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Musings of an Energy Nerd

Capillary Breaks Above Footings

Install a peel-and-stick membrane or a fluid-applied waterproofing product between concrete footings and basement walls

If the footing includes protruding rebar, it's usually easier to use a liquid-applied product. The photo was taken by GBA reader Jimmy Nguyen; in the photo, Jimmy's father is brushing a coat of Super Thoroseal on a concrete footing to act as a capillary break.
Image Credit: Image #1: Jimmy Nguyen

Builders routinely install several types of barriers to avoid damp basements. Examples of these features include a layer of crushed stone and polyethylene under a basement slab; asphaltic dampproofing on the exterior side of basement walls; and sill seal made of thin closed-cell foam between the top of a foundation wall and the mudsill. All of these materials are used to reduce the transfer of moisture from the damp soil surrounding a foundation to the interior of the building or vulnerable framing lumber.

Even when all of the listed features are installed, however, many builders forget to include a capillary break between the concrete footing and the basement wall. While installing such a capillary break isn’t common practice, it’s important.

About capillarity

If you place a large dry sponge in the middle of a shallow puddle, the top of the sponge soon becomes wet. This is a commonplace occurrence, so most people have an intuitive grasp of how capillary action works. Capillary rise isn’t a phenomenon that is limited to sponges, of course; it also happens with concrete walls, CMU walls, and stone-and-mortar walls.

Capillary rise occurs when the forces of adhesion (the attraction between the molecules of a liquid and those of a solid) are stronger than the forces of cohesion (the attraction of the molecules of the liquid for each other). In some circumstances, equilibrium between these two forces is not achieved until the liquid has risen many feet.

In many houses, capillarity is responsible for the rise of water from damp soil under concrete footings into foundation walls. This phenomenon can contribute up to 15 gallons of water a day to a home’s interior moisture load. Capillary action in soils and masonry — called “rising damp” in Britain — is a…

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16 Comments

  1. C. B. | | #1

    Another Product
    I used a water-based, environmentally-friendly product which isn't affected by UV rays (obviously only important for the part of the wall that is above ground). Made in the USA. Looks nice too (again, only important for the part of the wall that is above ground).

    It is ICC tested and certified:

  2. Ken Hodge | | #2

    FabForm?
    The Fabform system where the footing and the stem wall are a monolithic pour seems like it addresses the capillary issue and several other issues all in one shot. Or am I missing something? Considering using this system on a future house build.

  3. Charlie Sullivan | | #3

    FabForm
    It looks like FabForm uses plastic wrapped around the footer. That seems like it's subject to the same concern that Martin expressed about wrapping plastic under the footer. Basically you'd need the plastic good enough to keep it dry if it's sitting in a puddle. I suppose if the plastic is thick enough, it could work, but I didn't spend enough time at that site to see how they seal the seams of the plastic.

  4. Rick Milne | | #4

    Fabform Feedback for Ken
    Ken...I would consider minimizing the rising damp from below the footing and accepting less capillary action up the wall a better strategy as opposed to locking it into the footing with a barrier on top...assuming you have the option. I did use Fabform a woven poly product to create footings for a 2600 sq foot ICF garage in BC. I had never build footings and found once I got onto it it was OK to install but I loved it after the pour as I ran it up my ICF wall screwed it into the webs and ran the Soprema peel n stick down overtop. There are no seams to seal. On the interior I ran it up the wall and onto the EPS floor insulation and integrated it into the poly sheet to create a continuous barrier. I would not recommend the monopour other than for a short stem wall and not for any large basement ICF walls as I think from having seen it done there is too much room for errors. I am planning a house in the near future and plan to use Fastfoot again.
    Not sure that I would use the Fabform system AND put a coating over the top of the footing as I would rather have the footing have some ability to breathe. BTW...Martin suggested an air source heat pump and underslab insulation 8 years ago as opposed to in-slab radiant and his advice was golden.

  5. User avater GBA Editor
    Martin Holladay | | #5

    Response to Rick Milne
    Rick,
    I'm glad that my 8-year-old advice was helpful. Thanks for the feedback.

    I think we'll have to agree to disagree on one of your points -- "I would consider minimizing the rising damp from below the footing and accepting less capillary action up the wall a better strategy as opposed to locking it into the footing with a barrier on top." Of course, the risk I identified -- the possibility of the footing sitting in a puddle when the holes on the footing drain are located above the bottom of the footing -- will only happen on particularly damp sites. But it can happen.

