Strawbale Construction
Baled straw is a reusable agricultural waste product very valuable to builders. The difference between straw and hay is very important in strawbale construction. Hay is feed for animals and straw is not a food source, but what is left after the threshing of grains. Strawbale homes can be constructed in a number of different ways with varying levels of effectiveness and ease. We use several styles that have proven to be effective. The integration of exposed timber framing, conventional framing and modified post and beam are some of the available systems. We prefer to avoid thermal breaks in the wall by using an internally exposed timber frame structure and an unbroken bale wall wrapping around it protected by the roof overhang. This insures a consistent R-value and low draft infiltration. Strawbale walls are thick (18" or more) and are very high in R-value.
Thermal Performance:
- Very high R-value (2.25 per inch).
- Medium thermal mass, increased by thick earthen plasters.
- Typical strawbale construction provides an R-40 wall.
Characteristics:
- High breath ability if breathable plasters are used.
- Non-load bearing in New Mexico code.
- Bales accept earthen clay based plasters without wire netting.
- Bales are usually 18" x 36" x 14"
Construction Techniques:
- Bales are usually stacked in the 18" thickness.
- The roof loads are supported by a post and beam structure of various types.
- Post and beam structure can be embedded in the bale wall or exposed interior or exterior to the wall.
- Bales can also be used as infill in double frame wall construction. A 2x6 wall 18" o.c. will accept bales stacked on the 14" with on end.
- Overall wall thicknesses vary from 16" to 20" depending on technique used.
