Chimney Waterproofing

A breathable water repellent keeps rain from soaking into the brick while still letting moisture inside escape. It's the last step after masonry repairs, not a replacement for them.

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Signs you need this

Brick darkens and stays damp long after it rains
White efflorescence staining on the chimney
Early spalling or crumbling joints
You just had masonry repairs or a new crown

What’s included

Cleaning and prep of the masonry surface
Check that the crown, flashing, and joints are sound first
Vapor-permeable water repellent made for masonry chimneys
Crown sealing where appropriate

Why chimneys need a breathable product

A chimney takes more weather than almost any other part of the house. It sticks up above the roofline, faces wind-driven rain on every side, and goes through freeze–thaw cycles all winter. Water in the brick is what eventually breaks it apart.

A proper chimney water repellent soaks into the brick and mortar and lines the pores without sealing them shut. Water beads off the outside, while water vapor from inside the chimney can still get out.

Do it on sound masonry

Waterproofing works best right after repairs are done. If joints are open or the crown is cracked, we’ll recommend fixing those first. Otherwise you’re paying to coat a chimney that will keep leaking.

Common questions

Can't I just use a regular sealer from the hardware store?

Paint-type sealers and non-breathable coatings trap moisture inside the brick, which can make freeze–thaw damage worse. Chimneys need a vapor-permeable product.

Will waterproofing stop an active leak?

Only if the brick itself is the source. Most active leaks come from flashing or the crown, which need to be repaired first.