Mark Meshulam is an expert witness and consultant for brick leaks and masonry leaks.


“I’ve hit a brick wall”
“It’s as solid as a brick wall”
“I’m hitting my head against a brick wall”
“All in all it’s just another brick in the wall”

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 at brick walls 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:

Mass-type masonry wall
Mass-type masonry wall

Mass Wall

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.

Barrier masonry wall
Barrier masonry wall

Barrier Wall
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.

Masonry cavity or drainage wall
Masonry cavity or drainage wall

When water penetrates the exterior wythe, it runs down the back side of the brick and drains to the exterior via sill flashings.

Drainage Wall
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.

Skin Wall

Dreck wall. Break out the galoshes
Dreck wall. Break out the galoshes

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!

Video: Testing Masonry Walls

About Testing Masonry
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

ASTM E514 Masonry Water Penetration Test - schematic
ASTM E514 Masonry Water Penetration Test – schematic

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 tube test for masonry permeability
Rilem tube test for masonry permeability

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.

Water spray test for masonry
Water spray test for masonry

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 (5 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.

Interior view of the results of the masonry water spray test
Interior view of the results of the masonry water spray test

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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18 thoughts on “Testing Leaking Brick Walls”

  1. Mark:

    The link with this e-mail was interesting and humorous, especially the new wall type not previously described in the code. There is one minor correction that I would suggest in regard to your description of cavity walls:

    * The Masonry Code (ACI 530-05), in Section 1.6, defines a cavity wall as “a multiwythe noncomposite masonry wall with a continuous air space within the wall (with or without insulation), which is tied together with metal ties.”
    * Nowhere in the Code is the minimum width of the cavity specified.
    * In the same Code, the maximum width of the cavity is specified as 4.5″ in Section, unless a detailed wall-tie analysis is performed.
    * In the Code Commentary for Section, NCMA and the Canadian Standards Association (CSA) have the following recommendations: “The term cavity is used when the net thickness is 2″ or greater. Two inches is considered the minimum space to provide resistance to water penetration.”

    In your site, the cavity is indicated as 1″ to 2″. It is our experience that a 1″ cavity cannot be kept open and free of mortar bridges. Mortar “snots” at the inside face of the brick cannot be removed to provide a free path of water down the inside face of the brick. In brick veneer construction, the mortar “snots” are not as critical, since there is a waterproof barrier covering the wall sheathing. In a cavity wall, the mortar “snots” in a 1″ cavity will allow water to transfer to the inner wythe, thus defeating the purpose of the cavity. It has been proven that a 2″ cavity can be kept clean, thus preventing water from getting to the interior wythe.

    Air spaces of less than 2″ are simply called mortar voids and cause the engineering analysis of the wall to be “non-composite”, differentiating that kind of wall with a composite wall (barrier wall) that has the collar joint between wythes filled 100% solid and where the two wythes are connected by metal ties.

    You might want to show a detail or video of how to keep the cavity open during construction and show what happens when the space between wythes is bridged by mortar. I am sure you have seen many cases of the latter condition where you have found water infiltration in multi-wythe walls. We certainly have in our investigations.

    Keep the e-mails coming. I and our other engineers and architect find your website generally helpful.

    Stuart Jacobson

    Stuart K. Jacobson, President
    Stuart K. Jacobson & Associates, Ltd.
    400 Skokie Blvd., Suite 290
    Northbrook, IL 60062-7902

    Phone: (847) 480-8899 Ext. 12
    Fax: (847) 480-8872

  2. Hello Stuart,

    Thanks very much for the additional information you have provided on this subject.

    Although you are a design professional, and design pros do not traditionally specify means and methods, have you seen any effective ways that masons can employ to keep the airspace open (besides flogging the bricklayer)?

    Keeping the airspace open is so important to water control, yet so difficult to obtain in the field.

    Best regards and happy New Year to you and your excellent firm!


  3. This is frightening. The dreck walls are everywhere. What a scam played on consumers. The building inspectors were supposed to protect us from this type of construction. People were paying $300-$400K for these shitbox condos.

