I have a problem I hope you can help me work through.
I am building a deck off the back of my house. As I am preparing to attach the ledger to the house it has occurred to me the rim joist may not be strong enough to support the deck.
Here is why I’m concerned. The floor joists are 25 foot 14″ TGIs that run parallel to the rim joist – not perpendicular like I see in every “how to” book. I belive the rim joist is simply sitting on the sill plate and attached in a way that would not structurally hold the weight of the deck. There is no perpendicular joists or support to the rim joist and I’m afraid the weight of the deck could pull or twist the rim joist out of place from between the sill and the floor decking.
The deck will be 21 x 36. The 36′ section is the portion to be attached to the house.
Is this a valid concern? And if so, does anyone have any suggestions how to work around this?
Thanks for your help.
Daz867
Replies
go one better...
make the deck independent of the house and cantilever into the house wall..
no worries then...
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Great idea. ThanksDaz867
Ditto what Imerc said -- build the deck so that it does not depend on the house for support.
Politics is the antithesis of problem solving.
Yeah, an extra set of posts about 2 feet from the foundation. You can still attach the deck to a ledger, but support the weight with the posts.
The manufacturer of the I-joists should have allowable ledger details in their installation guides. you can probably get it in PDF form from their website.
The rim board won't "just be sitting there". It should be nailed to the sill plate below it, and the floor decking should be nailed into it from the top.
The rim board is apparently holding up your house. Why wouldn't it hold up a deck too?
should be is one thing..
if you have yur doubts...
don't trust it...Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming<!----><!----><!---->
WOW!!! What a Ride!Forget the primal scream, just ROAR!!!
If their rim board isn't fastened to anything, they have more serious problems than how to attach a deck. Actually - Attaching the ledger would probably HELP stabilize it.
Avoiding meaningful employment is hard work
Hi Daz867,
In my neck of the woods, if we have a rim joist that runs parallel to the floor joist it needs to be doubled up to match the wall thickness above or have the same size blocks running perpendicular from the rim to the 1st joist. I run blocks about 24" o.c.
The reason is to support the wall above and keep it from rolling in. If you only have a single rim and plywood then the wall above only has an 1 1/2" of bearing on the outside edge of the wall to support it.
As stated earlier your rim isn't just sitting there. It should be sitting on a plate thats supported by a pony wall and foundation under it. No problem for your deck ledger!
I would be more worried about your plywood floor sagging on the inside edge from the wall above it without blocks or a double rim " if that's the case".
Easy to solve though , add same depth blocks!
Howie
Howhighlites,Thanks for your help and reply.I hate when one question leads to other concerns.I checked out the framing - it is not blocked as you suggest. I checked the layout and with a tape measure and came to the following conclusion.The rim joist is a single 3 1/2" x 14" x 25' I-joist sitting on top and attached to the 2x6 sill palate. The I-joist is nailed to the sill and from above through the decking. The foundation wall is 10" concrete. The wall above is 6" - standard framing. The outside panel is standard plywood.Obviously the gap between the exterior plywood sheathing and the center of the I-joist wont allow a ledger to be attached to the outside. As earlier suggested, I will probably cantilever it.Now a new concern, your comments regarding the wall above rolling in on a single rim joist makes me wonder if the 3 1/2" wide I-joist is wide enough to support the 6" wall above. Decking is 3/4" plywood. I-joist are 18" on-center.Is this an standard practice with I-joist? And is this a problem?Thanks again for your help.
Hi Daz867,
If your rim is 3 1/2" then you have no problem! The rim is at least 2/3rds of the width your wall above which is plenty to keep it from rolling, that's pretty standard. I probably would have still blocked it every 24"o.c. but that is my habbit that I do for parallel walls.
I'm not following you on why you can't attach your ledger to the rim. It's is more than sufficient to support your deck!
What you want is to attach and "flash" the ledger correctly to keep water from getting between the ledger and the house. And the other way to do it is to make it self supporting as suggested and spacing it away from the wall. Either way would work.
Howie
Hi again Daz867,
I reread your reply and you wrote ,
"The rim joist is a single 3 1/2" x 14" x 25' I-joist. "
Sorry I thought it was a solid 3 1/2" rim. Now I know why you can't attach the ledger. But my concern is that , is the wall above a bearing wall?
Out here we can't use I-joist for rim material. It needs to be a solid rim especially under bearing walls. The single I-joist web is not strong enough to carry a concentrated bearing load.
But I would check the building codes in your area, I don't want to alarm you about something that may be fine in the area which you live.
Howie
Hi Howie,Thanks for taking the time and helping with this.Yep, the wall above is load bearing - exterior wall. The weight on the webbing bothers me as well. I did some research on Boise's web site. Their "how to install" I-joists instructions do show an I-joist used as a rim joist with a parallel run. Also looked through some of my Taunton framing books - they show and recommend adding blocking in this situation. Just as you advised. Luckily the area is very accessible and there is plenty of lip on the foundation to support blocking. Thanks for time and suggestions.Daz867
Daz,
In our area, all decks are now required to be self supporting. When you go to apply for your permit, the county or city will probably have a brocure thay will give you with all of the specs.
Bill Koustenis
Advanced Automotive Machine
Waldorf Md