Helpful Hints for Building a Tire House

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HELPFUL HINTS IN

THE TIRE-HOUSE PROCESS

FOR OWNER-BUILDERS

Michael Shealy

Someone interested in sustainability and building a residence with used tires should read the books "Earthship", Vol. l, ll, & lll by Michael Reynolds. These volumes are an excellent reference and include many ingenious methods and designs. Take them all with a grain of salt and use them in your best interest. Keep in mind that this is mostly old technology, and books at the library are available on every subject required to accomplish this task. Anyone interested in these subjects should also read; "Natural Solar Architecture, a Passive Primer" by David Wright, AIA **Excellent recommended reading if you're considering a house of this type**) Be creative. Be open to new ideas. Have fun.

1. The Site. For the most efficient and economical house, the site should face south. Exact facing angle of the solar window wall may vary considerably without effecting the solar effectiveness of the window plane solar gain much. For instance: facing 15 degrees either side of true (not magnetic) South will still produce 98% solar effectiveness; 30 degrees either side of true South will net 90% effectiveness as a solar-gain surface (as seen in "Natural Solar Architecture, a Passive Primer".

The slope may vary from level to 4’ in 12’ or steeper. However, if a good "sun-scape" is available, a successful passive solar tire-house may be built on a north facing plot (2’ in 12’ to the north). Any large deviation of terrain will cost more (maybe much more) money.

For most economical construction, east to west slope should not exceed the height of the end wall at the main east-west beam (roughly 7’ 6").

2. County Requirements. Every county (in Colorado) has their own set of requirements. These are given to owner/builders on request. This packet should contain answers to most of your questions (and mine too). Go to your Regional Building Department office and pick-up a couple (one for me).

3. The Soil Test. In most counties, any house requires a Soils Engineer's sample review, foundation design and report submittal, along with the plans set. This may, or may not be a requirement in your county. Check with the County Building Department to be sure. The soils report is used in calculating and designing a foundation, in this case a tire wall foundation. This report is created from data collected via sample cores from holes drilled around the proposed home site.

If a soil report is not generated, I still suggest at least a few test holes to expose any hidden rock formations.

If you are using a 'bottom course of tires at the sub-floor' plan (recommended), your soils test should provide:

If you are using an "earth-cliff" wall (not recommended unless you have very stable soil), the Soils Report must contain the following values in order for the structural engineer to calculate the house loads and the feasibility (always a tentative construction mode until this is calculation is done) of the "earth-cliff" wall design:

Note: the Soils Engineer may also be utilized to do a percolation test, probably required by your county for your septic system design and function. Talk to your local building official about your specific septic system requirements. See para. 4. below.

4. The Septic Permit. This permit is issued by the State Health Department, and in most counties must accompany the house plans when they are presented to the Regional Building Department for plan check and permit issuance. Talk to the State Health Department and see your County Building Official for any variation from the normal septic system, i.e., composting toilets, greywater treatment systems, etc.

5. The Plan Set. Keep in mind that the plans are not the house. They will, however, provide the information necessary to secure the building permit and give the owner/builder the basic and dimensional information necessary (all computer files will remain available for future evaluation) to construct the house. All required details should be provided. There is a given, however. That is: the builder knows how to build, or contract others to build a house. House plans are not intended to be a "How-to" manual. A set of computer files in the .PDF format (free download-Adobe Acrobat Reader) will be delivered via email. NOTE: .PDF files will be in the 600dpi format, are generic and can be copied by Kinko's or any modern reproduction facility to produce very high quality 22" x 34" prints. NOTE: No computer-aided-design (CAD) files (.DWG) will be supplied under any condition.

Free phone consultations are given to my Plan-Set Clients for the life of their project.

a) What I usually need from you to create these plans: (1) Rough sketch of floor plan with rough dimensions, all structural details will be discussed prior to beginning drawings. (2) Elevations in feet, of natural grade at all corners of the house; including a correct (magnetic or actual) heading. (3) Legal description of property. (4) Plot plan with at least two "set-back" dimensions, if a Plot Plan is required in your Plan-Set by your local Building Authority. (5) Site mailing address and owner name(s) to appear in the Title Block of the drawings. (6) Soil test results, if "earth-cliff" technology is to be used (see above under 'Soils Test'). (7) A copy of the local-to-you house plans requirements enforced by your Building Authority. (8) A check for half the quoted price as a non-refundable retainer. The balance will be due upon the delivery of the plans set. Once I have begun drawing plans, any changes you deem necessary will be billed separately for time-to-complete, at my normal hourly rate. Balance due upon completion. Errors corrected free, but new sheets do take time to generate.

b) After receipt of your set of plans, make two hard copies, and at least one hard copy for yourself to use for working copy(s) and "bid" copy(s). Your Regional Building Department will want one copy for their files (two originally), and they will issue you a corrected, stamped, and approved copy (identical to the one in their files) that must be kept at the building site in case an inspector should want to look at it.

c) At the time of issuance of your building permit ask for an inspection schedule that will relate to tire construction, ie., no footers, no foundation, tire-walls used as exterior walls.

