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What is the best approach to waterproofing stone foundation walls?

We have a 100-year-old home, and are introducing exterior foundation drains to help mitigate water infiltration in basement. What is the best approach to waterproofing stone foundation walls? Spray-on products?

We will be excavating to expose entire foundation wall, introducing perforated pipe to daylight, creating a drainage plane against wall with aggregate. Given the porosity of the existing stone foundation, we'd like to consider a spray on or paint on waterproofing application. Looking for advice.

Asked by Robert Post S.E. Pennsylvania Zone 4a
Posted Sep 25, 2011 12:54 PM ET
Edited Sep 26, 2011 5:49 AM ET


7 Answers

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I'd also be very interested in what the Pros say. I've seen discussions of using Hydraulic Cement such as Xypex Patch'n Plug http://www.xypex.com/products/product_types.php?pageID=18
combined with Xpyex concentrate http://www.xypex.com/products/product_types.php?pageID=14

apparently it literally plugs the capillary tubes present in porous rock. However, I've never done anything like this and I honestly wonder if something oil or rubber based would work better or worse.

Thanks anyone who can help us!

Answered by Danny Vanderbyl
Posted Sep 25, 2011 2:35 PM ET


I'll be interested too. My instinct would be to try to use some type of sheet material rather than a liquid-applied, but I have little experience with stone foundations (aside from taking them out and retrofitting concrete).

Answered by David Meiland
Posted Sep 25, 2011 3:48 PM ET


One of my concerns is compromising the integrity of the stone foundation wall during the procedure. Another is short-circuiting the walls ability to manage moisture. I've even considered shot crete on the exterior to sure up stone and waterproof.

Answered by Robert Post S.E. Pennsylvania Zone 4a
Posted Sep 25, 2011 4:35 PM ET


There are several ways to address your question. I would be inclined to install several inches of closed-cell spray polyurethane foam on the exterior of your stone walls. (Yes, spray foam can be used on the exterior of foundation walls.) You need to have a contractor who is experienced at such installations.

Below grade, the cured foam needs to be protected from physical abuse during backfill; XPS boards would work, as would dimple mat. Use a coarse granular material like crushed stone for backfill. Above grade, protect the cured foam with stucco.

Answered by Martin Holladay, GBA Advisor
Posted Sep 26, 2011 5:53 AM ET
Edited Sep 26, 2011 5:53 AM ET.


Try contacting a local Basement waterproofing company. My guess would be a spray on asphalt or rubber product. Not very green, but hey, it works.

Answered by shane claflin
Posted Sep 26, 2011 8:13 AM ET


Great approach Martin. I contacted my regular foam guy and he provided this detail:

Sub Grade Application working doc 010609.pdf 1.17 MB
Answered by Robert Post S.E. Pennsylvania Zone 4a
Posted Sep 27, 2011 4:16 PM ET


Sounds good. Glad I could help.

Answered by Martin Holladay, GBA Advisor
Posted Sep 27, 2011 4:28 PM ET

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