0 Helpful?

What is a capillary break between the footing and foundation wall?

Your details show a caplillary break between the footing and foundation walls. What is it? Is it continuous?

Asked by Arthur Ratner, AIA
Posted Jun 23, 2009 3:25 PM ET


12 Answers

Select your preferred way to display the comments and click "Save settings" to activate your changes.

A variety of materials can be as capillary break in this location. According to Joseph Lstiburek, these materials include "dampproofing, low-permeability paint, or elastomeric paint." 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.

Answered by Martin Holladay
Posted Jun 23, 2009 3:42 PM ET


Whatever is used between footing and foundation must not compromise the mechanical connection that resists lateral displacement, or - for practical reasons - not interfere with the subcontractors setting the foundation forms. The material should also be able to resist some hydraulic pressure.

Neither plastic sheeting nor asphaltic damp-proofing is acceptable. I use UGL DryLock latex masonry paint for this capillary break, as I do for general foundation waterproofing.

Answered by Riversong
Posted Jun 25, 2009 10:27 AM ET


Robert, what's your reasoning on the unacceptability of plastic sheeting or asphaltic amp-proofing for the capillary break?

Answered by Dick Russell
Posted May 27, 2010 10:18 AM ET

Answered by Michael Maines
Posted May 27, 2010 11:55 AM ET



As I already stated, the capillary break must not compromise the physical connection between footing and wall, which typically relies on a keyway and the friction of the concrete. If rebar pins are used, they will compromise the integrity of the plastic. A coat of hydraulic paint, like UGL Drylock will not change the bond of the wall to the footing or lose integrity with either keyway or pins.

Asphaltic damp-proofing is exactly what it claims to be, which is not water-proof.

Answered by Riversong
Posted May 27, 2010 10:03 PM ET


To follow up with this, should a capillary break be used when Concrete block is being used and not poured concrete? All the pictures I see have a Key and lock approach, that seems to me it keeps the wall from moving. But in the case of a concrete block, both surfaces (the poured foundation) and the block are flat. What would keep the wall from moving?

Thanks in advance.

Answered by Kurt Samson
Posted May 28, 2010 10:58 PM ET


Vertical rebar embedded in the footing. The rebar extends into block cores which are later filled with grout or concrete.

Answered by Martin Holladay
Posted May 29, 2010 5:14 AM ET



A concrete block foundation is no different from a poured concrete foundation in terms of wicking ability. If there is any possibility of moisture in the ground and you want a dry basement, then a capillary break should be installed between footings and walls, on the outside of foundation walls, at the wall/sill interface, and between the walls/footings and the slab (in addition to a thermal break).

Answered by Riversong
Posted May 29, 2010 12:03 PM ET


Very interesting, and new to me. Robert: I assume these are the steps: After footers are poured and are dry, the paint is applied. You apply the paint to the footers well before you pour the foundation wall, so the paint is dry. Yes? thanks. john

Answered by John Klingel
Posted May 29, 2010 11:08 PM ET



UGL Drylock Latex Masonry Waterproofing dries in less than an hour, can be second coated in three hours and is ready for foundation in 24 hours.

Concrete has a theoretical capillary limit of about 6 vertical miles. In other words, it has a high propensity for wicking moisture and requires a capillary break at each junction to prevent "rising damp".

Answered by Riversong
Posted May 29, 2010 11:40 PM ET


I spoke to Drylok's technical support, and they said the only one of their products suitable for this horizontal application is Drylok Clear. They recommended 2 coats and said to allow it to dry for 2 weeks before pouring the wall on top of the footing. The two week delay is obviously a problem for most construction sequences. Does anybody know of a brush/roll/spray applied product that has the manufacturer's and support for this application?

Answered by Eric Stear
Posted Jul 31, 2014 12:28 PM ET


Eric - what did you end up using? I'm considering the use of Thoroseal (or Super Thoroseal) on the footings after a 7-day wait, 2 coats with 24 hours between coats and before the foundation wall is poured. I confirmed Thoroseal can be used on green concrete. Is there anything better that would keep the schedule moving and be suitable for a footing with a lot of vertical rebar (no key)?
Would using HYDRALASTIC 836 (also ok on green concrete) be worth the extra cost vs Thoroseal?
Is everyone else who uses Drylock really waiting 28 days before applying?

Answered by e c
Posted Sep 9, 2014 5:06 PM ET

Other Questions in GBA Pro help

Is this a vapor-permeable air barrier?

In General questions | Asked by Rossn1 | Apr 21, 18

Are these calculations wrong?

In Mechanicals | Asked by Michael Grundvig | Apr 22, 18

vinyl siding over zip system

In General questions | Asked by Brian Ducharme | Apr 23, 18

Heated bath floor - system and flooring?

In Green products and materials | Asked by c l | Apr 23, 18
Register for a free account and join the conversation

Get a free account and join the conversation!
Become a GBA PRO!