Just looking for a little information and assistance perhaps. We are
presently beginning the process of building a small garage in Nova Scotia.
We will be pouring the slab next week. My query is whether it is advisable
to start the construction with a sill of pressure treated lumber (2x4)
anchor bolted to the slab with a membrane that is used to start a roof
shingling under it and then nail the wall to that sill. We would then let
the sheathing project beyond the plate, the sill and over the slab by 2".
Any ideas, suggestions or criticism. I worry about water and/or snow
getting under the sill.Thanks in advance
Most anything of that sort will work. The way the OP described his
project though, I doubt he'll have any serious problems. It seems that
he's going to have quite a bit of that slap above grade and water should
not be a problem from without. Might have a problem if he hoses down
the garage floor with any regularity.
My garage/shop (24'x36') went up in '83. I used PT 2x for the sill
plate and merely sandwiched the regular fibreglass insulation that was
then in vogue for use between the foundation and sill. Never had a
problem with it.
Siding on mine was 1/2" CDX and 5/8" rough sawn cedar faced ply which
dropped about 1" below the sill plate.
Even with the water INSIDE the garage, if his cement contractor knows
what he's doing he'll slope it from about 16" inside the perimeter
towards the center and overhead door opening.
What really worked nice for me was the 5 gal pail of concrete hardener I
bought and kept applying while the slab cured. Sprayed, I think, three
heavy coats on it and kept it watered and plastic covered for nearly a
week. Left me with a great finished floor that hasn't cracked yet and
no dust problems.
I would consider putting a row of 4" tall concrete block around for the base
of the wall and them build up from that. It will keep the wall sheeting a
few inches off the floor, and you can wash out the shop with a garden hose
if you like without soaking the wall. If nothing else use the PT bottom
plate, but seal it to the concrete with a good polyurethane caulk when you
set it in place.
If I were to build a garage again I would skip the floating slab, put down a
foundation wall below the frost line and build from that. My slab was poured
to code, but in the 20 years since, the outer edges are sinking from the
weight of the building.
You're pouring a floating slab? Personally I'd like 6-8" of masonry
above the ground before the siding starts otherwise you're likely to get
water migration and rot. I would definitely use a piece of pressure
treated lumber against the slab and you should use "sill seal" beneath
it. These days it's usually a strip of blue or pink foam 1/8" to 1/4"
thick. Pressure treated because the masonry will contain moisture and
may rot untreated wood. The sill seal primarily closes off any voids
caused by the unevenness of the slab. It won't keep any significant
water out but it does help keep bugs and cold air out. You could lay a
strip of rubber ice and water shield (I presume that's what you were
talking about?) over the slab/2x4 seam in the hopes of sealing out water
but I wouldn't count on it working very well.
Lots of ideas here. The 4" block is great.
Foamy seal will trap moisture and mold.
Let the 2X treated be the bottom plate of the wall. There's no need to have
I soak the bottom of the sheathing and the first siding board with copper
naphthanate, 19% if you can find it. If you get clear, there's no color
under the stain.
That's standard procedure, and it'll work fine. Only thing you might
want to consider is a 2 x 6 pressure-treated sill plate, but that may
not fit with your plans for finishing the interior. FWIW, they have a
producted called sill sealer that is designed for that, rather than
the felt paper you've got in mind. Comes in little rolls of 6" foam-
but I imagine the felt paper would do the job as well.
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