Brick wall weep holes below grade (C) Carson Dunlop AssocBlocked or Missing Weeps in Brick Veneer Walls
Masonry veneer wall drainage omission or blockage is risky

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Missing, blocked,or buried weep holes in brick or masonry veneer walls:

This article explains the risk of water damage, mold, rot and other building problems if a brick or other masonry veneer wall or cavity wall is built without proper ventilation and drainage. We also describe common site SNAFUS that cause failure of the brick / masonry veneer drain system such as burying the drains by backfill, blocking by a patio, or clogging by insects and / or mud from area flooding.

This article series explains the purpose of drainage openings & rain screens in solid brick walls and in some brick veneer walls: brick wall weep holes and recommends their use in new construction and in some brick wall repairs or retrofits. Weep holes in building exterior masonry walls (brick or stone) are a drainage system that is used in cavity wall or rain-screen wall construction methods to get rid of water that has penetrated the outer wall skin or surface.

Page top sketch: illustration of improper blockage of weep holes by backfill against a brick veneer wall, courtesy Carson Dunlop Associates, a Toronto home inspection & education firm. [Click to enlarge any image].

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Damaged Brick Veneer Walls - Blocked or Missing Brick Veneer Weep Openings

Not All Brick Veneers Lacking Drainage are Damaged - Some of these are Barrier Walls not Cavity / Rain Screen Walls

Brick veneer wall weep hole too small, clogged (C) 2013 Daniel Friedman

Above we illustrate a double-fault at a brick veneer wall weep hole found on a New York Home. This "Do-it-yourself" excuse for veneer wall drainage is too small, placed above the level of the wall base flashing, and is completely clogged. All of the weep holes we found in this wall were in the same condition.

Faux Bond Courses May Confuse the Identification of a Brick Veneer Wall - but is it a problem? Not Necessarily.

The brick walls of the New York home in our photo at below left contain no weep openings. Bricks were laid tight against a solid masonry block wall with "faux" bond courses to the left of the chimney and all stretcher brick courses to the right of the chimney.

Walls both left and right of the chimney were constructed with no drainage. Bricks were mortared against the masonry block structural walls of the home with no air space and no drainage provision.

This is a brick veneer on block structure approximately 30 years old. While the mason omitted weep openings, we did not find any evidence of water or frost damage to the brick veneer except at another wall where splash-up from roof spillage had worn mortar joints. This is a barrier wall design, not a cavity / rain-screen wall designed structure.

Photograph of - collapsing brick structure © Daniel Friedman

Traditional structural brick walls such as at the building shown at above left are comprised of two or more wythes [defined below] of brick laid in parallel and reinforced by bond courses at regular intervals. Such walls typically include an air gap between the exterior wythes of brick - the wall outside surface, and the wall interior. At above right the mason actually built a brick veneer wall over solid masonry block.

Fake bond courses in a brick veneer wall (C) Daniel Friedman

That space allowed water that leaked into the wall to run down the wall interior and drain at the wall bottom - provided that the wall bottom included weep openings or drainage.

At BRICK FOUNDATIONS & WALLS we describe the collapse of the structural brick walled building shown at right.

Definition of wythe or brick wythe

  1. Each continuous vertical section of masonry one unit in thickness
  2. The thickness of masonry separating flues in a chimney - Masonry Design Manual

If you look at a brick masonry wall, one brick thickness of the wall is one wythe. A brick veneer wall constructed using full-dimension bricks will be one brick wythe in thickness (of the veneer). The total wall thickness will include the veneer wythe plus the thickness of the wall structure itself.

A structural brick wall is normally two or more wythes of brick in thickness, usually separated by an air space of about an inch to form a thicker, more dry wall. In the cross section of the collapsing brick structural wall at above right you can see multiple wythes of brick. More brick and brick wall definitions and details are at BRICK VENEER WALL LOOSE, BULGED.

How are brick veneer walls usually supported?

Carson Dunlop Associates sketch (below) illustrates the usual manner in which a brick veneer wall is supported.

