Trying to build a deck. I looked in the basement of my house. My house appears to be built without a rim joist. There is just wood i-beams that sit on top of the foundation. Then plywood on the outside of the house. How do I secure a ledger board?
The building code doesn't seem to allow a free standing deck because the posts need to be 4 foot from the house.
I've read something about blocking but I've been unable to find a detailed description of how to accomplish this.
re: The building code doesn't seem to allow a free standing deck because the posts need to be 4 foot from the house.
You could build a free standing deck if you cantilever the joists or support them with diagonals. Just make sure you use the correct size joist based on the cantilever and support beam spacing. I'd say it couldn't hurt (except in the wallet!) to use 2 x 12's for a 4 ft cantilever which would help eliminate and deflection or bounce at the end of the joist.
This site has some hints and tips on joist sizing for cantilevers:
My advice would be to talk to your local government agency that issues building permits. They are there for your benefit. They can connect you to an inspector that will be able to offer suggestions to fit your specific situation. It may cost a few dollars for a permit but it can save you hundreds, maybe thousands, of dollars in repairs and aggravation.
G.S.
Is it possible that from the basement you are seeing an LVL rim? (similar to a microlam beam only not intended to carry a load). They look similar to plywood or OSB. It seems fairly unusual (from my part of the world) that there would be no rim (or a treated mudsill on top the wall). If you know the thickness of the wall, you can measure from the face of what you see to the edge of the wall and get an estimate of the thickness of what you are seeing. If it's an LVL rim board you should be reading a thickness of 1-1/2 to 1-3/4".
If indeed there is no rim another possibility for the deck addition would be to extend your deck joist through the wall and over the top of the foundation wall just like your floor I-joists are. We have done that regularly over the years for a variety of reasons (especially short span decks/balconies when we don't want posts at all
- they are cantelievered from the building).
I'm assuming you would be removing siding anyhow to place your ledger board. Now you would have to do some additional work - including removing that plywood rim (if that's what it is). You would want to add squash blocks to the web of the I-joists so you have a good surface to anchor your deck joists. The deck joists are set tight to the I-joists (with the squash blocks filling what would have been a void between them. Then you add solid blocking between each set of floor-joist/deck-joist combinations under the wall above (almost like a rim joist would have been). Of course I haven't mentioned that your floor and deck joists are going to be different heights (at least slightly) and you need to decide if you want them flush at the top or if you want the deck stepped down slightly. We have snow in my world so we usually opt for stepping the deck down slightly even though it's not handicapped friendly (it keeps melting snow from sneaking into the patio door). The approach you take will require some additional blocking to keep everything solid. One more thing. Don't extend your deck joists more than 12" into the house. In the old days there used to be codes about "over-extending" lapping joists more than a foot past the bearing point. I don't really remember what that was about - probably something to do with warping, cupping, etc.
I would make a sketch of this for you if I could. I think a detail drawing is worth a thousand words. I just joined this group today and need to figure a way to share sketches efficiently if I'm going to hang around - I tend to be visual. Good luck, I would be interested to see some followup as to how this unfolds.
re: need to figure a way to share sketches efficiently
Find a website to which you can upload your sketches and post the link in this group. Based on the multitude of ways people read this group. I doubt you could come up with a way that all of your sketches would be viewable (correctly) in the newsgroup.
Hey, good idea - which inspired me to use my head! How about a link to a Truss Joist Document and save me the time of making my own sketch. The link below is to a PDF detail book. In the middle of page 5 is a diagram that is closest to the situation in question. They are dealing with true cantelievers which is not the question here, so imagine that the outside end of the deck is supported by a beam (etc) and you can ignore the reference to a 4' maximum canteliever. What is most important is that they show blocking details, etc., and how you need to deal with a "run-through" situation. You will also have to "imagine" how your treated deck joists actually fit into this sketch rather than other I-joists.
By golly I think you're right. I took a closer look. I went to Google images and looked up plywood. It's definitely not plywood :) lol. I did the same thing with LVL and it looks more like that LVL. Also after taking a closer look it appears that this board doesn't go all the way up the way (I can see the small crack between it and the floor. So yes, this must be a LVL rim joist! Eureka! This is making much more sense now.
Thank you so much. I've been banging my head on this one all day :)
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WHEW!!! Your deck addition just got much easier, I was starting to think the alternative approaches were looking like quite a bit of work. Good luck, it should be pretty straight forward now.
I am not sure if it would be a good idea to bear on the existing walls, since your foundation was not designed originally to add half of your deck load to it. Staying 4 feet with the new posts is a great idea, since you wont be disturbing the existing foundation, you can get a little closer. I dont know of any code that requires you to stay away this far, but while you want to attach to the existing structure for lateral stabilty, you want to refrain from adding loads to it. here is a link for you
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architecturalrealms wrote the following:
Would that be "No more than 4 feet from the house"? I don't understand the logic of not having them closer to the house. Is this a ground level deck, or within a couple of feet off the ground?
Bill, you're responding to another one of those dimwits at that homeowner's spam site that post looooooooooooong after the fact. The question about the deck is from more than 2.5 years ago. Probably a safe bet that it's no longer an issue for the OP, eh?
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