would be great too.
However, fitting all of the drywall and trim around the trusses is a real pain. Tedious work. It has been in place for 14 years and now needs to be repainted. We are not looking forward to that.
W opted for exposing a portion of the trusses (to save space for ductwork and utilities, and to minimize the "busy" look of exposing all of the truses). We had planned to cover all of the exposed trusses with 3/8 inch trimwood, but opted not to do so beccause the overall mass of the framing would appear too bulky.
I think there was an article in FH (I will guess, 5 years ago) about a similar project.
If you would like more pictures or information, let me know at [email protected]
thanks for the input yours looks great as well. sounds like insulating down into the space is the way to go rather than over the roof, less work and less money. thanks
Hey Ickabod,
I did something in my house that sounds similar to what you are describing. I ran furring strips along either side of the trusses in question on the underside of the roof deck to hold rigid insulation 1 1/2" from the underside of the roof deck. I used 6" (built-up) foil faced poly icynaurate (sp?) rigid insulation board in that area with the foil side facing down. On the splayed walls, I used R-38 batts. Seeing that the rest of the ceiling didn't have a vapor barrier, I didn't bother to install any or use kraft faced batts but what you should use depends on what part of the country you're in (I'm in Cincinnati).
I was pretty fortunate with our trusses, they were in very good shape--they were made from #2's or better, maybe even #1. There was some leeching of pink from the batts onto the trusses that I didn't bother to try sanding out but used a semi-transparent stain that did a good job of masking it. See the attache photos...
Hope this helps,
Mark
It looks like you both put an angled coffer of sorts around the edges to provide ventillation/insulation/utility space where it otherwise would get kinda tight with a straight run from peak to wall.
So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
interesting . . . nice solution :)
Thanks draftguy, but I can't take full credit. I did get the starting idea from the back issue of FH everyone has mentioned. I just didn't care for the author's solution of the side walls warping along the side planes and thought this would be a slightly 'cleaner' look.
To ickabod, I hope you aren't dissuaded from trying it. It has made a HUGE difference in the feel of the room not to mention having to turn on any lights even on the darkest, overcast day. One side note on the lighting...I used low voltage techlighting and have since angled all the light heads to point at the side walls of the light well. The result is an even diffuse and ambient light in the whole room minimizing any hard shadows that you would get with more traditional downlighting.
Take care, have fun, and happy building,
Mark
thanks for the helpful info, great idea backlighting it at night. Looks even better than the article in the July 04 issue that featured this kind of project. If I go ahead with this project myself you might get tired of me grilling you for guidance. thanks again.
just wondering how much height you have there from bottom chord to peak, looks like 4-5' again it looks great
Nope, only 3' from B/ bottom chord to peak. The peak is @ 6' from ridge of truss. I wanted just enough volume to define the space and not overdo it. After all, even with 6" of rigid insulation, I do have more heat loss there.
As a design consideration, the pitch of the side wall of the wells perpendicular to the trusses equals the pitch of the truss web. The pitch of the side wells (parallel to the trusses) in my case was dictated by the truss spacing, 24" and the height 36". For me, I felt that the side walls were pitched too much more, it wouldn't look as good. Being an architect, I probably over-think things some times ;-).
Good luck, and have fun!
Mark
This post, from another thread, reveals another issue worth considering, when you talk about leaving trusses exposed.
Sheetrock has been used structurally as bracing on the bottom chords of trusses ever since the two were used together.
Every residential truss lay out sheet and engineering sheet I have looked at in 35 yrs. calls for rigid ceiling or bracing.
"I needed a drink, I needed a lot of life insurance, I needed a vacation, I needed a home in the country. What I had was a coat, a hat and a gun."
Raymond Chandler's Philip Marlowe
That's it! Just what My big open timberframe space needs. A giant mobile made of mixed trusses.
Might even put some nail plates under the glass on the coffee table. The sea shells are'nt bringing the conversation like they once did.
Huh? I guess I missed that one completely."I needed a drink, I needed a lot of life insurance, I needed a vacation, I needed a home in the country. What I had was a coat, a hat and a gun."
Raymond Chandler's Philip Marlowe
Me too. Maybe he is using the glass coffee table top to brace his hammerbeams....I think that somebody earlier in this thread did mention the need to alternately brace the lower chords when the rheetrock is removed. More paint and spider hangouts
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
However, I cannot see a need to brace the bottom chord unless the ends are not sufficiently secured. It should always be under tension (except maybe in a tornado), and will have no tendency to buckle.
