A roof is one of the most key aspects of a building. If you were to think of a building as roughly composed of three components: the floor, the walls, and the roof, you'd generally find the roof to be the most costly and difficult to make.
Any decent roof must withstand the following for 20 years, minimum, while still remaining water/wind tight:
- full sun, including both high temperatures and UV rays
- high wind gusts
- rain - must be water tight
- be "wind tight" or otherwise control airflow
- heavy snow loads, at least a foot or two
- ice, hail
- freeze/thaw cycling
- strong enough to walk on
- resist mold/moss
- either insulate the building or protect insulation under it
- generally provide structural support for the walls and be able to span a significant distance
Roofs are a challenge. They've been made of copper, lead, slate, stone slabs and domes, cedar, concrete, and more. They're also one of the most basic elements of shelter, and a requirement when building one.
There are two parts to a roof - the support, and the outer layer. While the support does have heavy structural requirements, lumber generally does quite a good job. Other alternatives are steel beams and trusses, wood/steel/concrete columns, and steel cabling, among others. The outer layer is generally the more difficult part because it needs to satisfy the requirements listed above, over a large area for a long period of time.
Currently the GVCS seems to be lacking provisions for a roofing system. The reality is, we need not only one but a number of them - different geographical locations have both different materials available and different requirements.
Sign your name by putting four tildas (~) in a row in the brainstorming area.
Wooden shingle maker
Machine to make wooden shingles? Jason 22:14, 28 May 2011 (PDT)
Concrete shingle maker
Concrete shingles are great in terms of durability. However, they do require a stronger support structure. I think all that's really needed is a mold, vibration mechanism, and perhaps a press to make the shingles. They need to be able to stay together physically until the concrete cures, because it isn't feasible to have a large number of molds. Obviously concrete mixer would be nice. Jason 22:17, 28 May 2011 (PDT)
Cast concrete tiles.
There are relatively small companies making these in Asia. The tile is cast in an mould made of cheap injection moulded plastic and is painted in the factory with weather resistant paints.
Asians make relativity heavy roofs with timber frames made of short pieces of timber that are interlocked loosely but not pinned or nailed. These move in earthquakes to dissipate the forces in the quake rather than not moving and eventually failing. The tiles on the gable ends and corners are heavier. This resists wind driven lifting forces in gales and Typhoons [hurricanes]. The typical Chinese convex roof also resists typhoon winds by converting the aerodynamic forces from lifting into forces pushing down.
Where high winds and earth quakes are a potential problem, adopting these designs for the roof should help.
The moulds can be made from cast concrete with two layers of plastic seating separating the mould from the casting. Cheep plastic moulds can be made from scrap plastic by chipping and pressing while heating. Several hundred would be made to support a suitable tile production run. Once the moulds are made they can be reused repeatedly. The Storage of unused moulds may require a sizeable shed. [My spell checker is having a fit over the differences in how we spell mold/mould. lol.] Wesley bruce 16:42, 4 January 2012 (CET)
Metal lath for laminated ferrocement
Thread about metal lath making machine to make cheap laminated ferrocement thin skin structures . Jason 22:14, 28 May 2011 (PDT)
Fibre reinforced cement corrugated sheet.
E.F. Schumacher the inspired Intermediate Technology Materials Workshop (I.P.M. parry and associates) to develop the corrugated sheet maker that is now used in the third world and China. This technology used 1 bag of cement and 1kg of fibre to make 5 1m x 0.75 m corrugated sheets. Fibres were sisal, coconut coir, jute, banana fibre. Production rate was 25 to 30 sheets a day with 4 men. Very labour intensive. Shredded plastic waste has been used more recently. Should work with hemp in temperate zones. It may work with willow switch based fibres and switch-grass. Both need to be tested. There are international standards for most materials now. http://www.cd3wd.com/CD3WD_40/CD3WD/CONSTRUC/SK12SE/EN/B1552_9.HTM
The Chinese have been mass producing these little machines for a few years now (2012).
Full technology links [I own a copy of this book and highly recommend it ]:
Wesley bruce 17:12, 4 January 2012 (CET)
I think the saw mill is pretty good for the support component of the roof. Jason 22:14, 28 May 2011 (PDT)
Metal lath for laminated ferrocement
Metal lath can be used for making ferrocement beams as well. See the metal lath section in the outer layer section above. Jason 22:14, 28 May 2011 (PDT)
With any of these materials it is important to consider where the dew point will be and make sure that moisture doesn't condense on support beams. In most standard construction, there is a water proof membrane which separates the point in the roof where dew condenses and the support beams. Tar paper or rubber are typically used, but these won't be easy to come by with OSE tools. Anybody have any ideas on how to do this? I can't seem to find any roofs that don't have rubber or tar paper, even in green design books! --Zdwiel 18:13, 16 September 2011 (CEST)