Vermiculite Ventilation?

[david]

I think I read somewhere (maybe Alan Scotts book?) that the enclosure for the Dome should be ventilated above the Vermiculite layer.I haven't done this,but could always add this if required.I don't see any mention of it here in this Forum/building plans.Any comments?Thanks,
David

[Keith Oertli]

I think the idea is to allow for any excess heat, or smoke in the case of the Pompeii where you most likely will have small crack lines in the dome, to escape.

Providing for ventilation in a housed structure is not difficult. An oven that is domed over with stucco is different. I think it would be a good idea to provide some type of vent to allow gases and heat to escape while not allowing any moisture in.

K.O.

[ColonelCorn76]

The venting also provides a way for the moisture in the cladding & insulation layers to escape. Both of these are much more massive in Alan's design so they can take as much as a year to drive out all the water before you want to seal it up. Of course during that time it can take on new water from the environment so it's just easier to vent the enclosure.

It's less of an issue with the Pompeii design due to the much lower amount of "wet" concrete used. Especially if using dry loose fill vermiculite as the insulation in a "house" enclosure. Venting then becomes just a good building practice as you want to be able to drive out any environmental moisture that might make it into your insulation.

If you go the stucco/igloo route, you'll want to make sure the oven has dried by using it for a couple or three months before applying the stucco. The stucco will breathe a bit but it's best to get the bulk of the moisture out of your insulating layer first.

Jim