  6. Kohta Ueno | | #6

    DELTA®-FOOTING BARRIER
    Sorry if this is pushing the edge of excess commercialization, but an excellent off-the-shelf product for the footing-to-foundation wall capillary break is Cosella Dorken Footing Barrier. It is a polyester/polyethylene-based membrane that is pushed into the top of the freshly cast footing. It adheres, because it has a fleece surface--for those who use Schluter Kerdi membrane, I believe it's really similar. Placing the Footing Barrier in place on a wet concrete footing allows for forming of the keyway as well; all of this is much more clear in the video.

    DELTA®-FOOTING BARRIER

  7. User avater GBA Editor
    Martin Holladay | | #7

    Response to Kohta Ueno
    Kohta,
    I am aware of the advantages of Delta Footing Barrier, which is why I listed it as a recommended product in the second bullet point of my article. Perhaps you missed the reference.

    Delta Footing Barrier was mentioned again in the last sentence of my article.

  8. Kohta Ueno | | #8

    Response to Kohta Ueno
    Whoops--my bad; thanks Martin!

  9. Catherine Young | | #9

    Xypex
    The Xypex product is also recommended for application directly to existing basement walls to stop leaks of water. Seems like it would be worth studying in this application if water vapor is not an issue:

  10. User avater GBA Editor
    Martin Holladay | | #10

    Response to Catherine Young
    Catherine,
    I'm aware of the recommended uses of Xypex. But it isn't necessarily true that a waterproofing additive (or a product designed to be applied as a waterproofing coating) will reduce capillary rise when added to concrete.

    The only way I know of to test the capillary characteristics of concrete or masonry is to test its capillary behavior.

  11. Sean Wiens | | #11

    Fabform System
    I used this system on my current build and would never use it again. The fabric is very vulnerable to damage during construction. Just brushing it with a shovel or rake will cause damage. Forget trying to blow gravel into the basement, I had to go around and protect all of the interior surfaces with plywood before moving gravel. Also the sewn corner will leak unless sealed up with P&S membrane. Red sheathing tape should not be used to seal, (vendor recommended), just pulls off (use a high stretch peel and stick). Membrane expands considerably during pour, so you need to estimate additional concrete, as well during the expansion it has a tendency to split any taped seams. It is very easy for the bag to get off centre during pour. I was lucky in that where it was the worst, I had a gable wall with very little load on foundation and so engineer signed off. Vendor will tell you to spike bag to ground, but this is just yet another set of holes you need to try and seal which is very difficult if fabric is expanding during pour. Also easy to get inboard and outboard sides of bag out of sink with one another (when being combined to an ICF situation), this will lead to fairly severe creases in the footing causing a stress riser that can lead to footing failure.

    Any hole in the system whatsoever, will defeat it as water will travel a very long distance from the penetration site down the footing and up into the foundation wall. I have been monitoring my 'bags' and often see water between bag and concrete if I let the water level get too high at the build site. If doing again, I would use the embedded membrane and key-way system.

  12. Don Jennings | | #12

    another concrete admixture
    I'm surprised there was no mention of Hycrete in this article. Would it not prevent capillary rise?

  13. User avater GBA Editor
    Martin Holladay | | #13

    Response to Don Jennings
    Don,
    Check out the three paragraphs of my article that follow the heading, "What about admixtures?"

    I tried to track down the truth behind the rumor that an admixture called Xypex might limit capillary rise. The manufacturer of Xypex said that they cannot endorse the use of Xypex for this purpose.

    You have proposed the use of another additive, Hycrete, for this purpose. Hycrete is sold as a waterproofing additive, and I can see why some people might assume that the product limits capillary rise. But in the absence of data, I'm not going to make any claims about capillary rise in concrete with Hycrete.

    Do any GBA readers have data on the issue?

  14. User avater
    Ethan ; Climate Zone 5A ; ~6000HDD | | #14

    MasterSeal HLM 5000
    Any experience out there with MasterSeal HLM 5000 for creating a capillary break?

  15. Dave B | | #15

    Epro Ecoline-R
    Just thought I'd update my experience with this product, now called E-Roll. I liked the ease of application especially around the rebar dowels, I put down 2 thick coats with a roller and still had some left over for a third. Footing was 2' wide and roughly 210'long.
    I also like the fact that it can be used to damp-proof my ICF walls and doesn't effect the foam, which I will be doing with the same product. They actually have a whole system for ICF walls. It comes in 5 gallon pails and cost around $120CDN.

  16. User avater GBA Editor
    Martin Holladay | | #16

    Response to Dave B
    Dave,
    Thanks very much for sharing your experience with Epro E-Roll.

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