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Community and Q&A

Capillary Break Between Footing and Wall

dennis_vab | Posted in General Questions on

I am about a week away or so from breaking ground and having my concrete contractor start on the footings. I have considered the different ways to apply a capillary break between footing and wall, thanks to this site, which has been super helpful.

There are good options such as drylok and masterseal (thoroseal) however some of these require the concrete to be more cured and the environment has to be ideal.

Someone commented on a previous post or question about using 12” strips of Henry Blueskin, which I liked the idea of. I will cut slits on one side so that it can hug the rebar, and I will overlap the other 12” sheet from the other end.

One question I had was if I should consider using this on the garage footings as well. The basement and frost walls will be monolithic so I was wondering if there would be any horizontal transfer of water within the wall?

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  1. Expert Member
    BILL WICHERS | | #1

    Henry makes several variants of Blueskin. For a capillary break, you want something that is a vapor BARRIER, not something that is a vapor RETARDER. Henry makes versions that have different levels of vapor permeance, so you would need to pick one that is a true vapor barrier in this case. For a WRB, you would normally want something that was more vapor open to allow for drying, so the products are not all interchangeable.

    Sill gasket is usually made of a thin sheet of polyethylene foam, and it can act as a capillary break, although I've never considered it to be a reliable one since it's too easy to damage. Dana, a frequent contributor here until recently, frequently recommended strips of EPDM roofing membrane. This material will work well as a capillary break, and it has the advantages of being reliable over the long term and also relatively easily available. I like using stripes of HDPE, basically rigid polyethylene sheet, which is often cheaper than EPDM and has the advantage of being fairly stiff and slick which makes it easy to slide in when doing retrofits which is where I usually use it.

    In my opinion, you're better off with EPDM or HDPE sheet than Blueskin for the purposes of a capillary break here.


    1. dennis_vab | | #2

      Thanks Bill, I will take a look at it. I am still looking a couple liquid applied options as well, as that may be feasible. Do you have any comments or thoughts on extending the capillary break for the garage frost walls?

      1. Expert Member
        BILL WICHERS | | #3

        Liquid applied capillary breaks make me nervous. If you go that route, try to pick something that applies a THICK coating. You don't want to get holes and tears in your capillary break as you install the sill plates, so you need something that is fairly tough.

        Ideally you want a capillary break between wood and masonry anywhere there is any possibility of water wicking. This would mean at any slab or wall connections, and possibly other places too depending on the design. The thinking is "concerete likes to be wet, wood like to be dry, so I need a barrier between the two". It doesn't hurt to have capillary breaks where they might not be needed, but it can be a problem to leave out a capillary break someone you didn't think needed one. Better to have it and not need it than to need it and not have it in this case.


  2. kyle_r | | #4

    If you are interested in liquid applied capillary breaks I would check out Henry’s CM100 and Aquabloc WB.

    1. dennis_vab | | #6

      I’m sure those are two great products. However one thing I learned was that it’s a lot easier to deal with supplies that are more readily available in the area. For me one would be W.R. Meadows. I spoke to their technical staff today and he recommended the Hydrolastic 863. It’s a roll on product that would work in my application.

      1. kyle_r | | #9

        I agree. I have found both of these online though, may be worth a cost comparison.

  3. AC200 | | #5

    Martin wrote an article on this. I'm planning on using the Delta membrane or the Henry CM100

    1. dennis_vab | | #7

      The delta membrane is a nice product from what I can tell. I asked my concrete contractor if he could use it if I bought it. And he said “ You would have to be there with everything cut to length. I don’t no how fast everything gonna set up”. At that point it makes me lean towards taking it upon myself to install after the fact.

  4. plumb_bob | | #8

    The capillary break between the footing and foundation wall will make the cold joint even weaker than usual, I would form a key way into the footing to lock the 2 pours together.

  5. drewintoledo | | #10

    I am in the same boat. I decided to select Xypex as a solution to be added to the concrete mix. Essentially, the concrete itself becomes the capillary break.

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