Cob building

[aramis720]

Has anyone tried cob building on the Big Island? If not, does anyone know if there are reasons why it woudn't work? I know it would be very hard to permit but my question here is about the technical issues, not the policy issues. Mahalo!

[Rob Tucker]

Cob is fine when you have locally available materials. Don't expect to find straw or clay or earth in Puna readily.

[MarkP]

My feelings exactly. Many alternative construction methods owe their desirability to the way they make use of readily available materials. Without trees for a log cabin or clay for adobe you might as well go to Home Depot.

[csgray]

The earthbag houses using cinders are the only alternative buildings I've seen making good use of the readily available local material from our volcanic activity. But most the designs I've seen for them are better suited to a desert climate than our semi rainforest climate, although people are starting to use them in the wet tropics with large overhangs for the roofs. The one someone built in Nanawale used Khalili's beehive design for desert climates, but they did get it permitted.

http://www.earthbagbuilding.com/projects...elters.htm

Carol

[kalakoa]

Ironically, the "superior" alternatives (Castleblock, et al) fail the "readily available locally" test.

[aramis720]

Thanks for the feedback. So is the bottomline that if you can find sufficient dirt and clay, plus straw, then there's no reason cob building couldn't work on the island? Does clay simply not occur naturally on the Big Island?

[Rob Tucker]

Kalakoa, I will say that, in response to your readily availability test, that it takes longer to get a permit than it does to deliver ordered materials. And that since our products are precut to the design there is little or no waste. Waste costs money.

aramis720, Can't say how well cob would work in an area with heavy rainfall. Unfired clay would be subject to damp in my opinion. Clay really isn't found in Puna. There may be clays of some type elsewhere but than immediately means finding it, buying it, loading it and trucking it. Each act costs money. I would guess that cob evolved somewhere where the ingredients were on site and likely a drier climate.

[kalakoa]

Rob, I'll split the red herring with you.

I really do want to build something "less wood". At the risk of derailing this thread (and this is probably already covered elsewhere if I dig far enough), what's the lead time (expressed as gregorian calendar days rather than imaginary County process-equivalent time) for a Castleblock/SIP/etc-style structure?

Something simple, say a 20x20 "shack", for a permit-exempt agricultural use.

[Rob Tucker]

My general lead time is six to eight weeks. I'm not trying to sell you anything. If for example you wanted to go with steel frame and cement panel siding you can get a schedule of precut metal framing in about two weeks from Honolulu. Anything that is not wood is an improvement.

[csgray]

FYI: Cob is used successfully in the coast range of Oregon with 4 foot roof overhangs. It was a traditional building material in rainy olde England for thousands of years with thatched roofs 3 feet thick with big roof overhangs.

"New" volcanic materials like those that form the Big Island are a long way from becoming clay, so no we do not have naturally occurring clay here. This is an archipelago of volcanically formed islands in the middle of the Pacific Ocean, there are a lot of geologic materials common on continents that just don't occur on volcanic islands.

After posting about the "earth bag" houses I looked online again; there is tropics specific research on that building material that has been published, easy to find but I don't have time right now to go back and find the links. There were more straight walled traditionally designed buildings shown than when I had last looked several years ago. The beauty of this building material is the crew doesn't have to be highly skilled, you can literally have a wall raising party and get the walls up in a day using cinders as your bag filling material, then another day for the same crew to plaster the walls with concrete over wire lathe and you are ready to put your roof on. After looking at the devastation in the Philippines and something with 18" walls looks pretty good.

Carol