# Retaining Wall Drainage?



## Daniel Holzman (Mar 10, 2009)

You have not told us what type of retaining wall you are building, wood railroad ties, segmental concrete block, stone wall, reinforced concrete, could be anything. The drainage varies with each type of wall.

The simplest retaining wall for a DIY person is a segmental block retaining wall. This type does not need a special footing, and for a wall three feet tall, may not need any special drainage. See the manufacturer's recommendations for drainage, they are all different. I built a three foot tall segmental block retaining wall underneath my deck for access to the basement, no need for drainage, any water collecting on the uphill side seeps right through the block. As I say, different block manufacturers, different design specs.


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## TarheelTerp (Jan 6, 2009)

dmennenoh said:


> So, I don't get how I lay the drain tile so it can get outside the wall.


Lets assume you have a positive grade AWAY from the house...
and that any drain pipe you use will be parallel to the house...
and down hill from it running along the length of the far retaining wall.

OK so far?

At the low end of that run you leave a gap in the wall that the 4" pipe can fit through and then "run to daylight" or a storm drain etc.

hth


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## dmennenoh (Jan 16, 2009)

Oh sorry, it's a segmental concrete block wall. We're using the Denver Straight by Midwest Mfg - just a gravity wall with a 3/4" set back lip. The manufacturer doesn't specify a drain pipe being used, just drainage aggregate as the wall isn't supposed to go higher than 36". Just everything I read/see shows using the plastic pipe... Is it ok to forego it?


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## Daniel Holzman (Mar 10, 2009)

Check with the manufacturer. I used similar block for my wall, no drainage pipe required for walls 3 feet and under. As I said before, only the manufacturer can tell you if that is OK for their particular block and backfill combination.


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## concretemasonry (Oct 10, 2006)

With a 3/4" set back and 3' high height limit, it sounds like it may be a Menards "knock-off" of the major products where they vary the dimensions slightly to avoid patent rights and the suggestion based on any of the 4 major domestic and internationally available may not apply but they look similar.

If they were purchased at Menards, their amount of design, testing and technical advice is limited and major manufacturers suggestions on any structural applications may not be applicable. Menards may be able to give you advice for darainage problem, but their exposure is somewhat limited.

Dick


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## Ravenworks (Oct 31, 2010)

If it were me I would put in the perforated black pipe with a silt sock on it and maintain a stone backfill (# 8's or 57's) one foot wide up the height of the wall to the bottom of your last coarse.You could let it drain out the end of the wall.
It may not be required,but it is very cheap insurance.


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