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A replacement is also the best chance in decades to fix problems that shingles alone can't solve. With the roof open, a roofer can replace rotten sheathing, correct poor attic ventilation, add eave protection where it's missing and redo the flashing at chimneys, walls and skylights. It's a good moment to have the attic's insulation and air sealing checked as well, since they decide how the new roof will behave in winter.
This page walks through the signs that a roof is due, each step from tear-off to cleanup, how to choose a material, what affects lifespan, the permits and code requirements involved, and what to look for in the warranty.
Signs you need a roof replacement
- Shingles curling, cupping or cracking across most of the roof, not just in one spot.
- Bald patches where the protective granules have worn away and the asphalt shows through.
- A wavy or dipping roof surface, a sign the deck or framing underneath may be damaged.
- Repeated leaks in different places despite earlier repairs.
- Moss or rot along the lower rows, or soft spots found by the roofer during an inspection.
- Heavy frost, mould or dark staining on the underside of the deck in the attic.
- An insurer or a buyer's home inspector flagging the roof's age or condition.
The roof replacement process, from tear-off to cleanup
A crew should never leave the roof open overnight. If the weather turns during the job, exposed sections are covered before anyone goes home.
- Protecting the site: tarps over plants and siding, a disposal bin in the driveway and precautions in the attic if dust or nails may fall through.
- Tear-off: removing the old shingles, underlayment and worn flashing down to the deck.
- Deck inspection and repair: replacing soft, rotten or delaminated sheathing so the new roof has a sound base.
- Eave protection and underlayment: a self-adhering membrane along the eaves and in the valleys, then underlayment over the rest of the deck.
- Drip edge and flashing: new metal at the edges and valleys and around chimneys, walls and skylights.
- Roofing and ventilation: installing the new covering along with intake and exhaust vents suited to the attic.
- Ridge and finishing: capping the ridge, sealing every penetration and checking each flashing detail.
- Cleanup and final check: a magnetic sweep of the yard for nails, removal of all debris and a walk-through with you.
Choosing a material for your new roof
Most replacements on sloped roofs stay with asphalt shingles, which most crews know well and which are easy to repair. Metal is worth considering if you plan to stay a long time, want snow to slide off a steep roof or live where wind and hail are frequent, but it needs snow guards over doors and paths and a roofer experienced with its details.
Heavier materials such as slate or concrete and clay tile need confirmation that the framing can carry the added weight on top of the snow load your region's building code expects. Flat and low-slope roofs need a membrane system rather than shingles. Colour matters too: lighter roofs stay cooler in summer, while winter performance depends mostly on the attic's insulation, air sealing and ventilation.
How long a new roof lasts in a Canadian climate
Lifespan depends far more on conditions than on the label. The terms of a manufacturer's warranty describe what the maker will cover, not how long a roof will actually last on your house. Sun exposure, slope, the colour of the covering, repeated freeze–thaw cycles and, above all, the attic below all play a part.
A hot, poorly ventilated attic ages shingles from underneath, and moisture carried in by air leaks can rot the deck long before the surface looks worn. Good ventilation and air sealing, clear gutters and prompt repairs after storms are what let a roof reach the upper end of its expected life. Ask your roofer what they typically see for your chosen material in your region, and why.
Roof replacement permits and building code requirements
Many municipalities require a permit to replace a roof, especially when the material changes, the structure is altered or the house is in a heritage district. The rules differ from one city to the next, so check with yours before signing. In Quebec, the contractor must also hold an RBQ licence with the subclass that covers roofing.
Provincial building codes, most of them based on the National Building Code of Canada, set requirements a new roof should meet, including eave protection on most shingle roofs to guard against water backing up from ice dams. For attic ventilation, the National Building Code calls for an unobstructed vent area of at least 1/300 of the insulated ceiling area, split between the lower and upper parts of the roof space, and more on low-slope roofs; Natural Resources Canada uses the same 1 to 300 ratio for peaked roofs with accessible attics. Ask your roofer to explain how the new roof meets these requirements.
Roof replacement warranties and paperwork to keep
- Get the manufacturer's warranty in writing and confirm whether it has to be registered after installation.
- Make sure the roofer's workmanship warranty is written into the contract, with exactly what it covers.
- Check whether mixing components from different product lines affects the materials warranty.
- Find out whether the warranties transfer if you sell, and what the next owner has to do.
- File the permit, the final invoice and before-and-after photos with the warranties, since buyers and insurers often ask for them.
Full tear-off or roof-over: removing the old roof versus covering it
Installing new shingles over an existing layer may be allowed in some situations, depending on local rules and the manufacturer's instructions, but it hides the deck, adds weight and leaves no real chance to install eave membranes and new flashing properly. Any soft sheathing, rot or hidden leak damage stays trapped under the new roof.
A full tear-off lets the roofer see and fix the deck, bring ventilation and eave protection up to current requirements and start the new warranty on a clean base. It takes longer and produces more waste, but it's usually the sounder choice for a roof that has to stand up to ice, heavy snow and freeze–thaw for years to come.
Roof Replacement: frequently asked questions
How long does a roof replacement take?
A typical house is often finished in a few days, but size, slope, the number of old layers, deck repairs and the weather can stretch that. Ask for an estimated timeline in the contract.
Do I need to be home during a roof replacement?
Not necessarily, but expect noise and vibration, keep children and pets away from the work area, and move anything stored in the attic that could be hit by falling debris.
Can a roof be replaced in winter?
It's possible in some conditions, but cold makes shingles brittle and slows the sealing of shingles and membranes. Most homeowners plan for spring to fall unless the roof can't wait.
Will a new roof stop ice dams?
A new eave membrane helps keep meltwater out, but ice dams form because heat escapes into the attic. Air sealing and insulation are what prevent them.
Does a roof replacement need a permit?
Often, but it depends on your municipality and the scope of the work. Call your city's permit office, and confirm in the contract who applies for it.
Should I replace gutters, soffits or skylights at the same time?
It's often worth it if they're near the end of their life, since the flashing around skylights and along the roof edge is redone anyway. Ask the roofer to quote them as separate items so you can decide.
Sources
Written by the LokalMatch editorial team. Reviewed by Zubair Afzal on September 10, 2026. How we write and check our guides