In A Straw House

Written by Tina Therrien

Once upon a time, there were three little pigs, and one built a house of straw. What the little pig forgot to do, of course, was plaster the warm and beautiful straw home.  Straw, mud, stone and wood have been used for thousands of years to construct shelters. The use of straw dates back to the late 1800s on the sand hills of Nebraska.

With no trees to build conventional homes, and the advent of the horse-driven baler, the resulting straw bales were quickly seen as useful building blocks. The early straw homes were load bearing; the bales would have been stacked, like Lego, in running bond, and then the roof would have been placed on top of the bale walls and left to naturally compress them. After the bales were fully compressed, the walls were plastered, likely with clay that came from the land, or lime from a backyard lime pit.

The modern version of building with bales does not differ much from the earliest building, except that most people do not wait for the bales to compress naturally with the weight of the roof. Modern methods for a load bearing building include stacking the bales, installing (usually) a wooden top plate assembly, and then running compression wires or plastic banding through the foundation and over the top plate, approximately every four feet, to compress the walls, using some sort of mechanical tool. Once the walls are compressed in a load bearing building, they are plastered, and the roof goes on afterwards.

The other way of building with bales is to erect a frame, which could be a traditional timber frame, a stick frame, laminated 2x6 boards buried in the wall, and then fill in the spaces with straw. 

Once the bales are stacked, the walls need to be trimmed and straightened, shaped and tweaked before plastering. Some people like a very organic, wavy wall, while others are more comfortable with a straight wall. Some builders use a reinforcement mesh on the walls which get stitched tightly onto the bales (reminiscent of a quilting bee) prior to plastering. Various tools are used, such as large persuaders (resembling a really big Fred Flintstone hammer), long sewing needles, grinders or chainsaws for shaping windows and more. Bales are malleable, forgiving, and easy to work with, so most shapes and finished looks are possible. Building with bales incites creativity and spontaneity, with impromptu bale benches, niches, and sculptures arising once the building is underway. 

The walls are then ready to be plastered, with either an earthen, a lime, or a combination cement/lime plaster. Synthetic stuccos must not be used; the plaster and any paint used on the bale walls must be permeable, to allow vapour to slowly travel through the walls. The thickness of the plaster varies, from an inch to two inches, depending on the materials. Earthen plasters tend to be applied thicker. People either love plastering, or they hate it. 

Plastering is a tremendously physical part of the job, one that many homeowners are happy to hand off to a professional crew. But beware of accepting a quote from a crew who have never plastered a straw bale wall. Straw walls use large amounts of material compared with conventional walls, so people who aren’t familiar with bale building will often be surprised by the quantity required (and by the exhaustion that comes at the end of a plastering day). For those who love it, it can be satisfying to look back on a window opening and remember how you struggled to get it ‘just so’. 

The ideal bale home will have a beautiful setting, with passive solar built into the design; it will be off-grid, and will use bales from a local farmer, if the owner hasn’t grown their own crop of straw. Clay from the site, if sifted and mixed with fibers & sand, makes a most beautiful plaster to coat the walls. 

For those who have never seen or heard of a bale building (rarer now than 10 years ago), there are questions about fire, moisture, bugs, and durability. Laboratory testing on plastered bale walls have proven good. One fire test (done in Canada) showed that the plastered bale wall passed a two hour commercial fire test at 1850ºF. 

Regarding durability, there are 100+ year old homes still intact and inhabited in Nebraska, where the climate is quite different from here, of course. There is a church on the prairies in Canada that dates from the 1950’s, and there may be older dwellings that haven’t been found yet! As long as you keep the bales dry during construction, and detail your building properly to keep moisture out (done whether building conventional or natural), there is no threat of the bales going mouldy. Straw bales have an amazing capacity to dry out on their own. Each bale has thousands of tiny straws bundled up tightly, which have a great capacity to wick moisture to the exterior. 

And as for critters: once the bale walls are plastered, the thick plaster coat on the exterior deters critters from entering for the most part. Also, there is nothing in the bales to attract critters, since (most) of the grain has been removed for baling. I would never claim that a straw bale house won’t have mice, but since most homes still have stud walls for the interior walls, these are much easier to chew through for a rodent home.
 
Straw is an annually renewable resource with which to build, and a straw wall system offers an R-value of 40, which is closeto double that of a standard home. They create aesthetically pleasing, healthy environments (as long as all of the materials going into the home are non-toxic) and have incredible acoustic properties. 

With over 200 straw bale buildings in Ontario, and the rising interest in more energy efficient, sustainable housing, there will be more bale buildings in our surroundings. There has been serious talk between bale builders and developers, town planners and cities, and it is only a matter of time before we see sustainable off-grid straw bale communities.

Bale building has up until now remained with the owner/builder and a handful of professional builders in the province, and has allowed an owner’s community of friends to come out and help, similar to old-fashioned barn raisings. This hands-on contribution to a beautiful living space is both fun and satisfying.

The Ontario Straw Bale Building Coalition hosts a tour of homes across the province each year. This year the tour is scheduled for October 4, and is an opportunity to see the diverse and shapely homes.
(www.strawbalebuilding.ca).
 
I advise people to research beyond the Three Little Pigs. Incredibly strong, bale buildings have been built in many parts of the world, and if built properly, can last a very long time.

By Tina Therrien
Owner/builder of Camel’s Back Construction

www.strawhomes.ca