Chimney Leaks & Waterproofing
Your chimney is the one part of your roof with a hole left in the top of it on purpose. When water starts getting in, finding where it's getting in is most of the job.
We find the leak before we sell you a sealer. Half the ones we see have nothing to do with porous brick.
Where it usually gets in
- A missing, undersized or beat-up cap
- A cracked crown, or a flat one with no overhang
- Flashing that's failed or was surface-mounted
- Open mortar joints and porous brick
- A rusted-through chase cover on a framed chase
- Condensation inside an oversized flue
The stain on your ceiling is not where the water got in
Water that enters at the crown can travel a long way down inside a masonry chimney before it shows itself, and it almost never turns up directly below the failure. That's why so many chimney leaks get chased for years with the wrong repair. We start at the top and rule things out in order instead of guessing at the cheapest fix and hoping.
What you see inside
- Brown staining on the ceiling or the wall beside the chimney breast
- Peeling paint or bubbling plaster near the fireplace
- A damp, musty or heavily sooty smell after it rains
- Water in the firebox, or an actual drip
- A rusted damper, or rust streaks running down the firebox wall
- A white, powdery salt bloom on interior masonry
What you see outside
- Dark patches on the stack that stay damp long after the rain stops
- White staining on the exterior brick
- A cracked crown, or one poured flat with no slope
- A rusted cap, or no cap at all
- Flashing lifting, or held down with nothing but roof cement
- Moss or weeds growing in the joints
The right product, applied at the right time
Waterproofing masonry works, but only once the structural entry points are closed. Seal a chimney that has open joints or a cracked crown and you trap the water that's already inside it, which makes the problem worse instead of better. We won't sell you a sealer application on a chimney that needs pointing first.
Find the leak
We look at the cap, crown, flashing and joints from the roof, then check the firebox and damper for the tell-tale signs of where water has been running.
Close the entry points
Cap fitted or replaced, crown repaired or rebuilt, flashing cut in and sealed, joints repointed. Whatever the leak actually calls for.
Let the brick dry out
Sealing wet masonry locks the water in. If the stack is saturated we come back another day rather than push on.
Apply the sealer
A full saturation coat over the exposed masonry, worked bottom to top so the surface stays wet and the product soaks in instead of skinning over.
Check it worked
Water should bead up and run off the brick rather than darken it. That's the whole test, and you can run it yourself with a hose next spring.
Leaks and waterproofing, answered
My roofer says it's the chimney and my chimney company says it's the roof.
That's the oldest standoff in the trade, and the honest answer is that the flashing sits right between the two. We work on flashing, we photograph what we find, and if the problem turns out to be the roof surface instead of the chimney, we'll say so. You deserve a straight answer, not a handoff.
How long does waterproofing last?
A good siloxane application on sound masonry usually holds up for several years before it wants doing again. Exposure matters a lot: a southwest-facing stack taking driving rain works a lot harder than a sheltered one.
Can I use a masonry sealer from the hardware store?
Check whether it's vapor permeable. If the label talks about forming a film or a coating, it's the wrong thing for a chimney. It fails slowly, and the damage shows up as spalled brick a few winters later.
Is a leaking chimney urgent?
More than most people think. Water is what destroys chimneys. It also rusts dampers, wrecks fireboxes, rots the framing behind the masonry and can make it all the way to the ceiling below. It rarely stays a cosmetic problem for long.
Do you fix the ceiling damage too?
We fix the cause and stop the water. Interior finish work is a different trade, but we'll tell you when it's dry enough to have that done.
Serving Chester County and the surrounding townships
We're based in Chester County and cover the boroughs, the townships and the rural stretches in between. Pick your town below, or just call and we'll tell you right away whether you're on our route.
Stop the leak at the source
Leak diagnosis, cap and crown work, flashing and breathable waterproofing across Chester County.