How Can I Fix a Chimney Flue Leak?

sid asks,

I have water leaking from my chimney, through the flue, and into my basement. This has happened twice – both times we had rain and heavy winds. The first time I had about 1-2 gallons leak in, whereas last week i had only about 1/2 gallon. Any idea what's causing this – and a possible solution? After the first incident, a chimney company came and checked out the flashing and chimney. They said the flashing was fine, and they did some repointing near the top – but then water got in again last week.

Our Answer

Keeping water out of your chimney is important – but sometimes feels like an uphill battle. I recommend a masonry sealer for your chimney. Masonry sealer is silicone-based, and does a good job of keeping out wind-driven rain. Buy a water permeable one because water permeable lets water evaporate out, and not freeze and eventually crack the brick. It’s a DIY product that can be brushed on, like paint, or sprayed on.