Are the roofs your building on your cob houses traditional in function and construction?
Example: Ventilated soffits under eves to wick moisture away from the moisture barrier (that is the roof) utilizing Truss and Timber with insulated voids?
Traditional building practices leave room for an attic space with, generally fiberglass or blown cellulose, insulation between the trusses. I'm not noticing the same practice being used with cob.
A lot of what I'm seeing from places like CobWorks, Barefootbuilder and others appear to be flat wooden surfaces on some sort of sloped truss (be it 1"x6" or roundwood) abutted up to the load bearing walls with no air exchange or insulation. I can't help but to think that these roofs sweat profusely due to temperature differences..... What am I missing?
I would like to plan on using tin sheeting on plywood laid on trusses leveled out onto the cob structure but my thought process won't deny the lack of ventilation and the possibility of condensation buildup - especially in our humid environment.
Also, how do you go about fixing the roof to the cob structure to ensure the roof isn't blown off in high wind conditions? I've seen adobe construction where anchors for the trusses are actually molded into the wall. But I've seen other videos/imagery which show the roofing process where the roof is simply laying on the walls with no explanation of anchoring..
Could anyone please clear this up for me? I feel as though I'm missing something of high importance here.
Bill Bradbury wrote:Most of the traditional/modern hybrids are heading toward trouble with the very problems you have stated.