Mark Meshulam is an expert witness and consultant for leaking brick walls.
All these commonly used (or sung) phrases refer to the brick wall as the standard of unyielding permanence, through which nothing can pass. Yet when water leaks are concerned, it soon becomes obvious that water never heard those phrases or sat around listening to Pink Floyd. Like love, water always finds its way.
The unfortunate fact is that brick walls leak, concrete block walls leak, mortar joints leak, flashings leak, and we sometimes have forgotten fundamentals of masonry design, making it that much harder to control those leaks.
Types of Masonry Walls
All masonry walls are not the same. Here are the basic types:
This is a big fat wall of masonry with so many thicknesses (wythes) of brick that water can’t get through. You see these in older masonry buildings, built when bricks and labor were cheap, and the greater wall thickness was needed to support the structure.
We don’t get leakage calls from the Monadnock Building, for example, where structural brick walls are six feet thick at the base.
All other wall types described below rely on a separate structure to support the brick, rather than relying upon the brick to support the building.
An example would be a brick wall consisting of brick backed up by brick or block, grouted solid between. The grout forms a barrier that is intended to stop the water.
Masonry Cavity Wall
This consists of an exterior wythe of brick with an airspace (usually 1″-2″) behind it, and another interior wythe of masonry.
When water penetrates the exterior wythe, it runs down the back side of the brick and drains to the exterior via sill flashings.
This is a cavity wall wherein the interior wythe may be masonry, or it may be of non-masonry design, such as studs with water resistant sheathing, or studs with sheathing and “house wrap”, etc.
Masonry Veneer Wall
This is a masonry wall where the interior wythe is not masonry. The most common back-up material would be sheathing, then studs. There are also veneer walls that use thin (about 1″ thick) veneer bricks that are laid into a bed of mortar or mastic, embedding into wire lath which is applied to the sheathing. You can’t get any more veneer-ish than that. These veneer bricks are also called “soaps”, because they are about as thick as a bar of soap.
This design involves the use of an impervious coating on the exterior face of the masonry so that no water is allowed to enter. That coating will usually be paint or a trowel-applied cementitious material sometimes referred to as “stucco”.
Dreck Wall (taken from the Yiddish)
We find this, sadly, in too many buildings. It is a single-wythe wall of unprotected concrete block with little or no water repellency. The use of this design should be limited to outhouses. Oy!
Testing Masonry Walls
Now that you are thoroughly confused, let’s talk about detecting and diagnosing leaks through masonry walls. As you can see from the descriptions of the various types of masonry walls, they are usually comprised of layers. All of the layers are important in the control of water leakage. Therefore, testing of the permeability of the exterior face of the masonry – and this is involved in all of the most commonly recognized test methods – can produce very limited information.
For example, if we demonstrate through testing that we can force a gallon of water into an 4′ x 4′ area of masonry in 5 minutes, we may then know that the exterior masonry is porous, but we don’t know if the wall is leaking. We only know that the wall is leaking if we can see water penetrate the innermost layer of the masonry wall system. If that innermost layer is the interior wythe of block in a brick and block cavity wall, or if it is the “house wrap” in a masonry veneer wall, we must obtain visibility to the interior side of those elements during the test. But I am jumping ahead.
Here are the most commonly used tests for masonry walls. Full copies of ASTM E514 may be obtained at the website of the American Society of Testing & Materials (of which I am a proud member), at www.ASTM.org
ASTM E514 Standard Test Method for Water Penetration and Leakage Through Masonry
In this test, a water-tight, pressurized chamber is sealed to a 12 sf area of the exterior face of a masonry wall. Water spray is applied within the chamber from a source whose volume is known, and the excess is collected and recycled into the system.
At the end of the test, the remaining water is measured. Water is missing is presumed to have been absorbed into the masonry. I am not a fan of this test because it can be costly without getting at the root of the problem.
RILEM Test Method 11.4- RILEM Tube
RILEM is an acronym for Reunion Internationale des Laboratoires D’Essais et de Recherches sur les Materiaux et les Constructions, the European counterpart to ASTM.
This simple method involves adhering a graduated test tube onto a small (approx. 1 sq inch) area and filling the tube to a selected graduation on the tube, creating a hydrostatic pressure corresponding to the height of the water column onto the face of the masonry.
The amount of water that is being absorbed into the masonry per unit time can be compared to a chart to determine the relative permeability of the small test area. Due to the small size of the test area, multiple tests are recommended. When I use the RILEM tube, it is for a few quick, specific measurements. I select a few areas right on the face of the “masonry unit”, this is tech-speak for brick or block, to gain a quick understanding of the surface porosity of the unit itself.
Results come quickly. If the water level in the tube goes down like a Sears, er, Willis Tower elevator, I know the face is highly porous. But if the water level hovers stubbornly at 1-2″ of water column height, the face of the masonry unit is pretty good. Completely different results can be obtained when testing the horizontal joints, known as the “bed joints”, and the vertical joints, known as “head joints”. Hairline joints visible in mortar joints can produce surprising results. Some suck water like a wet-vac and others refuse it like an anorexic refuses pound cake.
Chicago Window Expert Masonry Test
This test, adapted from window testing by yours truly, recognizes the need to view the innermost layer of the masonry wall system in order to prove that water is not traveling beyond that point, causing leaks, damage and the potential for mold. The good part of this test method is that you receive very good results which communicate well to construction professionals and normal people alike. If it leaks, you can see it.
The bad news is that the method requires the removal of interior finishes in order to gain visibility. In the test area, drywall, insulation and even vapor barriers must be removed. The good news about the bad news is that in severe leakage areas, this demolition is usually done anyway as a part of the remediation.
But the bad news about the good news about the bad news is that you better hurry up and test, because someone’s living space, has been severely disrupted.
The spray rack is the same as is used in ASTM E1105 Standard Test Method for Field Determination of Water Penetration of Installed Exterior Windows, Curtain Walls and Doors by Uniform or Static Air Pressure Difference, and at the same delivery rate (8 gal/sf/hour), however a pressurized chamber is not used. Since water from the spray rack will run down the wall beneath the spray rack, the area beneath the spray rack can be considered to be within the test area so long as that area is no greater in height than 1.5 times the spray rack itself.
The exposed interior surface of the masonry wall construction is observed during the test, and is encircled with marker in the location where leaks are observed. This outline is also marked with the number of minutes from start of test, to the initial observation of the leak. As time progresses, if the leak spot grows, its outline can be redrawn and marked with the new duration, so that a record of the progression of the leak can be made.
At the end of the test, these outlines can be photographed and included with the test results. The test report can also include an estimate of the percentage of wall surface which was wet at the end of the test.
As is true for all tests, the same test can (and should) be used to validate proposed remedial procedures, and new results can easily be compared with the wall markings that remained from the previous testing. New markings would be applied with a different color marker. Keying for the dates of the tests should be also drawn on the wall and photographed at the end of the test.
The test duration must be specified to fit the application, but one hour with no visible water on the interior side of the innermost layer of the masonry wall system, would be considered a bare minimum.
Validation of Remedial Methods
On a recent project, we used our test method to develop and validate remedial methods that were employed on the wall for the purpose of reducing or eliminating leaks. We were interested in testing a silane-based clear exterior spray as well as an interior applied basement waterproofing paint (designed to resist hydrostatic pressure on the “negative”, or interior side) on a brick and block cavity wall.
The sample areas for each were overlapped in order to provide three distinct test areas: 1) silane spray only, 2) silane spray plus basement waterproofing paint, and 3) basement waterproofing paint only. Guess what? The combo won.
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