Q: You mention in an article of yours I have read that poor workmanship by many masonry contractors may compromise the appearance and even the structure of older vintage homes through the use of incompatible techniques and materials, making the repairs look more like graffiti than anything else; how is that so?
A: I have nothing against modern masonry or the masons performing it. Assign them to modern masonry work, such as brick laying or building a concrete driveway, etc. and you’ll generally have no problems. When they do what they trained for, there’s no issue. There are associations helping them out and guiding them; they work with architects, engineers, etc. But when it comes to brick mortar replacement (or repointing), they all too often don’t have the full story. The world has changed tremendously in the last 100 years: we don’t ride horses now, we have electricity, TV, computers, cell phones and airplanes. And we don’t build houses the same way. And very importantly, today’s brickwork uses a different type of mortar as was used 100 years ago. And the bricks have different properties than the earlier hand-made ones. The modern bricklayer typically knows very little or nothing about this fact. These materials are not compatible, really. He is never taught this for the same reasons that you don’t have to know how to saddle a horse in order to get a driver’s license: the information does not apply anymore. Except that nobody stopped long enough to realize that these people are the ones home owners trust to repair their 70 or 100 years old brickwork. Large heritage projects don’t have that problem because the people involved know heritage conservation. But these large heritage contractors don’t usually work in the residential market as it is not profitable for them. So when the masonry contractor tries to repair homes built prior to 1930 with modern materials and methodologies, truthfully, he fails.

Q: So what has changed so much since 1930 from the much older, long established traditional methods?
A: For thousands of years, people were building with lime. This material comes from limestone that is fired at high temperatures to which water is subsequently added, creating a very good, plastic and resilient material which allows for movement and is somewhat soluble; therefore containing self-healing properties. It, however had drawbacks for the modern era, as it took time to prepare and set slowly. Portland cement was invented in England in 1834 and possesses a hydraulic set (getting hard through the addition of water) and is very fast to build with by comparison. It was introduced in North America in 1872 and was initially mixed with lime until 1930. Masonry cement came out in the 30’s. Today it typically contains no lime, just Portland cement, fillers and chemicals. The two are not compatible: lime is porous and softer, old bricks are porous and softer –- modern cement-based mortar is hard and so dense it does not absorb moisture, modern bricks are more vitreous (more like glass if you will) and they don’t, as a general rule, absorb moisture.

As I have just mentioned, there were certain disadvantages associated with the use of lime-based mortars, such as slow setting and slow curing periods and more labor-intensive preparation, which led to the search for a different approach about a century ago.

Today’s mortars serve different functions from their predecessors. In the old days, the exterior wall of a building was usually comprised of a double brick assembly; and the method used to lay the bricks so as to tie the two walls together (which we call the bonding method), was what largely gave the wall its strength -- as opposed to the mortar itself being required to provide much of the strength.

On the other hand, modern cement-based mortars have important roles to play in transferring the compressive, tensile and sheer stresses inherent with modern single-brick cavity walls, as per subject expert, Gerrard Lynch.

So the two have their place in the overall subject of building architecture; however, it is incorrect, to use modern cement-based mortars – as has typically and consistently been done in North America for over 70 years -- to restore buildings which were built before 1930, and which require traditional lime-based for the reasons given above.

Q: What can you recommend that would have a definite, positive and concrete impact
A: I have formulated a concept. It is called “Invisible Tuckpointing”, which means that when the mortar is being replaced, one cannot tell the difference between the old and the new. Here’s what I do that you can have your brick mortar replacement professional do:

• Select the joints that need replacement
• Determine by visual inspection the type of sand
• Determine by visual inspection and date of construction what the binder is
• Determine what style of tooling is needed
• Determine what pigments are required for the color
• That way, only the joints that require doing are done, making the project cost effective.
• No money is wasted on a lab test analysis or a consultant
• This is an approach which guarantees a harmonious job where only the joints that need repair are done, and they are performed so well so the work is completely invisible at a distance of 20 feet, and even at a lesser distance. It provides the home owner with the option that they can have a house that looks like it has never been repaired since its creation.

Q: Isn’t that what heritage consultants, architects and engineer already do?
A: Some of them certainly can achieve the result, but they make the process prohibitively expensive, so expensive that it is out of reach for residential homeowners. I have re-packaged the methods to be made accessible to residential homeowners who don't have the budget that the government has with which to restore buildings.

Q: Can you methods also help those with more modern dwellings?
A: Yes, although a traditional lime-based mortar may still or may not be required, the tooling style and the ability to match the color are just as important factors to consider.

Q: What advice can you give right now that I can put to use immediately to avoid my home from being incorrectly repaired?
A: • When you hire a masonry contractor, tell him the color match has to be right on and can he do it?
• Tell him you want also that the joint be finished off exactly as the surrounding joints he won’t be replacing, and can he do it?
• If the house was built prior to 1930, ask what kind of mortar he will be using. If he tells you "the same that he has used for 20 years", you would be better finding someone who knows what a lime-based mortar is, perhaps even trying to find a mason who has apprenticed in England, if you can.
• Make sure they know they have to remove the old mortar to a depth of at least twice the width of the joint, an average of ¾”
• See their work first or get them to do a sample before "rolling out" the entire project.