I am building a deck that is nearly 20 feet long by only 6 feet out … joined to the main structure along a ledger the full 20 foot length. On the two outside corners of the deck my 4×4 posts that hold it up 9 feet off of the roof-deck below extend up about 16″ above the new deck. After this deck is established solidly I’m going UP by extending the 4X4’s another 9 feet to a second deck/roof above the first.
My question is would it be best to join the second set of 4X4 posts at the tops of the first ones by ‘girdling’ them around with some sort of structure that ’embraces’ the splice … also employing a simpson strap — OR — would it be best to cut the 16″ off down to the deck level .. sheeth the top of the post over with the 3/4 t&g flooring .. and establish a new post rising up from this solid deck surface?
I am leaning towards the latter but was wondering if there’s something I don’t know … some great way to marry the ends of the 4X’s that I’m missing. And IF I cut them off at the deck level and take it up from there what might be the best way to affix the bottom of the posts to the solid deck flooring at these outside corners? (this deck is going to be solid flooring with epdm cover).
I hope the imagery of this is clear … difficult to convey in words. Any suggestions?
Thanks –
nb
Replies
Tough to say for sure...I've done similar with 6x6's by making a scarf joint and through-bolting the posts together...and if you were to run the engineering numbers you'd find that you could actually reduce the amount of deflection in the post by joining it 16" up.
But, with a scarf joint you are opening untreated wood up to the elements. Your "sheath" idea would trap a lot of moisture and lead to rot. It would be easier and smarter to just cut the first post off at the top of the joists, deck it over, and start fresh with a Simpson post base for your upper level.
Your "sheath" idea would trap a lot of moisture and lead to rot. It would be easier and smarter to just cut the first post off at the top of the joists, deck it over, and start fresh with a Simpson post base for your upper level.
=============================================
Thanks Mike. That's what we've been thinking. The first deck is up and absolutely rock solid. To finish it off completely at that level, then, as you say, 'start fresh' to build a deck off of this seems the best. Just wanting to hear what others who actually had constructive suggestions might have to say here.
Thanks again -
n
Uplift is a concern though--somehow strapping the upper posts to the lower ones is a good idea. Maybe the half-lap (scarf) joint would be better--just make sure you treat any cut wood with preservative.
Are the LVL's pressure treated?
I'm not sure what the tributary loads are in Seattle but maybe 60lbs or so for a deck--that's about 1500 lbs coming down on each post. When you add the second deck you'll double that load. I don't have time to do the calcs now, but 3000lbs sounds like too much for a 4x4x8'. You DON'T want to be the subject of one of those deck collapse articles, do you?
Don't trust that your architect knows what they're doing when it comes to sizing lumber. Things look a lot different on paper than they do in person.
You have 2- 4 x 4's as the only corner supports for 2-120 sq foot decks with roofs extending 18' in the air?
Oh..my...
Could you post some pictures? Please????
Edited 10/21/2007 10:04 pm ET by sledgehammer
Since the house is holding up 1/2 the load, that doesn't seem too bad.Rebuilding my home in Cypress, CA
Also a CRX fanatic!
If your hair looks funny, it's because God likes to scratch his nuts. You nut, you.
You could use pieces of angle iron on the four corners. This would hold less moisture than a "girdle", and would produce a stiffer joint.
(I'll agree with others that two 4x4s 20 feet apart isn't much support.)
(I'll agree with others that two 4x4s 20 feet apart isn't much support.)
I have seen, on several occassions, houses built to plans by architect/engineers ... legally permitted after a downtown engineering review ...of plumb 4X4's holding up decks that were 20 feet high with NOTHING between the deck and the ground. My arrangment has a deck at 8 feet and another at 8 more. The first is absolutely rock solid. This is not overdoing anything ... and has nothing to do with the question I asked. "What might be the best way to take it from 2nd deck to third in terms of the corner posts." If you'd like to answer the question "How big must my corner posts be in a deck of the size I'm building" .. you'll have to look elsewhere as the answer to that question is not being sought here!
