Vermicrete Layer Advice

[Spinal]

Re: Vermicrete Layer Advice

Neither of the two above are my ovens - mine's in the other thread ... I posted those pics to clarify the door issue (full arch vs. a straight sided arch).

Still can't make my mind up... but I'm leaning towards the straigh sided one - seems like it may be simpler to recess out the edges to fit a door...

M.

[Neil2]

Re: Vermicrete Layer Advice

"I could always angle the vermicrete layer a tad"

And just what would that achieve ?

[david s]

Re: Vermicrete Layer Advice

Neither of the two above are my ovens - mine's in the other thread ... I posted those pics to clarify the door issue (full arch vs. a straight sided arch).

Still can't make my mind up... but I'm leaning towards the straigh sided one - seems like it may be simpler to recess out the edges to fit a door...

M.

Sorry,
Silly me

[Spinal]

Re: Vermicrete Layer Advice

"I could always angle the vermicrete layer a tad"

And just what would that achieve ?

If (for whatever reason) there was liquid IN the oven, the floor base would be sloped as per the vermicrete layer - thus the liquid would flow out the oven....

In theory...

[Faz]

Re: Vermicrete Layer Advice

I don't think you need to worry about water inside the oven, it is water seeping in to the structure from outside that you need to worry about - any pooling water sitting up against the edge of theven will work its way in to the insulation / brickwork etc. and will cause problems. If you are building a full enclosure then you probably do not need to worry about water ingress, as long as the enclosure is watertight.

[david s]

Re: Vermicrete Layer Advice

When making vermicrete or perlcrete you require about double the content of water that you would normally use in a regular concrete mix. Given that a regular concrete slab still contains a fair proportion of mechanical water that eventually escapes to the atmosphere a vermicrete slab has proportionally a huge amount to be removed. This can easily be demonstrated by making a test slab and weighing the dry ingredients including the water, then weighing the slab daily to calculate the water loss over time. If I have time I'll do it and graph the results for you.

Here are the results of my test.

[Neil2]

Re: Vermicrete Layer Advice

It is so easy to make the structural slab slope slightly away from the middle there is no reason not to do so.

The vermiculite can be poured dead level and the hearth can be dead level.

[david s]

Re: Vermicrete Layer Advice

I re-weighed my vermicrete slab after it had been standing vertically in the sun for 12 cloud free days. It weighed 11.0 Kgs. The test clearly demonstrates the large quantity of water that has to be removed. It also shows that there was next to no water loss on cloudy days. I feel the slab is now completely dry but might just leave it a while longer as i thought it was perfectly dry at day 18. Water loss of 6 litres represents about 75% of the original water added.
I'm sure if the slab had been left sitting on top of a supporting slab and especially if it had been covered over with floor bricks most of the water would still be there. It is probably impractical for many builders to use the weather to dry their vermicrete, but the results are interesting (to me) nevertheless. Hope some others can benefit from them.

[Spinal]

Re: Vermicrete Layer Advice

I stupidly left my vermicrete uncovered due to the nice weather... so while it had been drying nicely, after yesterday's shower it will need to start again... grumble..