The quote said "17 square tear-off, bungalow, Ajax." Straightforward job. One and a half days. Then we started stripping.
Under the first layer of architectural shingles we found a second layer of three-tab. Under the three-tab we found the original cedar shake from what we estimate was the early 1980s. Three layers total. The homeowner had no idea.
Why this matters
Every layer of roofing adds roughly 2–3 lbs per square foot. A single layer of architectural shingles weighs about 3.5 lbs/sq ft. This roof was carrying close to 9 lbs/sq ft — nearly three times the intended load. The roof trusses on a 1980s bungalow were not designed for that.
Building code in Ontario does not allow more than two layers of asphalt shingles. Whoever installed the second layer over the cedar shake was already pushing it. The third layer was a code violation and a structural risk.
What made it hard
Cedar shake nails. Modern shingles use smooth-shank roofing nails that pull out with a flat bar. Cedar shake was installed with ring-shank nails — they have ridges that grip the wood and resist pulling. Every nail had to be individually worked out or cut. On a 17-square roof, that's roughly 5,000 extra nails we didn't plan for.
Disposal weight. We had budgeted for one 20-yard dumpster. Three layers filled it before we were halfway done. The second bin added $450 to the job. We ate that cost — the homeowner didn't know what was under there, and neither did we.
Decking condition. With that much weight sitting on it for 40+ years, we expected decking damage. We replaced 3 sheets of OSB where the plywood had delaminated. The rest was surprisingly solid — old-growth plywood from the '80s is denser than what's milled today.
What surprised us
The cedar shake, despite being 40 years old and buried under two layers, was in better shape than the 15-year-old three-tab shingles on top of it. Cedar is remarkably durable even without maintenance — as long as it can breathe. Once they sealed it under asphalt, the trapped moisture is what finally started breaking it down.
The takeaway
If your home was built before 1990 and has had a roof replacement, there might be an original layer underneath. When you get a quote for your next roof, ask what the plan is if they find multiple layers. A good roofer builds that possibility into the estimate rather than hitting you with a surprise change order on day one.
This job took us 2 full days instead of 1.5. The disposal cost $450 more than estimated. We replaced 3 sheets of decking. The homeowner got a properly stripped, code-compliant roof with new ice-and-water shield and GAF Timberline HDZ — the way it should have been done the first time.