View Full Version : french drain
08-29-2010, 08:59 PM
My contractor is putting in my french drain but the pipe does not have holes on the bottom, only on the top and the sides.. Is it correct? Will that be effective in carrying water away or should I have him redo the pipe? thanks
09-02-2010, 05:21 PM
pipes with holes...the holes should be on the bottom of the pipe. Otherwise, any and all water which goes below the top of the pipe can never "get in"..
By any chance does the pipe have holes top AND bottom.
This is a forum which we do not visit so often, hence the long reply time
09-12-2010, 01:33 PM
the pipe has holes on the sides and the top..
09-12-2010, 09:25 PM
The pipe should be turned so that the center row of holes in on the bottom.
09-13-2010, 01:25 AM
It seems counterintuitive, but holes down. The pipe in a french drain doesn't act like a gutter, catching water - rather it acts as a conduit - a path through which the subsurface water can flow more easily than through the surrounding soil. In fact, you don't even need the pipe -- simply making a gravel filled trench (properly pitched away from the problem area) will work - the pipe (in a fabric sleeve), just lasts longer, as eventually the gravel will become loaded with silt and will no longer function as an effective conduit.
If you were to place the pipe holes-up, it would still function, but it would only drain water higher than the level of the holes (and load up with silt faster). Placing the holes down also allows the water to flow out when it reaches an area where the soil is less saturated.
09-13-2010, 02:39 AM
Is the writing stamped on the pipe faced up? This is the proper way for the pipe to be layed. The holes are usually on the lower sides of the pipe.
Water will get into the pipe regardless of how the holes are oriented, but the real question is "what else will get into the pipes through the holes?" If the openings are on top, and are not covered, then debris WILL fall into the pipes and eventually could compromise it. On the bottom any water can either seep out of the pipe if the ground is dry, or discharge it if the ground is soaked.
09-18-2010, 11:08 AM
These things have never worked for me; the soil [clay] may not have been permeable enough or the surface area of the drain volume was too small.
What kind of rainfall did he size it for?
I guess a 25-Year Return Period, Fig. B-6, is pretty decent.