  4. The only way that I have seen this done is for the mason to place a continuous 2×4 on edge at the bottom of the cavity. The 2×4 had been drilled periodically along its length so as to permit the mason to install a cotton sash cord, similar to that often used for weeps, through the holes to the bottom of the 2×4, where the sash cord is knotted. Each sash cord is extended a sufficient distance above the top of the 2×4 to allow the mason to construct the wall while draping the sash cord over the top of the wall. Periodically and before the mortar is hard, the masons pull up on the sash cords, thus raising the 2×4. As the 2a4 is raised, it knocks off the mortar protruding into the cavity. The loose mortar ends up on top of the 2×4, which can be brought to the top of the wall at any time and cleaned off. When the 2×4 is started at a higher elevation, the sash cord is again draped over the top of the wall and the 2×4 is prevented from falling by placing a CMU or multiple bricks on top of the sash cord where it is draped over the fop of the wall. The process is repeated as many times as is necessary.

    Additionally, if the mortar space is at least 2″ clear, the mason has an easier time of removing mortar from each mortar joint than he can from thinner joints. Obviously, the wider the cavity, the easier it is to clean the mortar droppings. If the cavity gets closer to 4″, the 2×4 in the above example can be laid flat.

    Mortar Net, a product specifically made to help ensure that water infiltrating the wall will reach the weeps, and other similar products are designed in such a way as to virtually be foolproof in that they will never be fully plugged with mortar even if the cavity is not kept perfectly clean, I am sure that if you contacted mason contractors who routinely do cavity wall on commercial, institutional and other large buildings, they may be able to provide you with other “tricks that they use”. Usually, because of the Special Inspection provisions in the International Building Code (IBC), the special inspectors make sure the cavity remains open and without mortar bridges.

    Recently, I have seen cavity wall construction being done where the inner wythe is constructed first. Then the cavity-side face of the inner wythe is completely covered with Ice and Water Shield or similar product, before the exterior wythe is constructed. Obviously, in order for that system to work, there has to be two-piece adjustable wall ties used to tie the wythes together, since the use of 3 wire ladder ties is far too difficult to work with when the wythes are constructed at different times.

    I hope that answered your question, but if not, let me know.

  5. Hi Mark
    A very nice CWE edition. I found it informative.
    In your closing text you used the word “silane” without offering a definition. I was able to partly define it by inference, though I didn’t know exactly what it was. Being an uniformed reader I had to go to another source to find out more.

    Very nice article.

    Ken Lively

  6. I love brick walls, but there is certainly some maintenance and work that comes along with the beauty and benefits.

  7. Always interesting… I liked that you discovered, as we have found in our practice, that the expense of an ASTM test is not always justified. We usually already know a leak exists (or we wouldn’t be there). We just need to find it and determine a proper repair scope.

    In fact, sometimes if the proper repair would consume all of the possible sources, then we may not test at all and just catch and document the cause of loss during the demolition. We commonly find many leaks clustered together and the performance of multiple items are in question. …A wall with a kickout flashing above a control joint, above a window flashing and the HVAC lines in the same wall….

    As for water testing, the real value for the client is in the post-repair follow up testing. That’s when you know with a reasonable degree of certainty that the issue and any other latent issues are resolved. It also helps to more easily transfer future warranty responsibility from the original builder to the repair contractor, thus often giving the client a better warranty.

    John McReynolds
    President at Home Defect Analysis & Solutions
    Houston, Texas Area

  8. I have used the Rilem test extensively on masonry buildings, typically evaluating the performance of various types of coatings or sealers. It works fine in that capacity, however the small scale is typically not very helpful if you are chasing a leak. When done as a series with multiple locations, these tests can show how a wall (bricks/blocks/joints) are performing overall.

    For running down leaks, the ASTM 1105, or AAMA 502 nozzle test, (with adjustments to the distance and pressure), are really the ticket, as they can target specific locations and assemblies.

    Paul Bentz
    Lombard Consulting Services
    Greater San Diego Area

  9. John,

    I am happy that you amplified the importance of striving for having the investigation cost be in a reasonable proportion to the cost to fix. We need to work efficiently and intelligently in order to leave the client some funds to actually remedy the problem.

    I agree with your point also about how problems seem to cluster and congregate. I always advise clients that we are not looking for one leak, but 3-5 leaks.

    Paul, in my experience, whether we use a nozzle or a spray rack, we really must get good visibility onto the backside of the innermost element of the masonry wall, or we will still be guessing. Do you agree?

    Mark Meshulam

  10. Mark – Agreed – The test is only as good as the access to view the results. I am never afraid of breaking a little drywall. Drywall is certainly cheaper than your or my time and nine times out of ten it is going to be consumed in the repair anyway! Additionally, for post work testing, I usually require that the interiors are kept open until they pass the water testing anyway.

