Using Natural Vernacular Materials

Q: I am in the process of designing a small traditional Japanese house for myself. I am trying to use as many natural materials as possible. I believe one of the traditional methods was the use of clay in the exterior walls and finish. I would like to stay away from treated plywood if I can. Could you offer some suggestions?

A: I am no expert on traditional Japanese architecture and there is many books on this topic for example 'Minka', but they are buildings which are usually post and beam construction with the finest timber joinery and detailing (no nails), often using beautiful stone for foundations. The infill between the post and beam structure (leaving the timber structure exposed) is usually something like the british wattle and daub. Woven branches or bamboo or fine pieces of timber are covered with earthen mix which contains straw, then earth plastered and very often covered with a very smooth thin lime render externally and left as an earthen plaster finish internally. The earthen plasters are made very fine and smooth.

The wall of such a house is usually quite thin, the internal partitions are made of wood and paper, therefore the house can be very cold in the winter months. If you are building in a colder climate my advise would be to have thicker walls.....The roof of the house was often made of incredibly thick thatch.The plan of the house is usually designed in a 'tatami' (japanese bed) module, so the layout of partitions is flexible and can be changed if necessary.

Q: With rains now 'almost happening' in the rain shadow cold desert areas of Lahoul and Spiti in the Indian State of Himachal Pradesh, how in your opinion should the predominantly mud structures be protected or conserved, Pualina?

A: They need large footings/foundations, to be high off the ground using earthbags, or stone etc... so they are not affected by splash water and puddles, and they also need a substantial roof overhang to protect the walls, or porches to be incorporated into design.

Q: Does your organisation have any publications or information relating to the properties of anthill/termites soil and its use in construction. An Australian Aboriginal community in Nookanbah would like to construct a basketball court for their school using this material and have approached us for advice.

A: I just know that this type of soil has enough binder in it to form earth blocks, but have never tried it myself. Certainly will be good bag filling material. Also good for plastering, but I would suggest experimenting with it is the best way of finding out.

Q: Have you heard about any earth bag project implemented in Poalnd ? I have some doubts if our climate is suitable for this kind of system. Othervise I would build.

A: I haven't heard of any project that has happened in Poland with Earthbags, but this summer we will be building an Earthbag dome and a small straw bale house if you want to join in.

Q: I am building a house in Iowa by the strict requirements and dimensionality of Sthapatya-ved. As you probably know, these dimensions are specific to certain harmonic structures generated by the architectural style and my astologic chart. The outer walls will be approximately 10.5 inches thick. I would like to use some sort of straw/clay mixture, but I also live in a very cold climate. It is not unusual to have -10 degree temperatures for several weeks on end. I have friends who built with rammed earth and their environment is miserable during winter, always fighting the fly-wheeling of energy in the earth structure. Can you shed any light on the true insulation value of a straw clay mixture in this climate.

A: Clay for building has simillar insulation property to rammed earth as it is the same material just applied in a different way. As you have mentioned it really performs best where thermal mass is needed. Straw bales have insulation value twice that of the building regulations reguirement. When you mix the two together, depending on what proportions you mix you get somewhere in between the two. The best straw clay walls for this type of climate are ones where you mix as much straw with the clay as possible, to obtain as high an insulation value as possible, then apply thick internal earthen plaster and south-facing windows for the earthen plaster to act as thermal mass inside.

Q: I have really enjoyed your book "Building with Earth." I have a few questions about your commentary on the Cal-Earth 3 vault home. My son and I would like to build a small earthbag structure and we were thinking that a single vault might be the way to go. The demensions would be something like 10' X 10' or 10' X 15'. In your book you question the need to use the rigid foam insulation, the metal support structure and other purchased resource intensive material used in the Cal-Earth vault home but you never gave specific ideas on how to build a roof that you could plaster on the inside rather than using rigid insulation and an alternative to the metal support structure. Do you have any ideas on how we could build a single vault and use lower embodied energy products?

