Roofing guides · Calgary
Calgary neighbourhoods built in the 1990s are full of cedar shake roofs that are now 25 to 30 years old. Here is why they fail here, what a shake tear-off actually involves, and what the conversion to architectural asphalt costs you in scope and time.
Written by Johnny Anderson, owner of Mountain Standard Roofing Ltd. · Updated 2026-09-05
If your Calgary house was built between 1990 and 1999 and still has its original cedar shake roof, that roof is 25 to 30 years old and it is done. We see the same picture in Signal Hill, Woodbine, Scenic Acres, Hawkwood, Christie Park, Douglas Glen and half of Airdrie: shakes that have gone silver-grey, curled at the butt ends, cupped across the grain, split down the middle and dropped enough pieces into the eavestrough to plug the downspouts.
Cedar shake roof replacement in Calgary is not the same job as swapping old asphalt for new asphalt. The tear-off is heavier, the decking usually has to be replaced, the disposal costs more, and the insurance picture behind the whole thing has changed. This is what actually happens, in order.
Cedar works in a stable, moderate, well-ventilated climate. Calgary is none of those things. The City’s own climate projections report counts roughly 107 freeze-thaw cycles a year, about 43 of them in winter, and chinooks are the reason. A single January chinook can take us from minus 20 to plus 10 in a day and back down overnight.
Wood is hygroscopic, meaning it takes on and gives off moisture with the air around it. Every one of those cycles pushes water into the shake, freezes it, expands it and lets it back out. That is the mechanism behind the three failures we grade shake roofs on:
Then add the two things that finish it. Calgary sits in Canada’s worst hail corridor, and hail on brittle 25-year-old cedar does not bruise it, it fractures it. And dry Alberta summers with high UV and low humidity accelerate the surface checking that starts the whole sequence. The shakes on the south and west slopes always fail first, and that is exactly the pattern we photograph on the way through the inspection.
Homeowners often assume a roof is a roof and the labour is the labour. On a shake conversion, the demolition is a different job.
A 20 square asphalt tear-off produces roughly 4,000 to 5,000 lb of shingle waste. The same 20 squares of old cedar shake with its felt interlayment produces a bigger, more awkward pile that fills bins faster because shake debris does not compact the way shingle does. We plan more bin changes, more truck trips and more tipping fees. On most shake conversions in Calgary we budget the disposal portion at roughly double what the same-size asphalt job would carry.
Shakes are nailed high on each shake, buried under the course above. Stripping them means working the whole field loose in pieces rather than peeling sheets of shingle in long strips. Add the felt interlayment strips between courses on most 1990s installs and a two-person crew moves noticeably slower than they would on asphalt.
This is the big one. Cedar shake was traditionally installed over skip sheathing, which is 1x4 or 1x6 boards run horizontally across the rafters with two to four inch gaps between them so air could dry the underside of the wood. Asphalt shingles cannot be nailed to air. Once the shake is off you are looking at a striped roof with gaps, and the entire field has to be sheeted with new plywood or OSB before any underlayment or shingle goes down.
Every shake had two nails. On a 20 square roof that is tens of thousands of fasteners, most of which stay in the skip sheathing. They get pulled or driven flush before the new decking goes over, because a proud nail head under a fresh sheet is a hump you will see from the street.
On a straight asphalt re-roof, sheathing replacement is a contingency. You pull the shingles, you find four bad sheets around a chimney, you swap them. On a shake conversion in Calgary, new decking over skip sheathing is not a contingency, it is a line item, and any roofer who quotes you a shake job without one either has not been on the roof or is planning a change order.
Typical Calgary rates run $95 to $150 per installed 4x8 sheet of plywood or OSB. A 20 square roof is about 63 sheets of coverage before waste, so a full re-sheet is a real number that belongs in the quote up front, in writing, with the per-sheet rate stated. That is the single most common source of dispute on these jobs and it is completely avoidable.
The upside is that you end up with a better roof structure than you started with. Continuous decking gives you a proper nailing surface, a stiffer roof plane, a smoother finished appearance, and a solid substrate for the ice and water shield at the eaves and valleys that Calgary roofs need. Our ice dam guide for Calgary covers why that eave detail matters here, and our 2026 roof replacement cost guide breaks out the per-sheet and per-square-foot numbers in full.
A shake roof breathes through the shake. An asphalt roof does not, so intake and exhaust ventilation has to be right before you close it in. Natural Resources Canada’s Keeping the Heat In guidance sets the working rule for a peaked roof with an accessible attic at an unobstructed vent area to insulated ceiling area ratio of 1 to 300, with roughly half of that as continuous soffit intake. Most 1990s Calgary homes are short on intake because blown insulation has drifted into the eaves. Fixing it now costs a few hundred dollars in baffles and vents. Fixing it later means going back onto a new roof.
The conversation has shifted in Alberta over the last few years, and it is not about leaks. It is about wildfire. FireSmart Canada’s roofing fact sheet is blunt: fire-rated materials meeting ULC and ASTM standards provide the best protection, Class A gives the highest level of protection, and homeowners should avoid wood shakes or shingles. It specifically calls out untreated wood shakes as unrated material that combines combustible fuel with crevices where burning embers can lodge.
Insurers read the same research. What we hear from Calgary homeowners:
Standard architectural asphalt shingles carry a Class A fire rating as an assembly, which puts you in the category FireSmart actually recommends. If your renewal is coming and the roof is original shake, call your broker and ask the question directly before you get the letter.
