I’m getting conflicting advice on attaching a deck to a house with open web truss floors. One adjoining county says ok if I lag to vertical uprights, another says not allowed, and another has no opinion. Is there an issue bolting the ledger to the end uprights of the truss? There is no overhang. I could also add a 2x backer in between the joists to bolt to but the uprights seem much sturdier- and the backer would only be as strong as the uprights it is nailed across. Any truss experts care to comment?
Thanks!
Replies
I can't imagine any reason why you couldn't bolt through the end verticals of the floor trusses. They have very little force or stress in them. And they're often doubled.
Personally I'd rather see ya use through bolts rather than lags. I think they're much safer.
If your house is new enough, a call to the truss place that built them would get you an answer that your building department could live with. Or any local truss plant MAY give you an answer in writing that your building department would accept. Depends on how generous they are.
If you can't get that, you're probably gonna have to go with what your building department wants.
Thanks Boss- I've read you are the local truss expert so I trust you and appreciate it.
I've built a couple decks before, but not to houses with a web floor. The existing deck is just lagged to the sheathing - which is stupid because with about a minute of using a tape measure they could have hit the truss ends. It passed inspection though. I'd complain to the builder but since I am ripping it down anyway to build a larger, properly constructed deck it is sort of moot. The whole thing irritates me because they are requiring relatively detailed plans from me, but obviously the existing deck/house (1.5 years old) didn't need them or nobody cared.
I've been through this before. It was new construction and we got a letter from the truss company stating that the deck was to be through bolted to the end of the floor system web truss joists with 5/8 gal bolts and that the the max hole to be bored in he end of the trusses was 11/16". 5/8 gal washers were to be used on both sides of the through bolts. If the deck was attached to the side of an end joist, then solid blocking would be installed in the truss webs, and a long 2x10 backer was installed on the inboard side of the end joist. 5/8" through bolts were again required. I had an E-mail complete with a drawing of the recommended methods, but can no longer find it - it was > 5 years ago. Contacting the truss company would be the way to go, but if this is not new construction a I guess that may not be feasible.
My case was a small subdivision were several such attached decks were to be built.
Let me say though that this was undoubtedly tempered by the fact that our NC building code requires thru bolts for deck attachment - lag bolts are not allowed. Personally, I feel that lag bolts are substandard because you never really know how much holding power they provide. If, for example, the installer turns the bolt just 1 turn too far, the 'threads' that were formed in the wood by the bolt are stripped out and the actual holding power (resistance to withdrawal) is greatly reduced. As a matter of fact, I can't think of any instance where lag bolts are used in normal residential construction here in NC unless an engineer specifies them and stamps the drawing with his seal.
Another possibility is to just build a free standing deck right up next to the house. By this I mean support posts next to the house. In that case the deck could be lag bolted to the house - right through the siding - this would be more of a superficial connection designed simply to prevent a large gap from forming between the house and deck.
When I did my house in 98 NC code allowed joist hanger attachment to a PT rim joist/band with flashing. I did the standard nail pattern to nail rim to squash blocks but added lags at a slight down angle in every other truss.
Just because your local building inspections department passed it doesn't mean it was to code... NC code does not address and did address attachment of decks to trussed floor system.
I'm a little confused by your statement though:
>> When I did my house in 98 NC code allowed joist hanger attachment to a PT rim joist/band with flashing. <<
Was the "PT rim joist/band" part of the floor system of the deck or part of the floor system of the house? If it was a PT rim or ledger that is part of the deck and that was connected to the side of the house it was supposed to be through bolted.
