drain tile put not to spec, now what?
Went out to the site today to discover the drain tiles were laid into the sand without the pea gravel as spec’ed by the architech. My builder says they’ll fix it by laying the pea gravel on top of the drain tiles before back filling. Says everyone he’s talked to, and from their collective experience, that this would be ok with the good drainage from the sand.
My last house had bad foundation problems–so I am hyper sensitive about getting this right.
Aren’t drain tiles supposed to sit encased in pea gravel, basically keeping the sand away from the tiles? Now what if the bottom gravel layer is missing, the tiles are buried in the sand to the top, and only gravel is thrown on top?
Replies
Is this your footing drain?
& yes drain tiles are normally laid in pea gravel.
What type of drain tile are you installing & it's purpose?
It is the footing drain. It is (I guess) standard black tubing with slots in it.
Not sure that having gravel below the drain tile is essential however you said:
>> Now what if the bottom gravel layer is missing, the tiles are buried in the sand to the top, and only gravel is thrown on top? <<
Are you saying that the drain tile is back filled with sand? I assume the drain tile we are talking about is black corrugated pipe with perforations or some other type of pipe with holes in it? Unless the pipe has a filter material of some type around it the sand mixed with whatever organic material is moving with the ground water (silt?) will migrate into the pipe and eventually clog it rendering it useless. This is mostly a problem with fine granular soils/backfill.
Pipe can be purchased with a "sock" on it. Another filter material is called septic paper and comes in maybe a 200' roll about 36" wide for around $30. Around here they sell it at Lowes. It's kind of like that see through thin fiberglass material that comes on the bottom of a box spring. It's cheap insurance against >> My last house had bad foundation problems << however from the sound of it, at this point it is gonna be several hours of labor to install it.
If the pipe that is already installed does have a filter membrane of some sort, I wouldn't worry about it as the sand will drain well enough.
The tile is back filled with sand. I forgot to add that there is some filter cloth wrapped around the tube.My question is how well will this keep matters out of the tube AND allow for water to penetrate? My concern with this membrane is at some point, it will clog.
If the pipe is wrapped in filter cloth I think you are OK. May want to check around though. Also, find out the manaf. of the filter material or the pipe (if the cloth came on the pipe) and contact them. Also, try running a hose in the footer and see what happens.
Where I live [N.E.] the common practice is to lay filter cloth, pea gravel, drain pipe, more pea gravel and then wrap the filter cloth around the top. A fine thing like sand will clog up the drain in no time. I think that you have to make the builder go by the architect's spec. I think that you have to resolve this before any back filling is done. Lots of luck.
NDS (major seller of drain pipe) has a nice book on the subject. I'd call them up and get their advice. In general I find that the big companies that sell engineered products are great resources for questions like this. When you get your answer, post it back here - I'm curious what they say.
Check out the drainage books (see links on right side of page)
http://www.ndspro.com/technical_info/index.aspx
and their contact info is here:
http://www.ndspro.com/contact_us/index.asp
good luck!
Thanks, I will have to track this down.