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In the Western Cape Straw bales are harvested around November and December time....so this is normally the best time to buy ones bales. Bales bought later into the year tend to be more expensive and in less good condition unless they have been specifically stored under shelter. You can pay R5 – R10 a bale in season compared to up to R30 out of season!
Other parts of the country harvest a bit later into summer, so one always need to check with your local farmers if you are looking for bales anywhere else in the country.
Buying directly from the farmer is usually the best. There are plenty of farmers up the N7 ....around Malmesbury and Darling who can supply bales. There is also a wheat farm near Somerset West.

If I were you, I would start to phone the farmer’s co-ops and horse stable suppliers and enquire about where you might find straw as locally as possible. The co-ops generally know who farms what in their areas…..so they will know if any farmers in their area’s are farming any of the grains….remember wheat, rice, oats, barley and rye straws are all suitable. I would start more locally and then move further and further away from your location to try and locate the most local source possible.

The best resource to find contacts nationally is to go to the webpage: South African Grain Information Service

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This is a link to the South African Grain Information Service. It will take you to a page were you can select from a range of different grains ie. wheat, barley, oats and millet. From there you can download contact lists for different grain co-workers in all regions South Africa. Though these contacts you should be able to establish which farmers in your surrounding area supply straw.

Otherwise ask people who keep horses as you can always get bales from stable / horse suppliers. If you are only buying a few bales in the greater Cape Town area then Custom feeds is probably the best place: www.customfeeds.co.za / Hout Bay (021) 785 5773 / Noordehoek (021) 790 5030. They keep straw for bedding. However, especially with such suppliers be sure to ask for straw and not hay!

As straw bales are firmly compacted, they do not hold enough oxygen to facilitate combustion. Straw bales exposed to fire will smoulder and char, but will not burn. Typically walls are always plastered which further protects the walls. Extensive fire tests which have been conducted on straw bale structures have proven that a straw bale in-fill wall assembly is a far greater fire-resistant assembly than a wood frame wall assembly using the same finishes.

On the 4th of Juli 2003 strawbale building took a big step in Germany: a fire test, "F90", was done in a material-research-institute in Braunschweig. A strawbale wall, plastered with clay on both sides, was heated up to about 1000 degerees celsius, for 90 minutes.

Please click here for more info on the successful fire test in Germany.

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Please also see the video clip below which documents fire tests on a straw bale wall  in July 2006 in the USA which were also successful.

http://youtu.be/yb1WSh9UdiA

As per using hay…..strictly speaking one is not supposed to use hay ….because hay tends to biodegrade more easily. Generally hay is the more grassy part of the grain. Thus is not just silica and cellulose like straw but would contain more nutritious elements that will be more attractive to insects and fungal attack. Strictly speaking all the literature advises against using hay and recommends that one uses straw.

Fire Safety

• Contrary to what one might think, straw bale structures have proven to be exceptionally resistant to fire. As straw bales are firmly compacted, they do not hold enough oxygen to facilitate combustion. Straw bales exposed to fire will smoulder and char, but will not burn.

• Extensive fire tests have been conducted on straw bale structures by the National Research Council of Canada and by the State of New Mexico, and codes approving the use thereof are now in place.

• "The results of these tests have proven that a straw bale in-fill wall assembly is a far greater fire-resistant assembly than a wood frame wall assembly using the same finishes."  (BAINBRIDGE & STEEN, 1994)

• Fire retardants such as Boron may be used in high-risk areas, and as a further deterrent for termites and pests.

Termites and Pests

• Experience in both old and new homes has shown concerns relating to rodents and insects to be unfounded. Straw bales have fewer spaces for insects than conventional wooden structures, and a well-applied and maintained coat of plaster denies access to even the smallest pests.  Furthermore straw is a dead material of no nutritional value, and thus insects are not attracted to it. An added precaution would be to treat the bales with a boron solution, which acts as an insect repellent (in most cases unnecessary). In termite prone areas it is recommended that a solid foundation and termite shield – such as a galvanized metal flashing – be used.

