Efflorescence patterns to diagnose water intrusion

Around here, we have had 3 relatively warm and wet winters. Most masonry drying occurs during the windter months, when there are 10 - 15 days of single digit temps. This allows heat to flow out from the masonry, and the water in the masondy follows.

Because of this lack of drying time, we have a number of efflorescence teaching examples.

  1. Three year old building. Brick veneer with cinder block structure. Notice how the efflorescence displays below the stone. No flashing under the stone cap. Water goes through the stone and vertical mortar joints.

  2. Detail of proper single wythe CMU walls. Flashing must be in place above joist pockets with weep wicks. Above door and window lintals, similar flashing is needed with weep wicks. The lintal / brick space MUST NOT be grouted or caulked. It they are, this traps the water in the wall above the window and it leaks into the top of the window interior.

  3. Notice how all the efflorescence is below the stone window sills and the stone parpet wall coping? Wonder why? Around here, mo one flashes properly. The result? Many buildings with water intrusion, mold and even rotting wooden floor trusses (the grout the joist pockets). Am involved with litigation inspections on 6 such buildings and 3 have already been torn down (rotted floor joists, mold) at the City’s order. But hey, it’s good money for me. Even have a new template for it, mostly boiler plate because the issues are almost always the same.

  4. Lastly, got to see the spacing between the cinder block structural wall and the brick veneer. Where the efflorescence is, the required 1’ gap between the walls was filled with mortar. The “masons” (and I use the term loosely) didn’t bother to scrape the mortar off when laying the brick. Mortar bridges the gap between the walls. Any mositure going down the inside of the brick hits these bridges and seeps inward and outward. Moisture levels in the CMU, on the interior, was also elevated in these areas.

Put this together with themal imaging and mold sampling and you have a whole cottage industry for HIs.

Hope this helps;


CMU single wythe flash 1.jpg


efflorescence new building.jpg

Will, do you have any idea of what moisture migration rates are possible through stone or masonry?

I guess I don’t understand the question.

In our area, masonry walls are, usually, double wythe. Cinder block structural wall with a brick or split faced block veneer. Many of them built in the last 15 years with improper or no flashing.

I do MATS testing for absorbancy. Also, many don’t use the proper mortar for the split faced block.

Care to make your question more specific?

How fast can water move through stone or masonry?

In order to be accurate with that question Kenton, tests would have to be performed.

Using this method and equipment as shown here;

http://www.prginc.com/Masonry/rilemv.gif**Vertical Rilem Tubes — Regular **
Used to measure absorption of a vertical masonry surface.


Because masonry building materials are porous, they are all somewhat permeable to water. The interior structure of a masonry material is a system of fine interconnected pores. Wetting by liquid water involves capillary conduction (suction) through this pore system, proceeding along both vertical and horizontal pathways. Vertical transport occurs when water enters as ground water at the base of a structure or as rain water through leaking gutters. Penetration of driving rain into wall surfaces results in horizontal transport. (Under actual conditions, the amount of rain penetration depends on prevailing wind conditions as well as on the composition and condition of the exposed surface.)
When liquid water comes into contact with a masonry surface, wetting proceeds through the material as a front. Accurate measurements of the advance of this wetting front made on a variety of masonry building materials have demonstrated that the characteristic wetting rate and pattern of each material are directly related to its capillary structure and port size distribution. In fact, rate constants have been measured for brick, limestones and other masonry materials. RILEM Test Method 11.4 provides a simple method for measuring the volume of water absorbed by a material within a specified time period.


I guess so, Marcel. In addition to the porosity of the material, you 'd be dealing with moisture, temperature and pressure gradients.

What I did, when I first got my MATS tubes (same as Marcel’s, but different name) was do sime test of my own. Got a selection of brick and stone and did my own tests. Also bought different types of mortar that are used around here (called a local mason for advice. BTW, he was VERY interested in the results!) and built some test walls (might be a good project for you Ken, I know that you are always messing around with Nick and Ben :mrgreen:)

If anyone has some published results, please post.

One building I inspected (for the condo association) had problems. Built in 1929, three story courtyard building on the Lake. The east and south sides were directly exposed to the lake and wind driven rains. The building had recently had all their lintels replaced. The mason even installed metal flashing between the lintels and the overlying brick. The brick above the lintels were soldiers and were removed to replace the lintels, then reinstalled. The condo association was getting water entering the building at areas above the lintels (confirned by moisture meter and thermal imaging).

Did some MATS tests of areas where the original brick and mortar were and compared them to the replaced soldiers (they used the original bricks and just reinstalled them). The replaced brick absorbed moisture twice as fast. Seems that the original mortar was a lime putty mixture while the replaced brick was reinstalled using a standard N type mortar. The N type mortar was absorbing water much faster.

Had the mason’s come back and showed them the results and how I did the test. They removed the soldiers from 3 of the window lintels and reinstalled them with like putty. Sure enough, those three windows didn’t leak anymore.

It was fun to experiment, and to get paid to do so.

Hope this helps;

Sounds like you had some fun there Will.

