Anyone know anything about concrete?

[smhowell]

Our garage is 25' x 30'; unknown age. The stemwall is 1 foot high and about 6 inches thick. It was placed on top of the ground when it was poured. The entire north end (25') blew out (tilted) about 4" when they poured 3 - 3 1/2" unreinforced concrete on 12" of fine sand. The northwest corner shows exposed bricks within the concrete...this corner has to be fixed no matter what else. Other than this corner, the rest of the foundation doesn't seem to have shifted much if any. The north wall appears to be a curtain wall. Needless to say, the floor is badly cracked and uneven. We have chipped out the first 1/3 and plan to make 3 pours with 4" concrete reinforced with rebar and will remove just enough sand to keep the floor at its current height.

If we are to redo the foundation, now would be the time to do it. We personally plan to use the garage as a workshop and park cars in it, but it will probably eventually be converted into an apartment. I should mention that I plan to put 1.5" brick veneer on it as a siding. This would hide the blowout, which is fine IF the foundation is sufficient.

Should we jack up the garage, chip out the current stemwall and put in a proper foundation? How deep should it go? John wants to epoxy the rebar into the current stemwall to make all of it one unit - I think if we leave the old stemwall, we should put in an expansion joint between the old concrete and new concrete instead.

We need advice concerning what we should do with the stemwall.

[miscojohn]

Whenever new concrete is poured next to old, there should always be an expansion joint between them. There will surely be a crack otherwise because the new material will do some shrinking as it matures.

Can't imagine having a foundation for any wall, especially an exterior load-bearing wall, that doesn't have a proper foundation. Don't know where you live, but if the footings are not below the frost line and not wide enough (check local codes) to support the wall, there will always be movement of some kind, even if you epoxy in rebar! That's also an invitation for critters to make themselves at home.

[sulconst2]

wow!

first - you know this is a plumbing forum?

second - sorry to hear about the blow-out. gotta suck when pouring a floor and 1/4 of the building buckles!

third - when pouring a floor you need 2 guys per yard min. or you can lose it. "cracked and uneven"

i guess a stemwall is a footing? here a footing is min 16" wide by 8" deep, 36" down, with 8" block for walls. floors need 4" stone compacted plus wire mesh in 6" concrete for a garage

garage floors are pitched towards the door. if you make this an apartment then the slab needs to be flat and 8" above grade. maybe you can plan for this before your repair.

kind of feeling bad for "john" but then thats my name so i can relate!