Allergies and Odours

• Clean, bright straw has very little mould or allergy potential.  Hay fever is aggravated by the presence of pollen, which is mainly found in hay and not in straw. Asthmatics could still have problems with mouldy straw, however once sealed in with plaster there is no problem.

Humidity and Moisture

• Damage by water is by far the greatest potential hazard to a bale structure, and buildings should be detailed to provide the necessary protection. Problems arising from water damage range from complete disintegration of the bales to problems with mold and mildew. During construction the bales must be kept as dry as possible at all times. Wall building should preferably be done in the dry season and the roof structure should go on as quickly as possible. If there are delays, the bales should be protected with tarps. The most vulnerable parts of a straw bale wall are the tops and the bottom, which must be protected with an adequate moisture barrier. The bale walls should be raised above ground level on a masonry plinth. The sides of bale walls are less problematic and buildings left unplastered and subjected to rain and snow have shown virtually no signs of deterioration. The problem arises when moisture becomes trapped within the walls.  For this reason, it is important to allow the bales to yellow or season before plastering is begun. Likewise time should be allowed for the plastering to cure properly before any finish coatings are applied. The idea of a breathing wall, which allows for walls to dry out, will avoid this potential problem.

One can use various types of straw, including, but not limited to, wheat, rice, rye, barley, oats and similar plants, shall be acceptable if they meet the minimum requirements for density, shape, moisture content, and ties.
Bales used shall be rectangular in shape. Bales used within a continuous wall shall be of consistent height and width to ensure an even distribution of loads within a wall system. Bales used should be baled as densely as possible. 
Bales shall be bound with ties of either polypropylene string/strapping or baling wire.  Bales with broken or loose ties shall not be used unless the broken or loose ties are replaced with ties, which restore the original degree of compaction of the bale.
Moisture content of bales, at time of installation, shall not exceed 20 % of the total weight of the bale.

We advise against using hay bales for construction. Also see "Can I also use hay bales and not straw bales?"

Bale dipping is a recent technique developed by Tom Rijven in France and which Eco Design Architects first experimented with in 2004 and have been using ever since. It involves the dipping of  the bales in a clay slip which consists predominantly of clay and sand. It is highly recommended, as it helps solve some of the issues traditionally experienced with straw bale construction. The most significant advantage is all the time it saves in the pre plastering of the walls, a process that normally takes considerable effort. The walls are also immediately better protected against any risk from fire and moisture during construction. Furthermore these straw bale walls are of a much more solid and stable nature. One is able to get the base coat to penetrate a good 70mm or so into the surface of the bale with a minimum of effort.

For more detailed and technical information regarding this process, please refer to our construction  and info manuals. Click here for the manuals.

With finishes, it is critical that the straw walls / earthen walls should breathe. It has been found that walls can get wet provided they are able to dry out again. As such cement plasters are to be avoided, as they tend to trap moisture within the walls, which ultimately leads to the destruction of the wall. A traditional lime sand plaster is therefore used, either onto an initial coating of mud plaster or straight onto the straw. Clay sand lime plasters and lime sand dung plasters can also be used. Earthen plasters alone can also be used, provided lots of finely chopped/shredded straw or cellulose fibre (soaked shredded newspaper) is added to the mix and that weather walls are sufficiently protected with good roof overhangs or verandas. In all cases it is advised to protect the plaster with a good breathable paint.

Also see "With what can I plaster my walls?"

The simplicity of construction and owner-builder friendliness is such that anybody, including woman and children can be involved in the construction process. Bale buildings lend themselves to self-help, community-driven building processes where jobs are created locally and building processes are wholly inclusive of the building’s owners. As well as requiring only simple and inexpensive tools, construction techniques are uncomplicated and easily learnt. The basic skills can easily be taught to an unskilled person in a day workshop.

Bale walls can be built incredibly fast when the process has been well streamlined. The walls of a 150 sq. m-sized house can typically be built in just two days. The time needed to plaster will depend on the quality, type of finish and application method applied.  With hand applied earthen plasters taking much longer, being more labour intensive, and machine applied gunite plaster or using the bale pre-dipping method, the plastering can be done exceedingly quickly.

You obviously still need to count in the time used to build the foundations and roof structure, which could be similar to a conventional building.