We install a lot of different systems, and for a Calgary shake conversion architectural asphalt is the answer for most homes. Not because it is the cheapest, but because of how it behaves here.
Metal is a legitimate alternative if you want a 50-year system and are prepared for the price, and we do install it. For the vast majority of shake conversions in Calgary, though, the money is better spent on a good architectural shingle over a properly re-sheeted, properly ventilated deck than on a premium surface over compromises underneath.
One of our recent jobs is the textbook version of all of this. A 1990s two-storey with the original cedar shake, 25 years old. From the ground it looked tired. From the roof it was worse: curled butts across the whole south slope, splits running past the head lap in three separate fields, and shake fragments packed into the eavestrough.
We did a full tear-off to the deck. Once the shake and the felt interlayment were off, the skip sheathing was exposed exactly as expected, so the roof got sheeted over, then synthetic underlayment, ice and water shield at the eaves and valleys, new flashings at every transition, new vents, and new architectural asphalt shingles over the whole thing. Bins staged out front, magnet sweep of the lawn and driveway at the end of each day. Most re-roofs done in one to two days, and a shake conversion with new decking runs longer than that, which we say up front rather than after the deposit. Photos of finished work are in our gallery.
Mountain Standard Roofing handles residential roof replacement and shake conversions across Calgary, Airdrie, Cochrane and Okotoks. If hail is part of the story, see hail damage and insurance work, where we document the damage for your adjuster and handle the claim paperwork. If the attic is part of the problem, attic insulation belongs in the same scope. If you want to compare a longer-life option, read our metal roof cost guide. Not sure the roof is finished yet? Our chinook damage guide walks through the failure signs.
Book a free on-site inspection and we will lift shakes, confirm what is under them, photograph the condition and give you a written scope with the decking allowance and the per-sheet rate stated, backed by a written warranty. Call (587) 577-6170 or request a quote. Built for the harshest conditions.
Questions homeowners actually ask
How long does a cedar shake roof last in Calgary?
Untreated cedar shake in the Calgary climate realistically gives 25 to 30 years, and the last five of those are usually ugly. Chinook freeze-thaw cycling, dry summer UV and hail all work on the same shakes. If your house was built in the mid to late 1990s, the original shake roof is at or past the end of its service life right now, even if it has not leaked yet.
Can you put asphalt shingles over an existing cedar shake roof?
No, and nobody reputable will. Shakes are tapered and uneven, so shingles laid over them will not lie flat, will not seal properly and will telegraph every high spot. Shake also has to come off so the skip sheathing underneath can be covered with solid plywood or OSB decking. Any quote that offers to shingle over shake is a quote to create a problem.
What is skip sheathing and why does it mean new plywood?
Skip sheathing is 1x4 or 1x6 boards nailed across the rafters with two to four inch gaps between them, which let the cedar breathe from below. Asphalt shingles need continuous support and a nailable surface every inch, so once the shake is gone the roof has to be sheeted over with 3/8 inch or 7/16 inch plywood or OSB before underlayment goes down. On a Calgary shake conversion, plan on it as part of the job, not as a surprise.
How much more does a cedar shake tear-off cost than an asphalt tear-off?
The tear-off and disposal side alone typically runs two to three times an asphalt tear-off, because shake debris is heavier, bulkier and slower to strip, and it takes more bins to the landfill. Add new decking over skip sheathing on top of that. The finished shingle price is normal, but the demolition and decking portion is where a shake conversion separates from a straight re-roof.
Are insurance companies refusing to insure cedar shake roofs in Alberta?
More carriers are getting reluctant every year. Some will not write a new policy on a wood shake roof at all, others will insure it only at actual cash value rather than replacement cost, and others require an inspection and a replacement plan. Wildfire exposure is the driver. FireSmart Canada tells homeowners to avoid wood shakes and shingles and to move to a Class A rated material such as asphalt composition shingles. Ask your broker before your renewal, not after.
Do I need a City of Calgary permit to convert shake to asphalt?
Generally no. Calgary regulation bulletin RB06-040 treats re-roofing, eavestroughing and flashing as maintenance that does not normally require a building permit. A permit is triggered when the new material is heavier than the old one, which is not the case going from cedar shake down to asphalt shingle. Structural work beyond replacing damaged sheathing is a different conversation.
We will get on the roof, lift shakes, check what the decking is, photograph the condition and give you a written scope with the decking allowance broken out. Free on-site inspection, no obligation.
★★★★★ 5.0 out of 5 — 10 Google reviews
Every review below is a verified Google review of Mountain Standard Roofing Ltd. Backed by our 10-year written workmanship warranty. Built for the harshest conditions.
★★★★★
“Mountain Standard Roofing handled my storm damage roof replacement perfectly. They worked directly with my insurance company, handled all the paperwork, and made the entire process stress-free. The crew was professional, efficient, and left my yard clean.”
Nikki Rick — Google review
★★★★★
“John and his team were awesome to deal with. He did my roof and siding and they finished a day ahead of schedule. Not only was the service awesome but the price was much better than competitors.”
Kristoffer — Google review
★★★★★
“The owner John is very communicative and always took time to answer our questions. Our roof was re-done in the agreed timeline and for the agreed upon price. Would highly recommend doing business with Mountain Standard Roofing.”
Ryan Van Boven — Google review