Hi Chris,
I get the anti-tire sentiment from a couple perspectives.
The whole off-gassing over time argument, where people feel that the tire materials will degrade over time and offgas toxins into their homes, may be valid in some cases. I feel that the risk is overstated in most. If you're burying the packed tires in earth
berms, or finishing them with exterior envelopes, you're shielding them from most of the effects of wear. Ultimately, if you choose to build this way, it is possible to design the structure's airflow such that the interior house pressure is slightly above that of the outside air. This is a technique employed in the past where insulative materials were known to be toxic. The higher interior pressure would ensure that any toxic materials seeping out of the insulation would leak outside the envelope of the house. This technique would also address the issue of radon leakage into the house envelope, an issue sometimes seen with
underground dwellings.
For me, though, the idea of packing the tires is cumbersome and labour-intensive. I would want to cut off the upper tire wall to facilitate mechanical packing, and have a jump-activated tamping plate. It still represents a waste of resources, however, in that tires have other uses, and can ultimately be reprocessed into fuel or raw materials for other things.
I would simply build a rammed-earth dwelling, either using forms in the style of
concrete (insulated forms would be my preference) or compressed earth blocks. I would probably build insulated forms myself to leave in place and make use of all that thermal mass to help steady the temperature of the structure. Either one of these approaches has the advantage of being able to be approached from the standpoint of traditional masonry. In the case of the compressed earth block, you can make a masonry unit of a standard size and test it to determine its physical properties, which you could tweak until it falls well within accepted safety norms. You could then use any number of traditional building methods compatible with your blocks, and anyone assessing the structure for tax or insurance or safety purposes would recognise right away what they were looking at in terms of building materials and use, as it would be a very traditional masonry structure, and not something that requires sifting through a lot of alternative building information to decipher. I would think that this could only help with, for instance, the Ministry of Making You Sad.
As to the form of my insulated form rammed-earth dwelling, my dream is to make a Hall of the Mountain King scale wofati with rammed earth pillars holding up a vaulted cathedral ceiling, all of which would support several tonnes (metric, to be sure) of clean fill, soil, and forest.
I think I would choose rammed earth over compressed earth block for the ease of mechanisation, hydraulic tamper and concrete tools and methods being more readily accessible than custom-built brick presses. And you pour the mixed material in place and tamp it down, put up more form, rinse and repeat, and no lugging around blocks.
-CK
A human being should be able to change a diaper, plan an invasion, butcher a hog, conn a ship, design a building, write a sonnet, balance accounts, build a wall, set a bone, comfort the dying, take orders, give orders, cooperate, act alone, solve equations, analyze a new problem, pitch manure, program a computer, cook a tasty meal, fight efficiently, die gallantly. Specialization is for insects.
-Robert A. Heinlein
