Gap Filling 101

Bricks and mortar are a natural pair. Interesting fact: the phrase is an idiom with two meanings. The first meaning is simple or basic: a "The online course covered only the bricks-and-mortar of the subject". The second meaning describes a business that has a physical presence instead of only an online one. "The startup began online, but shifted towards a brick-and-mortar presence in major cities".

Mortar, however, is only one option for joining bricks. Mortar, grout, and caulking are all words that can be taken to mean a plastic substance that fills a gap between two solid objects. As well, there is a spectrum of resins and adhesives that can also be used to bond masonry. Here is a basic overview of some options.

Lime Mortar: This kind of mortar has been used for millennia. Its basic composition is lime putty and sand, although many additives such as plant fibres and clay have been used to improve its strength and flexibility. The Chinese even added sticky rice.

Cement Mortar: At the beginning of the 20th century, Portland cement began to replace some of the lime in mortar mixes. It was favoured due to its quicker setting time and higher strength. It has now entirely replaced lime for most conventional masonry. The basic formula is one part cement to 5 or 6 parts sand. Sometimes hydrated lime is added for increased workability, but this is not the same compound as the lime putty used on its own for lime mortar.

Grout: The Portland Cement Association differentiates between mortar and grout only by their fluidity, with grout being more fluid. A grout mixture is often used in concrete block walls to fill the voids and set rebar.

Epoxy: This substance normally comes in two parts, a resin and a hardener. They must be mixed in order to start the chemical reaction that sets the substance.

A resin adhesive can have different chemical compounds as its basis. Epoxies, polyesters, and vinylesters are three different classes of compounds that perform similarly.

Caulking: The words "caulking" and "sealant" are often used interchangeably. Caulking is often used to waterproof joints and is not structural, unlike mortar. It is often made of silicone.

So, which do I use for the roof? More on that later...