I no longer have my NC/CABO code book so can't look it up right now. I'd bet ya $10 though... I think we may have a cabo book at our office. Exterior wood decks and their attachment was in the back of the book as one of the appendixes. Same as it is now. I remember building decks in the mid nineties and being required to through bolt 'em - per the book.<!----><!----><!---->
A lot of/most of the folks I come across on site base their knowledge of building code on 2nd hand information such as what some "builder told me" or "what the building inspector said"... and a lot of BIs bend things around. I read and know the book and can find things quite quickly. <!----><!---->
For example, I helped with a hurricane relief project around 99 or '00 in Princeville - building new homes - the decks were only nailed to the house and OKed by the BI. I thought it was crap because I knew well what the Statewide BC said, but I wasn't running the show, and the decks (front porches) were only a few feet high so I didn't think it was a big deal.<!----><!---->
All that said, I have removed several decks for replacement with nailed only ledger - their nailed only ledger was holding on find after 20 or so years. Besides, if the ledger is bolted up to withstand 50 tons of withdrawal force, and then the joists are just nailed to the ledger (with hangers or whatever), what kinda sense does that make...<!----><!---->
BTW - all my info on mechanical, electrical, and plumbing code is via 2nd hand info... but I do know the Building Code well.
The packet I got from our ahj has what appears to be a supplement with Appendix C page 4d with a note saying "other means. dated or marked 1994 revisions. It appears to be a determination or something from Raleigh. I know our local department is not sophisticated enough to have done this on their own.
Some of these drawings are basically the same ones I saw in one of the magazines (JLC, FHB, or one of the remodelling ones I get and was attributed to the NCDOI)
I would have to agree with you as the current code only has about 1 page (at least online) appendix M for wood decks. http://www.amlegal.com/nxt/gateway.dll/NC%20Residential%20Code/part01409/chapter01512.htm?fn=main-nf.htm$f=templates$3.0
To clarify the question the drawing shows joist attachment to the house rim joist with flashing and joist hangers not adding a ledger..
Have you seen the "LedgerLok" ledger board fasteners by Fastenmaster http://WWW.fastenmaster.com? This page says they are icc/ibc code compliant but do not see anything about decks. I agree that bolts ae the answer. My sister has a deck that I question and there is no access to put bolts, thinking about adding some lags, can not see how it would hurt. realize that it would not be a good as bolts but better than what is there.
>> The packet I got from our ahj has what appears to be a supplement with Appendix C page 4d with a note saying "other means. dated or marked 1994 revisions. <<
What is ahj? I doubt it was from the DOI in Raleigh though. Their official mode of operation is that code revisions are released every 2 years - I think it is - and that in the mean time "letters of clarification" and "code interpretation" can be released but the code cannot be changed. This is good because they can't make "add-hock" changes to the BC so, when you have the current book with the current revisions it is good for a specific period of time (years). No need to worry about what somebody decided last week... or at least not on a statewide level. Local building enforcement jurisdictions (townships and counties) are a different story though - don't get me started on that!!!
I had a deck building 101 packet that was given out by one of our local townships maybe 8 years ago - maybe it was the same thing...
Still, these do not/did not modify what the state building code is/was. Local enforcement jurisdictions have the right to add stuff, but they do not (legally) have the authority to take away NC BC requirements. This is one of the things you learn when getting a GC license.
Here in NC, when the IRC 2000 was adopted in 2002 the NCDOI basically cut and pasted a number of things out of the old NC/CABO code - the appendix on wood decks being one. The 2 year lag gave them time to make their revisions.
Re the online code you referred to - I have used that a number of times too, however, although I don't have specific examples, in the past, I have found it to be incomplete. I'd recommend for anyone who is actively involved in building in NC to get the hardcopy loose leaf binder edition of the NC building code. Loose leaf so that the periodic revisions can be inserted. There is a totally new (I think) code due out 1/1/2006 so it may be best to wait.
As far as >> the drawing shows joist attachment to the house rim joist with flashing and joist hangers not adding a ledger.. << that is a totally different situation than we are talking about, (attaching to trussed floor systems) and generally you don't really have to worry about a (stick built) home's rim board pulling off the side of the house since it has floor sheathing, walls, etc nailed to it tying the whole floor system together. Further, none of the open webbed trussed floor systems I have installed/had installed had rim joists. Maybe there are some? They all did have a rim 2x4 though at the joist ends.
