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During a heavy rain storm the chimney leaked from the base of the flue. In the picture you can see the drop as it fell. The crown and the chimney was rebuilt to just above the roof line 3 weeks ago.

Is there no way to seal the chimney and this is normal. The amount that came in was enough to wet the bricks below. If this is not normal is the leak at the cap and the water runs down around the flue and drops down which in my untrained eye it appears to be doing. Does this require the crown to be now sealed with a waterproof sealant? I thought the mortar would prove to be enough but it is not in this case.

Edit: @Lee: the cap is on there and the wash installed though I need to see the pitch. Can you explain the sealer. Does that go on the crown too?

1 Answer 1


To properly seal the fireplace flue, I’d 1) Install a flue cap, 2) put a cement “wash” between the flue and fireplace bricks for positive drainage, 3) Install a clear sealer on the fireplace bricks, 4) Install flashing between the fireplace bricks and the roofing material, 5) verify that the roofing around the fireplace isn’t leaking.

If the flue only leaks during extra strong wind storms, I’d look at getting a flue cap that has a wind screen, like this:


  • I find in coastal areas where we regularly get horizontal rain those caps the best method to prevent most of the water from entering.+
    – Ed Beal
    Commented Sep 26, 2018 at 17:47

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