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What’s the difference between organic and fibreglass shingles?
What's the difference between fibreglass and organic shingles? I have to re-roof my cottage this year, and I'd like to use long-lasting shingles.–Joseph Fobert, Cornwall, Ont.
‘Organic’ is the current word used to describe traditional asphalt shingles, which differentiates them from an up-and-coming alternative called fibreglass shingles. The two types of shingles look the same on your roof: coloured granules held together by hardened tar. Both types are flexible and both are applied in exactly the same way. The difference has to do with what the tar and gravel mixture is bonded to.
Organic shingles are built on a substrate of heavy felt, while fibreglass shingles have a foundation of non-woven glass fibres. This difference doesn’t sound like much, but it actually leads to substantially different performance, especially in particular situations.
The main advantage of fibreglass shingles is their resistance to heat. They’re much less likely to curl up than organic shingles, even when used on hot, unventilated roof structures. This means they will last longer, especially when you use higher-end products. The longest-lasting shingles I’ve seen are fibreglass and carry a 50-year warranty. Fibreglass shingles are also less susceptible to catching fire or melting from the heat of a fire below.
I’ve used fibreglass shingles, and I’ll use them again. In the case of your cottage, I also recommend covering the entire roof surface with a self-sticking ice/water shield before any shingles go down. If your cottage is subject to a lot of high winds and goes for months without a visit, a few torn shingles could mean water damage. The ice/water shield provides a much more durable secondary layer of defence against water damage than tarpaper ever could. If your cottage has roof valleys, I’d suggest weaving shingles over valleys instead of leaving valley flashing exposed. This approach is much more reliable, especially on a roof that will be exposed to ice and snow buildup. Woven valleys are also faster and easier to install.