Fire pit bbq build

[charcoalchef]

Hi there, I'm new to this forum and building a fire pit come bbq in the courtyard of my restaurant for outdoor cooking and special events.
We're in a very exposed location on the cliffs in west Wales, the fire pit is in the open all though I'm weighing up the option of building a cover to shed the rain to the sides when not in use against the option of building a runoff into the base.
My main concern is the base; as our courtyard is heavily sloped I have begun by laying a level concrete plinth, see pictures. I have collected storage heater bricks for the base of the fire pit and have bought real fire bricks for the sides, see pictures.
I'm looking for advice on laying this base on top of the concrete plinth; can I get away with an inch of sand and the storage heater bricks on top of that or should I use a fireproof mortar or screed? should I build a run off (from the centre line) into the base to stop rain seeping through the bricks and pooling on the concrete below or will the cavity on the underside of the storage heater bricks allow for any steam expansion.
I've probably bitten off a bit more than I wanted to with this and trying to minimise the costs (our business is closed because of corvid now of course) ...could always turn it into a lovely flower bed.
Any advice would be much appreciated!

[charcoalchef]

Oh, I apologise as this isn't really a WFO project but I thought it would be the best place for help.
having trouble finding out how to upload images...

[charcoalchef]

[Thomobigands]

Apr 7, 2020 11:13:34 GMT charcoalchef said:

Hi there, I'm new to this forum and building a fire pit come bbq in the courtyard of my restaurant for outdoor cooking and special events.
We're in a very exposed location on the cliffs in west Wales, the fire pit is in the open all though I'm weighing up the option of building a cover to shed the rain to the sides when not in use against the option of building a runoff into the base.
My main concern is the base; as our courtyard is heavily sloped I have begun by laying a level concrete plinth, see pictures. I have collected storage heater bricks for the base of the fire pit and have bought real fire bricks for the sides, see pictures.
I'm looking for advice on laying this base on top of the concrete plinth; can I get away with an inch of sand and the storage heater bricks on top of that or should I use a fireproof mortar or screed? should I build a run off (from the centre line) into the base to stop rain seeping through the bricks and pooling on the concrete below or will the cavity on the underside of the storage heater bricks allow for any steam expansion.
I've probably bitten off a bit more than I wanted to with this and trying to minimise the costs (our business is closed because of corvid now of course) ...could always turn it into a lovely flower bed.
Any advice would be much appreciated!

Don't worry about the build. One step at a time and you'll do it.

You want some insulation between the standard concrete and your fire/heater bricks as the heat will bleed through and damage the concrete. Lots of options for insulation, have a Google. Calcium board good but expensive. Glass bottles I think some people use. I used fly ash building blocks from a builders merchant at £2 each.

Not sure about your drainage question as I don't quite understand what you mean.

[charcoalchef]

Thanks a lot that's really helpful, I will look into the various insulation ideas, fly ash brick sounds easy, could I just mortar them down with a lime based mortar as they will be beneath the fire bricks?
Drainage wise, I'm concerned about rain water pooling on the base, seeping through the fire bricks and gathering on whatever is below, to combat this I'm weighing up the options of either making a cover for the fire pit when not in use or sloping the base in some way so the rain runs to the sides and out through the holes in the brick that will be left for ventilation.

[Thomobigands]

If you used the fly ash blocks you could probably set them with normal mortar as be the heat shouldn't penetrate down through them.

I just bed mine on sand I think and surrounded them with normal concrete but my construction was obvs slightly different as it was an oven.

In terms of rainwater, a cover seems the simplest solution.

[charcoalchef]

After a bit more research I'm thinking about Pearlite concrete for the later below the storage heater bricks, Any thoughts on mix recipes and minimum thicknesses?
I can't find Fly ash bricks locally, it's really hard to get things at the moment anyway but the local garden centre has Pearlite and Portland cement is easy enough. Does this sound like a viable solution for protecting the concrete below? many thanks!