What is the cavity next to my chimney stack for?

[nicnac1]

Hi everyone, long time reader - first time poster. Hope you can help.

I am currently trying to improve the soundproofing of my 1930s semi and while I was in the loft I discovered a gap in the floor next to each of the chimney stacks. The hole is about 600x400mm across and seems to drop all the way down to the ground floor following the edge of the chimney. It only seems to be on one side of each of the stacks.

Does anyone know what these cavities are for? Can I pack them with rockwool or is there some regulation forbidding it.

Many thanks in advance!

 

[ree]

Sounds an interesting building detail.
Are the openings soot encrusted?
How many terminal pots do you have on that chimney stack?
Are there any small access doors at ground level?
Why not post pics from inside the loft, and a pic of the fire opening/chimney breast on the ground floor?

 

[endecotp]

In my parents' house, the living room chimney breast is symetrical with the fireplace in the middle. To one side there is a second chimney which used to connect to a solid fuel boiler in the kitchen. To the other side there is a void like thr one you describe. It is pirely to give a symetrical appearance.

 

[tony1851]

endecotp is spot on.

If you had x-ray eyes, your chimney breast would look like this. It's purely to keep the fire surround in the middle.

Untitled

• tony1851
• 2 Jun 2015
• 1