How to stop rain coming down a chimney

Question

We get a smell of damp and sometimes drips down our chimney (blocked off) stack when it rains heavily. What's the best way to stop this?

Lenny · Accepted Answer

The best way to stop dampness and dripping in a blocked-off chimney is to ensure it is properly capped at the top to stop rain entry and ventilated at the bottom to prevent condensation buildup, which is a common cause of musty smells. Also check the flauching and lead work

Andrew · Answer

You need to check all lead flashings and brick matter also a layer of water proof seal on bricks is a good solution

Mark · Answer

You could need the pointing and flauch the top chimney and lead work could also be felt demaged near the chimney

Graham · Answer

Yeah this is a pretty common one with old or capped chimneys.

What’s happening is, when it rains heavy, water is getting into the chimney stack somewhere and it’s not really got anywhere to go. Because it’s been blocked off at the bottom, any moisture that gets in the top or through the brickwork just sits there and you’ll get that damp smell and sometimes it’ll track down and drip.

Best way to sort it properly is to get the stack checked from the top down. Usually it comes down to one (or a mix) of these:

Capping on top not fully sealed or damaged
Old brickwork/mortar soaking up water like a sponge
No proper ventilation inside the blocked flue so moisture can’t dry out
Lead flashing around the base of the chimney letting water in (very common)

Proper fix is normally:

Fit or replace a proper chimney cap / cowl that actually sheds water
Repoint the stack if the mortar’s tired
Check and repair lead flashing if needed
Sometimes add ventilation so the damp doesn’t just sit in there

In most cases it’s not a massive structural issue, just water getting in where it shouldn’t and nowhere for it to dry out. Once it’s sealed and breathing properly, the smell and dripping usually stops.

Jonni · Answer

It could most likely to be lead work all round chimney or even possible re Flaunting on the top of the chmney

Mairead · Answer

Check crown lead pointing You have to get up an check it out.

Edward · Answer

You can fit a simple cowling over the pot which still allows airflow but prevents rain getting diwn

Lawrence · Answer

Get yourself a cowls for the pots, check the flaunching, flashing, soakers ect

Keith · Answer

Put a capping on top of chimney pot make sure it allows smoke out if still in use, or if your chimney is not in use take off pot and cap, or drop stack slate over, them are your options depending on which one applies to you.

Jamie · Answer

First of all check that the chimney isnt blocked by rubble/bird nest as this will act as a sponge within the chimney retaining moisture which will eventually penetrate through the brickwork.

If the chimney is unblocked then the next step is to check the pointing on the chimney stack as any holes will allow water in, you can also check the chimney pot flaunching to ensure it hasnt deteriorated and letting water in and finally ensure you have the correct chimney cap on that deflects rainwater.

How to stop rain coming down a chimney

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