Straw Bale Roof Insulation

Owen geiger yes you can use straw bales as roof insulation.

Straw bale roof insulation.

Straw bale construction is a building method that uses bales of straw commonly wheat rice rye and oats straw as structural elements building insulation or both. First you need to check the strength of your roof system. The straw clay material is a sort of hybrid between pure insulation straw baled or not and pure mass cob for ex. On end or flat.

Without an exterior stud wall most straw bale walls have an r value of r 33 or less. Strawbale insulation is tightly packed and 18 thick. This construction method is commonly used in natural building or brown construction projects. It can be made into different grades closer to one extreme or the other.

The typical straw bale is bound twice and is approximately 900mm long 350mm high and 450mm deep. 2 6 tongue and groove planking over beams girders to be engineered per the loads and spans. 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. The two layers of batts and 3 of rigid foam andrew describes would be about 240mm deep for r57.

A bale is 360mm deep. However if you want to use bales you can use an assembly that looks something like this. If you re wondering what the r value of strawbale construction is then it depends on a few things. For straw bale this can pose a problem in keeping the walls free from direct moisture.

Bales of r40 with ceiling airspace anticon then roof would rate somewhat above r40 and the standard r38 andrew talks about. The density of the straw how long the straw itself is as well as the moisture content how well the gaps are filled between bales and other things like how it s stacked. This implies that bales r factors would be considerably higher. Are there any very long spans.

What you want is closer to the insulative side. Personally i stick with light weight insulation materials in the roof and leave the bales for the walls. Make sure it s in good condition no rot termite damage cracked boards etc.