If you look at this here;

M A S O N W O R K It denotes all types of Masonry Mortar Cements used today.
Going from strongest to weakest in strength.

A good article here on the different types of mortars, and interesting reading for those interested in Masonry.

I also have a few comments on Initial Rate of Absorption (IRA);

The flexural bond strength of masonry cement mortar changes more with brick IRA than that of portland cement/lime and mortar cement mortars.

Mortar cements develop flexural bond strengths equivalent to those of portland cement/lime mortars with low IRA brick.

Flexural bond strength of low IRA brick improves as mortar water retention decreases.

Flexural bond strengths of very low IRA brick can equal or exceed those of higher IRA brick with proper selection of materials and Types.

Water penetration resistance is not related to flexural bond strength.

Walls of low IRA brick can be built to have not water penetration.

For walls of uncored brick and excellent workmanship water penetration resistance is directly related to brick density and inversely related to brick absorptions.

Any of this make sense to you?:):wink:

Marcel :):smiley:

Ok. Published paper and here is the abstract.


But, I had to do it myself.

Go figure :mrgreen:

Interesting article.
I am surprised about the lakeside building.
How far up did he place the metal flashing in relation to how far up new masonry was put in place.?

I would love to see that situation in a diagram.

Excellent paper Will. It was very educational. Thanks for sharing it with us!

BTW, on page 5 you reference photo 115, instead of photo 15.

Nice article Will, and this should add to what causes efflorescence;


I swan… the more I learn, the less I know.

Portland Cement Association also says soluble salts

Salt chrystals… that’s what I had thought all this time. Then today I was at a plant where they manufacture concrete tiles and was told something different by their engineer.

Calcium hydroxide. When the water and the cement mix together the result is calcium silicate hydrate. a by product is calcium hydroxide which is basically unhydrated cement.

Calcium hydroxide is leached to the surface by moisture moving through the porous masonry and upon coming into contact with carbon dioxide it turns white.

"The binding quality of portland cement paste is due to the chemical reaction between the cement and water, called hydration. Portland cement is not a simple chemical compound, it is a mixture of many compounds. Four of these make up 90% or more of the weight of portland cement: tricalcium silicate, dicalcium silicate, tricalcium aluminate, and tetracalcium aluminoferrite. In addition to these major compounds, several other play important roles in the hydration process. Different types of cement contain the same four major compounds, but in different proportions.

The cement in concrete needs water to hydrate and harden. Even though the chemical reactions may be complete at the surface of the concrete, the chemical reactions at the interior of the concrete take much longer to complete. The strength of the concrete keeps growing as long as the chemical reactions continue.

When water is added to cement, the chemical reaction called hydration takes place and contributes to the final concrete product. The calcium silicates contribute most to the strength of concrete. Tricalcium silicates are responsible for most of the early strength (first seven days)."

The original dicalcium silicate hydrates, which form more slowly, contribute to the strength of concrete at later stages.



This one just calls it “minerals”

So when I see efflorescence what type of recommendation should I make to properly cover my butt?

Since it’s a sign of moisture intrusion you should comment on the fact that there has been intrusion and look for evidence that it’s ongoing. If it appears that intrusion is ongoing you should recommend locating the source (if you can’t locate it yourself) and recommend correction.

The potential probelms to mention are human health: from excessively high levels of mold spores in indoor air, rust of metal components, wood decay and foundation undermining.

NACHI article time, Kenton.

Efflorescence is not always an indication of a defect. Masonry, all by ityself, absorbs water and moisture. If properly built (capillary breaks, flashing, proper mortar type use) then efflorescence can be merely an indication of the natural drying process.

But, it can also be an indication of bad construction.

Good information on efflorescence.
and check out Note 23 of BIA

Efflorescence in Brick Veneers



What is effloresence?
([source - BIA Tech Note 23](javascript:openpopup_4738(‘http://www.bia.org/BIA/technotes/t23.htm’)))
Efflorescence is a crystalline deposit of water-soluble salts on the surface of masonry units. Efflorescence is generally not harmful to the brick - nor is it toxic or a health hazard. The main problem with efflorescence is that it makes an otherwise beautiful masonry structure quite unsightly
Efflorescence is usually white in color; however, all white stains on brick masonry are not necessarily efflorescence. Also, certain vanadium and molybdenum compounds, present in some ceramic units, may produce a green deposit, commonly referred to as “green stain”. Occasionally, “brown stain” may occur, resulting from deposits of manganese compounds.
Under certain specific circumstances and conditions, it is possible for the crystals of efflorescence to form within the bodies of the units. When this occurs, it is possible that the pressure of crystallization and growth of the crystals may cause cracking and distress to the masonry.





Good suggestion, Gary!

I think the point the article I posted was trying to make is similar to what you’ve said. It’s that the hydration process takes years to complete. During those years, masonry contains unhydrated cement that can be leached to thte surface as calcium hydroxide and appear as white chrystals.

Rob’s out 'til next week but we should do an article on this and see if we can’t make this subject a little clearer.