Help - Foundation Drains

[Tractor_Jim_CT]

Live near the shore in Connecticut and the soil is a sandy dirtm with no rocks. Just added a crawl space for an addition and need advise if I should add a foundation drain around the living areas of the foundation.

The escavator and the company installing the foundation said a drain was not needed since the soil is very sandy, yet the person who would be water proofing the foundation with a spray on Tuff-and-Dry process said a drain should be installed with the holes down.

Questions
1) Should I install the drain
2) I found PVC pipe at HomeDepot with holes on two, opposite sides. I would think the holes should be at 3 o'clock and 9 o'clock, so water entering the pipe can exit at 6 o'clock. Everywhere I've read, says to put the holes on the bottom, which would mean 6 o'clock - so how does water travel through a pipe if all of the holes are at 6 o'clock, wouldn't it just grain thru the next 6 o'clock hole and travel nowheres.
3) I read to put a material around the pipe - a fabric screen to prevent the holes from clogging - any thoughts n a brand or where to get this material.

Thanks everyone

Jim

 

[PAexcavator]

I beleive the material you're looking for is Geotex, it's sort of a woven polyethylene, lets water through. It's what silt fence is made of, that black material strung between stakes about 2' high on slopes around consruction areas.

 

[randy41]

if you use the drain pipe with the holes facing down then all the holes would fill with water and then the water will flow out the end. it needs to be laid in a bed of gravel. sloping down toward the discharge end. then covered in gravel. then you cover the whole thing with that geotextile stuff to keep dirt out.
i guess a good test of its necessity is if theres standing water around after it rains a lot. its relatively inexpensive to do it and real hard to do once you back fill.

 

[MarkV]

Jim, I would put in a drain for sure. Your excavation contractor may well be right about the soil but putting in the drain is not that expensive and would be a costly repair if you had to come back and do it later. Around here we use a perimeter drain material that is rectangular in shape, about 2” wide and 8” tall, and is a honey comb type of plastic covered in silt cloth to prevent clogging. It runs somewhere around a $1 per foot and is normally installed by the water proofing contractor. The drain is set vertically along the base of the wall and does not require a gravel bed.

If you can’t find something like that you could use the round black perforated drain pipe that is sold in rolls at Home Depot type places. Home Depot also sells the silt cloth socks that fit right over the drain pipe so a gravel bed is not required. With that type of pipe you do want the holes facing down.

MarkV

 

[Defective]

I'd agree. Put the drain in regardless. Don't do it without gravel tho. I had to replace the drain pipes around my foundation in a place I used to have because someone figured that gravel was not needed due to incredibly sandy soil. The sand eventually worked its way through the silt cloth and filled up the pipe. Gravel will not stop this, but it will delay it for decades.

The pipe I used had holes all the way around. It's not critical to avoid holes on top, just to have holes at the bottom so that the water can make its way up into the pipe. The only benefit to a solid top is that it helps slow down (not stop) soil getting inside the pipe.