Hi - a few pointers based on many years living in Kenya including building our own cob cottages in Laikipia, and owning a makuti roofed house at the coast for many years.
- When made by local experts, makuti roofs last 20 years, not 5. They are by FAR the best option and the most beautiful. Ours was built separately from the house, ie the roof stood alone on its structure, and the house ws built underneath it like a box (with ceoling boards in the bedrooms to allow for fans, net etc.) The only thing that sometimes lives in makuti are bats, which you can deter (their droppings stink) by stringing close-together fishing line or string across the whole width of it. Grass roofing attracts all kinds of insects, snakes, scorpions and other dudus you don't really want to be living in close proximity with (it sounds exciting to begin with but very quickly gets old/dangerous).
- Termites are a disaster for straw bales, wood, cob and any other natural material in direct contact with the soil that isn't properly treated (and even when it is treated, they still get through); the house needs to be built on a slab of rock/hardcore (concrete, preferably) or at least have the first 3 feet of every wall and the floor made of this, to give you a fighting chance against them. The local huts are not made with cob as we know it; they are made with sun-dried earth bricks that don't have straw in them, usually. The only wood termites don't eat is cedar.
- Make sure you factor adequate security measures into your design, such as metal grills on all windows and doors (doors must be metal or wood with a metal inner). Don't mess with security in Kenya. People right now are struggling to survive with the hike in taxes, cost of basic goods and lack of jobs, especially in the coastal region, and good people to do bad things out of desperation.
Good luck!
