Sill for garage on slab

[Joe Larade]

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

[bridger]

I've seen a product like a ribbon of glazire's putty in a roll for sealing the joint between sill and slab.

no idea of the name of the stuff, but it looked like it would work.

[Unquestionably Confused]

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.

[Greg O]

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. Greg

[Stephen M]

I used a product referred to as "sill-seal" I've no Idea if that was a trade mark or just a generic term.. It came as a 50' roll of light blue soft styrafome. It was about 1/8" thick.

-Steve

[Leon]

That will work but drill the holes in the sole plate first and then attach it to the wall before raising the wall.

[Rick Beebe]

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.

--Rick

[Wilson]

[Prometheus]

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.

[Joe Larade]

Thanks to all who replied to the group. As always your comments were dead on and very helpful. I'm rarely disappointed by this group. Thanks again