Best regards -
n
If you have a 20' span using two 2x10's and two 4x4 posts at the each end then according to Simpson Strongtie: tributary area= girder span x joist span
6x20= 120 the table says you would require two 2x10's girder supported at 10' max span. If you used 2x12 girder then max span would be 12'
you should be support at 10' and your post ht at 8' using tri-area(6x10=60) the max allowed tri area is 92. With 6x20=120 tri area your way over the max.
your tr area must be less than the max allowable tri area
If you used a 4x6 post the max is 145...but you need support at 10'
http://www.strongtie.com Got the info off one of those Simpson Deck Plans
I would definately start a new post off the roof deck.
I'm going to trust my architect on this one ... he's never failed me.
The outside 'girder' that I'm assuming your refering to is two super-married 1 3/4" X 10" manufactured lvl's. In other words ... a 'beam' that is 3 1/2" X 10" by 17ft. 6" (in my OP I stated "just under 20")
Thanks for your research ... but thanks mostly for your comment on my actual question. I'm not concerned about the span .. I'm ok on that. What I was wondering about was the corner posts and how to extend them upwards.
n
As long as your architect is happy with the calcs that say 4x4's will be sufficient to support two decks..
I would leave the posts as they are and use a half lap over the entire 16", taking care that the shoulders are firmly together. Use two or more large through bolts with large washers to spread the load.
Check with the architect for stresses developing at each shoulder and be prepared to add a 3 1/2" wide steel plate to each side that would extend past the upper lap shoulder and incorporate at least one more through bolt above the lap. Using steel plates you could also shorten the lap so that the plates extend downward past the lower lap and incorporate another through bolt.
Don't forget to flash each post where it comes through the deck.
"you'll have to look elsewhere as the answer to that question is not being sought here! "Feeling a little snotty this weekend?The two things are not at all separate issues. One can bear on the other. The architect should have designed the whole thing, not discreet parts of the whole, especially given your seismic location. If indeed you do have an archy involved in this, he has done you a dis-service by leaving you without complete information to build his design. That is the extent of my constructive advice on this one since you have already announced that anything else I have to say is un-wanted.
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
Further, the potential overloading of the posts is a factor in deciding what options (if any) are reasonable for the extensions.
If your view never changes you're following the wrong leader
Yes. I didn't jump into the fray on the Q of overspanning first mentioned beaus I knew there are ways to handle that distance for framing the deck itself, but the 4x4 sizing is marginal at best, then when you add more upper levels and seismic designing, it gets scarier by the minute.A 4x4 is normally going to be twisting and checking too. When we use them, we wrap them with 1x4 to trim them for looks. I am sure there are situations where that could be designed to add strength to the overall at the same time it is making things look decent.What makes me question the involvement of an architect is that this guy has been here a number of times asking structrual questions like this that in most normal situations have to have been worked out just to be able to get the permit, but somehow this new builder is forging ahead in a California city without such prior planning and piecemealing his three story structure together and trying to build on the cheap.This is not a recipe for a happy ending. My picture of any involvement by an archy is that newbuilder asked a friend who might have some architectural experience, " What size beam do I need to support a porch that will span 20'" He may not even hae informed him that there will be another story up above the first porch, explaining why the 4x4s are fine so far....The answer he seems to have works, but it is incomplete. No archy worth dealing with will design a structure one piece at a time like that.So when the guy says he only wants one piece of information and refuses to listen to good advice, I don't get too excited about playing his game his way
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
Piffin,
Your completely dreamed up assessment of my situation is so far from the truth it is UTTERLY absurd. PURE imagination on your part. ABsolute RUBBish!
Your made up story about how I'm proceeding and your pile of bull fairy tale about my relationship to my architect and your comPLETEly pathetic rendering of what he's about is a TOTAL steaming LOAD! You're going out of your way to accuse me of being "snotty" when you are a TOTALLY off the mark know-it-all! Utterly in the dark!
