Roof Leak Repair in Unionville, PA

The most common roof leak sources on Unionville homes

Most leaks we trace fall into a short list. The order changes with the age and type of the house, but these are the places that fail first.

Chimney flashing

Stone and brick chimneys are the top leak source on older homes around the village. The chimney and the roof move differently with temperature, mortar erodes, and old lead, tar or caulked flashing cracks. Failed flashing is widely described as the leading cause of chimney-related leaks (Networx via KSAT). A lasting repair uses step flashing woven into each course of roofing plus counter flashing cut into the mortar joints, not a bead of sealant along the face of the stone.

Plumbing vent pipe boots

Most homes have one or more plumbing vents through the roof. Each one is sealed by a boot, often a rubber collar on a metal or plastic base. The rubber dries and cracks in the sun, and a hairline split lets water run down the outside of the pipe into the attic. A cracked pipe boot is a very common and often overlooked cause of leaks (NRCIA). The stain often appears over a bathroom or laundry room.

Valleys

A valley carries water from two roof slopes, so it handles more water than any other part of the roof. Leaves, seed pods and pine needles from the mature trees around Unionville pack into valleys, slow the water down and push it sideways under shingles or slate. Worn valley metal and shingles cut too short in a closed valley are other common causes.

Step flashing at walls and dormers

Where a roof meets a wall, a dormer or a second story addition, small L-shaped pieces of step flashing should be woven into every course and tucked behind the siding. When siding is replaced or a past repair skipped this detail, water gets behind the wall. These leaks often show up as stains on a lower ceiling or bubbling paint near the bottom of the wall.

Skylights

Older skylights rely on curb flashing and seals that age out. Condensation on the glass can also drip and look like a leak, so we check both.

Ridge caps, rakes and wind-lifted shingles

Ridge caps and the shingles along rakes take the most wind. A shingle can lift, break its seal strip and settle back looking normal. The next wind-driven rain gets under it. After the windstorms that hit Chester County in 2026, these were among the most common repairs we would expect to see.

Slipped or broken slates

On slate roofs, the stone usually outlasts the nails that hold it. When nails rust through, slates slide down and leave a gap. A single missing slate can leak for years before it shows inside, often rotting the sheathing below.

Built-in gutters and box gutters

Many 19th century homes have gutters built into the cornice and lined with metal. When that lining cracks or its seams open, water goes straight into the wall cavity and the soffit. These leaks are easy to misread as a roof field problem.

Nails, fasteners and past repairs

Exposed nail heads, backed-out nails, loose screws on barn metal and old roofing tar patches all let water in. Tar over slate is a frequent culprit: it traps water and makes the next proper repair harder.

How we find a roof leak, step by step

1. We ask the right questions. When did it start, does it follow every rain or only heavy storms, which way was the wind blowing, and has anyone worked on the roof, siding or chimney recently.
2. We start in the attic. Where the attic is accessible, we look for wet insulation, darkened decking, water trails on rafters and rusted nail tips. The highest point of moisture is closer to the real entry than the stain on the ceiling.
3. We inspect the roof details above. Chimney flashing, valleys, vent boots, skylights, wall flashing, ridge caps and any slipped slates or lifted shingles uphill of the moisture.
4. We test when it is not obvious. A controlled water test starts low and works uphill one detail at a time, with someone watching inside. It takes patience, but it isolates the source instead of guessing.
5. We use moisture readings where they help. A moisture meter on decking or drywall confirms how far water has spread. On flat roofs, water can travel under the membrane, so we check seams and edges carefully.
6. We document everything. Photos of the source, the path and any damage go into your written estimate, so you can see what we saw.

What to do while you wait for the repair

1. Protect people first. Keep everyone out of a room with a sagging ceiling and switch off power to wet light fixtures at the breaker if you can do it safely.
2. Catch the water. Buckets and towels under drips. Move furniture, rugs, electronics and documents.
3. Check the attic if it is safe. Put a tray or plastic sheet under an active drip on the attic floor to keep insulation dry.
4. Take photos and notes. Date, time, weather and wind direction. These help us trace the leak and help your insurer.
5. Stay off the roof. Wet slate, metal and shingles are slippery, and a leaking area can hide soft decking.

Roof leaks and homeowners insurance

Most homeowners policies cover sudden damage, such as a tree limb puncturing the roof or wind tearing off shingles, and the resulting interior damage. They generally do not cover leaks caused by age, wear or lack of maintenance. Your policy wording and deductible decide what applies, so check with your agent.

• Report storm damage promptly and keep receipts for any emergency protection, such as tarping
• Take photos before anything is moved or repaired
• Keep damaged materials until the adjuster has seen them, if you can do so safely
• Ask for a written report that separates storm damage from existing wear

We document leaks with dated photos and a written description you can send to your insurer, and we can meet the adjuster on site if you want us there.