GoodTemp Perlite Block for Floor Insulation

[loganc10]

I've been calling around my area to get some pricing on CalSil, foamglass, blankets, etc. I stumbled upon a potentially viable option they are calling Perlite Blocks. The product is manufactured by Howred Corp. out of Houston and the product line is called GoodTemp.

I've gotten several insulation prices locally:

• CalSil at $4.75 and $5 / sq ft @ 2" thickness, minimum 27 sq ft
• FoamGlas $6.11 / sq ft @ 2" thickness
• Perlite Blocks $2.36 / sq ft @ 2" thickness, minimum 1 board
  • 1m (~40") lengths
  • 6", 12", or 18" widths available, also can be purchases as circles > 20")
  • Thickness available in 1/2" increments up to 6"

Since the perlite blocks are half the price, I'm trying to determine if they will be suitable.

I've compared it side by side to Thermo-12 Gold; specifically the K/R-value, compressive strength, flexural strength, etc. It seems to have sufficient strength, and comparable K/R value though slightly worse than CalSil.

Spec	CalSil (Thermo-12)	Perlite Brick (GoodTemp)
Density (Dry)	>14 lbs/cu ft (230kg/m3)	12 lbs/cu ft (192 kg/m3)
Compressive Strength - 5%	>100 psi (690kPa)	134 psi
Flexural Strength	>50 psi (450kPa)	54 psi
Water Absorption - 90% humidity 4 wks	?	1.3%
Water Absorption - Immersed 24 hrs	?	2.7%
K-Values (ASTM C-335)
200F (BTU/hr/sq ft/F/in)	0.389	0.48
93C (SI Units W/M-k)	0.056	0.069
700F (BTU/hr/sq ft/F/in)	0.647	0.76
371C (SI Units W/mC)	0.093	0.11

*K-value note - Thermo-12 also had lower K-values reported from ASTM-C518, but the perlite block only had C335 and C177. C335 were compared above.

In terms of water absorption, would this stuff fall closer to CalSil or FoamGlas with its water proof qualities?

What are everyone's thoughts? If relevant to the question, I am planning on building a ~30" homebrew cast oven. Build will be very cost conscious; and I'm not looking to over insulate; primarily looking for pizza nights and maybe a couple loafs the next morning. I'm considering going with a 3" thick perlite block (likely ~$3.5 per sq ft), and calling it good.

Engineering Toolbox - Perlite
Engineering Toolbox - CalSil

Thermo-12 Gold Datasheet
GoodTemp Perlite Block Datasheet

[UtahBeehiver]

Based on the data you provided it looks like a possible less expensive option and more water resistant than CaSI. Based on your cooking criteria, 2" is probably enough.

[david s]

Some perlite is silicon coated which drastically reduces its water absorption. I can’t find a supplier here so don’t use it but I would if I could. If they’ve used this then it could be an even better option than the cal sil which is very water absorbent. The Foamglas does not absorb water at all.

[Chach]

Some perlite is silicon coated which drastically reduces its water absorption. I can’t find a supplier here so don’t use it but I would if I could. If they’ve used this then it could be an even better option than the cal sil which is very water absorbent. The Foamglas does not absorb water at all.

I used loose perlite that was silicon coated for my enclosure fill. They usually use it in masonry applications such as cement block voids as insulation. Company I used sells it but shipping is high...they have 2 manufacturing areas in the US that you can pick up the product and those are in Chicago, Pennsylvania...if you want to have it shipped the website is www.hometownperlite.com

Ricky

[Petter]

Some perlite is silicon coated which drastically reduces its water absorption. I can’t find a supplier here so don’t use it but I would if I could. If they’ve used this then it could be an even better option than the cal sil which is very water absorbent. The Foamglas does not absorb water at all.

The binder is Sodium Silicate, so the perlite will be covered with silica if the block is cured above 100 C. If not, the block would disintegrate in water. The data sheet states water absorption, and thus it has to be cured.

[loganc10]

Thanks everyone for weighing in.

I found out that the gotcha here is that the local vendor don't carry it in stock, thus it will have to be shipped via freight and I'd be on the hook for that shipping. My guess would be with that considered, it might end up more expensive than CalSil and other options.

Distribution International and a couple other local vendors seem to have a similar perlite block product as well, so hopefully I can track some down that won't require shipping.

Does anyone know the water absorption by volume numbers of CalSil to compare against this stuff? I couldn't find it in Thermo-12 or Super Caltemp® Gold 1700 CalSil datasheets.

[Petter]

Why dont make it your self? I will, just got 500 liters of perlite delivered. I plan to casting bricks of about 30 x 30 x 7.5 cm, let them air dry (pick up CO2 and evaporate water), then you can cure them in the kitchen oven or bbq above 100 C. You first make sure the amout of Sodium Silicate you add to the mix gives a cured density of 150-200 kg/m3.