Perlicrete depth and heat island

[kd2724]

Been lurking since 2007. At this point I'm pretty sure I'm going with a 42" Pompeii design (though reading Brickie in Oz thread certainly makes me consider a low barrel vault design) as part of an outdoor kitchen with cabinets, pergola, smoker and considering one of those FB outdoor fireplace kits that James sells.

Stand is built. Mortared block / cores filled with a 4 inch reinforced slab.
I decided on using Perlite as the primary insulator as Harbison Walker only wanted to sell me 72 sqft of ceramic board. I wont be using the blanket as I dont really like the description of using a respirator and feeling itchy regardless of how careful. Somewhat reminds me of the asbestos fibers that never go away (anyway for those that use one I would think the biosoluable version is the way to go).



A few questions. Does anyone use any reinforcing wire in the perlicrete/vermiricrete? Also I'm going to use some calcium aluminate cement as the binder for the last 1 to 1.5 inches of the perlicrete.

4" inch minimum seems to be the consensus?

I'm planning on using a soapstone and firebrick as an underlayment to a standard firebrick hearth to gain some extra thermal mass. Likely around 4" total.

Anyway. Amazing site and some spectacular builds.

I'll post some photos once I get to an interesting part.

kd

[Neil2]

Re: Perlicrete depth and heat island

"A few questions. Does anyone use any reinforcing wire in the perlicrete/vermiricrete? ".

Just go with straight portland cement/perlie (or vermiculite) for the whole depth. No reinforcing. This layer will act only in compression therefore no structural benefit to reinforcing it. In addition, the pearlcrete is quite porous and the reinforcing will rust inside the layer.

[stoveup]

Re: Perlicrete depth and heat island

You could use the soapstone as the cooking surface in the dome - the hearth. If you have large pieces of soapstone, you will have a smoother cooking surface with fewer joints to contend with.

Soapstone holds more heat than brick (of the same thickness) and transfers the heat faster than brick. Why put the coldest and slowest material on top?

[kd2724]

Re: Perlicrete depth and heat island

Thanks Neil - good point about the rust.

Stoveup - I only have a 20x30 inch chunk leftover from installing countertops in our old house. Love soapstone but I was putting it underneath as I don't have enough for the entire cooking surface and wanted to avoid a half on half off scenario as the materials would cook at slightly different speeds.

Kd

[stoveup]

Re: Perlicrete depth and heat island

Kd, I agree that the entire cooking surface should be the same material. I have two pieces of soapstone that I got from two different counter top fabricators. My hearth won't all be the same color (part gray/part green), but the thermal properties should be similar enough. You might want to look around for some cut-offs.

How did you like the soapstone counter tops? My wife and I are currently debating granite vs. soapstone. I much prefer the soapstone look, but at the moment we are leaning towards granite due to its hardness and somewhat lower maintenance.

[kd2724]

Re: Perlicrete depth and heat island

Soapstone was great. I have had both soapstone an granite and I really prefer the soapstone.

I actually had a bunch of "trimmings" from fabricating the countertops but when we moved I just wasn't sure what I would ever do with them.

I got the materials from M. Teixeria and fabricated them myself. Really pretty easy to do. Lots of dust and really heavy but manageable with at least one other person to set them on the cabinets.

My wife would like to ditch our current granite and return to the soapstone.

It's pretty indestructible stuff (heat and chemicals) and any gouges could be repaired with some dust and marble epoxy.
Kd

[kd2724]

Re: Perlicrete depth and heat island

Just to be clear. I never had any "gouges" to repair. The relative softness originally worried me but it is the best and easiest product to maintain as leaving oil or a lemon or other spills on granite will stain it while the soapstone is unscathed. Can you tell I'm a fan?!?

[TropicalCoasting]

Re: Perlicrete depth and heat island

Thats strange
I have had black granite bench tops and nothing stained it.
Still have a small piece from the sink under my barbie.

[kd2724]

Re: Perlicrete depth and heat island

If sealed well granite has pretty good stain resistance. Oil typically will cause it to leave a bit of a darker spot. With black granite maybe it's not an issue?

[stoveup]

Re: Perlicrete depth and heat island

My wife and I were looking at granite slabs at a very large warehouse two weeks ago. The warehouse manager, who spent many years as a fabricator, confirmed to us that the darker, more uniform granites have less of a tendency to show stains with Absolute Black being the most visible stain resistant. Problem is, I don't want dark counter tops.

I have a small piece of grainy medium brown granite that we use as a trivet. It's a great trivet, but it has several stains - the worst one from a dish of Mac and Cheese that ran over a bit while cooking.