Building an ICF house with a full basement. Footings are 24″ wide and 12″ deep. Excavator dug down an extra 12″ around the perimeter so we wouldn’t have to dig out the footings.
We are using 6″ Form-a-Drain for the footing forms. What do we do about the 6″ gap under the Form-a-Drain?
Options we’ve thought of:
a) On the exterior, we figure we can shovel in dirt to the bottom of the Form-a-Drain, then pea gravel above that. We’re afraid to do the same thing on the inside because of compaction and subsequent cracking of our basement floor.
b) Could use more pea gravel, but are afraid we’d have trouble keeping the pea gravel where it belongs and the concrete from pushing it out.
c) Considered putting the Form-a-Drain on the bottom and 2x6s on top, then pulling the 2x6s off.
d) Putting 2x6s underneath the Form-a-Drain, then pulling them off after the pour.
Comments on the above? Other suggestions?
Thanks, in advance.
Replies
my basement guy just runs concrete around the footer up to about the bottom of the form,goes all around,then comes back and final fills it.by that time the first pour has lost some water and firmed up a bit. say's that the 1 yd maybe 2 he wastes is cheaper than trying to contain it.larry
hand me the chainsaw, i need to trim the casing just a hair.
Drape a geotextile cloth (soil separator) over the side of the forms. Leave about a foot of it on the ground and then it goes up the outside of the form and lays over the top to the inside. Fill the six inches of open gap with crushed stone and the add another couple of inches to buttress the forms. Fold the cloth back over the stone and pour the concrete. You now have the drainage stone and cloth in the right place to keep the Form-A-Drain and crushed stone from loading up with silt when you back fill the dirt.
Dave
Fill below the slab with crushed stone. We would use something called #67 washed which is think is 1 1/2" minus or even use screenings (fines) if there is going to be a bunch of plumbing under there. Stone grading is very regional though. Just curious - why are you suggesting using pea gravel - maybe it's a regional practice? As you state - pea gravel doesn't stay in place very well.
The footing concrete needs to extend down to solid, undisturbed ground. If it is poured thick - maybe at a 3.5" or 4" slump, it will stay in place pretty well and give you a strong outcome. A 6" gap is too big though. Your ideas will work fine but sound expensive.
Over-excavation can be a costly mistake but is no big deal just so that it is dealt with properly.
Making some assumptions here: Sorry, but looking at your screen name I have to say that this is a perfect example of why owner/builders don't save much money as they think they can by not using a pro builder.
Subtract $1000 from your savings, and move to next square on playing board. Do not pass 'go' until you roll at least an 8.
We are in the process of doing the same thing right now.
We used the 6" Form-a-Drain with 1" crushed stone. The stone holds its position well, along with a thick pour, we didn't have a problem with the concrete running out. You're better off with thick concrete anyway.
If you change the elevation of your form-a-drain, i.e. lowering it 6" w/ 2x6 on top, could affect your water removal method...if your using a sump pit, I wouldn't think you'd want your sump pit to be in a pit.
Best of luck to you,
Rip
If you go to Form-a-Drain on their site all the info. is right there. Luck.