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grover
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# Posted: 4 Aug 2013 12:32am
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My lumber should be delivered this Thursday so things should start moving much faster now. I read somewhere today that some hold the sill plate in from the edge of the block 1/2 inch. This is so the sheathing will come out flush with the block. I had never thought of this but it make sense. Guess it's not a big deal if you didn't do it this way but I think I might.
Is it commonly done this way?
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toyota_mdt_tech
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# Posted: 4 Aug 2013 12:48am - Edited by: toyota_mdt_tech
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Sill plate and rim joist needs to be flush with the block. The sheeting should extend down past the block. If you are using a 2X8 floor joist, get sheeting in 9 foot length for the siding. This will extend past the rim joist and over the block.
My sill plate was flush with the stemwall, location of attaching bolts are critical. Within 12" from the ends/corners, or on each side of a splice. So its a good idea to use full length boards, so no splice is needed. Then so many between the corners (so many per X feet)
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bldginsp
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# Posted: 4 Aug 2013 01:07pm - Edited by: bldginsp
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In the long term, the first places you will see rot on a light frame building are at the rafter tails, roof drip edge, and at the plywood down at the sill plate. Anything you can do to drain away water that gets there is desireable. I've never seen the sill plate held in from the foundation, but perhaps there is a good reason for this. One problem with it could be that it creates a ledge on the block or concrete that can hold water and promote rot on the plywood. I think it's best to let the plywood hang over and then use flashing on the plywood at the bottom, before the paper, to add more barrier to keep moisture off.
The PT sill is protected against moisture, the plywood isn't. On my build I may cover the sill plate and rim joist with bituthane flashing that overhangs the concrete before I put on the plywood, to keep any moisture that gets in the concrete or sill plate away from the plywood. Having seen many old demolished walls, I want to protect that lower plywood edge as much as possible. But I'm an anti-water nazi, maybe you don't want to be so extreme.
A simple, inexpensive precaution would be to use 8-10 inch wide strips of 30lb felt on the sill and rim, overlapping the block, to protect the plywood. I see no advantage to insetting the sill plate, except that then your siding lies on the block, rather than being held away by the thickness of the plywood, which is just a visual thing, not a practical advantage. I think this could promote rot by putting the siding in contact with the block (if you extend it down that far), and by creating the ledge as I said before.
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grover
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# Posted: 4 Aug 2013 07:40pm
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Well anything I can do to prevent water damage I will do.
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WY_mark
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# Posted: 4 Aug 2013 08:22pm
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FYI, I didn't know this till after - if you're using a big-box store they'll deliver 8' sheathing BUT if you ask/order they'll deliver 4x9' sheathing - the extra foot is immensely helpful when you have an 8' wall and need overlap.
Also, if you sheath the walls while they are laying down, also wrap them while they're laying down and tuck that bottom edge of the wrap around the bottom of the sheathing, you stand up your wall and it's neatly (and smoothly) wraped and it's all nicely tucked under the osb or whatever giving a nice little seal and tidy presentation.
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Martian
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# Posted: 4 Aug 2013 08:44pm - Edited by: Martian
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I inset a half inch in when I want my siding to lay flush against the foundation. having OSB exposed to splashing water is asking for trouble at some point. I have been known to take 6" flashing and nail it to the outside of the sheathing down to the beams. It ties everything together, and seals the bottom to critters and moisture. The siding hangs a bit below that.
Tom
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toyota_mdt_tech
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# Posted: 4 Aug 2013 10:55pm
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Quoting: WY_mark ask/order they'll deliver 4x9' sheathing
Exactly what I did. If you use full 8 foot walls (92 5/8" studs) and its on a slab, the 8 foot sheeting will work, but if you have a floor with 2X8 joist, sill plate, the 9 foot sheeting will extend past the rim joist and overlap the foundation by a few inches, assuming you use 3/4"-1"
I reviewed my lumber pkg and seen they have me down for 8 foot sheets, I called in and changed that to 9 foot sheets (5/8" T1-11 "actual plywood, not strand board stuff)
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