Loadbearing, also called "Nebraska Style" because of the historical precedents, describes construction in which the weight of roofs and floors above the ground are supported, partly or entirely, by the strawbale walls. Loadbearing structures are easier to build because the skilled work of framing is replaced by the simpler task of stacking bales.

The easier and quicker system of building loadbearing walls will save costs by reducing timber (or other framing material) needs as well as reducing the need for skilled labour. However, the loadbearing system does have some disadvantages and faces more difficulties from building officials than other systems.

Wall raising for a loadbearing structure with temporary corner braces in place

Today, most strawbale buildings in Australia are infill structures, mainly because building inspectors, architects and builders are still unfamiliar with the loadbearing concept and retain some resistance to it.

Non-loadbearing, also called post and beam or infill, describes construction in which no weight of roofs or floors above the ground are supported by the strawbale walls. Instead, strawbales are used as infill material between or around a structural frame, which can be timber, steel, concrete, masonry, LVL (structural plywood) or any combination of these. This construction method has become predominant, as most builders, architects, building inspectors, lenders and insurers are familiar and comfortable with its application. Again, this method has advantages and disadvantages over others.

Infill construction has usually a better chance of council approval. The design is very flexible and easily adaptable to conventional systems. Large openings for doors and windows to gain from passive solar energy do not pose a structural problem. There is even compression on all walls even the ones with little or no bales. It is easier to replace sections of a bale wall if moisture or other problems with the bales were experienced. Completion of the roof provides dry storage and protection for the bales while not rendered, as well as for the balers at wall raising time. Last, there is no settling period and work on the building can continue without delay.

Wall raising for a post and beam structure; steel posts are wrapped in Hessian

Disadvantages of the infill building method include the possible greater expenses for framing material and frame construction time, extra footings for posts and increased need of skilled labour.

The potential for volunteer labour and owner-builder involvement may be lower with this more complex construction system.

Bales are usually tied with polypropylene string, sisal twine or wire. It is best to choose poly-string, as sisal is not as strong and prone to rot and wire may rust if it is not galvanised.

For residential building two string bales are the most commonly used. Their general size is about 350 millimetres high, 900 millimetres long and 450 millimetres wide.

However, these dimensions are not as important as the close uniformity of size, especially the proximal consistency in height and width is. 

Dryness of the bales is one of the most important characteristics you need to observe for. Like any organic material, straw will decompose if the right conditions of moisture and temperature exist. The moisture content of a bale suitable for building should be less than 15 percent.

A specialised moisture meter can measure the percentage of moisture content of a bale, the farmer or farmers supply shop may be able to lend you the tool.

However, there are many other simple signs and methods to check for moisture in a strawbale. Open the strings of several bales and have a good look inside the straw. Feel if it is moist to touch and check if it has a damp smell. The bales should have a golden yellow colour; any sign of black mould is a sign of composting. Observe the storage facilities carefully; check that there are no leaks in the roof, that the floor and walls are dry. Always sample a number of bales from different places in the stack to allow for highest accuracy in the assessment of your bales.

Each bale has a cut and a folded side; the folded side is the shaggier one. Look at both sides and make sure they are relatively even as they will require less trimming later on.

Observe that the straw is clean. If too much grain is left mixed in with the straw it may attract pests and activate microbial activity.

The average costing of a strawbale lies between $4.00 and $8.00. The price mainly depends on if you can load and pick them up yourself or if they need to be delivered and how far they come from. You need about 3 bales per square metre when laid flat.

We are happy to help if you have problems sourcing the right bales, please e-mail us at strawbales@bigpond.com for supplier contacts.

If you need to store the bales before use they are best stored in a dry barn or shed. If you build infill walls you may stack the bales under the finished roof construction. If you cannot store them properly have them arrive on the day of your wall raising.

Concluding a few recommendations on safe handling of the bales. Wear gloves when lifting bales by strings to avoid pinching or cutting skin. Long shirt sleeves help to avoid scratching and itching to arms. If the bales are very dusty or you suffer from allergies/asthma use a face mask when handling bales. Remember proper lifting techniques such as bending knees, no twisting of body, and getting help if it is too heavy.

Do not forget to install fastening points where you plan to hang heavy items to walls later on. One method is to hammer wooden pegs into walls where needed, or at regular intervals if no plan for hanging things is as yet in place. For very heavy wall hangings you can secure the pegs with a large plywood square on the outside wall. Mark location of pegs etc. on a diagram to be able to find them after bales are rendered.