I have just laid down the skirt insulation around my monolithic slab. Slab is on 3/4 clean which extend out about as far as the skirt insulation does so there should be no issues with water accumulation under the slab and skirt insulation. I have started backfilling on top of the skirt insulation but I’m beginning to wonder if I’m going to end up with drainage issues in the 12” of soil that is above the skirt insulation. I installed the skirt insulation at a downward angle to help with drainage and the soil will be graded away from the slab on all sides. Any input would be appreciated.
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Perimeter skirt insulation
- Thread starter Mike_72
- Start date
kaymccampbell
Well-known member
Looks fine.
I looked online and couldn’t find too many details on types of backfill and/or drainage to put on top of the skirt insulation. Would I have been better off backfilling with river rock or something else that would encourage more drainage?
Looks fine.
Thanks Kay
The only reason I see to use rock would be if you also put in a perforated pipe to redirect the water somewhere else. Rock just creates a place for water to pool right up against your foundation.
Most of the images I’ve seen online show the drain pipe and coarse aggregate below the skirt insulation. I am planning on planting a small garden on that side of the garage from the slab out about 2-3 feet. I guess I’m concerned with the soil becoming drenched in that area when the water can’t drain from the soil due to the skirt insulation below. I’m also concerned what effect the soaked soil will have on the slab when it freezes.
spudley
Well-known member
If you slope the soil away from the garage you should be ok, but if you're concerned with moisture (and gardens need moisture) here's what I did.
Around my house foundation I placed doubled up 6mil black plastic sloped into an excavated trench directly under my gutterless roof eave. I then put 4" of filter sock corrugated black drain pipe in the plastic lined trench. Covered everything with 2-3" of 3/4" stone. The area extends about 30" out from the foundation wall.
The collected water goes to daylight forty feet away from the house.
This place is on a lake and the full basement (no crawl space) is bone dry so I guess this system is working.
Around my house foundation I placed doubled up 6mil black plastic sloped into an excavated trench directly under my gutterless roof eave. I then put 4" of filter sock corrugated black drain pipe in the plastic lined trench. Covered everything with 2-3" of 3/4" stone. The area extends about 30" out from the foundation wall.
The collected water goes to daylight forty feet away from the house.
This place is on a lake and the full basement (no crawl space) is bone dry so I guess this system is working.
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If you slope the soil away from the garage you should be ok, but if you're concerned with moisture (and gardens need moisture) here's what I did.
Around my house foundation I placed doubled up 6mil black plastic sloped into an excavated trench directly under my gutterless roof eave. I then put 4" of filter sock corrugated black drain pipe in the plastic lined trench. Covered everything with 2-3" of 3/4" stone. The area extends about 30" out from the foundation wall.
The collected water goes to daylight forty feet away from the house.
This place is on a lake and the full basement (no crawl space) is bone dry so I guess this system is working.
Thanks for your input. I was kinda thinking the same thing, if I have too much drainage there nothing will grow.
Unrelated to my first question but should I have put some 6 or 10 mil poly down on the XPS foam to prevent it from becoming soaked in water?
spudley
Well-known member
What's in your soil? If it's clay, not much water will get thru 12". If sand, slope is more important to shed water. I don't think I'd worry too much about buried XPS.Thanks for your input. I was kinda thinking the same thing, if I have too much drainage there nothing will grow.
Unrelated to my first question but should I have put some 6 or 10 mil poly down on the XPS foam to prevent it from becoming soaked in water?
What's in your soil? If it's clay, not much water will get thru 12". If sand, slope is more important to shed water. I don't think I'd worry too much about buried XPS.
Not very sandy, I would consider it pretty typical top soil. Compacts pretty well so I’m hoping that once it’s graded nicely I shouldn’t end up with too much water build up in the soil over the insulation.