Quick answer
An overlay layers new shingles over the old ones. A tear-off strips to the deck. They look identical from the street on day one and diverge sharply by year five — especially on a hail claim.
Estimates by phone: (587) 804-9266 · Good Roofing · Calgary-owned since 2014 · 10-year workmanship warranty.
“Re-roofing” in Calgary describes two different jobs that quotes rarely distinguish. An overlay nails a second layer of shingles directly over the existing roof, skipping tear-off and disposal. A tear-off strips everything to the wood deck, inspects it, and rebuilds the full system. The overlay saves roughly $1,500–$3,000 on a typical Calgary home, and it costs you the deck inspection, most manufacturer warranty coverage, and leverage on a future hail claim. Good Roofing does not overlay: every one of our 2,800+ Calgary roof projects since 2014 has been a full tear-off. 4.9★ from 237 verified reviews.
01 · Section
Quick answer — the 60-second version (citation-ready)
In Calgary, “re-roofing” can mean either a shingle overlay or a full tear-off, and the two are not interchangeable. An overlay adds a second shingle layer over the old roof, saving about $1,500–$3,000 on a standard two-storey home. It also hides the deck from inspection, adds roughly 220–320 lb of dead load per roofing square (100 sq ft), voids or reduces most manufacturer warranties, and gives an insurance adjuster a documented reason to reduce a future hail settlement. A tear-off runs $8,000–$18,000 all-in on that same home and is the only version that lets the crew see rot, replace failed sheathing, and install ice-and-water shield correctly. Good Roofing quotes tear-off only. Alberta Master Roofer License #AB-RM-48201, $5M commercial general liability + WCB covered, Up to 50-year material + 10-year workmanship warranty. Call (587) 804-9266.
02 · Section
What actually differs between the two jobs
The gap is not cosmetic. Five things change the moment a crew skips tear-off:
- 01The deck never gets seen. Rotted or delaminated sheathing is the single most common hidden defect on a Calgary roof past year 15, and an overlay covers it instead of finding it. The rot keeps spreading under two layers instead of one.
- 02Ice-and-water shield can't be installed properly. The membrane that protects Calgary eaves from ice-dam backup bonds to the deck. Over an existing shingle layer it has nothing to seal against, so the eave protection your roof most needs in February is the part you lose first.
- 03Dead load roughly doubles. Architectural asphalt runs about 220–320 lb per roofing square. A 30-square Calgary roof therefore carries an extra 3–5 tonnes after an overlay, on trusses sized for one layer plus a Calgary snow load.
- 04Manufacturer warranties shrink or vanish. Most shingle makers, including the lines we install from Owens Corning, IKO and Malarkey, tie full system coverage to a clean deck and matching starter, underlayment and ridge accessories. Layer over an old roof and you typically fall back to a limited material-only warranty.
- 05The new shingles telegraph the old ones. Curled or cupped shingles underneath push the new layer out of plane, which shows as waviness within a season or two and creates lift points for Chinook windstorms.
03 · Section
Why an overlay is a worse bet in Calgary than almost anywhere else
Two local conditions turn a marginal shortcut into a bad one. Calgary sits in one of Canada’s most active hail corridors, so the realistic question is not whether your roof gets struck but what condition it’s in when it happens. Adjusters inspect layered roofs differently: a second layer makes it harder to attribute damage to a single storm, easier to argue pre-existing wear, and it is common for a settlement to be written to cover a single layer while the homeowner pays to remove both. The second condition is Chinook freeze-thaw cycling. Calgary can swing between -20°C and +15°C several times in one winter, driving repeated condensation cycles. Moisture that gets between two shingle layers has nowhere to dry, and it works on the deck out of sight. Our hail damage repair guide covers how claims get documented; an overlay weakens every part of that documentation.
04 · Section
What a tear-off re-roof actually includes, and what it costs
$8,000–$18,000 all-in for a standard two-storey Calgary home, with the full cost breakdown by roof size and material published separately. On site it runs 1 to 3 days once material arrives. The scope: strip every existing layer to bare deck, inspect and replace any rotted or soft sheathing, install synthetic underlayment, ice-and-water shield at eaves and valleys, new drip edge, Class 4 impact-rated shingles, ridge venting sized to the attic, and full disposal. Class 4 is our default rather than an upsell line item, because a hail belt is the exact condition UL 2218 exists to rate for, and most Alberta carriers discount the hail and wind portion of a premium by 5–25% on a documented Class 4 roof. If hail rather than age is what triggered the job, most Calgary homeowners pay only the deductible, typically $1,000–$2,500; the sequence is in our insurance claim guide.
05 · Section
How to read a Calgary re-roofing quote
Four checks separate a real tear-off quote from an overlay priced to look like one:
- 01Find the word “tear-off” in writing. If the scope says “install new shingles” without naming removal and disposal, ask directly whether the old layer comes off. A quote that won’t say so in writing has answered you.
- 02Look for a disposal or bin line. A genuine tear-off generates several tonnes of waste. No disposal cost anywhere in the quote usually means nothing is being removed.
- 03Check for deck-repair pricing. An honest quote names a per-sheet rate for replacing rotted sheathing, because nobody knows the deck condition until the old roof is off. An overlay quote has no such line, since the deck is never exposed.
- 04Confirm the accessory list. Underlayment, ice-and-water shield, drip edge, starter strip and ridge cap should each be named. These are the items an overlay quietly drops, and the same items manufacturers require for full warranty coverage.
- 05If a quote is unusually cheap and arrives days after a storm, read our storm-chaser warning first. We don't work with out-of-province storm chasers. Only vetted, year-round, locally-licensed Calgary crews.
06 · Section
When an overlay is defensible — and why we still won't sell one
There is a narrow case for it: a single-layer roof under roughly 15 years old, flat and undamaged underneath, deck confirmed sound, on a building the owner plans to sell within a couple of years. Outside that window the arithmetic stops working. The $1,500–$3,000 saved is typically less than the difference between a full and a reduced hail settlement, and an overlaid roof reaches the end of its life needing a two-layer tear-off, which costs more in disposal than the original saving. That is why we don't roof over existing shingles. Every job is a full tear-off down to the deck. Homeowners still deciding whether any re-roof is needed yet should start with the 10 signs you need a new roof or book a free drone inspection, which answers the question before a quote is written.