So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
DanH is ABSOLUTELY correct! The bottom chords are in tension and don't require the sheetrock to provide bracing for the trusses. It does, however, have the benefit of providing 'some' stability to the overall roof assembly by diaphragm action but this amount is negligible compared to the diaphragm action provide by the roof sheathing.Those naysayers who don't care for the aesthetic of exposed trusses might be biased on personal opinion rather than fact. They may also be the type of people that can't/don't think outside of the box. Instead of "It can't or shouldn't be done" try "How can it be done". For the most part, Fine Homebuilding and its readers are generally the latter type--problem solvers. The former are more likely to be in the mass production home market. Then again, I might just be full of it...
I think it,s great to show a bit of the structure . I have never seen the cieling drywall included in the engineering of the trusses. Most common here is max 10' span on bottom cords between bracing. But that can also be blocking installed to look like a component of the roof.Have you thought of spray foam then adding a nailer to either side of the truss to hold your cieling. Then add a 2x2 trim in top cord place to hide your ceiling material joints.cheers Rik
m04arch, Be thinking You and Dan or I need to have a talk with our respective truss suppliers. I have had to do one or the other on every project I have ever done that I recall.
I am no engineer just a dumb old carp, So I try to do what is printed on the sheets that come from the truss plant.
Hoping our resident truss guru will speak up here.
"Poor is not the person who has too little, but the person who craves more."...Seneca
I suspect that the bracing is speced partly as simple CYA and partly to protect the trusses during construction. Of course, the drywall provides little protection during construction (since most hazards occur before drywall is installed), but like I said it's CYA.
So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
Most truss suppliers that I've worked with are using a software program (usually Alpine in this market) to do their truss design and layout. These are always accompanied with blanket CYA specs. If they actually do ANY in house engineering by a registered P.E., I'd be shocked. Having an engineer around to ask if removing a portion of the gyp ceiling to create the effect describe in this thread is possible, is not always on option. But if there were, more often than not, they'll tell you it's not a problem and has little/no bearing on the overall roof system. The truss supplier and structural engineer I work with regularly both said in most cases (and in my house) it's a non-issue.The engineer did go on to say that if there were NO gyp ceiling installed ANYWHERE it may need to blocked at the ends to create, in essence, a moment frame at each end of a simple gabled roof depending on things such as loading, span, etc. but in most single-family dwelling sizes (as opposed to commercial applications) it wouldn't be needed."Poor is not the person who has too little, but the person who craves more."...SenecaIf we didn't aspire there would be little chance for improvement in our lives. I suppose the operative word here appears to be crave...
I emailed our engineer at Alpine to ask about this issue. The answer I got was basically what I said before - That the trusses *DO* need B.C. bracing, for the reasons I mentioned.
We believe that lasting peace comes only through strength and not through the good will of our adversaries. [Ronald Reagan, 1988 GOP Convention]
I'm curious as to why two separate engineers that our firm works with would tell me something different.Maybe someone's not getting the whole picture..."Funny how such a thing as a quote can be taken out of context to suit ones own needs"
Me too. Of course - My engineer is better than YOUR engineer.(-:Hard to say. It could be that there's some difference of opinion.Maybe you've heard the saying; "If you took all the engineers in the world and laid them end to end, they wouldn't reach a conclusion."
A woman never forgets the men she could have had. A man, the women he couldn't.
That's good, I hadn't heard that one before :-) There's probably one floating out there about architects as well ;-)Have Fun and Happy Building,
Mark
m04arch,
I won't argue the issue of case by case engineering being able to solve a specific buildings design question. I will stand by what I said though about the specifications from the truss companies calling for "either bracing or rigid ceiling applied".Beyond that I am, as I said, neither an engineer nor a truss specialist. What I think doesn't matter in this case. I was only pointing out that a blanket statement had been made to the effect that one didn't have to brace the lower chords of trusses and that statement that was incorrect.
"Poor is not the person who has too little, but the person who craves more."...Seneca
FWIW,
I happen to think the concept that the OP has going would be a nice feature in many situations. That is all a matter of personal taste. If beauty was all the same you would all look like me.
I was not speaking out against the design premise at all, just commenting on the truss bracing info .
"Poor is not the person who has too little, but the person who craves more."...Seneca
This would be a better looking situation.
http://www.oldwoodworkshop.com/salvaged_wood_9.html
There ya go!;)
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Bottom chords of trusses most certainly do require bracing. There are a couple of reasons, as best as I know things.First - Trusses are required to be designed for wind uplift. In uplift situations, the B.C. is in compression, not tension. Second is for general vibration and movement. All buildings move a bit in the wind. Get a bunch of unrestrained lumber in a truss system, and it will move around wherever it feels like as the wind moves the structure. That would eventually loosen the connector plates, and/or other connections. There may be other reasons I don't know about. If I find more info I'll post it.