    During one interesting exception to the rule, a home required the interior to be completed prior to the stucco exterior due to weather and a pending sale. On that one, we soldered equal length leads to copper tacks and then lined the framing sill with tacks (spaced the same distance apart as the moisture meter pins) at all of the usual failure points. The dozen or so leads were left protruding from the between the apron and the sill. We used alligator clips to attach the pairs of leads to a pin style moisture meter and took baseline readings (which all were about 8-11%mc).

    We tested the installed tacks by adding one drop of water near a pair of tacks. The meter pegged at 100%. The others didn’t move. A week later, we monitored each pair of leads during the test and at 30 minutes and 1 hour after the test. There were no changes and we called it a pass. After the test, we cut the leads flush with a razor knife and the contractor merely caulked the joint to complete the job.

    We explained the test method to all before performing it and all agreed to accept the limitations of the test and to accept that a failure would require opening everything up.

    John McReynolds
    President at Home Defect Analysis & Solutions
    Houston, Texas Area

  11. We just repaired a leak behind the men’s urinal of one of our Clubhouses- not fun but much needed.

    Cindy Montsinger, RealManage CMCA®, LCAM •

  12. I sent a photo to your CWE email. I did find a picture of the leads in use during testing of the completed assembly, but not a picture while open. I had over 600 defects spread over more than 100 homes on that case and well over 50,000 pictures, so needless to say, once that one closed, I archived most of them.

    Here is a photo of the test leads in use. I couldn’t find a picture of the tacks in place when open, but they were just little 1/2 inch or so, sharp copper tacks I got at Home Depot. I used wire from length of network cable and soldered the leads to the heads.

    John McReynolds
    President at Home Defect Analysis & Solutions
    Houston, Texas Area

  13. Mark,
    There is a very short section of requirements for flashing and water repellency in the Chicago Building Code in 13-120-150, paragraphs B and C. These were added in 2000, with some adjustments in 2001 and 2003. Perhaps you’re already aware of these:

    13-120-150 Exterior wall materials.

    (a) Exterior wall surfaces shall be of solid wood, or weather resistant materials not less resistant to moisture absorption than grade MW clay or shale brick as determined by ASTM C-62-97a.

    (b) Any concrete masonry unit and mortar used in the construction of any part of any single-wythe exterior wall of any building containing a residential occupancy for which building plans have been submitted after the effective date of this ordinance:

    (1) shall have integral water repellant included in the manufacturing process and all joist- mixed mortar shall have a compatible water repellant added to the mixture; and

    (2) shall meet the “excellent” rating when tested in accordance with ASTM E514. Standard Method of Test for Water Permeance of Masonry.

    Any concrete masonry unit or mortar used in the construction of any part of any multi-wythe exterior wall of any building containing a residential occupancy shall not be required to comply with the aforementioned provisions of this paragraph (b).

    (c) Exterior walls constructed of concrete masonry units shall have flashing, weep holes, sealants and caulking which prevent the accumulation of water within the wall assembly and provide a means for draining water that enters the assembly to the exterior so as to prevent moisture from passing beyond the exterior wall cladding or veneer and entering the interior of the exterior wall.

    (d) Wall anchors and metal veneers shall be of noncorrosive materials, or shall be protected by corrosive resistant treatment acceptable to the building commissioner.

    (Prior code § 69-7; Amend Coun. J. 9-13-89, p. 4604; Amend Coun. J. 5-17-00, p. 32653, § 2; Amend Coun. J. 7-25-01, p. 64905, § 4; Amend Coun. J. 3-5-03, p. 104990, § 27; Amend Coun. J. 11-13-07, p. 14999, Art. II, § 1)

  14. Hello,

    Does anybody know any tuckpointers to recommend for replacing some bad mortart on a couple of buildings? Getting water in through deteriorated and poorly installed mortar joints.


  15. Mark,

    I was very impressed with your blog and your intent to help educate the masses on leaks and leak detection. I have been a project manager at Arrow Masonry in Chicago for the past 16 years and specialize in leak detection as well as repairing leaks in condos, homes and industrial buildings throughout the Chicagoland area. I use many of the tests you use as well as thermal imaging to find the nature of the leaks. Its a shame to have so many building in the Chicagoland area constructed of single wythe block as these leak so badly and many have mold. I just wanted to say I liked your blog and your helpful hints, I believe it will help many “leaky” people!!


    Kathy Torres
    Arrow Masonry

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