Re the ledger lock screws - yes I have seen advertisements for those, they obviously don't meet the requirements shown in appendix m that you posted. As far as >> This page says they are icc/ibc code compliant but do not see anything about decks. << , I don't know what the difference between IRC2000 and icc/ibc is, but again, appendix m is something that NC added. In the hard copy, all the amended pages (and added pages) are blue. If only a sentence or word is changed it is underlined. If you have a letter from NCDOI allowing them then they would be acceptable but I'd be very surprised if anyone could get one - like I said before, how can a BI tell if the ledger lock screw was tightened just a few turns too far...
That is the trap one can easily fall into with generic code books and manufacturers claims to code compliance - we have to build to the NC building code (and all it's amendments). Not some generic manufacturer's claim.
Still the NC code book is not totally comprehensive - that was why in the instance I sited some 5 years back we had to get a stamped engineers letter from the truss company specifying the proper method of attachment to their trusses. This was per the building inspector's demand.
AHJ-Authority Having Jurisdiction, a key definition in the code. The packet came from local (county) building dept as part of their continuing education program. I am guessing further that it may have been a handout from the DOI's ( or approved) inspector course.
We chose to use pt 2x band with the floor trusses. I cannot believe that a band end nailed to "stick framing joists" is secured as well as this band is secured to my trusses (not tji). I was only pointing out that there may be some uses for lags to go over and above a requirement.
When my local Building dept who signs my CO gives me something I tend to consider it. I had the red binder that was current when I built the house.
Cheers, Bob
Agree with all you have said. And, OK I should have known what AHJ was. Still, I like being well versed - often these BIs are not the most qualified, as, at least around here, it's not a real high paying job. And don't get me wrong - 95% of the time I do what they say - my success rate at arguing has been very few and far between. Still if I can initiate an intelligent conversation, most of these guys are not totally inflexible. Intelligent infers that I have done my homework... I had the red binder but threw it out some time ago.
>> We chose to use pt 2x band with the floor trusses. << Again, I have never seen that, especially since floor trusses are normally a minimum of 12" tall and 12" tall dimensional lumber is not readily available. I would guess that your setup is stronger - if not redundant though. I guess the bottom line though is that you did not have a deck ledger attached to the house. Rather the deck joists are connected directly to the house band, so the attachment schedule in appendix M, or whatever it was called back then is/was N/A.
I agree about arguing, working with an inspector in Asheville who said one of his cohorts had a sign over his desk. "Arguing with an inspector is like wrestling with a pig in mud, sooner or later you will figure out the pig likes it". They don't know everything, he11 they would be on Breaktime then.{:->
An intelligent discussion, especially when it involves alternatives is usually recieved well unless you have tinkled in their Wheaties.
My trusses were ordered with a drop down and squash blocks. Standard 2x10 worked fine. The strength of the attachment to band puts all load downward on mudsilll. Pullaway forces are pretty well covered with joist hangers.
Your profile does not say where you are located .
Edited 8/28/2005 1:56 pm ET by rasconc
OK - those are a different kind of trusses than I have mostly used. Have used trusses that hung from the top chord, but not in the application you describe.
Raleigh - I had a profile and all that good stuff but the new registration system nixed that. I'll fill it out again...
It is only a year or two old . . . I considered the freestanding deack but I am leary of putting posts a foot or two away from the foundation on backfill, or excavating 7 feet down to undisturbed soil. I trust the end plates of the truss more than the soft soil that is still settling!
Agree on carriage bolts, I should have been more specific.
Seeing as how the existing deck ledger from the original builder is lagged into the 1/2 osb sheathing BETWEEN the ends of the trusses, I think pretty much anythng (drywall screws excluded) would be better and safer. Not to mention that it is just lagged through the siding without crushing it. I'm just surprised only one deck in the neighborhood has collapsed so far.