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Post by slen916 on Sept 26, 2016 8:52:31 GMT
Just wondering if it would make a big difference. Was looking to put 50mm of ceramic blanket plus 80mm of vermiculite then a 20mm render,but for not much more money I could up the blanket to 75mm..do you think it is worth it or not..
Cheers Justin.
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Post by downunderdave on Sept 26, 2016 10:09:41 GMT
Just wondering if it would make a big difference. Was looking to put 50mm of ceramic blanket plus 80mm of vermiculite then a 20mm render,but for not much more money I could up the blanket to 75mm..do you think it is worth it or not.. Cheers Justin. The ceramic fibre blanket is usually more expensive than the equivalent thickness of vermicrete, and this may be a big consideration, but it has the big advantage of quicker application and the fact that it's dry. Because vermicrete contains so much water it is best applied in layers of around 35 mm with at least a week left to dry after each layer, otherwise the water trapped in deep is more difficult to remove. I think you'd be better off with more blanket and less vermicrete |
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Post by slen916 on Sept 26, 2016 11:26:24 GMT
Thanks for the info, more blanket it is.
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Post by slen916 on Sept 26, 2016 11:48:30 GMT
Do you think 2 layers of 35mm vermiculite plus 15mm of render will be strong enough..
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Post by downunderdave on Sept 26, 2016 12:08:49 GMT
Hi Justin,
The strength of the vermiculite depends on how much cement you mix with it. My feeling is that you want it to insulate so make it as lean as you can. I find 10:1 is about as weak as is practicable to apply. I also think that all you really need from a vermicrete layer over blanket is something that will even out the lumps and bumps of the blanket layers, yet provide a firm substrate to render on to.(blanket being a bit too springy). I only do one layer of 35 mm or so over the blanket. You can do more if you feel so inclined. I also think 20 mm is overkill for the outer shell unless you want to park your car on the thing. Most renders are recommended not to exceed 10 mm in thickness, if going much thicker it is prone to cracking. . You can do it in layers, but I only do one layer rich with fibres, around 12mm thick, then give it an acrylic top coat 2-3 mm after lots more fires and you're sure it's dry, otherwise the acrylic can blister. There' re many ways to do it, most depend on finding a balance of expense, labour and time.
Cheers,
Dave
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