slab or wall

[steeve]

hi,
the garage will be half part of the house, ground level, house basement 8', 3'out ground main floor, will the garage have 8' foundation walls or only the inside walls. :?

[Rich]

Think of the garage and your basement foundations as 2 seperate things. You'll want the house foundation/basement at 8' (I would probably go 9' or even 10') and the garage foundation attaches to the 8'/9'/10' walls.
If you want to have 3' from grade to the main floor level your foundation would probably only be 2' above grade. When you add your floor framing on top of the foundation it will be 3'+.
The 2 foundations will be at the same elevation and you'll get a step from the garage into the main house - it will be the thickness of your floor framing.

[steeve]

if the 2 foundations are even, i ll have to digg at least 6' down ,and then refill the hole garage space to ground level with gravel?,can't i just put a slab in the garage section instead... BTW it's gona be a two floor house. - and if i do the two foundotions, will i have to waterproof the inside wall of the house section before refill. thanks

[Rich]

Shouldn't have to dig the garage space all the way down. Do your basement foundation first - put first floor framing in - backfill and compact... then do your garage foundation and slab.
Don't you have freeze/thaw conditions in Montreal? You'll want a foundation under your garage IMO - and at least 3' deep.

[steeve]

yes i do, 4' frost line
what would be the best way to attach the garage foundation wall to house wall.and what about garage footings, isn't there like a risk of mouvement, du to soil backfill even if it's compacted.maybe i should just do the hole thing at once, go higher above ground level,less process steps ? thanks

[steeve]

hi Rich,
another of my brite questions,sorry but i have to ask, what about if i do a min. frost line foundation ( 4') around the hole parametre, a foot above ground, and build up the extra 4' with studs for the house part, would it be safe and cost effective, framing vs concrete, thanks :)