mouldable firebrick in a form?

[Harry Davis]

I am enlarging a fireplace and will need a bigger throat-supporting lintel than usually available. Can someone tell me whether this can be made using mouldable firebrick (not firebrick mortar) inside of a timber form, and if so, what's the best way to dry the material prior to exposing to full heat.

Many thanks in advance :-)

Harry

[newshound]

Without being quite clear about the geometry, do you really need firebrick properties here? And what sort of load is it supporting? When I reinstated an inglenook by removing georgian *and* edwardian structures, I took out an arch about two feet wide made from 2 inch x

1/4 inch steel strip which was supporting the brick outer throat.

By its nature, a lintel will normally have tensile stresses on the bottom face. Firebrick isn't good in tension.

[Harry Davis]

newshound wrote in news: [e-mail]:

My mistake - I should have said "throat-forming lintel" rather than "throat-supporting". It will hardly be supporting any load at all. There is a concrete lintel in the wall about 15cm above it, and I think there is a steel arch directly above where it will go. (I'm not at the house and can't check.) The idea is to have it the same shape as one of these, but wider:

The fireplace will be 24" wide and 12" deep; unless I change my mind, I'm not taking it right back to the builder's opening.

Harry

[harryagain]

You can buy refractory cement and refractory concrete. No rebar should be used Eg

[Harry Davis]

"harryagain" wrote in news:l39ead$etc$ [e-mail]:

Thanks for this. The same manufacturer also makes mouldable firebrick. Are you saying the mixable stuff would be better, if I'm going to put it in a form? That may sound like a silly question, but I've not worked with either material!

Best,

Harry

[Harry Davis]

"harryagain" wrote in news:l39ead$etc$ [e-mail]:

Thanks for this. I've been thinking about this some more. My options for making the throat-forming lintel seem to be

1) make it from mouldable firebrick, using a form 2) make it from refractory cement using a form

And the two issues seem to be:

1) is the firebrick sufficiently castable? 2) whichever route I take, how to deal with the expansion problem?

I'd appreciate further advice on any of this.

To recap: I'll be making a throat-forming lintel for a 24"- (possibly

27"-)wide fireplace, similar to the standard commercially-available TFLs used for 18" fireplaces, e.g. the first 3 shown here:

but 6-9" wider. The width of the throat itself will be about 10-12cm.

Harry