Under construction – How bad is my foundation drainage?
I’m hoping to get some input. My house under construction is in 6B and the contractors didn’t follow the drawings.
Footings are 5 or 6′ deep due to frost line.
The main house foundation is ICF block with a waterproofing membrane and drain board with filter fabric. There is a footing drain, and it was supposed to be backfilled with gravel surrounded by the filter fabric (the “burrito”). Instead of backfilling with gravel, the contractor used dirt. He said the geotech engineer was onsite and told him it was okay. I don’t know yet if the burrito was done.
I know that if you have filter fabric, it is okay to backfill with dirt, but was planning both as belts and suspenders. I have been obsessive in my design about drainage because we have an underground stream during high snow-melt years, and I am massively mold sensitive. But I suspect this is probably okay even with the dirt fill.
But I’m not sure how well compacted it is; I told them several times how important the compaction is to me so the dirt near the house doesn’t settle and drain toward the house. Also the dirt has a lot of big rocks, up to 10-12″ etc. Is that good or bad for compaction and drainage?
The next issue is we have a hobby room off the garage which is slab on grade. We’ll spend a lot of time in there so it was supposed to be built as “good” as a house, not built like a garage. We bought the same R7 windows, have a zehnder ventilation loop, exterior insulation to prevent condensation on the sheathing , etc. In this case the foundation is poured concrete plus waterproofing membrane and 3″ un-taped EPS. The entire space under the slab/vapor barrier/sub-slab insulation is filled with gravel. But the exterior has no drain board or filter fabric, and they used the same dirt to backfill instead of gravel. Does the EPS foam there help in some way to create a drainage plane and relieve hydrostatic pressure, or is it just going to get soaked leaving water right against the membrane?
In addition I have learned there is no footing drain there like I expected. I haven’t studied slab on grade as much as crawlspaces and basements, but I think they still should have footing drains, right? Maybe this whole thing will work though because it will only be wet for a few weeks each year and then will dry?
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