French Drains

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    • #278612
      Avatar photoMasterPlumbers

        I am getting ready to build a new house, and don’t plan on using a sump pump. The lot I have seems to drain well.

        A friend of mine suggested I think about installing a “french drain” around the basement to relieve any water under the basement slab.

        I have never heard of a french drain, and was wondering if you could provide me some information from a professional standpoint.


      • #298869
        Avatar photoArt_xyz

          It is much easier and cheaper to install drainage for the basement now. If I were building in the Sarah Desert I’d install a drainage system just to be safe.

          I’m sure there are many ways to lay out a drainage system, but I’ll tell you what has worked for me.
          1. Tar the outside of the foundation.
          2. unroll a heavy guage plastic sheeting and stick it to the tar(start at the footer and work up).
          3. Run 4″ drainage pipe (with holes in it) around the outside of the foundation (lay it right on the footer). Cut in a tee and run it under the footer into a sump pit in the basement. You will need a sump pump to pump the water away from the house.
          4. Cover your pipe with appx. 18″ of #2 stone.
          5. Cover the stone with Typar (will help keep sand out).
          6. Backfill foundation after house is framed up.

        • #298870
          Avatar photoSylvanLMP

            Before you go out and “tar” the side of your building I think you had better talk to your builder about hiring a professional water proofer.

            You see a lot of NON Professional water proofers say buy TAR but they have no conception of what they are talking about. Its like a roofer saying get pipe to a plumber. Duh what kind? One size does not fit all neither does “TAR”

            There is “flashing cement” “TAR” and roof cement “TAR” and bitastatic ( great for lining gutters) “TAR” and coal “tar” enamel and “pitch” or any of various artificial mixtures resembling resinous or bituminous pitches that are all used for various water proofing applications.

            Plumbers use a TAR for protecting steel water tanks from rusting through.

            Plumbers also hire “pipe smokers” to coal tar enamel the inside and outside of water mains and man holes as well as other applications like steam and gas piping under ground.

            There is also certain grades of flashing cement and roof cement (summer grade and winter grades) Hot applied either sprayed on or with a daubing brush OR cold applied with a trowel or brush and then there is tar coatings like asphalt used on drive ways or older roofs where the rubberoid is dried out from the ultra violet rays and the roof is getting showing signs of alligatoring

            Flashing cement being slighter thicker and having a different consistency is used mostly on parapets and other vertical applications, roof cement does flow easier and thus is great for flat (hence the word ROOF).

            The bad part about using roof “tar” on the vertical is it can run as soon as it get warm and it is applied thinner ( normally) the bad part about flashing cement is its tendency to get hard and thus crack and must have some kind of medium to help it remain in tact

            This is why Water proofers use of various bituminous substances like cotton impregnated membrane or 15# felt or JR Grace has a fantastic cold applied application VERY expensive but it works wonders if applied properly and kept out of direct sun light.

            When I install roof drains for example I coat the 4 PSF sheet lead with an asphalt primmer so the “tar” will adhere better PLUS I prime the cement slab prior to using either flashing or roofing “tar” cement

            The hot applied applications under pressure can fill the voids that plumber doing water proofing can miss as the trowel can skim over lower areas of the foundation.

            There is also certain tars that can just flake off the walls if not properly prepared.

            I know of several cases I had to go to where the TAR applicator did the inside of the walls not realizing that cement has to breath and thus the foundation started crumbling.

            If you use “plastic” for example and vapor gets behind it where can it escape?

            Ever go on a roof and see blisters Or fish mouths? As a one time roofing inspector and now roof drain expert I see lots of failures due to the UN knowing using the wrong materials or the right materials for the wrong applications.

            Think about hiring a “professional” in the field your going to have them work in.

            When a future employee tells me he can do plumbing and electrical work and other trades I show them to the door. I believe in doing one thing BUT do it right. I hire plumbers to do plumbing and roofers to close up my roof openings. I do not believe in a tech doing all aspects of all professions.

            Ask your local licensed plumbing contractor OR water proofing engineer if you do need external drains.

            When they start the foundation work see if you can locate the water table NOT all houses need French drains. Damp proofing if applied RIGHT makes sense.

            Have a great week end

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