It is true that I came here to ask a specific question. Some few here addressed my question and I am very gratefull ... TRULY appreciative of that! Some suggested that I look into some other aspects inclusive to my situation and that's fine and I have and will further. But I WAS asking a specific question and I DID wish to have it directly addressed and NOT lost in other considerations. And somehow you see a problem in that? There are many here whose assistance has been tremendously helpfull to me over the last couple of years while I've been on this mammoth and unusual project, working alone. But again, your assessment -- all total guesswork on your part -- is 100% wrong. But you ARE right about one thing and one thing only: Anything else that you -- and this applies to you alone -- may have to say in response to any future posts of mine I can happily do without. And I just gotta say .. your picture on your profile does you perfect justice. (I am so sorry for that!)
I have SO much work remaining ahead of me on this project I TRULY cannot waste time on know-it-alls spewing wrong viewpoints and assessments on situations they know absolutely nothing about.
Best of luck! -
n
You're going out of your way to accuse me of being "snotty" No, he's not.You're being snotty.
" But I WAS asking a specific question and I DID wish to have it directly addressed and NOT lost in other considerations. And somehow you see a problem in that? "Since you asked -
yes, there is defintiely a problem with that. I pretty well explained it already but since you seem to not have gotten it, here goes...A struture is not a bunch ofindividual elements thrown together. it never is.The individual elements all have to work together. The sizes, types, lengths, and how they are all joined are parts of the whole. It is notr possible to accurately answer your question without reviewing all the other adjacent elements that contribute to the design.The fact that your architect did not or cannot adress this for you indicates that either you did not provide him the necessary information to work with or that he is incapable of performing in this field. There simply are no other choices.And now you will not allow others to help yopu by providing them all the information needed and tell them to restrict themselves to only one portion of this structure.So for you to tell people here who were trying to render you helpfull assistance to butt out from their questioning and to only stick to the question at hand was both snotty and ignorant.I have helped you mmany times on this building with advice. a couple of times, I have been astonished that you could have even obtained a permit and experessed that but have never gotten a striaight answer from you on how you could do this so the question lingers. But it still remains - the fact that you want what you want the way you want it.That is fine when you dine out and order the steak done your way.But this is a forum of peers who volunteer their time to help people and disseminate knowledge. You don't treat volunteers that way. I learned that over thirty years ago. You still need to grow up.
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
Dude, seriously, you need professional help.
Every time you attempt to write something in this thread it is nothing but arrogant pontification: "...you definitely have a problem ... and I will explain it all to you. a structure is not this .. it is that. The elements of a structure do not function this way .. they function that way. It is never this .. it is always that. Your architect cannot address this ... for he is incapable of performing in his field. I have helped you so many times .. but you always astonish me. But the fact remains ... you want what you want. But this is a forum .. and you don't do this .. and you should always do that ... and I am grown up and of great value to all ... and you are not ...
PLEASE make the call tomorrow morning.
Any reputable shrink in your area.
It will be the best money you ever spent.
You know, Piffin and I regularly get to the point where we hate each other's guts, but you're actually making me feel sympathetic to him.
If your view never changes you're following the wrong leader
Ya know, Dan, of all the people here I regularly disagree with, you are the most fun to volley points with. I've never felt the sort of negativity with you that I have with some of the others in the Tavern. But even at that, we leave the Tavern BS in the tavern and get more professional when it is called for. You were the first one here that he went off on IIRC, when I decided to jump in on his attitude.
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
It's not necessary to insult the person who was attempting to help regardless of whether or not you like their style.
It's VERY easy to ignore advice that you don't find useful. Try it.
And you can start with this post. There's no need to reply to me because I'm not getting into a mud-slinging contest.
Take a deep breath and calm down. People here are actually trying to help you.