Brick wall weep holes below grade (C) Carson Dunlop Assoc

On occasion we find an "add-on" brick veneer supported by a steel lintel bolted to the building structural wall bottom.

Details about brick veneer wall support, bulge & damage, fasteners, and repairs for attached veneers on wood frame construction are found at BRICK VENEER WALL LOOSE, BULGED.

Is it OK to Seal Weep Openings in a Brick Veneer Wall?

Reader question: can I seal off weep holes where flashing is wrong and the wall leaks?

4/18/14 Ted Asked:


The weep holes over our windows and doors are leaking into the building interior. I think the flashing was not done right. Can I just close them off to solve this problem?

Reply: no

Ted, I agree that it sounds as if the flashing above windows and doors was omitted or not properly installed or punched or damaged during construction. I can't see how to fix this easily without some exploring into the wall cavity to see what's going on. Check out Carson Dunlop Associates' page top sketch (click to enlarge any image) to see what the flashing position should be.

Keep in mind that even if the flashing is properly installed, if a lot of water is leaking into the wall from higher-up, the water might be running down the wall sheathing and behind the flashing and out from underneath it. That diagnosis is what's needed before we try to fix anything.

Reader Question: wicks instead of flashing and drain openings in veneer walls?

(May 12, 2014) Norma said:

My daughter's house was finished in August 2013. It is located in Oklahoma. The bricklayer did not install flashing behind the weep holes. To make matters worse, the weep holes are less than 6" from the soil. Some weeps are at ground level.... Someone has suggested installing wicks to wick away any moisture. What is your opinion on wicks?

Do you have another suggestion other than removing portions of brick and installing the flashing?

Reply: no

In my OPINION this is a mess. I'm worried that wicks won't allow sufficient drainage, that close to soil is an insect attack risk. If it's not reasonable to lower grade (and slope away from the home), we need to investigate further: is there a basement? can we see the house sills from inside?

Question: interior floor damage after sealing brick veneer weep openings

(Oct 6, 2015) Diana Persh Bogden said:

I had wood flooring installed in a new home for a builder client of mine. The homeowners had a raised concrete patio installed and all the weep holes along the back of the house were covered by concrete after we installed the floor.

Several months later they called the builder and complained that the wood floor about 3 feet deep along the whole back of the house was buckling and heaving. I went to inspect it and attribute the problem to the covering of the weep holes thus preventing ventilation and moisture build up. Am I right.


Not exactly, Diana. "Ventilation" in the sense of a moving air current through the veneer wall, or loss of it, may not be the exactly-correct explanation of the buckling wood floor, though there can be little doubt, given the timing you describe, that adding the raised concrete patio and sealing off the veneer weep openings led to the floor buckling.

The purpose of weep openings is to let water out of the veneer wall rather than sending it into the building wall (and possibly floor) structure. That drainage is needed when wind-blown rain (or possibly significant amounts of condensate) in the cavity space between the veneer wall and the exterior sheathing of the wood framed wall behind needs to get out.

I see that more as water drainage than as air movement. Air movement might address or reduce condensation IF there were a lot of air movement but with just weep openings at spaced intervals along the bottom of a masonry veneer wall, there's not much air flow in that cavity space.

I would want a further on-site investigation to understand what happened. I suspect that actual water entered the wall cavity and the floor structure at the bottom of the wall.

If the floor is built on a slab then we can't see into that space without a borescope or some demolition, but I'd bet that if you did look into such a cavity for the case you describe, you'll see water stains (and maybe rot). Water and high moisture can indeed cause severe buckling of a wood floor, more so if the floor was installed without an expansion gap around the floor perimeter.

For the case you describe, I doubt that the floor buckled from normal expansion from normal moisture level variations - otherwise the buckling ought to have occurred when moisture levels changed (perhaps seasonally) even before the patio and outdoor raised slab installation were completed.

I suspect that water from rain penetrating the veneer wall, or perhaps even excess water from the add-on slab itself are what entered the wall and floor of the home.



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