Bale walls can be built incredibly fast when the process has been well streamlined. The walls of a 150 sq. m-sized house can typically be built in just two days. The time needed to plaster will depend on the quality, type of finish and application method applied.  With hand applied earthen plasters taking much longer, being more labour intensive, and machine applied gunite plaster or using the bale pre-dipping method, the plastering can be done exceedingly quickly.

You obviously still need to count in the time used to build the foundations and roof structure, which could be similar to a conventional building.

Annually Renewable Resource

• Like wood, straw is produced by photosynthesis, a natural process, fuelled by solar energy. Unlike timber, straw is annually renewable.

• Reduced Environmental Impact: Straw is essentially a waste product.

• Being a non-nutritious, by-product of cereal grain farming, straw is often left rotting in fields and in many parts of the world or simply burnt - including South Africa – causing excessive pollution. On site, no waste is generated and all left-over straw can be either composted or makes excellent mulch for the soil.

Energy Efficiency

• Plastered straw bale construction creates long lasting, super-insulated buildings offering superb thermal comfort. A standard plastered concrete block wall will insulate at R1,5 compared to straw bale walls which insulate at a phenomenal R8 to R9, depending upon their thickness. The savings this makes possible is not to be underestimated.

• The capital costs normally needed for heating and cooling, along with their associated pollution and environmental costs of energy production will be drastically reduced. This factor could be of particular significance in low-income scenarios where much income is spent to keep the cold winter nights at bay, often resulting in appalling pollution and ill health.

• The health aspect of improved thermal comfort also contributes to capital savings as well as improved well-being and productivity.

• The embodied energy spent in building with straw bales is relatively small when compared to the high pollution costs associated with burnt brick or cement production, especially when considering that straw is for the most part a waste product. This makes their contribution to the increase of C02 and global warming associated with construction, very slight indeed.

     
Sound Absorption

• As with their thermal insulation, straw bale walls offer superb acoustic qualities. Being virtually soundproof straw bale walls are ideal for noisy high-density environments.

     
High Seismic Resistance

• Conventional Buildings are extremely hazardous in earthquakes and costly to reinforce. In contrast buildings of straw have a good width to height ratio and are adequately reinforced. The very nature of a bale, their flexibility and strength are ideal for seismic design provided the connections between the walls, roof, and foundations are adequate. A bale wall actually absorbs much of the shock of an earthquake, instead of transferring it to the roof as in conventionally built structures.

     
Self Build, Job Creation, Ease and Speed of Construction

• The simplicity of construction and owner-builder friendliness is such that anybody, including woman and children can be involved in the construction process. Bale buildings lend themselves to self-help, community-driven building processes where jobs are created locally, and building processes are wholly inclusive of the building’s owners. As well as requiring only simple and inexpensive tools, construction techniques are uncomplicated and easily learnt. The basic skills can easily be taught to an unskilled person in a day workshop. Bale walls can be built incredibly fast when the process has been well streamlined. The walls of a 150 sq.m-sized house can typically be built in just two days. The plastering time depends, with earthen plasters being more labour intensive, taking longer, while a gunite plaster is done by machine and can be done exceedingly quickly.

     
Affordability and Local Economic Empowerment

• The financial benefits of building with bales are both immediate as well as long term. Bales themselves are extremely cheap and the ease and speed of construction makes for relatively low building costs. The construction process is ideal for community building. With the higher proportion of costs being in human labour, less money is spent on transportation and factory made goods leaving more money to circulate locally. Furthermore significant savings are possible especially where the owner becomes an active participant in the process. With bale walls offering superior thermal performance, major long-term savings are assured with reduced heating and cooling costs.

Not at all, it was first initiated in North America at the turn of the century. The oldest documented bale building was a one-roomed school building in Nebraska, built in 1886. Straw bale construction is presently experiencing a major revival in today's housing market. It is worth pointing out that many of our countries oldest buildings especially in the Cape which suffers from wind driven rains are in fact made of mud brick - most of the old city centre of Cape Town, and its suburbs - Woodstock, Salt river, Observatory, Wynberg etc. They were always built off the ground with a good stone or fired brick foundation and protected with breathable lime based plasters and paints.