Are fire bricks necessary?

[ray99]

Hi guys. Not been on here for ages and have a question from my daughter.
Old coal fire has been removed and opened up to the 'builders opening'. She is fitting a 5Kw multifuel fire (done by a HETAS qualified fitter)
To line the builders opening up to steel register plate height does she have to use fire bricks or can a cheaper brick be used?
Thanks.

 

[theprinceofdarkness]

Fire bricks are not required if there is an air gap around your stove.
Frank

 

[ray99]

Thanks. The opening as it is is 36'' before finishing / lining and the stove is about 20'' I think ( need to measure it next time I am there ) so there should be an air gap of about 7'' all round when the opening has been prepared.
So normal bricks with the appropriate mortar mix would be ok?

 

[theprinceofdarkness]

Normal bricks but it would be good to use the softest mortar mix you can handle. The bricks will get at least warm, so will expand, if they are locked by a very hard mortar they could spall.
Frank

 

[maltaron]

A possible alternative is to render the opening and fit brick slips. It looks like brickwork but easier to fix and leaves a wider opening. I fixed mine with tile adhesive on the sides and fire cement on the back, pointed with grout using an icing syringe.

 

[ray99]

Thanks for the replies. I will report back to my daughter and she can look at the available finishes.