Rooftop decks & pilothouses
Roof deck leak repair in Philadelphia
On a lot of newer Philly houses, the roof is also the backyard. A deck on top hides the membrane, the drains and every spot where a post goes through, so leaks start where nobody can see them. Call to reach a local roofer who works under and around roof decks.
The decks
Where Philly roof decks are, and how they're built
Roof decks took off with the new-construction wave in Fishtown, Northern Liberties, Kensington and Port Richmond, then spread to Point Breeze, Graduate Hospital and Brewerytown. The typical builder's version is a three- or four-story house with a low-slope roof, a pilothouse (the small stair enclosure that opens onto the roof) and a deck laid over the membrane. In Queen Village, Bella Vista and Fairmount, decks are more often added later to older rowhomes, sometimes over a roof that was already worn.
How your deck is built decides how a roofer gets to a leak:
- Sleeper decks. Pressure-treated runners laid flat on the roof, with deck boards screwed to them. Simple to build, but the sleepers trap grit and moisture against the membrane and can wear through it where they rub.
- Pedestal or paver systems. Adjustable pedestals hold wood, composite or concrete panels above the roof. The panels lift out, which makes the roof underneath far easier to inspect and repair.
- Framed decks on posts. Joists carried on posts that pass down through the roof to the structure, or bolted into the parapet walls. Every post is a hole in the roof that has to stay flashed.
When to call about a deck leak
Any of these, especially after a heavy rain:
- Stains on the top-floor ceiling under the deck
- Damp drywall or bubbling paint at the pilothouse door
- Water sitting on the deck or spilling over the parapet instead of draining
- Soft, spongy or bouncy spots in the deck boards
- Rust streaks or dark, rotting wood at the base of posts and railings
- A musty smell in the top-floor bedroom after rain
Why they leak
The six places roof decks usually let water in
A deck doesn't leak by itself. It hides and adds to the weak spots in the roof below it.
The pilothouse threshold
The door onto the deck sits just a few inches above the roof. If the pan flashing under the sill was skipped or poorly lapped into the membrane, wind-driven rain gets under the door and runs down the stairwell walls.
Hidden, clogged drains
Scuppers and roof drains often sit under the deck boards. Leaves, grit and bottle caps collect there, water backs up, and it finds the nearest seam. The first sign is usually a stain on the ceiling below.
Posts and railing brackets
Each post through the membrane needs a sealed boot or pitch pocket, and those sealants dry out. Railing brackets screwed through the parapet cap open the top of the wall to water as well.
Sleepers rubbing the roof
Sleepers laid without protection pads shift with heat and foot traffic and slowly scuff through the membrane. Wet wood resting on the roof also keeps that spot damp for days after every rain.
Joints at taller walls
Where the roof turns up a taller wall, whether that's the pilothouse or a neighbor's new build, the flashing has to be tucked behind the siding or into the masonry. On rushed construction it often just gets caulked.
Condenser stands
AC condensers often sit on stands bolted through the roof or tucked under the deck, with refrigerant lines running through a wall or roof opening. Each bolt and line set is one more detail to keep sealed.
The work
What a roof deck leak repair involves
Trace the water
The roofer checks the ceiling stain, the pilothouse and the drains, then lifts boards or panels over the likely spot.
Open up the deck
Pedestal panels lift straight out. Screwed sleeper decks come up board by board and are stacked in order. A framed deck may need a section taken apart.
Repair the roof
A worn spot, failed seam or leaking post boot gets patched or re-flashed. If the membrane under the deck is worn out or wet underneath, a new roof under the deck is the lasting fix.
Protect it & put it back
Protection pads go under sleepers, drains get strainers and a clear path, and posts get new boots. Then the deck goes back down, ideally with a lift-out panel over each drain.
Planning your job
What affects the price
Deck jobs vary more than most roof work, because half the job is getting to the roof. These make the biggest difference:
- How the deck is built. Lift-out panels are quick to move. Screwed-down boards and framed decks take far more labor to remove and reset.
- Whether the deck can be reused. Brittle or rotted boards may not survive coming up.
- Height and access. On four-story new builds, materials and debris go through the pilothouse or up a hoist.
- How many penetrations. Posts, railing brackets, condenser stands and the pilothouse each need their own flashing.
- The roof under the deck. A spot repair is a much smaller job than a new membrane across the whole roof.
- Who handles the deck. Some roofers remove and reset it themselves; others bring in a carpenter.
Want a quick read on your situation first? Try the Roof Problem Checker for decks.
Related pages
- Fishtown & River Wards flat roof repair: new builds, pilothouses and tie-ins next door
- South Philly flat roof repair: Point Breeze and Newbold infill homes
- Center City flat roof repair: decks added over older roofs
- Flat roof replacement: when the membrane under the deck is done
- Roof leak repair: water coming in right now
Newer-home tip: if your house was built in the last several years, dig out the builder's paperwork before paying for a repair. A roofer's photos of the failed detail are useful if the builder's coverage still applies.
Roof deck leak questions
Does the whole deck have to come off to fix a leak?
Not usually. For a leak, the roofer lifts the boards or panels over the problem area and works from there. Taking the whole deck off is normally only needed when the entire roof underneath is being replaced.
Can a new roof go under my existing deck without ruining it?
Often, if the deck is sound and built in sections. Pedestal decks come up cleanly, and screwed-down decks can usually be saved if the boards are in good shape. Ask the roofer to look at the deck first, so you know what will be reused and what won't.
Water only comes in at the pilothouse door in windy storms. Is that the roof?
Often it's the door, not the roof. The sill needs a pan flashing that laps into the roof membrane, and wind pushes rain under a door that doesn't have one. A roofer can test the door area separately from the rest of the roof to tell the two apart.
How do I keep the drains under my deck clear?
Lift the panel or boards over each drain a couple of times a year, especially after the fall leaves come down, and clear out the debris. If there's no way to reach a drain without tools, ask the roofer about adding a lift-out access panel above it.
Do I need a permit for roof deck work in Philadelphia?
Building a new roof deck or rebuilding one generally needs a permit from Philadelphia L&I, and some properties also need zoning approval. Repairing the roof under an existing deck is a different situation. Ask the contractor what applies to your job before work starts.
Have a different question about your roof deck? Call and ask a local roofer.
(215) 702-6130