A roof doesn't need much from you, but it does need you to look at it. Many expensive roof problems start as something small: a lifted shingle, a cracked pipe boot, a valley full of spruce needles, an eavestrough that overflowed all spring.
This checklist is built around Calgary's seasons. You don't need to get on the roof for any of it. A pair of binoculars, a flashlight, a sturdy ladder for the eavestroughs and twenty minutes a season will do.
Tools and ground rules
Walk all the way around the house and look at every slope. Binoculars let you see shingle edges, flashing and pipe boots clearly from the yard. Take photos each season from the same spots, so you can compare year to year and have a record if you ever need to make an insurance claim.
- Binoculars for the roof surface, flashing, vents and pipe boots.
- A flashlight for the attic. Step only on joists or boards laid across them.
- A stable ladder, set on firm level ground, for eavestrough cleaning only. Keep three points of contact and don't overreach.
- Your phone for dated photos.
Spring: find what winter did
Spring is the most important check of the year. Snow load, ice dams and months of freeze-thaw cycles have had their turn, and the heavy spring rains are coming.
- From the ground, scan every slope for missing, lifted, cracked or creased shingles.
- Look at the eaves for bent drip edge or damaged shingles where ice dams sat.
- Check flashing at chimneys, walls and skylights for gaps or pieces pulled loose.
- Look for granules collecting at the bottom of downspouts. A little on an older roof is normal. A lot can be a sign of wear, so have it checked.
- Clean the eavestroughs and flush the downspouts.
- In the attic, look for water stains, damp insulation or dark spots on the decking after the first heavy rain.
- Check the soffit and fascia for sagging, rot or peeling paint where water overflowed.
Summer: hail, trees and ventilation
Summer is Calgary's hail season. It's also when trees are in full leaf and when a badly ventilated attic gets hottest.
- After any hailstorm, walk the property. Dented eavestroughs, downspouts, vents and siding are clues the roof took hits too. See what to do in the first 48 hours after a hailstorm.
- Trim branches that touch or hang over the roof. Rubbing branches wear shingles, and shade helps moss grow.
- From the ground, look for moss, and for dark streaks of algae.
- Make sure soffit vents aren't painted over or blocked.
- Check pipe boots with binoculars for cracked or split rubber around the pipe.
Fall: get ready for snow
Fall is about making sure water and meltwater have somewhere to go before everything freezes.
- Clean the eavestroughs after the leaves are down. The Insurance Bureau of Canada lists clearing eavestroughs as one way to help prevent ice dams.
- Clear valleys and the areas behind chimneys of leaves and needles, from a ladder or with a pro.
- Check downspouts are attached and pointed away from the house. In Calgary, the Stormwater Bylaw requires downspouts to end at least 2 metres from any sidewalk, road, pathway, alley or lane.
- In the attic, check the hatch seals, the insulation is even, and it isn't pushed against the eaves blocking the vents.
- Look over any heat cables before winter: clips secure, cable undamaged, and plugged in and tested before the snow comes.
Winter: watch the eaves and the attic
In winter you're watching, not working. Chinook swings make this the season for ice dams and attic frost.
- After a heavy snowfall, look for thick ridges of ice and large icicles along the eaves. That's an early ice dam.
- If it's safe, rake the bottom edge of snow off from the ground with a roof rake.
- During or right after a cold snap, check the attic for frost on nail tips and the underside of the decking. Natural Resources Canada says heavy buildup, about 10 mm (3/8 in.) or more, means you should check that ventilation is present and not blocked.
- Watch ceilings near exterior walls for new stains, especially after a chinook.
- Don't chip ice off the roof or climb up to clear it. See ice dams in Calgary.
Moss, algae, and when to call a pro
Algae shows up as dark streaks and is mostly cosmetic. Moss is the one to worry about. The Asphalt Roofing Manufacturers Association (ARMA) says moss can lift or curl the leading edges of shingles, which raises the risk of blow-off in wind. ARMA's cleaning guidance is a 50:50 mix of laundry-strength liquid chlorine bleach and water, left for 15 to 20 minutes and rinsed with low-pressure water, and it says never to pressure-wash an asphalt shingle roof. It also advises against adding zinc or copper strips to an existing roof, because the installation can damage the seal or create nail-hole leaks.
Bleach on a roof means slippery footing, damaged plants below and a real fall risk, so for most people this is a job to hire out.
- Call after any hailstorm or wind event that damaged things you can see from the ground.
- Call for missing or creased shingles, lifted flashing, or a cracked pipe boot.
- Call for any stain in the attic or on a ceiling you can't explain.
- Call for anything that requires walking on the roof.
How often should I have my roof inspected?
Do your own ground-level check each season and after any major storm. A professional inspection makes sense after hail or high wind, before buying a house, or if your roof is getting older and you're starting to see wear.
How often should I clean my eavestroughs in Calgary?
Twice a year is a sensible habit: late fall after the leaves drop, and spring after the snow melts. If you have trees overhanging the roof, you may need to do it more often.
Can I pressure-wash moss off my roof?
No. The Asphalt Roofing Manufacturers Association says pressure washing an asphalt shingle roof causes granule loss and very likely premature failure. Use its recommended bleach-and-water method with a low-pressure rinse, or hire it out.
Where the facts on this page come from. If a source has changed since we last checked, tell us and we'll fix the page.
- Algae & Moss Prevention and Cleaning for Asphalt Roofing Systems · Asphalt Roofing Manufacturers Association
- Stormwater Bylaw for homeowners · City of Calgary
- Keeping The Heat In, Section 5: Roofs and attics · Natural Resources Canada
- Stay protected: Understanding and helping prevent ice dams · Insurance Bureau of Canada