The short answer
Chimney waterproofing protects your masonry from rain and snowmelt with a vapor-permeable repellent that keeps water out but lets the brick breathe. We inspect first, repair the crown, mortar, flashing or cap where needed, and then treat the exterior so small leaks don't turn into major masonry damage.
Brick and mortar look solid, but they soak up water like a sponge. Every rainstorm, snowmelt and freeze-thaw cycle pushes moisture into the masonry, and over time that water breaks down mortar joints, flakes the face off bricks, rusts dampers and stains ceilings. EmberGuard Chimney Sweep's certified technicians find where water is getting in, make the repairs that have to come first, and then apply a breathable water repellent made for masonry. It keeps rain out while letting trapped moisture escape. Waterproofing works best on a chimney that is already sound, so every job starts with an inspection rather than a sprayer. This page covers the warning signs, what the service includes, how we work in your home and on your roof, and what affects the cost.
Signs you need it
Water damage in a chimney is slow and often hidden, so the early signs are easy to dismiss. If you notice any of the following, have the chimney looked at before the next wet season. Small problems caught early usually need less repair work.
- Water in the firebox, or rust on the damper, grate or firebox floor after rain
- White, powdery staining on the outside brick (efflorescence), which means water is moving through the masonry and leaving minerals behind
- Brick flakes, crumbled mortar or small pieces of masonry falling into the firebox or onto the roof
- A strong, musty or creosote smell from the fireplace, especially in humid weather, since damp creosote gives off more odor
- Stained or peeling paint on walls or ceilings next to the chimney
- Cracked or crumbling chimney crown, or gaps where the flashing meets the roof
What is included
Waterproofing is more than a coating. A repellent only protects masonry that is in good shape, so we deal with the entry points first and treat the brick last. If we find damage beyond the scope of waterproofing, we explain it and you decide how to proceed before any extra work begins.
- Chimney inspection inside and out to find where water is getting in
- Camera inspection of the flue when there are signs of interior water damage
- Cleaning of the exterior masonry so the repellent can bond and soak in
- Repair of cracked or missing mortar joints before treatment
- Chimney crown repair or a crown sealing coat where cracks are present
- Flashing inspection and sealing where the chimney meets the roof
- Chimney cap check, with a cap recommendation if the flue is open to rain
- Application of a vapor-permeable masonry water repellent, not paint or a film-forming sealer that traps moisture
- Photos of problem areas and a plain-language summary of what we found and did
How our crew works inside your home and on the roof
Inside, we lay drop cloths from the door to the fireplace and cover the hearth before we open anything up. If soot or debris needs to come out of the flue so the camera can get a clear view, we clean it with rotary brushes while a HEPA vacuum runs at the firebox opening to keep dust out of the room. The camera then shows us the liner and the inside of the flue, where water damage, cracked tiles and loose mortar often show up first.
On the roof, we set up ladders and fall protection, then work from the top of the chimney down. We check the crown, cap and flashing, clean the brick, and let it dry before any repair or treatment. Mortar repairs need time to cure before the repellent goes on, which is why we watch the forecast closely. The repellent is applied in dry weather above freezing, and we keep overspray off windows, siding and roofing. Before we leave, we clean up both work areas and walk you through the photos.
Time for your annual chimney check?
The standard we follow
The NFPA 211 standard calls for chimneys, fireplaces and vents to be inspected once a year. Chimney professionals use three inspection levels. Level 1 applies when nothing has changed. Level 2 applies when the system changes, such as a new appliance or a switch of fuel, or when the home is sold. Level 3 is used when a hidden hazard has to be reached by opening part of the chimney or the building. Most waterproofing visits start with a Level 1 inspection, and we move to a Level 2 when water damage calls for a camera look inside the flue.
Moisture matters inside the flue too. When a New York City building converts its boiler from oil to gas, the chimney has to be evaluated as part of the work. A new liner is often needed because gas exhaust produces acidic condensate that can corrode a masonry flue. If your system has changed fuel, we will check for that kind of damage during the inspection.
What affects the price
Every chimney is different, so we give you a written quote after the inspection instead of a flat number over the phone. The main factors are:
- Chimney height, roof pitch and how easy the roof is to reach
- How much exposed masonry needs treatment
- The condition of the crown, mortar joints and flashing, and how much repair is needed first
- Fuel type and flue size and condition, which affect what we check inside
- Whether soot or creosote buildup has to be cleaned out before the camera inspection
- Whether a camera inspection or a chimney cap is needed
How a visit works
When you contact us, we ask about the signs you have noticed, your fuel type and the kind of roof you have. We schedule a visit and arrive in the window we give you. The technician inspects the chimney inside and out, shows you photos, and explains what needs repair and what can simply be treated.
You get a written quote before any work begins. Small repairs and waterproofing can sometimes be done the same day if the weather is dry. Larger mortar or crown work usually needs a second visit so repairs can cure before the repellent goes on. New York City's heat season runs from October 1 through May 31, so late spring through early fall is the best time to book. That gives repairs time to finish before you need your heating system.
