Three tips for a great new roof
Most houses in Canada have asphalt shingle roofs, and June is an excellent month to have new shingles installed. With hot weather on the way, shingles will seal down reliably later on in the summer sun. But June itself is also not usually so hot that the shingles will be soft and easily damaged underfoot during installation.
If you’re interested in getting the best possible asphalt shingle roofing job, there are details you need to discuss with your roofer. As with any other professional in life, don’t assume all roofers necessarily use the best possible techniques. Be your own watchdog by asking about the re-roofing details here and you’ll get the best possible results.
There are three parts to any great asphalt shingling job — the shingles themselves, the underlay system and the roof vents that round out any good installation.
Improved tar, gravel and substrates have boosted potential shingle lifespan enough that 40- and 50-year shingle warranties are now common. Thirty years ago shingles were sold with 10-, 15- and sometimes 20-year warranties at the top end. These days all manufacturers have doubled these numbers, and the difference is about more than just marketing.
The “10-year” shingles on the left lasted for 30 years before needing to be replaced. Thefibreglass shingles, right, have a rated lifespan of 40 years. (STEVE MAXWELL)
Most of the gain in shingle life comes from the use of fibreglass as a shingle substrate instead of the more traditional organic felt. Fibreglass shingles look the same as organic ones on your roof because they’re impregnated with the same kind of tar and gravel used as part of all asphalt shingles. That said, fibreglass is much more resistant to heat than felt, and this makes all the difference. Even on very hot, unventilated roof surfaces, fibreglass shingles consistently deliver their expected lifespan without curling. You also get a higher fire rating with fibreglass. In addition, fibreglass shingles are about 30 per cent thinner than organics for a given quality of shingle, making them easier to install on ridges, as part of woven valleys or any other application where bending of some shingles is required.
Ventilation is another critical roof issue. Most roofs need more of it than they have for two reasons — first, more ventilation reduces attic temperatures during summer, making it easier to keep upper floors cool, and second, attic ventilation allows internal moisture from domestic activities like washing, showering and breathing to vent away freely in winter, in case this moisture happens to enter the attic incidentally. You can’t have too much attic ventilation, and there’s no better time to install more vents than during a reroofing job. Ridge vents deliver the most ventilation for the least amount of visual distraction.
The best roof installations are waterproof before shingles go on, and this means more than just a layer of that old-fashioned, 15-pound tarpaper nailed to roof sheathing. There are two philosophies behind creating a reliable secondary layer of protection underneath your shingles, and they’re completely different.
The black fabric being installed here keeps water out if the shingles fail, but also allows watervapour to escape if necessary. (STEVE MAXWELL)
When self-sticking ice and water shield arrived on the scene about 25 years ago, it didn’t take long for it to replace tarpaper as a complete roof underlay on high-end installations. And this approach still makes a lot of sense, except for one universal Canadian issue.
Cold climates create a moisture threat that can attack roof structures from both top and bottom. In addition to the usual hazard of water leaking from above, there’s also the possibility of moisture condensing in parts of the roof structure from below during winter. This is why the best roof underlay these days is breathable. It combines the ability to shed water along with the ability to dry out from the inside.
Ask any prospective roofers for homeowner references, check them out, then go with a contractor who has a track record of good work and is willing to use today’s best shingling methods.