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Community and Q&A

Foundation capillary break & waterproofing

Martin_F | Posted in General Questions on

My wife and I are building a small home (First Day Cottage) on a full foundation with a walkout on the downhill end. I read about having a capillary break between the footing and foundation wall and it makes sense to me. When I asked the concrete contractor about it he said he’s never done it (though he did remember one other customer who asked about it a couple years back). I get the impression they won’t leave me much time to do it myself between pours. I was thinking I’d use Drylok Clear but their tech support said I would need to let the concrete cure for 28 days before applying to the footing. So that’s out. Is there anything I can use on uncured concrete that is relatively easy to use? If not is there a workaround – a way to mitigate after the fact?

The other aspect of the foundation I’m struggling with is what to use for waterproofing, again planning to do myself. My original thought was the black stuff but turns out that’s damp proofing and sounds like waterproofing is a better idea. Looking online there are as many opinions as products. I’d like to use latex Drylok or Drylok Extreme but worry about how well it will hold up over time. I’ll be installing 2″ XPS foam board over the waterproofing whatever it turns out to be. Any advice about waterproofing options is much appreciated.

Martin @ Hollow Hill

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  1. kenorakq | | #1

    I am following this thread as well...thanks for asking.. I need to know as well!

  2. user-953897 | | #2

    I recently had the same issue finding an appropriate product for a capillary break in a foundation wall. We ended up using MasterSeal 581 (aka Thoroseal) which we were told was appropriate for the use and timing. I can't verify yet that it is accomplishing its purpose but it seemed to work well and didn't cause any problems for the concrete sub other than requiring an additional day before building the wall formwork.

  3. GBA Editor
    Martin Holladay | | #3

    Here are four products that can be used for a capillary break in this location:

    1. Asphalt-based dampproofing

    2. Latex-based low-permeability paint (elastomeric paint) -- for example, UGL DryLock latex masonry paint

    3. Delta Footing Barrier

    4. Cementitious coatings (cement-based waterproofing)

    Here is a link to a relevant video:
    Installing a capillary break on top of concrete footings.

    Some builders have used 6-mil poly, although poly isn't easy to work with in this location. (Then again, asphaltic dampproofing isn't easy to work with either.)

  4. Martin_F | | #4

    Robert - thanks for your response, I'll check out the Thoroseal. I liked the idea of using Drylok because of the ease of application but having been told by UGL that the footing needed to cure for a month before application made it impractical.

  5. Martin_F | | #5

    Martin - thanks for your response. I had mentioned the problem with using Drylok which presumably would apply to other coatings of this type; Is a damp proofing product effective as a capillary break? It's not waterproof. I'll check out the Delta Footing Barrier and video. Don't think the poly would be feasible especially since the contractor doesn't want to bother with a capillary break at all or be inconvenienced by me doing it. Timing is his main interest so I need something that can be used on uncured concrete, applied in a day, and then have the wall poured a day later or however soon they come back. I'm thinking Thoroseal that Robert used is one of the cementitious coatings. Think my big mistake was not knowing enough soon enough to get a cement contractor who was on board with having a capillary break.

  6. GBA Editor
    Martin Holladay | | #6

    All of the products I listed, including asphalt-based dampproofing, will work as an effective capillary break at this location.

    You are correct that Thoroseal is an example of a cementitious coating (a cement-based waterproof coating) listed as option #4 in my list.

  7. Martin_F | | #7

    Martin - do you see a best option for applying to concrete footings that haven't had much time to cure?

  8. GBA Editor
    Martin Holladay | | #8

    I guess you would have to check with the manufacturer of the product you choose. But I know that asphaltic dampproofing can be applied right away. Of course, dry sunny weather helps the dampproofing cure quickly -- otherwise it's a sticky mess.

  9. Martin_F | | #9

    Robert - I see in the MasterSeal 581 data sheet the concrete should "obtain 80% of its design strength" which they say will take 3-14 days. How long did you wait before application after the footings were poured - one day?

  10. Expert Member
    MALCOLM TAYLOR | | #10

    See if your concrete batch plant offers crystallizing admixtures like Xypex. It will act both as a waterproof on the walls, and effectively a capillary break.

