Chimney breast insulation

[JohnS]

My house has solid brick walls - 9inch.  I have a unsued chimney breast which I have draft proofed by stuffing newspaper up it and having a rain hood on the chimney pot (with ventilation).

Does anyone have any ideas on how I could further insulate it to leesen the impact of a column of cold air?

John

[Countrypaul]

Be careful if you block both ends as it can cause condensation resulting in stains appearing on your walls, the usual advice is to maintain some ventillation in an unused chimney. Having said that I blocked both ends of ours a number of years ago and have had no problems.

Paul

[JohnS]

Paul

Thanks.  The top has something like this on it

http://www.hepworth.wavin.com/master/master.jsp?FOLDER%3C%3Efolder_id=2534374305508436&PRODUCT%3C%3Eprd_id=845524445170242&middleTemplateName=oc_middle_product_detail_I

I have removed the cast iron fire place, removed all the debris behind it and before reinstalling it I am thinking of lining the big space at the bottom with Kingspan/Celotex and having a small opening eg 22mm tubing into the chimney.  I am also internally insulating the walls so the cast iron fireplace had to be brought out by 80mm.

Does this sound sensible?

[Countrypaul]

John,

I am no expert at insulating fireplaces, but I thought it worth passing on the warnings I had been given.

My main concern with what you are suggesting is would anyone be able to light a fire in it and how would the insulation be affected then. I am thinking of a few years time when we are gone, and the top of the chimney is reinstated etc.

Paul

[KLD]

More an added question than an answer: If you were to fit an chimney liner, you'd possibly backfill with mica or similar. In that case, you'd not expect to get any condensation. What if you blank your chimney off at the bottom and backfill the whole thing?

Klaus

[JohnS]

Interesting idea Klaus.  I shall investigate further.

John

[JohnS]

Thanks everyone. 

I got Silvapor from William-Sinclair.co.uk.  It is their recommended product for cavity fill etc as "Silvapor coated expanded perlite is a hydrophobic insulating aggregate. This water repellent, non-flammable, loose-pour insulant significantly improves the thermal performance on masonry walls and floors and is easily installed without special training or equipment for new build, extensions and established properties".  They were plesant to deal with.

I sealed the bottom of the chimneys with a Kingspan bung.  I cut a hole for a 500mm piece of perforated land drain which I wraped with landscape fabric and tied with wires.  The theory is that any moisture in the chimney will drain down through the Silvapor, through the fabric into the land drain and drip/evaporate into the fire place.  I squirted expanding foam up a tube throughthe bung to seal everything to the chimney.  It set solid.  I poured the Silvapor in from the top. 

John