local sustainable bldg materials and methods?

[Ccat]

I would like to start a discussion on locally available, cheap or free, durable building materials and methods for long term sustainability.  I am talking DIY construction of comfortable, durable, maintainable individual homesteads that will survive and can be maintained on this island for the long haul.

The US/Hawaiian economy is no longer sustainable for doing things the "standard" way.  Hawaiis comfortable climate and ample rainfall are a major plus.  It is ridiculous to build a falling-apart, California style tract house here with everything shipped in and then you have to have totally modify it for the local climate.  (And it will still crumble apart in 30 years.)

I suspect there are alot of us listening.  What is available, what works, doesnt work, how long, how hard, permitting, the whole thing.  I suspect the local authorities might be ultimately amenable to a better method of DIY homesteading.

Dry pack concrete, concrete alternatives, wood, steel, aircrete, lava, etc.  Is it locally sourced, durable, maintainable and sustainable?  What can we manufacture ourselves from locally sourced materials?

What are your ideas?

Ccat

[Rob Tucker]

I have been dealing with this here for thirty years. There have been a small number of attempts in the state to produce locally sourced building materials. I have tried to do this as well. All attempts have failed to date. Part of this is due to the general lack of local raw material. Recycled material technologies hold the most promise but run up against the wood mafia and corruption in general. I still keep my eyes open for potentials.

Best I have been able to do is focus on building materials and systems that offer the lowest maintenance burden and longest lifespan. If one an produce a home that will predictably last 100 years instead of the (HUD) average of 33 years here then one could say you have effective built three homes for the price of one.

My own home has an engineered lifespan of 200-300 years and has a six hour fire rating and is 9x more resistant to earthquakes and hurricanes. I built it myself for about $80 psf. Most people I've met show no interest in anything beyond their own projected lifespan... which is too bad because it is not necessarily more expensive to build better it just takes a willingness to do things differently. We have the technology.

[randomq]

Lava rock doesn't seem to be successful in concrete or as a wall building material, but I wonder if maybe it would be useful for building a berm home, with some kind of local wood with locally sourced preservative for the actual living area. Berm homes might be desirable as we have more extreme winds.

Some local students also demonstrated that albizia wood could be used for building. That stuff grows fast, so that would be kinda sustainable.

We also have miles and miles of lava tubes, layer over layer. Wonder if anyone has seriously tried to partition them and live in them?

[MarkP]

If you are not going to ask for approval then you can try anything you want.. If you ARE asking for building code approval, what Rob says rings true. You are not going to build with local timber and get it approved.

Various types of earth and stone masonry are the most common building materials in developing countries but when an earthquake hits, thousands die. Deaths are at least an order of magnitude less in areas with wood and modern steel reinforced construction. The 2010 quake in Haiti killed 200,000 people, most crushed in the rubble of poorly built masonry buildings (including the palace) but a properly built tele-communications building just down the road survived well. In northern India there is a traditional form of architecture that is a sort of alternating layers of logs and stone rubble and the form of the buildings is tall and skinny towers. Those still standing today have survived hundreds of years in a seismically active region. How? Part of the answer is the massive timbers built in which are no longer available due to deforestation. Also it must be drier there since I have seen ohia logs rot in 5 years if left on the ground in the rain.

Then there's Machu Pichu which is dry stacked stone and has survived hundreds of years in earthquake country.

That's cool and all but the knowledge and skills to do that are gone and the bldg dept wouldn't care anyway. I can't say that I blame them as the average DIY builder in Puna would do just as bad a job here as they do throughout the rest of the developing world.

Personally I favor concrete block with lots of reinforcement and the cores poured solid. That could be code approved. For non-code approved, some kind of pole barn if you can avoid burying the timber poles in the wet ground. The Hawaiians did it somehow. A quick search on the internet shows single story structures with stone foundations and walls that come up only waist high and are thus not likely to fall on the occupants.

[Ccat]

I have been dealing with this here for thirty years.  There have been a small number of attempts in the state to produce locally sourced building materials.  I have tried to do this as well.  All attempts 

My own home has an engineered lifespan of 200-300 years and has a six hour fire rating and is 9x more resistant to earthquakes and hurricanes.  I built it myself for about $80 psf.  Most people I've met show no interest in anything beyond their own projected lifespan... which is too bad because it is not necessarily more expensive to build better it just takes a willingness to do things differently.  We have the technology.

so, please describe your method and materials.

Ccat

[Rob Tucker]

My home's structural walls are made using a product called Rastra which I distributed for a number of years. There are other things I incorporated as well. For example I have long been using a structural fiber cement panel as a substitute of plywood. It is termite proof, water proof and fire proof (and tile ready). Some of my decking is made with a wood substitute that is 100% a composite of recycled material... automobile tires and HDPE plastic. It is as close to indestructible as any material as I have seen. Looks nice and is soft on bare feet.

https://en.wikipedia.org/wiki/Rastra

[punikahakaiferret]

Sorry, I deleted my post instead of just editing it...I started to ramble. Suffice to say I love this thread and will be following it and hope to see real results in this area.

[dobanion]

Well I built a concrete dome. The concrete was 70% by weight of various levels of crushed lava rock out of the side of the hill in Kona, the cement was made on Oahu, and the fly ash came out of the powerplant on Oahu.

I have several concepts I'd like to try next that use larger lava rocks in a stacked wall with mortar and a reinforced backing. Also a type of roof that uses super thin layer of concrete, in a hypar shape (hyperbolic parabaloid). I was considering then covering this roof with natural thatch, either grass based (pili, if I can find enough) or coconut palm (Mexican looking). Yeah the thatch would be very flammable, but the roof under it wouldn't burn.

One of the worst challenges on permitting is insulation requirement. Requiring insulation means you need to build in a hollow cavity somewhere for you to stick the insulation, or use foam board. Speaking from experience, a concrete structure in Hawaii does not need insulation. The thermal mass of it releases so much heat at night that it takes most of the next day for it to start coming through, by which time the sun is going down again.

[Rob Tucker]

The Rastra product I used does not have a thermal mass issue. Also by its design it allows me to build a full strength concrete wall with a 26% volume of concrete. Properly insulated concrete gives it a high fire rating. Reinforced concrete itself will not survive a hot fire. What happens is the wall heats up and the steel rebar expands and contracts at a different rate than the concrete itself. This expansion issue causes the bond between the rebar and concrete to break.

I have found no product better than Rastra to economically build a concrete wall. Unfortunately the manufacturer was horribly mismanaged and while it should have become a major player it did not.

[dobanion]

Not arguing against Rastra, I think it's a good product.

Was it manufactured locally and the company failed?