If I were you at this point.... I'd realize I may not get the information I seek from this post. I would contact the inspector of the job for the correct connection they require under your local building codes. I'd post that information here to help anyone in the future that may have the same question.
Let us know what they require in your area, I for one would be very interested.
"And I just gotta say .. your picture on your profile does you perfect justice. "Oh, and you're also being childish.
You mean he wasn't complimenting me on my likeness?My DW absolutely loves that picture. She kisses it every morning 'cause it shows me at my best!;)This guy was right that I did some guessing at his relationship with his architect. but based on what I have read from him previously here, it is educated guesswork.For instance, in this thread notice that he only claimed that the archy friend he trusts who has never let him down before, only sized the LVL for that 20' span. And I never questioned that item in itself.But for his reference to his 4x4 in this 'design', he does not refer to his arcchy friend. Instead, he says that he is copying some other commercial sites similar to this that were engineered downtown. Hmmm, I wonder how they scarfjointed their three story tall 4x4 porch systems. Maybe he needs a camera to review his designers 'plans' downtown again.
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
n..... 9' off the ground
and 9' to the top sounds like 18' to me
why aren't you using 20' posts ?
and further more
9' posts in 4x4 look like shid...
they are out of scale to the vertical dimension
so.. they look bad , they act bad ( twist & turn unless purchased ahead of time and stickered )
the joint ( since you seem convinced of the rightousness of your soulution ) should occur in the framing of the first floor deck and you need some mechanical device to tie the posts to the ground.. tie the upper & lower to each other ... and tie the roof to the posts
on high decks like that i would use 6x6
BTW.. you could lose the attitude... you are one soliciting information.. that comes under the heading of supplicationMike Smith Rhode Island : Design / Build / Repair / Restore
N - I just read thru this thread.
And I gotta tell you, after post #7, I was thinking "What a snotty, arrogant, and ungrateful comment."
People here were answering your question and more!
So you're pizzed that they are giving you a larger gift than you asked for?
The gift being their experience, knowledge, and time.
buic
I would ask the architect for a connection method, then run it by the building inspector for an official okie dokie.
I'm glad you trust your architect. I work for architects...I trust them also.....But!!!!
Architects make errors in judgement, design and drafting everyday. I do not suggest that you call the architect "wrong", but I sure would ask him to re-evaluate the loading and stress for your double tiered deck on 2 4x4 posts at 20' LVL span.
In a prior life I sold building materials and I know that standard LVL's are not rated for high moisture applications or exterior exposure.
Too many red flags popping up in the above discussions, not to check it out!
FWIW...................Iron Helix
Wow, the first 10 posts aren't nearly as interesting as the last 10!
As for how to connect the exposed posts on the deck, I'd lean towards a through bolted connection with spacer to hold the post off the deck and allow drainage. Galvanized off the shelf or custom fabricated and either galvanized or powder coated.
As for how to design a multistory deck in an area with no snow loads it's my understanding you take the square footage of the decks times the weight per sqft of drinking college kids jumping up and down to the latest hip hop and add in the increase in your insurance premium if the deck fails, times 2 for good measure.
In snow country it's usually best to simply design for all the snow that's possible to fall on the roof and then onto the deck. Dang that's usually a big number, but not as big a number as what a lawsuit from 100 angry parents will take out of your kids' inheritance from the situation above.
Beer was created so carpenters wouldn't rule the world.
Edited 10/23/2007 6:27 pm ET by IdahoDon
You know... I was gonna ask how you attach a 3 1/2" x 10" LVL beam to a 4 x 4 but I was afraid of getting yelled at. ;-)
*chuckle*
Beer was created so carpenters wouldn't rule the world.
I read this thread, with ..........amazement..WOW. What kind of fool would not even look at the advise he is receiving?
I wish... just once.....A thread like this would make it to the magazine.
It would make thousands feel better about their construction abilities.
Edited 10/23/2007 8:29 pm ET by sledgehammer
Thing is, FHB isn't a humor magazine.
