straw Bale weight for use in building

“ Some people are under the impression that “the denser the better” and others that an “overly” dense bale will insulate less, as the fibers of straw would be crushed and retain less air - therefore insulating less.”

Re posted in part from the GSBN forum. lance

My experience when people are talking about very dense bales it is “export Bales” they are talking about. These are highly compressed some ending up as small as 450mm x 350mm x 200mm with a weight of 12kg. Giving a total weight of around 380kg per m3 and strapped with steel or polly straps. These bales will perform more like timber , perhaps with a lower R value. But due to their weight will have increased mass as well as thermal mass.
As 3 or more standard small square bales are compressed into the space of one, They become a 2 person lift, along with the additional overall Wall weight this has an impact on footing design.
Garden mulch bales less than 100 kg / m3 may well have a reduced R value , along with other issues if used in construction.
Construction grade bales around the 115 /120 kg per m3 will achieve great performance , as shown by any existing R value testing.
Export grade bales of over 350 ( even over 200 kg ) per m3 may not ( I suggest will not) show any increased R value , but only add to construction costs.
R5-6 as a standard ( construction grade) bales produced on farm, is preferred by me to making more work / inputs into a product ( bales ) for a perceived minor gain.
Regards Lance Kairl