Written by William Quinn
|Tuesday, 10 May 2011|
BENEFITS FOR YOU AND THE ENVIRONMENT: When done properly, your passive solar home can reduce an enormous amount of strain on the environment. You do not need to purchase or create new materials, cut down trees, or drain public utilities such as water or electric. You will be recycling old materials, designing an eco-conscious structure, and feel more at one with Mother Earth. This design has great insulating qualities, so it works well in warm and cool environments. It works based off the concept of “thermal mass,” where the massive structure gradually absorbs heat during the day and gradually gives off heat during the night, maintaining thermal equilibrium and resisting overall internal temperature changes.2
Time: This takes a good amount of time. Depending on how dedicated you are, what sorts of previous construction experience you have, and how many people you have working with you, this could take anywhere from several weeks to several months (or years if you want this to be a long-term hobby).
Costs: These are variable, but when compared to a “normal” home, your passive solar home will typically be much cheaper. The largest cost is undoubtedly labor, but you might live here for the rest of your life—wouldn’t it be fun to have some say in how it looks and functions?! Let’s get started ☺
Step 1: Logistics
Head to your County’s Building Department and look into what permits you will need to build your tire-house. You will often need to perform soil tests, receive a septic permit, and turn in all of your building plans to the county office so they can sign off on the construction. You will almost always need a registered Professional Engineer or Architect to “evaluate and approve the structural aspects and foundation design of the house.”3 Once you have received your building permit it is time to get to work!
Step 2: The Structure
You want to pick a relatively level location that has good sky visibility, especially towards the south, as this will be important for direct sunlight to heat your house. One you have a rough sense for the shape of your house, you should clear away rocks and debris to make a level and solid surface upon which you can begin to construct your external supporting walls. Make sure to keep any dirt you move in the process nearby because you are going to need it to fill in your tires. When you draw out the general footprint of your house, keep in mind that your house will be quite thick and dense from the tires stacked on top of one another and internal walls needed for further insulation.
Now you just need your tires! You can often go to local tire dealers and find used tires that they are willing to part with for free or a small fee. The idea is to spend as little as possible, and reuse as many resources as you can. The challenge is going to be moving the tires. I would recommend renting a large truck/U-haul for the day to move all of your tires. For a mid-sized house, you will need more than 1,000 tires, so keep this in mind when doing your planning and scouting for sources. You will not be able to move the supporting tire walls once they are constructed (each filled tire can weigh 300 lbs), so make certain that your plans and measurements are accurate before construction begins.5 You also want to make certain to leave your south facing wall tire-free. This allows you to install large glass windows which provide passive solar heating throughout the year.
Step 3: Building the Walls
This is where the work comes in. This style of house was first popularized in Michael Reynolds’ books Earthship, Vol. I, II, & III, and Reynolds recommends filling the tires with dirt to establish your structural walls. This technique is quite burdensome, and some people have turned to other methods for tire construction, but we will address those later. You should ensure that all of your tires are the same size, because if there are discrepancies you will need to fill the gaps later, and this won’t be very fun.
1) Place cardboard under each tire so soil does not spill out and you can pack the tire effectively.
2) From here on out it is essentially fill and pound. You want the dirt nearby so you can add it easily. Each tire will consume around three wheelbarrows full of dirt. Once a tire is seemingly full, start pounding the dirt with a sledge hammer and add more dirt as room becomes available. Make sure that all parts of the tire are pounded evenly. When all spots seem hard and the tire is bulging, you are done. Earthship says this process will take 5-20 minutes, but many people report it taking at least 20 minutes.6 Once pounded, make sure the tire is as level as possible, and not tilting in or out.
3) Once you move on to the second layer of tires, ensure that they are staggered from the first set, i.e. they are not directly on top of one another, and repeat the dirt-packing process described in step #2 above.
4) The height of these tire walls is the same as the height of your house, so you can end at your discretion. You may need to use ladders or other structures to help you pack up the higher levels of tires.
Note: You can also use equipment to pound the tires. There are several mechanized tools used to pound tires, such as modified jack hammers, an air compressor, and a pneumatic "pogo-stick" with a special 4" in diameter, spherically radial head.8 These work similarly to a sledge hammer and require a constant addition of soil while in use, so you will need at least a two person team.
Step 4: Internal Structure
The external structure is the most vital part of your home, so once you have this nailed down you have more choices in how you construct the rest of your home. Some people choose to create walls, either laid in concrete, or even from tin cans laid in concrete or stacked vertically.9 This is a sustainable way to add further insulation and separation from the tires to your home. These walls are not load bearing, and are used to make doorframes, or add interior sectioning to your home. They can be added to both the inside and outside of the structure and are covered in concrete, stucco, or adobe to further improve insulation and hold everything together.
I recommend hiring an electrician and a contractor to deal with wiring and plumbing if you do not have experience as either one. This may seem expensive, but having these systems installed properly is critical. You also need to decide what style roof you want. Again, I would recommend spending more money now to ensure the protection and longevity of your structure. The roof needs a tight seal against the structure to make sure no water can get in—this should probably be professionally installed.
Now is also a great time to consider adding sky lights to your roof for additional passive solar energy, and considering wind and/or solar power for your roof. “It is often less expensive to purchase a complete stand-alone photo-voltaic or wind-powered system than the cost of the hook-up to the unreliable grid, to say nothing for the cost of the power you could save over the term of your occupancy.”11 For these obvious reasons, invest in solar and wind power to make your home self sufficient.
You should also do research into water catchment systems, and grey water systems, though you may have to leave these out of the initial plans in most counties. Floors are also your choice (concrete, slate, brick, etc.), but I recommend against wall-to-wall carpeting as this will “insulate your thermal mass from the ambient temperature of the house” and reduce its functionality in that way.12 But from this point, the possibilities are endless—this is your project, make it your own and embrace the tedious, but incredibly rewarding, process of constructing a home.
Alternative to Tire Stacking
If you are turned off by the idea of pounding tires full of sand and dirt there is another option that people are beginning to embrace—tire bales! This is essentially a brick of 100 tires, 2.5 feet by 5 feet by 4.5 feet, weighing about 2,000 pounds (a literal ton). They are made from a large hydraulic press, often at landfills, and reduce the space that tires take up.14 After being pressed “the bale is now the density of packed earth, weighing in at roughly 90 pounds per cubic foot and containing only 5% air.”15 You will need a forklift or backhoe to move the bales, but the reduced labor costs may be worth it. You then stack these bales, often three high, resulting in a wall that is 7.5 feet tall and 5 feet thick.16 This makes an incredibly solid structure and provides ideal thermal mass. For a great step-by-step story of a couple who made their home from tire bales check out this website: www.hagartirebales.com.
If you are interested in some less extreme ideas for living “off the grid,” read here: Sustainable Living.html!
Only registered users can write comments.
|Last Updated ( Tuesday, 10 May 2011 )|