If your view never changes you're following the wrong leader
For our deck we had to meet code for the kids jumping up and down in two feet of snow.
If your view never changes you're following the wrong leader
If homes were simply designed for teenage house parties we'd have much better construction! *chuckle*
Beer was created so carpenters wouldn't rule the world.
My back porch was originally an open deck. The 4x4 posts came up through the decking about 35" and served as the support posts for the railing.
When the previous owner wanted it roofed over, the workers cut the posts off about 18" or so above the deck. Then they extended the posts with new 4x4s and scabbed 35" 2x4s to both sides of the 4x4s. The top of the 2x4s supported the new railings. I would guess this was done at least 20 years ago - we bought the house 8 years ago. It's still solid. The material appears to be Douglas Fir.
A few facts:
-This is a building project I've been on for two years -- working alone. I purposefully 'assigned' myself this undertaking, to build a four story tower with only a few basic tools and my own bare hands (as they say) for the challenge and joy of it. I have learned and am learning a LOT about the art/science/drudgery of building and also about myself under pressure.
-The architect who helped me to get it though Dept. of Land Use/Development has been in business as an Architect/Designer/Builder and teacher in the field for over 30 years. He fell in love with the project as soon as I showed him my drawings and worked to get it through with the 'downtown powers that be' with as few changes to my original concept as possible. It is a VERY unusual project. They held it up downtown ... would not grant a permit for no obvious reason ... for several months. When I began getting angry about it I went down and confronted them. They said that they'd "just never seen anything like it". I asked them if it was legal and satisfied code requirements. They admitted that they did and I told them point blank that they had no alternative then but to permit it and that I was tired of waiting. I had the permit withing the week.
- This building is in the 'backyard' of my house and I am in the center of a major urban metropolis. The building regs are stringent and I have been inspected by the city every few months along the way. The inspector loves the project as well and has complimented me on my 'overbuilding' and on the decisions I've made in solving various problems that have arisen. Since the tower has become fully visible from all directions -- I am now at full heighth -- I have had several builders and interested folks drop by with questions about it. I've received nothing but compliments and encouragement from the builders that have dropped in. There is no question that I am building to a high standard of perfection, that all code requirements for my area are being exceeded, and that the work is uniformly good.
Once in a while something will arise and I'll go to this or that board seeking the opinions of others on how they might address a particular problem. I always have several things that I'm working on relative to the project so I sometimes REALLY just desire this one issue addressed! I have been extremely and quite expressively grateful for the help that i"ve received here (and elsewhere). But there are times when I don't wish to get in to a long discussion on other points. The building I'm creating is solid, plumb, tight, secure, well-built, exceeds code, and appreciated by all who have seen it and climbed it. In coming here for some opinions on specific situations now and then I've been told repeatedly that I must have an ignorant architect, that what I'm doing is a joke, that it was doubted that I really was building what I said I was and that I should supply pics of the original plans (which I did), that I MUST be doing it 'the wrong way', etc. These sorts of comments ... RIDICULOUSLY asserted by people who have not and never will see what I'm actually doing ... are, as I've said here, simply absurd! If there are problems with anyone here in my asserting the truth of this then .. well ... I guess you'll just have to deal with it!
There are CLEARLY some stable, sane, well-informed, good-natured folks here as well who have taken my interest and efforts seriously and who have helped me tremendously in what I'm attempting. I have marvelled at their friendliness and true helpfullness. They've responded both here and through email to me and really have made a difference in several elements of my project. I aint so young anymore and this is an enormous undertaking for me, and needless to say any support I have been able to find in the form of true helpfulness, knowledge or even just a serious response my inquiries has felt like a godsend. Working for over two years straight now on this project and clearly having at least another to go ... working on it very nearly every single day with no 'crew' or backup of any kind ... I do feel frustrated, at times, when asking a question here results in one guy taking issue with my 'approach' and five others jumping in like cowards to 'get their hits in' after the first shot's been fired. It's not something I have time for.
