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Community and Q&A

Waterproofing (Blueskin) applied over tar?

Rickman75 | Posted in General Questions on

Our contractor has mistakenly applied roll-on tar (damp proofing) to our new residential build as opposed to waterproofing.
we are now looking for ways to further enhance the water/damp proofing and just wondering what your thoughts would be of applying the BlueSkin WP200 stick on membrane over the applied tar.
My concerns would be if the Blueskin would adhere properly and if there would be any chemical reaction between the two that would actually hinder the water/damproofing ability of either or both (tar and Blueskin).
Either way (with or without the Blueskin membrane applied), we will be adding the Delta drainage board and backfilling with sand against the house.

If anyone has another idea to enhance waterproofing outside of applying blueskin, please share as well.

I’ve discussed with contractors regarding spray on a rubber over the tar, but due to tar being chemical based and the spray on being water based, the tar would render the spray substance useless quickly.

I know the Blueskin in addition to tar/delta/sand may seem like overkill to some, but this was planning to be a forever home and any chance i have at this stage to enhance the waterproofing ability, I will gladly pursue.

Thank you in advance for any help/advice you can provide.

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  1. Expert Member
    Michael Maines | | #1

    Rick, I haven't used that product but based on the data sheet it seems like a perfect product for the application:

    "Blueskin WP200 is a self-adhering waterproofing membrane consisting of SBS rubberized asphalt compound, which is integrally laminated to a blue, tough, high-density cross-laminated polyethylene film. The membrane is specifically designed to be self-adhered to a prepared substrate providing a high-performance waterproofing barrier even under hydrostatic head pressures to 231feet."

    You should check with their technical support staff to make sure, though.

    This is your one chance to make your foundation waterproof, so don't skimp!

  2. GBA Editor
    Martin Holladay | | #2

    Once you've taken Michael's advice (and you've contacted the manufacturer of Blueskin to find out whether the product can be applied over a wall that is covered with asphalt dampproofing coating), you can consider whether or not you want to install a dimpled membrane on the exterior side of the Blueskin. A dimpled product provides a drainage path to the footing drain, and relieves the hydrostatic pressure against the wall.

    If you don't want to install a dimpled membrane, make sure that you backfill with a coarse, granular material like gravel or crushed stone -- some type of material to facilitate drainage.

  3. user-6184358 | | #3

    A product like XYPEX can be applied to the inside (or outside but directly to the concrete) surface of the wall. It interacts with the concrete to make crystals in the concrete. It was used in the new Panama Canal concrete.
    Pea gravel may be a better back fill in that is self compacting, so no equipment will be used that could surcharge the wall and push it out of plumb.

  4. Matt27 | | #4

    Hi Rick, what was your solution for this in the end? I am a similar situation. Thanks!

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