Flat and commercial
Flat Roof Repair in Calgary
A flat roof is not flat. Any roof with a slope below 1 in 6 is a low-slope roof, and it sheds water by membrane rather than by gravity alone. Marku Roofing Repair Ltd. repairs and replaces low-slope roofs in Calgary on houses, garages, additions, and small commercial buildings.
- 24/7 emergency line
- Licence BL272564
- WCB 9892020
- $5M liability
- Free written estimate
Free written estimate
Tell us what the roof is doing
We reply with a written scope and a price, not a range.
City of Calgary licence
BL272564
WCB Alberta account
9892020
General liability
$5,000,000
Written estimate
Free, itemised
Call 403-700-7542 for a free written estimate.
01
Why low-slope roofs fail in Calgary
A steep-slope roof leaks when water gets past a lap. A low-slope roof leaks when water sits on it long enough to find any weakness at all. Calgary adds two accelerants.
Freeze-thaw cycling. Standing water at a low point freezes overnight and thaws during a chinook. Ice expands roughly 9 percent by volume. Each cycle works at a seam.
Thermal movement. A dark membrane on a summer afternoon runs far hotter than the air temperature, then drops below freezing the same night. The membrane moves. The parapet it is bonded to moves differently. The joint between them is where the two arguments get settled.
02
What we repair
Open and fishmouthed laps
Side and end laps are the first thing to inspect. A lap that has lost adhesion lifts at the edge and forms a fishmouth. Water enters sideways, travels between plies, and emerges somewhere unrelated.
Blisters
A blister is trapped air or moisture between plies expanding under heat. Small stable blisters are monitored. Blisters that have split are cut, dried, and patched with a torch-applied or self-adhered repair sheet.
Punctures and traffic damage
Rooftop mechanical service, satellite installs, and window cleaning all put boots on a membrane that was never designed as a walking surface. Punctures near equipment are common and easy to miss.
Ponding
Standing water 48 hours after rainfall indicates a drainage problem, not a membrane problem. The fix is tapered insulation, a relocated drain, or a cricket, not more membrane.
Flashing at parapets, curbs and drains
Most low-slope leaks are flashing leaks. Base flashing pulling away from a parapet, a curb with no counter flashing, and a drain with a compressed clamping ring are three of the most common Calgary failures.
Wall and deck tie-ins
A low-slope addition tied into a shingled main roof, or a deck-as-roof over living space, concentrates every failure mode in one 300 mm strip. That transition gets inspected first.
Stop guessing
Get flat roofing priced in writing
We look at the roof, photograph what we find, and hand you a scope with a number on it. If a repair is the right answer, we say so rather than quoting a replacement.
Estimates are free and written. Not a range, not a verbal number.
03
Systems we work on
SBS modified bitumen. Two-ply, torch-applied or self-adhered. The dominant low-slope system on Calgary residential and small commercial roofs. See SBS roofing.
EPDM. Single-ply synthetic rubber, seamed with tape or adhesive. Repairs are patch-and-prime.
TPO and PVC. Single-ply thermoplastics, hot-air welded. Repairs are welded, not glued.
Not tar and gravel. Our insured scope of operations is roofing and repair excluding hot tar, so we do not install or rebuild traditional built-up kettle systems. We repair the membrane systems above.
04
Repair or replace
Replace the low-slope roof rather than repairing it when the insulation below the membrane is saturated, when the membrane has widespread splitting rather than isolated defects, or when more than roughly a quarter of the field has already been patched. Wet insulation does not dry out under a membrane. It stays wet, loses R-value, and rots the deck.
Draft The only way to know whether the insulation under a membrane is wet is to check, and there are two accepted ways. A core cut takes a small plug out of the assembly and you look at it; it is definitive and it makes a hole that has to be patched. A moisture scan, infrared or capacitance, finds wet areas without opening the roof and is better for mapping how far the water has travelled. On a repair-or-replace decision worth five figures, one or the other is worth doing before anybody quotes.
Cost
What flat roofing costs in Calgary
Draft Calgary market rates, 2026. Ranges, not a quote.
| Work | Typical Calgary range |
|---|---|
| Small patch: a puncture, an open lap, a blister | $300 to $800 |
| Flashing repair at a curb, parapet or drain | $500 to $1,500 |
| Section replacement, wet insulation removed | $2,000 to $6,000 |
| Two-ply SBS replacement, residential garage or addition | $14 to $22 per sq ft |
| Two-ply SBS replacement, larger commercial field | $9 to $16 per sq ft |
The range on a full replacement is wide because of what sits under the membrane. Tearing off to a sound deck is one price. Replacing saturated insulation and rotted sheathing is another, and it cannot be priced accurately until the roof is open or scanned.
Our own photographs
Work on Calgary roofs
Every photograph on this site is taken on a job we did. No stock libraries.
Checkable, not claimed
Credentials you can verify before we set a ladder up
Marku Roofing Repair Ltd. holds City of Calgary business licence BL272564, WCB Alberta account 9892020, and $5,000,000 in commercial general liability through Sandbox Mutual Insurance. The company was incorporated in Alberta in 2022.
No awards, no rankings, no "best in Calgary". A licence number, a WCB account and a policy limit are things you can check yourself.
More about the companyAnswers
Frequently asked questions
Still unclear? A five minute phone call usually settles it faster than reading.
Ask us directlyCan a flat roof be repaired in winter?
Torch-applied SBS can be installed in cold weather with proper surface preparation. Self-adhered membranes need surface temperatures above the manufacturer's minimum. Emergency containment is possible year-round. See emergency roof repair.
How long should a Calgary flat roof last?
Draft Plan on 20 to 30 years from a properly installed two-ply SBS system here, and the top of that band only if the drains are kept clear. Ponding water is what shortens a flat roof in this climate: it freezes, it expands, and it works at every lap and every flashing all winter. A roof that drains within 48 hours of a rainfall will outlast an identical one that does not by a decade.
Why does my flat roof leak only in spring?
Snow load melts, refreezes at the perimeter where the roof is coldest, and backs up behind the ice. The membrane never had to handle standing water at that depth.
Is ponding water covered by the manufacturer warranty?
Most membrane manufacturers exclude damage caused by ponding, because ponding is a design and drainage issue rather than a material defect.
Free written estimate
Book it before the next chinook
Freeze-thaw turns a small opening into a large one faster here than almost anywhere else in Canada. Get it looked at while it is still a repair.
Serving Calgary, Airdrie, Cochrane, Okotoks and Chestermere.