Garage Roof Replacement in Philadelphia
Garage roofs get ignored until the ceiling sags or the car gets wet. Most are small, simple roofs, and replacing one is usually a one-day job.
A garage roof replacement means removing the old covering, replacing rotted decking and fascia, and installing a new flat membrane or shingle roof with proper edge metal and drainage. Rear rowhome garages are usually flat and drain toward the alley; detached garages are often pitched. Either way, the job is short but the decking underneath is often the real issue.
What Replacing a Garage Roof Involves
Garage roofs fail the same way house roofs do, only faster, because nobody watches them. On flat garage roofs the covering cracks and water ponds; on pitched ones shingles wear out at the edges. Because garages are unheated and often damp, leaks rot the decking and the fascia board along the front long before anyone notices from inside.
We strip the old roof, replace soft decking and fascia, then install the new roof: a modified bitumen or single-ply membrane on flat roofs, with the slope toward the drain or alley improved where water sat, or underlayment and shingles on pitched roofs. New drip edge and, where needed, a gutter carry the water away from the door and the neighbor's garage.
What Sets the Price of a Garage Roof
- Roof size and typeFlat membrane or pitched shingles.
- Decking repairsSoft or sagging boards replaced.
- Fascia and gutterRotted fascia and new gutter where needed.
- Deck aboveDecks must be supported or lifted.
- AccessAlley access and disposal.
Garage roofs are priced after we walk the roof and look at the decking from inside the garage.
Membrane or Shingles on a Garage?
The slope decides most of it.
| Roof type | When it fits | Tradeoff |
|---|---|---|
| Modified bitumen | Flat rear rowhome garages | Durable, walkable, needs proper slope |
| Single-ply (EPDM, TPO, PVC) | Larger or low-slope garages | Fewer seams, heat or adhesive installed |
| Architectural shingles | Pitched detached garages | Matches the house, not for flat roofs |
Rear Rowhome Garage Roofs
Many Northeast rowhomes have a garage built into the rear under a flat roof, often with a small deck or the kitchen above. These roofs drain to the alley and share edges with the neighbors, so the new membrane has to tie into the adjoining roofs cleanly and keep water heading for the alley rather than the house. We replace soft decking, set new edge metal and flash the wall where the garage roof meets the house. Where a deck sits above, the membrane runs under the deck framing with protection pads so it lasts as long as the deck.
Detached Garage Roofs
Detached garages in the Far Northeast and the suburbs usually have small pitched roofs with shingles, or a low slope covered in rolled roofing. On pitched roofs we strip to the deck, add ice barrier at the eaves and install new underlayment, drip edge and shingles, often matched to the house. Low-slope garage roofs that keep leaking under rolled roofing get a proper membrane instead. Gutters on detached garages are often missing; adding one keeps water off the door and away from the slab, which is where most garage floors crack and heave in winter.
Garage Roof Decking and Fascia
The decking and fascia are where garage roof jobs grow. Old plank or plywood decking that has been wet for years is soft and sometimes sagging between rafters, and the fascia along the front is often split or rotted where the gutter hung. We replace the soft wood before the new roof goes on, sister cracked rafters where needed, and cap or paint the new fascia. We show you the soft boards before replacing them, and photograph the new decking before the roof covers it, so you know exactly what was done under the roof.
Garage roof sagging or leaking?
Call and we check the decking and quote the roof.
What We See on Philadelphia Roofs
Mayfair grew from the 1920s and after World War II as larger rowhouses with rear parking garages, laid out around Frankford and Cottman Avenues, and Morrell Park's late-1950s rows put the garage at the front. That gives our part of the city thousands of small flat garage roofs, many of them under decks or bedrooms, which is why the joint where the garage roof meets the house gets as much attention as the membrane.
How Long a Garage Roof Takes
Most garage roof replacements take one day. Decking and rafter repairs can add a few hours, and garages under a deck take longer because the deck framing has to be supported or lifted while the roof is replaced.
How a Garage Roof Replacement Runs
- 1
Inspect inside and out
Decking, rafters and edges checked.
- 2
Protect the garage
Car and contents covered or moved.
- 3
Tear off
Old roofing removed to the deck.
- 4
Repair the wood
Decking, rafters and fascia replaced.
- 5
Install the new roof
Membrane or shingles with edge metal.
- 6
Flash and clean up
Wall joint flashed, debris hauled away.
Garage Roof Questions
Yes. It is a separate job from the house roof.
Yes. The deck is supported or lifted while the roof is replaced.
Usually a re-roofing permit; we confirm for your address.
On pitched detached garages most owners do.
A properly installed membrane or shingle roof should last as long as the same roof on a house.
More Replacement & Installation Work in Philadelphia
From our guides: Roofing Permits Outside Philadelphia
Replace That Garage Roof
Call and we quote it after a look at the decking.