Interior French Drain – Flex or Hard Pip
Hi
The basement is leaking in an end of group rowhouse I am renovating. I dug a trench around the interior walls and am about to put a perforated drainage pipe in that will connect to a sump pump. I have 2 choices for pipe that I can use. A white hard PVC pipe that has one row holes along the top. The other choice is a black flexible pipe that has holes all around the pipe. I don’t which is the better choice. I bought the white one, but is the flexible one with more holes a better choice. I did not buy the black one because I wasn’t sure how the water would flow to the sump with holes on every side. Does anyone have any suggestions?
Thanks
– Kevin
Replies
Put the holes on the bottom.
Steve
use the hard pipe you can't keep the other stuff on a level plane
The holes are to let the water in, keep them on the bottom, the water will know where to go. It comes up through hydraulic action. I don't like solid pipe and contractors in my area haven't used it in years. It doesn't have to be perfectly level, it should pitch slightly towards the drain. We use the rolls of black plastic with a silt sock over 3/4" crushed rock. There are no joints to come apart, sediment won't get in and block the flow.
Beat it to fit / Paint it to match
Thanks to all, I am glad I asked. I certainly was going to put the holes on the top. Glad that did not happen!
Hard pipe can be fitted with cleanouts, which would be the main advantage other than it can actually transport water if it's coming in from only one area rather than just spreading it around. By putting the holes near the bottom, but not directy on bottom, water entering the pipe on one end has a solid surface and with proper slope will flow.
Flex is cheaper to install, which is why everyone uses it, not because it's better.
Beer was created so carpenters wouldn't rule the world.
You should be putting the pipe in a drainage 'sock' of filter fabric ...
http://www.carriff.com/Products/drain-sleeve.htm
Keeps the pipe from silting up.View Image
Jeff
Lots of interesting perspectives here.
If you have general water and you are not along an underground stream, a flex pipe is easy to install and works fine. Definitely put in filter fabric.
I put filter fabric in the trench, push in the pipe and then backfill up close to the top with clean 3/4" stone. You can then put a little concrete on top of the trench (code for new construction now requires 4" in a lot of areas but no one will beat you if you put 2" in there.
Re. the slope of the pipe, level is fine. If you put water in a level pipe it will spread out along the length of the pipe. You have probably heard the term, "water seeks its own level"
Before lasers, water was used to level lots of stuff including acuoustic ceilings for a lot of guys.
If you have a hole at one end, the water will drain to the hole (sump) to the point that the pipe is mostly empty which is perfectly aok. You just dont want the whole pipe filled with water which would only happen if you unplug the sump pump.