Prefabricated Straw Bale Wall Panels

Ever since Camel’s Back Construction went to the Toronto Home Show in 2001, the idea of prefabricating straw bale wall panels has been tumbling around in my brain, and every so often I’ve had a chance to play with the idea. Home show displays, a small shed and lots of small scale test panels have all helped the idea develop into a fairly sound approach to building plastered bale wall panels off site and installing them ready to bear a roof quickly.

In 2009, we were able to put the idea of load bearing prefabricated bale wall panels to full scale use on the Camp Kawartha Environment Centre project. The following slide show gives an overview of the construction process in the shop and the installation process on site.

In 2010, we used the same prefab idea to build a LEED Platinum certified home for Habitat for Humanity. You can see a video about the construction of these panels at http://www.youtube.com/watch?v=q61og2ydZKcPrefabricated Straw Bale Wall Panels.

Why prefabricated bale wall panels? The panels address all the aspects of bale building that have proven to be obstacles to widespread adaptation of bale walls in the housing market (weather issues, delivery and storage of bales on site, the need for skilled plasterers, uneven curing of plasters, the mess of plastering, keeping walls plumb and square, needing to train new workers, etc), while maintaining all of the advantages (low embodied energy, high insulation value, great aesthetics etc). In fact, the prefab panels end up costing less than conventional stud walls!

If you are interested in the prefabricated straw bale wall panels, please use the contact form on this site to let me know. You can also contact Ian Weir of NatureBuilt Wall Systems. Ian is a graduate of the Sustainable Building program who is now manufacturing prefab bale walls for residential and commercial clients.

Prefab bale walls slideshow Prefab straw bale walls by Chris Magwood

The top and bottom plates for each wall section are built The top and bottom plates for each wall section are built	The shop space needs bale storage, a chop saw, compressor and table saw The shop space needs bale storage, a chop saw, compressor and table saw	Each wall section has plates made to define the length of the wall Each wall section has plates made to define the length of the wall	The 2×4 box beam bottom plate has notches for lifting straps or forklift tines The 2×4 box beam bottom plate has notches for lifting straps or forklift tines	The 2×4 box beam bottom plates are insulated with vermiculite The 2×4 box beam bottom plates are insulated with vermiculite	The 2×4 box beam top plates are insulated with sheep’s wool The 2×4 box beam top plates are insulated with sheep’s wool	All top and bottom plates are built in advance All top and bottom plates are built in advance
The raised form allows lifting straps to be passed under the wall The raised form allows lifting straps to be passed under the wall	Top and bottom plates are placed on runners to keep form off the ground Top and bottom plates are placed on runners to keep form off the ground	The form box includes temporary sides, which house the permanent window stud and mesh The form box includes temporary sides, which house the permanent window stud and mesh	A finished form box, with plywood bottom that is later removed A finished form box, with plywood bottom that is later removed	The "exterior" plaster is poured into the form box The "exterior" plaster is poured into the form box	Care is taken to make sure the mesh is well embedded in the plaster Care is taken to make sure the mesh is well embedded in the plaster	Plaster is poured until it’s one inch thick in the form box Plaster is poured until it’s one inch thick in the form box
The plaster is vibrated to get rid of air pockets The plaster is vibrated to get rid of air pockets	The straw bales are "buttered" with plaster on the "exterior" side to ensure good penetration of the bale The straw bales are "buttered" with plaster on the "exterior" side to ensure good penetration of the bale	Buttering the bales with hands in gloves tends to get better penetration Buttering the bales with hands in gloves tends to get better penetration	Buttered bales are placed into the plaster in the form box Buttered bales are placed into the plaster in the form box	The courses of buttered bales are laid into the wet plaster The courses of buttered bales are laid into the wet plaster	The last course of bales fit tightly into the form The last course of bales fit tightly into the form	A bale dance helps embed the buttered bales into the plaster in the form A bale dance helps embed the buttered bales into the plaster in the form
A bit of trimming where the last course has been packed into the form A bit of trimming where the last course has been packed into the form	Mesh and barrier are stapled and pinned onto the interior face of the bales Mesh and barrier are stapled and pinned onto the interior face of the bales	Plaster is poured and vibrated down the sides of the forms to meet up with the embedded window stud Plaster is poured and vibrated down the sides of the forms to meet up with the embedded window stud	As the edges are poured, any gaps in the bales are well stuffed As the edges are poured, any gaps in the bales are well stuffed	The first layer of plaster is worked into the straw by hand The first layer of plaster is worked into the straw by hand	Mesh and barrier at the top of the interior face Mesh and barrier at the top of the interior face	Form box is filled to the top to complete the 1 inch of plaster, then screeded Form box is filled to the top to complete the 1 inch of plaster, then screeded
The interior face is given a trowel finish The interior face is given a trowel finish	Corner panels have the plaster held back to accomodate the intersecting panel Corner panels have the plaster held back to accomodate the intersecting panel	A shop full of panels! We could only fit four, so we did two batches A shop full of panels! We could only fit four, so we did two batches	The cured panels are loaded onto a boom truck. These were too tall to tansport upright, but that would have been preferrable The cured panels are loaded onto a boom truck. These were too tall to tansport upright, but that would have been preferrable	Lifting the first panel Lifting the first panel	One prefabricated straw bale wall panel, ready to be placed on the foundation One prefabricated straw bale wall panel, ready to be placed on the foundation	One prefabricated straw bale wall panel in place! One prefabricated straw bale wall panel in place!
The boom truck is able to make fine adjustments to the position The boom truck is able to make fine adjustments to the position	The first prefabricated straw bale wall panel is set in position The first prefabricated straw bale wall panel is set in position	The pre-built frame wall section for the window opening is installed The pre-built frame wall section for the window opening is installed	Prefabricated straw bale wall panel number 2 is moved into place next to the frame Prefabricated straw bale wall panel number 2 is moved into place next to the frame	The next window section is installed and panel #3 is ready to go The next window section is installed and panel #3 is ready to go	The plywood base from the panels are unscrewed to be reused on the next batch of walls The plywood base from the panels are unscrewed to be reused on the next batch of walls	The final prefabricated straw bale wall panel is put in place The final prefabricated straw bale wall panel is put in place
The preplastered bale walls are weather ready the minute they’re set in place! The preplastered bale walls are weather ready the minute they’re set in place!	One side of the building is completed in about 2 hours One side of the building is completed in about 2 hours	The completed roof is craned onto the prefabricated straw bale wall panels The completed roof is craned onto the prefabricated straw bale wall panels	The interior plaster surface only required painting with silicate mineral paint The interior plaster surface only required painting with silicate mineral paint	The difference in wall depth at the framed openings helped create nice window seats The difference in wall depth at the framed openings helped create nice window seats	At this corner, prefab bale wall intersects with site baled wall At this corner, prefab bale wall intersects with site baled wall	The prefabricated straw bale wall panels contribute to a pleasing aesthetic The prefabricated straw bale wall panels contribute to a pleasing aesthetic
The window seating also includes storage capacity The window seating also includes storage capacity	The prefab bale walls intersect with slip straw and hempcrete framed walls The prefab bale walls intersect with slip straw and hempcrete framed walls	On the exterior, the framed sections are shingled, not plastered. Treatments here could be done in many ways. On the exterior, the framed sections are shingled, not plastered. Treatments here could be done in many ways.