Bricking up around a chimney iner

[cmd@kss]

Hi I'd like some advice re closing the fascia of a chimney stack..... the chimney above is supported and so structurally no problem. However I'm concerned about the heat from the liner and what material I can use .... I would prefer not to use brick as it will decrease the width of the corridor. I've considered 10mm cement board followed by fire proof board on top that can be decorated.... any ideas

 

[Doggit]

Chimney flues tend to be sqaure, so as the liners gone in, and there's space either side of it, then you should be able to brick it back up at the front. The liner seems to be sitting slightly forward, so can you put in some vermiculite fire board, and then brick the front back up - actually, why was the front taken out.

 

[cmd@kss]

When I originally purchased the house the chimney had been reduced in size to create a wider corridor. The front fascia was removed to allow space for a 6inch liner.
Can I use self taping screws to tie the new block brick into the existing chimney?

 

[Corgigrouch GTi]

I'm afraid that with the arrangement that you have, your only option is to use brick. The only other option would to have used twinwall flue. Cement board wouldn't give you enough heat protection and would be a fire risk.. If by fireproof board, you mean fire rated plasterboard, then forget it as fire rated plasterboard isn't heat resistant and will rapidly decompose and since it is coated in paper, it isn't fireproof either

 

[Doggit]

I was thinking he might be able to use vermiculte fire board (not plasterboard) to provide a degree of heat resistance to whatever he blocked the front the the chimney breast up with

 

[Corgigrouch GTi]

I was thinking he might be able to use vermiculte fire board (not plasterboard) to provide a degree of heat resistance to whatever he blocked the front the the chimney breast up with

A lined chimney must be at least 100mm thick, 200mm between another property... Usually it is fine dropping a liner down a chimney as they are usually thicker than that but when folk mess with chimneys, then you need to be careful. A vermiculite board will help to reduce the distance between the liner and combustibles to 1.5 times the diameter of the flue but there is no way to stop anyone from placing combutibles near to the board, so that is why they insist on 100mm brick or block

 

[Doggit]

There's been a few intersting thread on here where it'd been obvious that there's been an uninsulated liner in the chimney, and in sitting up against the bricks, it's transmitted a hell of a lot of heat though. In one case, the front of the chimney was reaching 100C.

 

[Corgigrouch GTi]

I've not seen that one, perhaps before my time but I would suggest that there is something seriously amiss as liners are intended for use inside brick chimneys to repair the chimney when the original lining has failed or been damaged though I have seen flexiliners used inside timber studing.. I would first look at the flue temperature if the brickwork was ok as there may be too much draw on the flue causing high flue temperatures and a draught stabiliser may help..

 

[Doggit]

Unfortunately, we didn't get a conclusion from that thread. Interestingly enough, stainless steel 306 flexi liners seem to be pushed as the main option nowdays.

 

[Corgigrouch GTi]

316 is the cheap option but I prefer the durability of 904 stainless... Fitting a liner is the default for most chimneys as it saves on checking the chimney properly on a survey for pricing. If the chimney is in an exposed location then even an 8inch ceramic lined flue can give issues with condensation and overcooling if a small stove is fitted, so a liner can be beneficial in such cases as they can be backfilled with vermiculite or a flue wrap