  11. Martin_F | | #11

    Martin - just watched the video you sent the link for. I liked the looks of whatever it was they used for the capillary break, appeared to be roll or sheet goods of some sort, but other than referring to "capillary break material" and the "black stuff" they didn't say what it was, any thoughts? Sorry to be such a pest but our footings will be poured in a couple of days so I'm stressing about coming up with a solution that provides the CB and the contractor can live with schedule-wise, thanks.

  12. Martin_F | | #12

    Malcom - great idea and it solves the waterproofing problem too. Not sure if feasible especially with this contractor but I'll find out, thanks.

  13. GBA Editor
    Martin Holladay | | #13

    I'm not sure what it is. I just sent an e-mail to the guys at Hammer & Hand; if they respond, I'll post their answer here.

  14. GBA Editor
    Martin Holladay | | #14

    I got a fast answer from Skylar Swinford. Here's what he wrote: "We typically use TREMproof 250GC by Tremco. It can be installed on green concrete."

    It's a fluid-applied product. Here's a link to a web page with more information: TREMproof 250GC.

  15. GBA Editor
    Martin Holladay | | #15

    In a followup email, Skylar wrote, "Henry CM100 Cold Fluid-Applied High Building Waterproofing and ePro ECOLINE-R Liquid Applied Membrane are also both intended for application over green concrete and should be suitable alternatives. I've also seen BASF MasterSeal HLM 5000 (formerly SONOSHIELD HLM 5000) used for this application, but the data sheet recommends a primer before installing on green concrete."

  16. Martin_F | | #16

    thanks for all the research Martin - not sure how much luck I'll have getting a relatively small amount of either the Henry or BASF products but I'll look into them. I've got a call in to the local concrete supplier, they never heard of Xypex but are going to call me back to let me know if they will do as a batch admix. It would be a great solution in that both problems are solved (capillary break, foundation waterproofing) without taking scarce hours of my time. If the Redi Mix guys will do as an admix can't see that the contractor would have a problem with it since no impact on what they do. It's tough around here because it seems many contractors are just doing what they've always done (and they say so proudly) rather than keeping up on current technologies, maybe it's that way everywhere.

  17. Andrew_C | | #17

    This is a good thread - capillary breaks are always specified and shown in drawings, but the details are harder to find. Thanks to the contributors.

    Off topic: speaking of contributors, I really appreciate builders who provide technical details and information at their websites. Hammer & Hand provide terrific information. I also like Matt Risinger's site. (I know there are other many others to supplement the GBA library and articles, but I just visited those sites in the last couple of days so they come to mind.)

  18. Expert Member
    MALCOLM TAYLOR | | #18

    We don't use a capillary break as we generally do the footing and foundation walls as one monolithic pour., but wouldn't the simplest way be to use blueskin (peel and stick membrane)? It comes in 12" rolls and is fairly cheap.

  19. user-953897 | | #19

    Martin F- The footings were placed on a Friday and the MasterSeal was applied on Monday. The only problem we had was if we later had to bend any of the rebar that went through the capillary break it tended to come off in chunks.
    I personally wouldn't recommend a sheet product if you have much rebar to work around.

  20. Martin_F | | #20

    Thanks all for the continuing info/suggestions. I just got a callback from the Xypex rep for this region and if I can convince the batch plant guys to order it or get it to them myself and they will do the admix (they thought it would be done at the job site but it has to be done at the batch plant) I'll have a waterproofed wall structure with integral capillary break. I'll post how it turns out, thanks again for all your help!

  21. Bill_NC | | #21

    I've got a question to those that have used the UGL DryLok latex product as a capillary break at the footing before laying block. I know that UGL only recommends using their clear product in this application because the white latex product reduces the bonding of the mortar to the footing. However, I have rebar dowels at 16" oc at corners, 32" oc every where else, so I don't think that will be an issue. The dowels were drilled in and installed with Super PorRok. The first course of block and the top course of block will be bottomless bond beams. Total of 4 courses of 8" block. All block will be filled with concrete mixed with pea gravel. (So even if I used a non-wicking mortar additive, the block fill would still be in contact with the footing.)

    1 ) When using UGL DryLok white latex, has your mason had any issues with getting the bed joint to support the 1st course of block to elevation due to a lack of suction? My bed joint should be pretty close to 7/8".

    2 ) Any other readily available alternatives to DryLok white latex?

    Thanks in advance for any and all feedback,


    PS, I did find Tremco Tremproof 250 GC in stock locally, but it was going to be much more expensive than the DryLok. This crawlspace will not be subject to any hydrostatic pressure, just wicking.

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