Before permanent metal roofing became available on Vancouver Island around 1998, concrete tile roofs were likely the best bet for Vancouver Islanders comparing their roofing options.
Like permanent metal, concrete tile roofs are beautiful, incredibly durable and completely fire-resistant, an increasingly important feature given Vancouver Island's trend toward hot, dry summers.
The two major drawbacks to a concrete tile roof are weight and maintenance.
Concrete roofing tiles can weigh as much as 10 pounds per square foot, five times heavier than asphalt shingles and 10 times heavier than permanent metal roofing. In fact, new homes that are built with a concrete roof in mind need a specially engineered truss just to support the weight of the roof.
Concrete's weight also makes it incredibly dangerous in the event of an earthquake. In fact, engineers in California have recommended against its use in earthquake-prone regions.
As for maintenance, although a concrete roof won't decay or attract vermin like asphalt and cedar roofs can, it is still susceptible to moss growth. In order to maintain concrete's high-end beauty, most experts recommend having it professionally power-washed every couple of years.
A concrete roof should also be inspected periodically to check for cracked or broken tiles, especially after extreme weather. Ironically, concrete roofing tiles are often broken by people walking on top of them checking for damage!
While this regular maintenance pales in comparison to that required to preserve a cedar roof, it is much more than is required to maintain an asphalt or permanent metal roof – which is none at all.
When considering an asphalt roof for your home on Vancouver Island, there are several things to keep in mind:
Concrete tile has a lot going for it in terms of withstanding Vancouver Island's hot, dry summers and wet, stormy winters. It is fire-resistant, wind resistant and won't rot or decay under wet conditions.
However, concrete's incredible weight remains its biggest downfall. Assuming your home is engineered to support the weight of a concrete roof, you still need to consider how your roof will perform in the event of an earthquake, for which experts agree Vancouver Island is long overdue.
In the wake of the 1994 Northridge earthquake in southern California, civil and structural engineers agreed that concrete roofs were responsible for a disproportionate share of damage and destruction. Their recommendation? That homebuilders increase their use of lightweight roofing materials, such as aluminum and metal.
Concrete roofs are also susceptible to the same enemy that is the downfall of so many other roofing materials on Vancouver Island – moss. Vancouver Island gets a lot of rain, fog and generally moist conditions, perfect breeding grounds for moss and lichens, which flourish on concrete roofs.
"Place your elbow on a table and hold a baseball in your hand. If you swing your arm around, it is easy to stop the baseball from moving. Now replace the baseball with a bowling ball. Huge difference! That may be the difference between your house surviving an earthquake or collapsing."
- Sydney Chai, civil engineer specializing in structural seismic retrofit design
Concrete tile roofs have a lot going for them, and a few years ago they might have even been the best roofing material for Vancouver Island.
However, permanent metal roofs, which were introduced on Vancouver Island around 1998, offer more benefits and fewer drawbacks for a comparable price.