Basement Sill Plate - need help

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Old 11-19-07, 10:51 AM
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Basement Sill Plate - need help

I framed up our non-load bearing basement's exterior walls (and a couple internal walls) using standard 2x4 construction lumbar. The frames are sitting on concrete and have been glued and nailed down. I have found out after the fact and just before I am planning to pull the permit for framing inspection that the sill plates should have been done w/ green treated lumber. I really have no idea/way of being able to pull these up but I'm looking for ideas. I plan to talk to the city first but I see nothing in their guidelines referring to the requirement although I assume it is an IRC code. The basement is in new home with foam board insulation on the outer walls. I have no idea as to whether any type of moisture barrier was laid down before the concrete was laid. Any help/comments you can give would be appreciated.
 
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Old 11-19-07, 01:39 PM
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Yes, and additionally any lumber in contact with concrete must be pressure treated. This is to negate the wicking effect of wood that sucks water out of the concrete itself. You'll likely have to pull it out and replace in order to pass inspection. I cannot think of any alternative, however, this is just one man's opinion.
 
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Old 11-21-07, 05:14 PM
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The Ohio guy is right about the pressure treated plates and the wicking. Before you trash your basement I would talk first, to an architect or engineer where you are about any possible options. Secondly, you could talk to your building inspector and maybe he'll cut you a break (if your basement is dry, the plate material really isn't that big a deal), try seeing him around 4:00 on Friday afternoon. From my experience, that's the best time to see these guys.
 
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Old 11-21-07, 05:42 PM
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Brawney - My kid just finished her basement and one of the things the inspector emphasized (and looked for) was pressure treated plates.

If your inspector is going to require this (check first) I would beg, borrow or steal a sawzall (if you don't have one) and cut the studs where they are nailed to the sole plate. Then I would slide in a replacement sill made from PT. If you used dry 2X for your sill, the extra thickness of PT will make up for your saw kerf and you should be able to get a good fit.

It will probably be a PITA to get the sole plates out. Probably a lot more sawzall work.
 
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Old 12-20-07, 12:57 PM
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I'm getting ready to do a similar job, and have 2 questions.

1. There is plastic UNDER my concrete floor. Does that in any way negate needing the treated lumber.

2. Many sites recommend a foam/plastic barrier under the bottom plates. Is this INSTEAD of using treated lumber, or in ADDITION to using it???

I may do both, but am trying to figure out what is required.

Thanks
 
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Old 12-20-07, 01:46 PM
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Also, besides treated - where I come from - a thin foam strip is layed down under the sill, as a seal. Also stops direct contact between board and cement.
 
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Old 12-20-07, 02:22 PM
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yes, I noted this is part 2 of my question. I plan on doing both on my new walls, but am unsure of what the home builder did on the interior basement walls.

I guess I want to know what is actually REQUIRED by most codes, and what is simply good practice.

Originally Posted by ecman51` View Post
Also, besides treated - where I come from - a thin foam strip is layed down under the sill, as a seal. Also stops direct contact between board and cement.
 
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Old 12-20-07, 04:56 PM
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I've never really understood the real purpose of the foam strip between sill and foundation. I have been told by an inspector that it's primary purpose was to act as an air seal. I do know that the local inspector requires PT sills in interior basement walls but doesn't require a foam strip.

A framer told me that it separates the wood from the concrete and was only needed if PT wasn't used.

I remember years ago (when it was a tarred strip not foam) being told that it was a termite barrier.

I do know that I have a shed that was framed with a PT sill more than 20 years ago and the sill hasn't rotted.
 
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Old 12-20-07, 05:01 PM
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I've never really understood the real purpose of the foam strip between sill and foundation. Local code requires PT sills have a foam strip. It is not required for interior wall sole plates. I have been told by an inspector that it's primary purpose was to act as an air seal.

A framer once told me that it separates the wood from the concrete and was only needed if PT wasn't used.

I remember years ago (when it was a tarred strip not foam) being told that it was a termite barrier.
 
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Old 12-20-07, 06:36 PM
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Originally Posted by cwbuff View Post
A framer once told me that it separates the wood from the concrete and was only needed if PT wasn't used.
If ever you go down into a basement and peel away the insulation in the joist cavities, you just may see daylight where the sill plate sits on the top block or poured wall, if some form of seal was not used under the sill plate. (Actually, if the insulation is ONLY in the cavity above the sill plate, without extending down to the top of the block wall, you would be able to see daylight without moving it.)

At my friends 1950's apt. building, the sill plate is on a 3/4 inch thick strip of tarred Celotex-like fiberboard.
 
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Old 12-21-07, 07:54 AM
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I know the reason for using it is simply that concrete can allow moisture through, and even treated wood (eventually) can act as a Wick and absorbe moisture throught the floor. However, since pretty much ALL concrete flooring has a moisture barrier under the concrete, it seems like using foam AND PT is a bit overkill.

Again, I'm going to do it anyway on the walls I put in, but the whether the existing interior walls have the foam is unknown.

thanks for the input.
 
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Old 01-03-08, 08:21 AM
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Actually the original post refered to the governing code as the IRC. The 2003 and 2006 IRC states that pressure treated lumber is needed if

"Sills and sleepers on a concrete or masonry slab that is in direct contact with the ground unless separated from such slab by an impervious vapor barrier,

Also the original post says that it's a new home and it's in a code enforced (and inspected area). Before you start trying to replace all these - I would do some digging. If it is a new home, I would go back to the city to find out when the permit was pulled for building the original house and see what building code was enforced. I'm willing to bet that whatever code was enforced at the time required a vapor barrier under the basement concrete floor. Since this an inspected area, this would have to confirmed by the building inspector. So if you can prove this, then you wouldn't need to have pressure treated bottom sills.

Of course you need to run all this by the building official first to see if it would be an acceptable approach - I don't see why not since they keep inspection records.
 
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Old 01-14-08, 08:17 PM
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As a licensed structural engineer who has inspected a lot of old houses that do NOT have treated sill plates and have survived a long time, i can say with certianty that if it were my house i would not be concerned that this would cause a problem and i would do whatever i could to convince the building official that it is okay. try to get him to consider the glue and the vapor barrier as a barrier and anything else you can think of.
 
 

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