We tasked ourselves to find a straw bale house and were happy to trace one here in Nairobi and we have posted the pictures here.
From the last discussion; The hard questions involved
- What exactly is straw?
- Termites & pests
- Fire resistance
- Straw as food and not construction material.
- How ‘eco’ it is.
What exactly is straw?
Straw is the dry stalks of cereal plants, after the grain and chaff have been removed. It is usually gathered and stored in a boxy thingy that we are calling a bale, which is a bundle of straw tightly bound with rope or wire. In principle, it is really an agricultural by-product.
Termites & Pests.
Straw bale walls are thick and dense enough to keep out many kinds of pests. The outer layer of plaster makes them unattractive or impenetrable to animals and insects. Finally, because straw contains little nutrient value to most animals and insects, it is not ‘hot cake’. Termites like moist damp conditions. There is little danger termites would have any interest since straw is also quite hollow and lacks the starch to attract these insects. When termites do manage to enter a wall, they tend to bypass the straw and attack any wooden poles/studs.
Although loose straw is quite flammable, once packed into a bale it is too dense to allow enough air for combustion. Take a real-life example, it is easy to light a single piece of paper on fire, but difficult and time-consuming to burn say a rim of photocopy paper. In straw bale construction, it is critical to have, at a minimum, a coat of plaster on all surfaces of the wall. Any hungry cows will also not be tempted to dig their muzzles into cement in an attempt to reach the not-so-nutritious straw.
Straw as food and not construction material.
Straw in practice is fed as part of the roughage component of the diet to bovines. It has a low digestible energy and nutrient content (as opposed to hay, which is much more nutritious). Due to the risk of bowel obstruction and its poor nutrient profile, straw is generally used as restricted to part of a cow’s diet. So straw bale construction can save your bovines from constipation. Major advantage right there.
How ‘eco’ it is.
This word ‘eco’ is like the word ‘love’; everyone has their own perception of what eco entails, owing to their personal beliefs, interests and principles. Eco is about carbon footprint and how fast the energy used and, materials used can be renewed. Straw has a negative carbon footprint because in its production, it ‘eats’ carbon as opposed to emitting it. Grass embodied energy is entirely from solar energy which is very ‘Eco’. It is also fairly renewable as it takes a few months to grow as compared to say sedimentary rocks that took millions of years to form. But with major global polluters pulling out of the ‘Paris climate accord 2017’ because ‘global warming is a lie’, you can tell that ‘Eco’ can get controversial. But to us, straw bale construction is ‘eco’.