Bumpersticker: Body By Nautilus; Brain By Mattel
Thanks Boss!
"Poor is not the person who has too little, but the person who craves more."...Seneca
Man, I gotta learn to type faster or be more succinct!
:)
Geoff
m04arch, you're wrong, the bracing(and sheet rock) is still needed even though the bottom chord is in tension. If the load applied is not completely perpendicular to the truss, (and it will never be) then there is "twisting" (moment arm) of the truss which occurs, the bracing (horizontal) is there to prevent that twisting. It's much the same as bridging in a typical 2x floor framing system, albeit a floor system does not require the blocking to achieve its structural design.
As some one else mentioned , the truss specs usually say to apply horizontal bracing every 10' across the bottoms of the trusses.
Thinking out of the box is fine, ignoring engineering specs for the sake of aesthetics is dangerous, and arrogant.
One other item no one has mentioned is the fire aspect. In some juristictions it may be illegal to leave the truss exposed as it needs the fire resistance protection offered by the SR.
To All
"gaum" - means to smear or smudge, gaummy means having those characteristics. It derives from the word "gum" and is a regional variation of that word.
Geoff
Drywall would provide negligible protection against twisting of the bottom chord.
So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
Thanks, Dan. You're right IMO (not to mention all those registered P.E. engineers)Hmmm, let's see here. Let's put put a fastener in gyp board. Let's put another fastener in plywood. Then let's see what has better holding power in any capacity--tension, compression, shear. My money's on the plywood and the roof deck doing the lion's share structural work.Mark
Your point about fire rating is a good one and depends on local code jurisdiction. Here in the Midwest, most jurisdictions are based in large part by the IBC. If it were supporting an occupiable space, then yes it would need to be fire rated. It is not required to be rated unless there is not an occupiable, habitable space and is not open to any adjacent, separate dwelling units. The light well is still enclosed limiting any flame spread potential. Your assessment of truss design is only half valid. You are looking at forces applied to a singular truss instead of a roof assemble. Most often, the horizontal bracing I believe you are referring to resist the twisting (lateral torsional buckling--not moment arm) is there for the initial erection of the trusses prior to the installing the roof sheathing. Once the roof is skinned, it becomes an integrated system and different structural dynamics are in effect. Any other blocking or bracing, where/if needed, can be relocated if needed. Incidentally, there is more more bracing/blocking in between the trusses to hang the gyp board.And yes, wind uplift would put the bottom chord in compression for those building in coastal or mountainous areas with high sustained winds. An intermediate bearing wall will also change the forces from tension to compression depending on loading conditions.I don't disregard engineering/manufacturer specs but I do question them when there is cause to in our clients' interests. I ask questions to understand the how's, why's, and what if's. We consult structural engineers that we work with to come up with a workable solution (as I did when I did this in my own home.)To Ickabod, you probably are thinking you got more than you bargained for, but the bottom line recommendation is analyze your own situation with the appropiately qualified people familiar with local conditions. Describe to them what you want to do. Ask questions, pose what if's. If someone says "you can't/shouldn't" ask why and work towards a solution. Surround yourself with problem solvers.
Mark,
there is a moment arm within the "beam" but LTB(lateral torsional buckling) is actually a failure mode of the beam........Anyway, the bracing I was refering to is the bracing along the top of the bottom chord. This bracing is rquired bracing to prevent the above mentioned type failure. In all the pics posted the affected areas are relatively small, and they do not extend the exposure to the ridge.
The OP's question and subsequent feed back seem to indicate he wants to expose the trusses to the ridge and,it would seem, across a large portion of the, what I assume is, first floor. That is quite different from what was posted in the pics.
Wind uplift occurs in all areas, period. Designing may need to include sustained wind loadings in some areas.
I agree about being proactive in finding solutions, but sometimes the want is outweighed by the given constraints. If the OP is really talking about a small area like the pics that have been shown, he probably has a good chance of doing it successfully, But, if he wants to do the whole house, as I seem to interpret his post, that's a whole different ball of wax.
Geoff
I have seen exactly three houses where this has been done and all of them look like crap.I am a problem solver and do think outside the boxBut I have some sense of taste too and don't waste my time solving a problem that is doomed to fail. It is a waste of time, IMO
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I move that here on out, this type of open truss ceiling remodel be refered to as a Piffin ceiling system.
Do I have a second on that? ; ^ ) Mike
Trust in God, but row away from the rocks.
GROAN!!!!How 'bout calling it a groan vaulted cieling
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