Replies

1. GBA Editor
   Martin Holladay | Jun 28, 2017 12:42pm | #1

   Jim,
   I suggest that you check out this article: Capillary Breaks Above Footings.

2. 
   swazo | Jun 28, 2017 09:12pm | #2

   Martin, I reread (scanned and did a key word search) the article about capillary breaks.

   I did not see anything about my two questions;

   1. Does 5,000lb concreate require a capillary break. (supporting documentation?)

   2. Does anyone know of a product that will provide a capillary break and soak into the concreate like the foundation company requires.

   Please let me know if I missed either in this article.

   I did find an product that might be suitable. Rust- Oleum Moisture Stop

   I wouldn't have as much confidence in this as a peal and stick or a "paint" but it might be worth doing considering the circumstances.

3. GBA Editor
   Martin Holladay | Jun 29, 2017 06:46am | #3

   Jim,
   When you refer to "5,000 lb concrete," I assume you mean "5,000 psi concrete" -- that is, concrete with a high compressive strength. To answer your question: I have never seen any information showing that capillary rise in 5,000 psi concrete is less than capillary rise in 3,500 psi concrete.

   I still think that the capillary break is a good idea, although I'm willing to be convinced by data if anyone has information showing that 5,000 psi concrete somehow affects capillary rise.

   Concerning your second question: I'm not sure what is meant by "soaking in."

   "Soaking in" is not a technical phrase. Does the concrete contractor simply want a product that looks the same color as the concrete, so that it is invisible once applied? If so, what's the point?

   From a technical standpoint, the hope is that the product creates a barrier that prevents moisture transfer via capillary rise. A barrier is a good thing. We don't want a product that "disappears" -- and in any case, you really can't use visual clues to determine the effectiveness of the product. Whether the product appears to "soak in" or appears to create a visible film is irrelevant. What is relevant is how well it works.

4. 
   swazo | Jun 29, 2017 09:36am | #4

   I'm meeting with the foundation contractor today. I will try to find out what his issue is with a product that sits on top of the concreate and his documentation about the 5,000 psi concreate. Sorry, I did mean psi rather than lb.
   The Rust-Oleum product says it "penetrates into concrete and reacts with the free calcium and water to form a gel in cracks, pores and capillaries to protect against the ingress of water". Does that make sense?

5. 
   msloot | Jun 02, 2019 01:53am | #5

   Has anyone found anymore documentation as to whether 5,000 psi concrete serves as a capillary break to prevent water from moving through it and up into the foundation wall?
   I hear it from concrete contractors on almost every project, but have not seen any documentation yet.
   Thanks,
   Marc

1. 
   Jon_R | Jun 02, 2019 12:23pm | #6

   Ask them for a chunk of their concrete and lightly wet the surface. Weigh it very accurately. Then let it sit for a week in water. Weigh it again.

   I suspect the more important question is "how little moisture transport is OK?". That depends on drying rate and why you care if the concrete is dry.

2. Expert Member
   BILL WICHERS | Jun 02, 2019 03:58pm | #7

   I’d try contacting civil engineer. They live and breath concrete, and would probably answer your question over the phone for free.

   Personally, I’d go with a capillary break to be safe. Water can still condense on the top of the concrete and soak into any wood there.

   Bill

1. 
   msloot | Jun 02, 2019 09:28pm | #8

   Thanks Jon R. and Bill.
   Yeah, I keep insisting on the capillary break to be safe.
   -Marc

1. Expert Member
   MALCOLM TAYLOR | Jun 02, 2019 09:37pm | #9

   To be fair, capillary breaks are relatively new and hardly ever used on residential projects. I'm not saying they aren't a good idea, but omitting one isn't the end of the world.