OK, it is probably not a surprise when I admit about a third of my television viewing is focused on design, restoration and renovation programs.

And, on various occasions, I have sat and shaken my head over certain mistaken practices displayed when it comes to a very common building material: brick.

So, I thought this week we might begin the column by considering brick and a couple of these “mistaken” practices.

Prior to the advent of machine-made modern brick late in 19th century, bricks were handmade by workers who mixed native clay with water to make the slurry that was then hand-packed into rectangular forms, then laid out to dry.

Once sufficient moisture had leached out, the clay blocks were carefully removed from the forms and stacked in a wood-fired beehive kiln.

For one and a half to two days, the fire in the kiln was constantly monitored around the clock to maintain the high temperatures required to make the molecular changes which produce a hardened brick.

This process resulted in three general product grades: the bricks closest to the fire were generally over-exposed to heat, often resulting in a shiny blackened surface, flawed shapes and referred to as “clinkers” after the metallic sound they produced when stuck together.

First quality brick came from the middle of the stacks where the clay blocks had received the proper amount of heat to create both the strength and hardness to be weather resistant.

Finally, “soft” or “salmon” brick was produced from the outer of the stacks where, furthest from the heat, the clay blocks had been imperfectly fired and lacked weather resistance.

Although the clinker bricks were water-resistant and durable, they had a higher thermal conductivity than the more porous, first quality and salmon bricks, lending less insulation to climate-controlled structures.

This, combined with their irregular shapes, resulted in clinkers often being relegated to discards throughout most of the 18th and 19th centuries, although they were occasionally used as pavers or in decorative elements incorporated into a building’s brick field.

Clinkers did enjoy a relatively brief period of popularity when architects of the Arts & Crafts movement — who found them distinctive, charming and evocative of their Romantic ethos — incorporated them into their builds and, in the eastern North America, they found their way into many Colonial Revival designs.

First quality bricks were the product of choice for the outer layer or “wythe” of buildings where their uniform size, strength and resistance to climatic conditions produced an outer sheathing that was long-lived, visually appealing, and easy to construct, this last point saving on labour costs — important since these bricks were the most expensive to purchase.

Our ancestors, typically being a frugal lot, used structurally sound (and cheaper) salmon bricks on the inner, unexposed wythes of their buildings where their lack of weather resistance didn’t matter.

To be clear, even the first quality handmade brick was not as strong as modern machine-made brick … however, since historic brick was laid with lime mortar (not as strong as Portland mortar), the structural integrity of the brick was maintained.

Which brings us to the first and second of the “mistaken” practices.

The first I most recently witnessed while watching a segment of a popular restoration show wherein the host assisted the homeowner of a mid-19th century house in cleaning old mortar off bricks that had been salvaged during a renovation of the building.

These bricks, the homeowner stated, came from the inner and outer layers of a wall removed as a result of the building alterations and he planned on reusing them to clad the outer surface of a new chimney.

No one mentioned that, if the salmon brick was used in a fashion which exposed them to the weather, these bricks would inevitably fail in pretty short order.

Salmon bricks belong on the inside of a building, not the outside. And, it should be noted that I have even seen masons who are not familiar with handmade brick make this same mistake.

The second erring practice made by those inexperienced with historic brick is to lay or repoint them using Portland mortar.

Bluntly, the rigidity of modern mortar will cause handmade brick to crack, spall and fail over the near term.

But, historic brick is not alone in suffering from errant practices — modern brick is also susceptible to the vagaries of the uninformed.

Take, for instance, a long standing exercise of applying paint on clay brick, something that has become more popular in the last few years as renovation television has expanded its reach into homes around the world.

There are a number of reasons why painting brick is a bad idea but most revolve around the nature of clay brick itself.

You see, unlike cement for example, brick is porous. This porosity is expressed in tiny voids that allow moisture vapour to pass through in both directions, helping to regulate humidity and prevent moisture from being trapped within the walls.

One can easily say brick “breathes” and must be allowed to do so.

However, applying paint to the brick creates a barrier, effectively sealing the voids and results in trapping moisture inside the brick.

Amongst other issues, this situation can lead to the following:

The trapped moisture creating the ideal environment for the growth of mold and mildew in the materials — wood framing, drywall, some types of insulation, etc. — behind the brick.

During seasonal freeze and thaw cycles, the trapped moisture will expand and contract causing the outer layer of brick to flake, spall or crack.

The trapped moisture can cause deterioration (softening) of the clay brick, potentially compromising the structural integrity of the brick field over time. 

Moreover, just like clapboard, painted brick must be regularly addressed to maintain a pleasing appearance.

Further, once painted, it is incredibly difficult and expensive to strip the paint off the brick.

Now, if you are dead-set on changing the appearance of your brickwork — and there can be good reasons to do so — there are alternatives to paint.

The most traditional method that can be seen on some historic masonry buildings would be a limewash.

Consisting only of lime putty, water, and pigment, it keeps the brick’s texture and breathability, offers buildable colour intensity and weathers naturally.

This application offers a light or whitewashed look that can either fully cover the brickfield or allow portions of it to be visible.

Another option some folks find attractive is a mortar wash and German smear, which involves applying a very thin layer of mortar over the existing brick and mortar joints, and subsequently wiping it down (smearing) to subtly alter the overall colour of the brick façade.

Note that this method actually allows the character of the brickwork to be visible through the mortar layer.

Then there is water-based brick stain that offers a practical and cost-effective solution to change the colour of brick or brick-and-mortar surfaces, while still maintaining the appearance of its natural texture.

Brick stain colours can range from classic reds and browns to more contemporary shades like grays, whites and even blues.

Unlike paint, which creates a surface barrier, stain actually slightly penetrates the masonry to colour the material while leaving the voids intact preserving its “breathability” — a new fresh, vibrant hue that doesn’t mask or inhibit its innate character.

In addition, you have the option to restain the brickwork with a different colour should that be desired in the future.

Understanding brick, whether you have historic or modern, is the key to its use, maintenance and making the right choices to keep it beautiful.

Brian Marshall is a NOTL realtor, author and expert consultant on architectural design, restoration and heritage.