Vermicrete v Castable

[james9]

I've had a chat with Liam at Kiln Linings and he suggested covering the insulation blanket with castable as it offers better insulation properties and is lighter in weight compared to vermicrete albeit more expensive.

Has anyone got a good example of a build using castable or have an opinion verses vermicrete? (most people seem to go for the latter)

What impact would it have on thickness and heat retention?


www.kilnlinings.co.uk/categories/castables-refractory



Thanks
James

[downunderdave]

Jul 5, 2017 10:13:30 GMT james9 said:

I've had a chat with Liam at Kiln Linings and he suggested covering the insulation blanket with castable as it offers better insulation properties and is lighter in weight compared to vermicrete albeit more expensive.

Has anyone got a good example of a build using castable or have an opinion verses vermicrete? (most people seem to go for the latter)

What impact would it have on thickness and heat retention?


www.kilnlinings.co.uk/categories/castables-refractory



Thanks
James

He wants to make a sale. Because the layer is outside the blanket there is not much point using an expensive calcium aluminate based castable as it won't see high temperatures. You can also make vermicrete as light as you like.As lean as 10:1 is still workable and extremely light. You can then cover that layer with a standard cement render.

[oblertone]

What Dave says makes perfect sense; I used ready mix waterproof tile cement as external render directly over my blanket (& chicken wire) because I was going to mosaic the dome (and didn't have room for vermicrete).

[james9]

So are we saying the main purpose of vermicrete is maintaining form factor rather than acting another insulation layer and secondly acting as an precursor to the render layer?

[downunderdave]

Jul 6, 2017 12:45:38 GMT james9 said:

So are we saying the main purpose of vermicrete is maintaining form factor rather than acting another insulation layer and secondly acting as an precursor to the render layer?

Yes, it does all of those three things. Take your pick over which you consider most important.I like to do a 10:1 layer which is strong enough to act as a decent substrate for the render while still being workable for application and having decent insulating value.