Best way to block up a chimney?

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mjgreen81

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Hi all,



We recently had an old gas fire removed and the chimney opened up. We now just have an open fireplace which we have tiled and plan to just keep a few big candles etc in.


I couldn’t decide whether to block off the chimney or just leave it open. However, the noisy wind and the old black deposits that keep getting dumped down it have made up my mind!


However, I cant decide the best way to do it. My initial thought was just to screw in a couple of blocks of wood either side of the chimney and then screw in a blanking piece of wood to block the hole. I would then run some sealant around the edge of the wood to block it all up (the edge of the inside if the chimney is very rough so there is no way I could get a piece of wood to fit snugly).


However, I am a bit concerned about using wood as I could imagine the occasional few drips of water making its way down the chimney and potentially rotting the wood.


I then thought about getting a bit of plastic/perspex, but I was then concerned about the potential the odd drip sitting on the plastic and building up over time.


I also wondered if (for safety) I should drill a few small holes in whatever I use to block it up, just in case the stop end for the gas pipe failed and leaked (which is still in the side of the open chimney in case we ever wanted to reinstall a gas fire at some point in the future)


I am sure I am overthinking this, but I just want to try and get it done in the best possible way!


Many thanks
 
Last edited:
If you block up the bottom, then condensation will form in the flue, and this will leech through the wall and stain the plaster. You can block it up with whatever you like, but there needs to be ventilation from top to bottom.

If you dont cap the top, then rain can get in too.
 
Yes.

Bear in mind that it won't deal with any soot or debris that might fall.
 
get the chimney swept, or you could fit anther board half way across a few inches above that will cover your vent as a baffle.
 
If you are concerned with draughts down the un-used chimney, fitting a vent like that isn't going to help, surely......I don't what the answer really is, though!
 
To be honest I was standing by the fireplace earlier, the wind was howling and it was pretty noisy but I dont think much of a draught was actually coming down the chimney. Its more noisy than anything else.

Following the advice in this thread and my own thoughts I think my plan will be as follows...

* Fix an MDF 'shelf' to one side of the chimney which covers just over half way
* Just below this, fix a second MDF shelf to the other side of the chimney which again covers just over half way

The idea being that these shelves will catch any falling debris/old soot deposit.

Then below this I will get something that is flame retardant (as I want to place candles below - not sure what to use yet) in which I will cut a hole in and fit a metal vent to allow air-flow.
 
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