HOW A ROOFGETS BUILT.
Tear-off to magnet sweep, and the details that decide how long it lasts.
- GUIDES
- 5
- GLOSSARY TERMS
- 22
A good installation and a bad one use the same materials. The difference is nailing, flashing, ventilation and how the eaves are protected, and every one of those gets covered by a new layer of shingles within hours.
Knowing what should happen, in what order, is the best protection you have. It lets you ask the right questions before the job and recognise a shortcut while it's still fixable.
- What happens on the day my roof is replaced?
- Why does attic ventilation matter so much?
- What are underlayment and ice and water shield for?
- How do I get my house and yard ready?
READ THEM IN THIS ORDER.
- 01Roof replacement, day by dayA roof replacement runs in a fixed order: protect the house and yard, tear off the old roof, inspect and repair the wood deck underneath, then build the new roof up from the eaves to the peak and finish with a magnet sweep for nails. The steps that decide how long the roof lasts are covered up within hours, so they're worth asking about before day one.
- 02Attic ventilation explainedYour attic needs air flowing in low at the soffits and out high near the peak, so it stays cold in winter and dry all year. The building code asks for vent area of at least 1/300 of the insulated ceiling area, and in Calgary an attic that can't breathe shows up as ice dams, frost on the nails and mould.
- 03Underlayment and ice and water shieldUnderlayment is the sheet laid over the roof's wood deck, under the shingles, and ice and water shield is a self-sealing waterproof membrane used where water is most likely to get under them: the eaves, valleys and around anything that comes through the roof. Alberta's building code requires that eave protection to run at least 900 mm up the slope, because ice dams in a Calgary winter push water uphill under the shingles.
THE BASICS
Plain-language primers. Assume nothing.
Roof replacement, day by day
A roof replacement runs in a fixed order: protect the house and yard, tear off the old roof, inspect and repair the wood deck underneath, then build the new roof up from the eaves to the peak and finish with a magnet sweep for nails. The steps that decide how long the roof lasts are covered up within hours, so they're worth asking about before day one.
Preparing your home for a roof replacement
To prepare for a roof replacement, clear the driveway and the drop zone, take pictures and mirrors off top-floor walls, cover anything stored in the attic, keep pets and kids away from the work side, and tell your neighbours. Settle the decking price, start time, weather plan and cleanup in writing before the crew arrives.
Roof flashing explained: walls, chimneys, valleys and vents
Roof flashing is the metal, or sometimes waterproof membrane, that seals the joints where your roof meets a wall, a chimney, a skylight, a pipe or another slope. Those joints are where most leaks on an otherwise healthy roof start, and the building code Alberta uses sets minimum overlaps for each kind.
DEEP DIVES
For when you're mid-decision, mid-claim or mid-argument.
Attic ventilation explained
Your attic needs air flowing in low at the soffits and out high near the peak, so it stays cold in winter and dry all year. The building code asks for vent area of at least 1/300 of the insulated ceiling area, and in Calgary an attic that can't breathe shows up as ice dams, frost on the nails and mould.
Underlayment and ice and water shield
Underlayment is the sheet laid over the roof's wood deck, under the shingles, and ice and water shield is a self-sealing waterproof membrane used where water is most likely to get under them: the eaves, valleys and around anything that comes through the roof. Alberta's building code requires that eave protection to run at least 900 mm up the slope, because ice dams in a Calgary winter push water uphill under the shingles.
THE INSTALLATION GLOSSARY.
- Air sealing
- Closing gaps between the living space and the attic, such as around light fixtures and hatches, so warm, moist air stays out of the attic.
- Attic ventilation
- The system of intake and exhaust vents that moves outside air through the attic. It helps control heat and moisture and keeps the roof deck cold in winter.
- Baffle
- A channel fitted between rafters or trusses at the eave that holds insulation back so air from the soffit vents can flow into the attic.
- Balanced ventilation
- Attic ventilation with intake and exhaust split evenly between the eaves and the upper roof. Shingle warranties often expect it.
- Box vent
- A static exhaust vent, also called a roof louvre, set into the roof near the ridge. Box vents work when there are enough of them, and they shouldn't share an attic with a ridge vent.
- Drip edge
- A metal edge installed along the eaves and rakes that directs water off the roof deck and into the eavestrough and protects the edge of the deck.
- Eave protection
- Membrane or underlayment along the eaves that protects against water backing up under shingles. Building codes and manufacturer instructions set how far up the roof it must extend.
- Flashing
- Thin metal or membrane that directs water away from the joints where a roof meets a wall, chimney, skylight or another roof plane.
- High-wind nailing
- An installation pattern that uses extra nails per shingle, often six instead of four, for windy areas or steep slopes. Some manufacturers also require hand-sealing for their higher wind warranty.
- Ice and water shield
- A self-adhering rubberized membrane installed at eaves, valleys and around penetrations, where ice dams and wind-driven rain can push water under shingles.
- Magnet sweep
- Rolling a large magnet over lawns, garden beds and driveways after a roofing job to pick up dropped nails.
- Nail line
- The marked strip on a shingle where nails are meant to go. Nailing above it weakens wind resistance and can void a manufacturer's warranty.
