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Capping a non existent chimney!

Postby damian » Tue Jan 29, 2008 9:35 am

I have a chimney that is no longer used so I want to cap it.
The chimney doesn't actually have a proper chimney pot on it so I can't just buy a cap as there's nothing to fit it to.
I was advised by a company that caps chimneys that I would need to have a proper chimney pot fitted then fit a cap on to it but it seems a little excessive not to mention expensive to buy a new chimney pot just to cap it!

Is there another way to seal off this chimney?
As far as I know, I need to ensure airflow so I can't just seal it with a piece of slate as no air would be allowed in to the chimney.

Thanks for your help!

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Simply Build It

Postby Perry525 » Thu Jan 31, 2008 8:44 pm

Buy a stainless steel cowl, a piece of plywood large enough to cover the hole, cut a hole in the plywood smaller than the cowl, place cowl over hole, cover plywood with about 100mm concrete - job done.
However, you could just take a brick out of the chimney side and proceed with plywood and concrete.
The important thing is to keep the rain out of the chimney, so check the bricks and pointing, and repair any damage then paint with silicone to encourage the rain to run off. Check the flashing as well.
Once the chimney is dry ventilation becomes less important.
Keep in mind that the chimney is only one brick thick, the chimney breast brings the cold outside right into the middle of your room.
If you must ventilate it, cover it with an inch of two of polystyrene to help keep the heat in the room.
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Postby TheDoctor5 » Thu Jan 22, 2009 10:37 am

Last year 64% of the questions asked in our forum were answered within our DIY project pages at The project pages are now separated alphabetically and your answers are accompanied by diagrams and the ability to see, and buy, the tools and/or required to complete your project. Use our search box to look for your answer and save a great deal of time and money!
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