A fun and quirky video about using straw bales for building.

Pic by iphilipp

Straw is a left-over consequence of farming and makes up half of the produce of most cereal crops. Straw doesn’t nourish animals like hay does. It is rather used as bedding for animals.

Straw briquettes are also burned as biofuel as a replacement for coal. When harvested, the straw is tightly packed into bales and tied with string. These are the bales that can be used to build well-insulated environmentally-friendly walls.

Straw bales come in various sizes and need to be dry and tightly packed. Damp straw may compromise the integrity of the building and can cause mold. The straw bales are stacked into a frame similar to laying bricks. When the straw bales are laid, they need to be rendered and properly sealed with plaster or stucco.

Straw bale structures are growing in popularity and are attracting interest from all over. A luxury lodge in South Africa was made from 10 000 straw bales and has hosted Nelson Mandela and Tony Blair. In the Swiss Alps is a three story hotel, the Maya Guesthouse, that intends to be the first straw bale hotel in Europe.

Straw bale homes are a natural, eco-friendly alternative to traditional building methods. We are building our straw bale home in the North of Johannesburg and are so excited for the project to get started shortly. We will share all of our adventures as we progress.

For those of you who have built before, I can hear you chuckiling under your breath. Pfah, building a house is supposedly up there with death (and I can totally get why murder is committed in the name of construction). I know, that’s not what is meant – but I have been staying away from sharp and explosive objects just in case.

I have recently been exposed to teachings that sagely advise us that the results of our actions are NOT up to us (translated into layman’s terms it means that we have absolutely bugger-all control over anything). This idiom was forcefully put to the test over the last few months. We had plently meetings and phone-calls with the design team – yet each time it felt as though we took one step forward and about twenty back.  I felt as though I was on the Star Trek Enterprise and was sucked into a worm-hole (at minus 2000 warp-speed) into another dimension where the standard laws of physics and logic just did not apply. So I decided that the only way to deal with the situation was to become a cling-on and not let our design team out of my sight.

The reality is that when one embarks on building a house, the first drawings are so exciting. Finally those bits and pieces that have been floating in your head are projected onto a piece of paper, and we are lulled into a false sense of security that it is “all system’s go”. In the mean time it is but one giant step for me and a infinitesimal step for the architectural team who now have to spend an inordinate amount of time fine-tuning. And that they did, over and over and over and (you get the picture). Every last thing needs to be accounted for – where the plug points go, how thick the tiles are how wide the dado rails are. I have even learned a new language in the process (maybe it is cling-on?). And every single time a minute change was made, it had to be evaluated in order to see what kind of knock-on effect it might have on everything else.

And so many agonising hours were spent on honing every tiny bit so that it all fit snugly together. I suppose this is what seperates the wheat from the chaff (I have to use terms like that now), when comparing your run-of-the-mill architect/builder who is only in it for the profits and who doesn’t give a damn if the plug is behind the door that was accidentally put on backwards because the calculations were a ‘bit’ out.

And finally today, the plans were handed over to two builders who will now pore over them diligently and will come back in two weeks time with a quote, so that we may choose the victor so that building may commence.

So if it sounds like I’m whining – I’m not; I’m merely expressing myself enthusiastically. And I am so very grateful to the team that we have! And even more so now knowing that there is some movement and that we might even get the first proper peg in the ground this month.

Watch this space………

Pic by Ru Temple

Straw bale construction is growing in popularity due to its versatility and the ability to go off-the-grid. Straw bales are also inexpensive and generally available.

The Construction Process

Straw bale buildings are not completely made from straw. Both the foundation and the roof are made with regular materials. Only the walls are built of straw bales that are  placed on top of each other like huge bricks. Other materials, such as bamboo pins or timber are used to join the bales firmly together, and plaster is used over a supporting wire mesh to cover the straw bale framework.

Benefits of Straw Bale Construction

Toughness – Due to the tightly packed straw, the density of a bale gives it the ability to hold heavy loads. It is said that straw bale structures that have been constructed with the latest methods can resist hurricanes and earthquakes.

Energy Efficiency – Straw bales are fantastic insulators. Straw bale walls are over three times as energy-efficient as normal structures. The energy usage can be decreased by 50 to 75 percent.

Durability – Oxygen cannot penetrate the thick insides of straw bales, thus preventing decay and if the bales are kept dry and airtight, they should preserve their structural integrity.

Fire Resistant – Due to the thickness and impenetrability of straw bales, they are extremely resistant to fire. Many straw bale homes have outlasted brick and mortar homes in fires.

Cost and Availability – 200 million tons of waste straw are dumped or burned each year, so it is easily available and affordable.

Pest Resistant – Creatures and insects cannot eat or tunnel their way through straw bales, making straw bale structures safe from pest infestation.

Sound Insulation – Once again, due to their width, density, and physical properties, straw bales have amazing soundproofing characteristics.

Disadvantages of Straw Bale Construction

The danger of straw bales being wet before construction is a disadvantage as they become useless for building if they are wet. The bales cannot dry and will slowly rot from the inside out.

When purchasing, make sure that the straw bales have a consistent, golden look. Bales that are uneven and dotted with dark patches could indicate that the bales are wet, allowing rot or mildew to spread. Green straw bales usually mean that the crops were harvested too early, allowing a higher water content of the plants that are cut. Before buying, use a hand-held moisture meter and if a reading is greater than 14 percent moisture content, then the straw bale is too wet for use in  construction.

