If you live in a Philadelphia rowhome, you share more than a wall with your neighbor. You share a roofline, a seam where your two roofs meet, and sometimes a leak that nobody wants to own.
We get this call every week at our shop in South Philly: water is coming in along the party wall, and the homeowner isn’t sure if the problem is on their roof or next door. Here’s how to figure out where the leak is coming from, who’s usually responsible, and how to get it fixed without a fight.
Why Leaks Happen Between Rowhomes
On a typical row, each house has its own flat roof, and the roofs meet over the party wall. Where they meet, there’s flashing: a strip of roofing material that seals the seam between the two roofs, or between a roof and a raised parapet wall.
That seam is one of the most common leak points on any rowhome. The most common causes:
- Failed party wall flashing. Flashing dries out, cracks, and pulls away over time, especially where it’s been patched or coated many times.
- Mismatched roofs. When one neighbor replaces their roof and the other doesn’t, the new roof has to be tied into the old one. If that tie-in isn’t done right, water gets in at the joint.
- Height differences. If one roof sits higher than the other, water can run off the higher roof and pool against the lower one’s flashing.
- Cracked parapet walls. Brick and mortar on top of the party wall let water into the wall itself, and it shows up inside as a stain along the wall.
- Ponding water. A low spot near the party wall holds water against the seam after every rain. (More on why water pooling on a flat roof is dangerous.)
See our flat roof repair and replacement page for more on why rowhome flat roofs fail.
How to Tell Whose Roof Is Leaking
A stain on your side of the wall doesn’t always mean the leak is on your roof. Water can enter on one roof and travel through the wall or along the roof deck before it shows up inside. A few clues help:
- Where the stain is. A stain right along the party wall points to the flashing or the parapet. A stain in the middle of your ceiling usually points to your own roof.
- When it leaks. A leak only during wind-driven rain often means flashing or the parapet. A leak after every rain usually means a hole or open seam in the membrane.
- What the roofs look like. If your neighbor’s roof is visibly worn, patched, or holding water near the shared seam, that’s a strong hint.
- Recent work. If either roof was replaced or repaired recently, check the tie-in at the party wall first.
The only way to know for sure is to get up on both roofs. A roofer can usually see the problem from your roof, and with your neighbor’s OK, check theirs too. Ask for photos of what they find. You’ll need them for the next step. (Here’s what to expect during a roof inspection.)
Who Usually Pays for the Repair?
In most cases, the simple rule holds: whoever’s roof is leaking is responsible for fixing it. If the problem is a hole in your neighbor’s membrane, it’s their repair. If the problem is on your roof, it’s yours.
The gray area is the shared seam itself. Party wall flashing often sits on both roofs, and when it fails, it can be hard to say whose side it is. In that case, many neighbors split the cost of fixing the seam, which is usually much cheaper than either side arguing about it.
A few things to keep in mind:
- Talk first. Most neighbors want a dry house too. Share the photos and the roofer’s findings before anything else.
- Get it in writing. If you agree to split a repair, put a short note in writing about what’s being fixed and who’s paying what.
- Check your insurance. Homeowners insurance may cover the interior damage from a sudden leak, even if it doesn’t cover the roof repair itself. Call your agent.
- For real disputes, get advice. If a neighbor refuses to fix a leak that’s damaging your home, talk to your insurance company or a real estate attorney. Rules and options depend on your situation, and we’re roofers, not lawyers.
How the Fix Usually Works
The right fix depends on what’s failed:
- Flashing repair. For a single bad section, we cut out the failed flashing and install new flashing tied into both roofs.
- Parapet repair. Cracked caps and loose bricks on the wall get repaired, and the top of the wall gets properly covered so water can’t soak in.
- Tie-in repair. When a new roof meets an old one, we rebuild the joint so both sides stay watertight.
- Replacing both roofs together. If both roofs are near the end of their life, replacing them at the same time is often the best deal. It means one seamless tie-in, one crew, one cleanup, and often a better price for each neighbor.
Most rowhome flat roof replacements are done in one day, and the repairs above often take a few hours.
What to Do Right Now If Water Is Coming In
- Protect the inside. Move furniture, put down a bucket, and take photos of the damage for insurance.
- Look at the roof safely. Only if you can get up there safely. Look for standing water, torn flashing, or obvious damage near the party wall.
- Knock on your neighbor’s door. Let them know, since water may be getting into their house too.
- Call a roofer. Get someone to inspect both roofs and send photos. For active leaks, ask about a temporary patch or tarp until the repair is done.
Get Help From a South Philly Roofer
Top Tier Roofing is based at 200 Jackson Street in South Philadelphia, and party wall leaks are one of the most common problems we fix. We can usually have someone out the same day, we’ll show you photos of exactly where the water is getting in, and if your neighbor wants to fix their side at the same time, we can quote both roofs. Every job comes with a 10-year workmanship warranty.
Call (215) 330-2664 or request a free estimate. For an active leak, see our emergency roof repair page.
We work throughout South Philly, including Whitman, Pennsport, Queen Village, Bella Vista and Packer Park.
Frequently Asked Questions
Who is responsible for a leak between two rowhomes?
In most cases, whoever’s roof is leaking is responsible for fixing it. When the shared seam at the party wall fails, many neighbors split the cost of fixing it.
How do I know if the leak is on my neighbor’s roof?
A stain right along the party wall points to the flashing or parapet, which may be on either roof. The only way to know for sure is to have a roofer inspect both roofs and send photos.
Should I replace my roof at the same time as my neighbor?
If both roofs are near the end of their life, replacing them together often means one seamless tie-in, one crew, one cleanup, and a better price for each neighbor.