So .. thanks again to those of you who have truly offered your support in the form of your sincere thoughtfullness and knowledge. To those who just sort of enjoy strutting around and shaking things up with what they may or may not know ... feel free, as I stated earlier, to neglect my questions here. I never have responded well to arrogance, to pontification and to pulling rank. And many of you know that there IS an element of that here as well.
So I'll continue to ask a question or two here from time to time. If you'd like to ignore them then by all means DO! My sense is that there will always be enough good folk around that are willing to discuss and throw out possibilities and give their best shot without requiring 'supplication' (as someone on this thread suggested) that it will be worth my while, and, I hope, worth the while of at least some of those who attend here.
So .. as they say .. "That's my story and I'm stickin to it."
Thanks again to many of you!
nb
I am willing to bet, if you come back with an apology to Piffin, DanH, IdahoDon,Mike Smith ETC. These guys....I mean professional builders, might just jump in and help you save this piece of #### you are building without have to tear it down and start over.I feel they could come up with ideas of adding more support to the bottom post and putting in additional post that would make you proud of the structural strength of you project.
You like to pat your self on your back.....why not beef this thing up so you can tell your friends, BI and arcky that you can train dancing elephants on you deck!
...... read this thread as it got interesting.... .
Calcs for this type simple structure one should be able to do in one's head even without a calculator. e.g beam: sigma*Z=w*l^2/8; post: Pc=pi^2*E*I/12
Doing so (simplifying to a worst case by ignoring the cantilever ends - less mid span moment if loaded) my number is just under 1 ksi for the 3.5 by 0.0" LVL. OK.
Harder to do a spliced column without using a paper, so simplify. Firstoff, I'd splice (as others have said) with 4 steel plates and 3/8" bolts. Bolt pattern at least 16 bolts per splice - this keeps the moment of inertia at that point > the 4x4, so calcs are simplified. Then calc a simple 8 ft beam and the load allowable at crippling is about 12K for a clear 4x4, plenty margin unless you run into the 4x4 with the car or riding mower.
However, unless you are building a shed, a 4x4 as support looks asthetically unpleasant*, I'd opt for 6x6, with some carving or routing so it dont look so plain.
* or like $h1t; own house has some 10" dia posts (sized for sesmic side loading) holding up some 2 ft dia log beams. Even then, DW thought the posts looked to 'skinney' to hold up the bigger logs.
Edited 10/27/2007 9:42 am ET by junkhound
Why doesn't post like this get routed to the Tavern? Good Grief!
Isn't this amazing, for all his protest of not wanting to get involved in the minutia of this project and wanting to just deal with his one question only he sure does engage in the typical BS.
IMHO, the only purpose for some who post like this is to bit ch. Some kind of mental illness maybe a type of Munchausen by Breaktime.
I wouldn't go quite that far with the psyche analysis. Obviously he is proud of himself for what he is acomplishing. Some guys stick to treehouses for the grandkids in their retirement years, some guys invent cures for cancer, and some waste their time on ####....He is obviously taken with a different tack.
More power to him. he doesn't need to kiss ####, bow down, supplicate anyone, nor apologize, as long as he realizes that he will find far more decent complete advice if he takes a freindly attitude instead of a snotty one.
Some people say - it's just the internet - but it really ain't any different. Same rules of polite society work here as anyplace else. I know a guy here who is also 'different'People also act impressed with his 'accomplishments' when exposed to them. The building authority lets go what they have to let go while strenuously avoiding conflict with him otherwise because he is an indignant PIA. They only step in when they are compelled to by obvious infraction or complaint.
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
Munchausen by Breaktime.
NOW THAT'S FUNNY! *chuckle*
Beer was created so carpenters wouldn't rule the world.
Can we see some photos?
Ahh, you stole my thunder...I was just going to say, 'sounds cool, newbuilder---show us some pics!'