The foundation platform that the straw bales will rest on needs to be raised above the ground, and the plaster applied to the bales should be thick enough to prevent moisture infiltration. A roof overhang is also a good idea.

Fortunately, it is quite simple to create a watertight framework that protects the straw bales and keeps them dry. When proper techniques are used, straw bale buildings are durable even in humid conditions.

Watch the progress of a straw bale home going up in South Africa in this video.

Passive solar design aims to create structures that use the natural warmth from the sun in winter and the coolness from the shade and wind in summer.

Basically, the sun’s rays shine through windows, warm the air and are absorbed by the surroundings. Some materials, like brick, stone and plaster, absorb more heat. When the air cools during the night, the absorbed heat discharges and keeps a comfortable temperature.

How Passive Solar Works

There are a number of things to consider to most effectively utilize solar energy:

North-Facing

The first is to have north-facing glass in South Africa. Too much glazing can have a negative effect, making it too hot during the day and too cold at night when the heat escapes. Around 7 to 12 percent of the floor area of a building needs to be exposed to the surroundings.

Thermal Mass

Thermal mass is another factor to consider. Adequate thermal storage mass needs to be in place for a passive solar thermal building to function effectively. Materials that absorb heat should be considered when designing a building. That is where straw bales do so well.

Insulation

Insulation is also an significant factor of passive solar design. The heat from the sun needs to be retained rather than escaping through the walls. Once again, straw bales come to the rescue as they have wonderful insulation properties.

Shading

A well-designed passive solar building needs to be warm in winter and cool in summer. Shading can be used to reduce cooling costs and to prevent overheating. Make sure that the designer let’s you know when is the best time to keep the different rooms shaded for sun angles at your latitude.

Proper planning is important when considering passive solar design, however it can be applicable in all kinds of buildings.

South Africa has some amazing examples of green architecture in the local hotels and spas. They have managed to merge luxury with a minimal impact on the local surroundings.

Both the Woodlands Spa and Forum Homini Hotel, located in the Cradle of Humankind close to Johannesburg are great examples of  using natural materials that fit in with the local environment. Indigenous plants are used in their gardens, and the buildings were created to mirror the natural setting.

KwaZulu-Natal boasts the Karkloof Spa’s subtle effect on it’s habitat. The spa was built from reclaimed bricks and other natural materials. The grey water on site is all recycled. An interesting feature is the living roofs that allow smaller game to graze on.

Even city life has adopted green building with the Absa Capital Building and Nedbank’s Head Offices in Johannesburg being good examples by using solar power, capturing run-off water and using eco friendly materials.

All of this is hopeful for the future of design and construction in South Africa. We are delighted, at Project Starflower, to be playing our part in building our environmentally friendly straw bale home in Johannesburg.

Well, it’s nearly time to begin building on the Starflower Straw Bale Project, but until then, let’s take a look at the insulating properties of straw bale.

Some of the properties of straw are the outstanding thermal and acoustic insulating properties as well as the fact that straw bale houses are resistant to both fire and earthquakes.

Thermal Insulation – Straw bales are an affordable thermal insulation material with walls that are vapor-permeable, in other words, they allow vapor molecules to travel through them.

Heat Insulation – Research at the Vienna University of Technology showed that the heat insulation performance of straw bales had potential for considerable savings of insulation costs in comparison to other types of insulation. It was also found that the smaller straw bales with a lower density continued to meet the technical requirements for a highly heat-insulated straw bale construction. The more precise and compacted the straw bale’s shape, the less heat escapes.

Acoustic Insulation – Straw bales are also an effective source of sound insulation. This characteristic is an important factor in a home. Research has shown that straw bales can barricade sound from being transmitted and that they can absorb sound over a broad range of frequencies. It is advocated that straw bales be used as sound barriers in order to reduce environmental noise from highways and other noise pollution.

Once again the benefits of straw bales are well worth the challenges. Who doesn’t want a home that is cool in summer and warm in winter, with a propensity to keep out bothersome noise?

pic by wharman

Do you know what the difference is between hay bales and straw bales? Most people think that they are the same thing, however there is a difference.

What are Hay Bales?

Hay bales are basically animal fodder used to feed animals such as sheep, goats, cattle and horses when the pastures are lean and food is scarce. Hay is cut while still alive and there is still grain on the plant.

What are Straw Bales?

Straw bales are stalks that have no grains. Once all of the grain is gathered, the stalks are left standing and they die. When they are dead, without any moisture, they are cut, grazed and baled. Straw bales are used for several purposes, including animal bedding, home construction, erosion control and as insulation material. Straw bales are a great eco-friendly natural building material, which is growing in popularity around the world.

A short while ago hardly anyone had heard of straw bale construction and looked at you as if you were crazy when you spoke about building a home with straw bales. Today, browsing through the Internet, straw bale homes seem to be springing up all over the globe. They are growing in popularity and acceptance as a viable form of construction. I even read about a hotel being built with straw bale walls.

Here are a few other interesting projects to look at:

• a home estate in England
• a home in Australia
• a home in Canada

Please follow our Facebook page for regular updates on straw bale construction and green building as we keep finding other projects and posting updates on Project Starflower in Johannesburg..