Warning Signs Your Asphalt Roof May Need Replacing


Asphalt is a naturally occurring residue formed from remains of microscopic algae, and other once-living things. Canada has one of the largest deposits of this natural bitumen in the world. Prospectors discovered it in the 1960’s, although First Nations people had long used it for waterproofing their canoes. Shingles made from asphalt are popular in Calgary because of their relatively-low upfront cost, and fairly simple installation.


Two Types of Asphalt Shingles in Common Use


There are two types of asphalt shingles in common use, namely organic and fibre glass ones. Both types use a base material saturated with asphalt, and covered with asphalt or modified asphalt.  The top surfaces have a coating of slate, quartz, vitrified brick, stone, or ceramic granules to protect them. While the undersides have a mica, talc or sand coat to prevent the shingles sticking together during shipping.

# Organic Shingles use a base material derived from cellulose, wood fibre, waste paper or other materials. They are more prone to fire damage than fibreglass ones, but are less brittle in winter.

# Fibreglass Shingles replaced asbestos when health authorities restricted asbestos use. Their base layer comprises wet, random-laid glass fibres bonded with resin. Hence they are less prone to fire damage.

Both shingles come in two primary designs. These are simple, flat shingles, and thicker, more-expensive architectural shingles with greater aesthetic appeal


How to Care For Your Asphalt Shingles


Although asphalt is an ancient, organic material it starts deteriorating as soon as it is exposed to the elements. Solar rays gradually break down the material. This can happen faster in Calgary because of the relatively harsh climate. The main defence is the granular coating. However, petroleum oil gradually travels to the surface where rain, snow and ice destroy it.

We can delay the process by regularly removing algae, lichen, and woody debris from the surface. We can for example wash it down with a copper sulphate, zinc chloride, or other solution followed by thorough rinsing. However asphalt shingles inevitably become hard and brittle over time. A falling tree branch, a burst of hail, or a strong gust can eventually tear them apart. It follows that timeous replacement is essential. This begins with a visual inspection.


Warning Signs When Inspecting Asphalt Shingles


An asphalt shingle roof can last for up to twenty years if correctly installed. However this life is shortened if it was not adequately ventilated during construction. An aging or prematurely-aging asbestos roof will have shingles curling at the edges, and buckling in the middle. This can allow them to admit water into the roof space.

Shingles shed their protective granules as they decay.  These accumulate in eaves-trough gutters, and appear at the bottom of downpipes. While individual damaged shingles may be replaced, it is hard to match new with aging ones.

There comes a time when we should replace the patchwork effect, because this is degrading the appearance of our home, and hence diminishing its market value. Please call Valiant Exteriors on 403 829 1661 or send us an email if you have a concern about your roof.

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Image: Seventy Years Old Overdue for Repair: Mark Clark BY CC 2.0