A: If you look on page 25 of my book it shows a small sketch of a vault built in Mexico on the Steen's project. It uses the bamboo-like reed (about 3 layers) to form the shape of the vault, then straw-clay for insulation (about 12") then lime to cap it. I think this is a very good method for Mexico type climate.

Q: As an architect, how do you blend contemplory materials used in construction with the natural?

A: When I design I always first take note of the natural resources that are available close to the land that I will be building on, and try to use them in my design as much as possible, trying to minimize the use of the contemporary materials. I only use contemporary materials where absolutely necessary, usually for very practical functional reasons.

Q: I have recently bought a 1 acre site on Clare Island, county Mayo, Ireland. The climate is windy, wet and warm in an Irish way in the summer. I would like to source as many of the materials locally, and it is mostly bog land, sheep farming and some arable.Temperatures should never go too far below zero in winter.

A: (Kelly) I suggest that you investigate what long-term vernacular building has been done in that region. Often the old-timers know best how to build. Since I am not familiar with the area, it is hard for me to know.

Q: I have used rough unpolished Kotah Stone flooring in my house. I want to know how to protect it from dust/grime accumulation. Currently there is no coating on the surface. Do I need to coat it with some stone protection clear coating?

A: There are clear polyurethane coatings  which nearly doubles the life of the stone, and other vinyls etc.. but if you want to go the eco-way you need to look into waxes and oils that are available in India.

Q: My husband and I are intending to build a home in the Gambia, basically a large round house with a circular courtyard. We intend to use the traditional mud bricks and also utilize solar energy, and seem to be unclear if the corrugated metal roofing sheets are a good roofing solution below the grass roof in order to keep the water out during the rainy season, as many locals do? We are also unclear if a metal construction is better than a wooden one...personally I like the look of wood much better, but it hurts to see how many trees get chopped down and how there seems to be even war over forests and wood...metal is locally easily available, but I cannot find many examples of eco housing using metals... except for the steel -spanish tile, which looks far too European for the location, any advice and suggestions?

A: (Kelly) I agree with you that the wood looks better but the effects of over harvesting wood is a major problem world-wide. At least much of the steel that is in use today has been recycled. If the roofing is covered with grass above it, this will not only hide it from the exterior view, but will also insulate it to some extent from the hot sun. You might also consider lining the interior with grass mats, and even insulating the underside with bags of grass or straw, such as is shown at http://earthbagbuilding.com/articles/ceilings.htm  .

Q: Quite a lot of attention has been focused on traditional building materials as a way of creating a climate-responsive design in Africa. This research is limited to the query of flexibility, sustainability of traditional building materials and products and systems in local, rural residential buildings in tropical Africa. What I'm trying to propose is a traditional/conventional system for Africa, whilst preserving our cultural significance and esteem, at the same time, withstanding the harsh climates of Africa. No one seems to be querying the sustainability of these materials. We claim because of the large expanse of land, grand structures, several-story structures aren't part of our culture and are termed by many African green proponents as "Undesirable"...but I think if these materials have been used for some grand structures, we would have been celebrating African Architecture beyond this level. What if we are hit with a 7.5 earethquake or severe flood? You wouldn't want to be in those traditional houses built with traditional materials and products...would ya? This research is not intended to puncture Taditional Systems, but to improve on it. I love our traditional styles, but lets make it durable, sustainable, resilient.

A: (Kelly) I agree that it can be a delicate balance to find the right response to the addressing issues related to housing people appropriately, considering cultural and traditional values, while also finding ways to improve the durability and resilience under extreme climate conditions. One approach that you might investigate that has the potential to address both of these concerns is earthbag building. I have a website, www.earthbagbuilding.com , that is devoted to this way of building. If you take a look are the vast range of building types and styles, as well as the potential durability, economy and sustainability of this method you may see something that could work in your area.