As i look at this i think a roof would almost be better with loose fill chopped straw inside of a 2 6 roof framework.
Straw bale house roof.
Today insulated homes usually have r 20 in the walls and many old homes have r 14 for insulation or considerably less.
While cement stucco is convenient and low maintenance it can cause moisture problems once it cracks and may actually keep the bale wall from drying properly.
The weight of bales within a roof has to be a very serious consideration.
Most straw bale builders use clay based earthen plasters or lime plaster which require regular reapplication.
It is built with straw bale walls and limestone plaster log roof rafters an.
When attaching a straw bale addition to an existing house the biggest concern is to make sure that the two structures are tied together well.
Post and beam construction is where a structural frame is built and the bales are then placed into that frame as insulation.
The papercrete is completely unsealed and thus breathable.
All straw bale houses need a layer of plaster on the outside to keep water out.
The bales have no structural value for the loads of the building which are all carried by the structural frame.
If you were building in a fairly arid environment you might experiment with a papercrete plaster as i have done with my earthbag home.
A good straw bale home is significantly warmer than conventional building methods because a well packed bale is rated at r30 r35 minimum or considerably more.
There are two general styles of straw bale construction.
It just has to be kept dry.
A good time to use this roof is obviously when the budget is tight or if you want a larger exposed side of the structure as in a greenhouse or in cooler climates.
Post and beam or in fill and load bearing.
The easiest way to do this is with expanded metal lath at each course.
Zhang s next project is to construct an entire habitable building in dubbo in collaboration with john dash and the landowner.
The strawtron roof is lookin good and green these days when we built our two story timber frame straw bale house in 2012 13 we incorporated a green roof into the design.
It was a hell of a task to pull it off especially since we loaded all the soil onto the surface of the roof one bucket at a time.
For straw bale this can pose a problem in keeping the walls free from direct moisture.