Concrete as fireplace base

[TK1]

Hi all,

We have just resurrected our fireplace, a standard setup in a 1969 Melbourne house. It's had an electric heater in it for many years - that has been removed, curve at back of hearth has been replaced (wood for now, will be steel soon, as bricks were cut out when heater put in by former owner). We opened the top of the chimney and it draws well.

So, to the question...the base/bottom of the hearth has a few bricks, otherwise appears to be sand over the main base of the structure....do we need it re-bricked, or can I use concrete/cement as a base?

Will the cement or concrete stand up to the heat (grate is about 10cm off the ground)? Or is this why bricks were used? Obviously cheaper for me to go and buy a bag of cement/concrete and fill in the base than to have it re-laid with bricks. I suppose I could brick it myself if it is necessary.

Any answers or ideas appreciated.

Thanks,

Darren
Melbourne

[TK1]

sorry for the typo!

[BobL]

It all depends what you plan to do with it and how long you want it to last. If you are going to burn wood in it all day you should seriously think of lining the fireplace with refractory bricks (clinker bricks are OK) and use refractory cement in the mortar. If you don't, the heat will eventually shatter the bricks and existing mortar. If you only plan on using the fire a couple of times a year then straight bricks and mortar will last a long time.

A layer of normal cement will probably crack whereas you could use a layer of refractory cement (Bunnys has it). You should make it as thick as possible if you don't want it cracking. I would go for 1.5 or 2 inches if you can.

I installed cast iron fireplaces into two of our rooms and used the heritage fireplace tiles on a one inch thick refractory mortar layer over a 12mm thick sheet of fibre cement sheet, it's lasted for 12 years with just 2 tiles coming loose and having to be recemented. These tiles look nice but are quit exy.

Cheers

[Tote]

After just having rebuilt one of our 1860 vintage hearths ours are brick laid over sand using lime mortar instead of cement to hold the bricks together. I was surprised how they constructed it with just bricks over a sand base but the fireplace in our loungeroom has fared pretty well for the last 140 years.
regards,
Tote

[TK1]

Hi,

Thanks Bob L and Tote. It looks like our one did have bricks, just over a sand and rubble base.

I'll get a fireplace person to look at it, and may go for the special cement Bob mentioned with tiles over the top.

Thanks,
Darren