I am looking into building a garage this winter still, and the concrete guys I talked to said that doing the foundation in freezing weather is not a problem as long as it is poured quickly after the trench is dug and before any significant amount of frost can accumulate in the bottom of the trench. The bottom of the deeper trench typically is not saturated with water/frost as the surface. Thats kind of the whole point of digging the footings below frost depth, right?
[ Digging the trench through the frost, though, that is another story. My excavator said it might be quicker and certainly cheaper to just wait for spring. ]
The concrete guys said that one issue with trying to pour slabs in the winter was not so much the concrete freezing (they can use blankets, heaters, tents, etc to keep it warm), but getting the ground underneath graded properly.
Another problem they mentoined is that even if they can get the grade worked out, when the ground underneath thaws in the spring, there will certainly be significant settling. Normally, when a driveway or floor slab is poured over dry dirt, the dirt tends to stay dry because all the water runs off of the slab (assuming no hydrostatic pressure pushing water up from below). The next winter there is little or no moisture to cause the dirt to move when it freezes again. But if you pour over ice/frost-saturated ground, the slab will sink and crack in the spring.
Note that slabs poured in low spots with improper drainage will also eventually have problems because water can still accumulate underneath them (through cracks, from the sides) and the frost heaving will likely break them up.
So my plan is to put in the foundation now (assuming the excavator gives me a reasonable bid) so I can get started on framing, roofing and siding. Then wait until everything is dry early this summer to do the floor and driveway.
- Rick
[ Digging the trench through the frost, though, that is another story. My excavator said it might be quicker and certainly cheaper to just wait for spring. ]
The concrete guys said that one issue with trying to pour slabs in the winter was not so much the concrete freezing (they can use blankets, heaters, tents, etc to keep it warm), but getting the ground underneath graded properly.
Another problem they mentoined is that even if they can get the grade worked out, when the ground underneath thaws in the spring, there will certainly be significant settling. Normally, when a driveway or floor slab is poured over dry dirt, the dirt tends to stay dry because all the water runs off of the slab (assuming no hydrostatic pressure pushing water up from below). The next winter there is little or no moisture to cause the dirt to move when it freezes again. But if you pour over ice/frost-saturated ground, the slab will sink and crack in the spring.
Note that slabs poured in low spots with improper drainage will also eventually have problems because water can still accumulate underneath them (through cracks, from the sides) and the frost heaving will likely break them up.
So my plan is to put in the foundation now (assuming the excavator gives me a reasonable bid) so I can get started on framing, roofing and siding. Then wait until everything is dry early this summer to do the floor and driveway.
- Rick