** NOTE: Every change that you make in your house does not have to be reflected in the plan set. All interior walls (NOT INCLUDING tire-walls or load bearing walls or posts) may be moved as desired, without approval. The span of beams must remain as approved. Any structural modification must be re-engineered and re-approved by your Regional Building Department. Simply put, "structural" refers to anything that holds the roof in place.

6. Registered Professional Engineer. In almost any situation requiring permits and/or inspections, a Registered Professional Engineer or Architect must, at some level, evaluate and approve the structural aspects and foundation design of the house. He then normally stamps and signs each sheet of the plans (both sets you will give to Regional Building Department) in approval. The RPE may also write a letter of description with recommendations regarding structure or foundation. This is not required, but is sometimes necessary when he makes changes to the original plan set. By signing and approving your plans within certain parameters set down by the State, the RPE is literally staking his profession (and quite a pile of money) on the building's structural integrity and foundation value. Always, check with your local building authority for their requirements.

7. The Building Permit. The plans will be inspected by the Plans Examiner (or equivalent in your county), and if approved, a building permit will be issued. Many times there will be minor corrections which will be necessary. These corrections must be made to both copies in ink, and may be made by hand. Permits often are only good for a specified length of time. Inquire as to the length of effectivity and renewal fees required. Ask for an inspection schedule at this time. NOTE: As mentioned in para. 5c, tire-houses require a different schedule than conventional houses (no footer, no concrete foundation).

8. The Excavation. The house perimeter should be established and marked, use tires and stakes for this. From these locations the cut lines can be determined (paint lines on the ground). A back-hoe with a front-end bucket is recommended for use in excavations utilizing "earth-cliff" walls, for the "fine" cuts and curves required.

For a "tires-to-the-floor" version, a large front-end loader is the usual choice. Even though more dollars per-hour, the amount of dirt moved per bucket makes up for the difference, and then some. A sighting level is required on the job during excavation, ask your excavation contractor if he will bring one to your job. Be prepared to assist the operator with these sightings. The contractor used for excavation is usually also able to accomplish septic system installation. This may, or may not, be accomplished concurrently with site excavation.

a. Tire sizes should, in my experience, be all one size. The reason for this is that if sizes are varied, as suggested in the "Earthship" books, spacers are required to make up for the variation in sizes. Spacers take time I don't see the value in spending. My preference is 235/75-15R, large passenger car, small truck tires.

b. Lay-out the whole course of tires to establish the optimum lay with the least spacers.

After installing cardboard, and when loading the tire with dirt, use two nine inch long sticks to prop the tire in the "open" position to accept the most dirt with the least effort. Load and kick soil in place. Just prior to pounding remove the sticks. An alternate to this is the "pull stick". This tool is a "T" with a hook at the bottom. With the top of the "T" being the handle. Three feet is a good length for the vertical. With the hook engaged under the bead ring of the tire, pull up on the handle and kick the dirt into the tire.

10. Tire Pounding. Two types of tire pounding now exist: a) Manual. b) Mechanized. Manual would be as described in "Earthship" Vol. l.

Mechanized tire pounding can take several forms: The most readily available is a) the 60# electric jack-hammer with a special 4" in diameter, spherically radial head. This most available of the alternatives, is the least expensive (as little as $500 used & rentable at virtually any rental yard), but somewhat difficult to handle (the weight being around 75# total) and somewhat slower rate/less power. The radial head (the size of half a grapefruit) allows it's use in a continuously vertical position and is simply moved around the wheel opening. This head will have to be fabricated by your local metal fabricator, usually at a reasonable price, however. The grapefruit size and radius of the head will provide sufficient radial "flow" of compacted earth to "inflate" the tire(s) to the required minimum heights. b) The gasoline-engine-powered air-compressor and pneumatic "pogo-stick" with the head as described in "a", only 5-6" in diameter, is the choice of the "pros". The compressor is roughly a $2500 investment (used) to go with this type of machine. Rental is a valid option here. The engine is an automobile sized unit and uses gasoline or diesel, oil, and tune-ups/oil changes accordingly. Using this approach, a tire may be packed in five minutes. The slow "link" in the chain becomes the flow of dirt to pack, a close second to mechanical maintenance of the compressor/pogo-stick. c) A stand-alone gasoline powered tamper could be modified to install a suitable head, as described above. Using any of the mechanical compaction methods, the top "dish" is filled-in and packed by hand with a flat tamper.

I saw a crew of 7 using one b) pogo-stick/compressor and one skid-steer (bobcat), pack 100 tires in ~9 hours. Did a good job, too.

11. Half-tires and Spacers are installed in the tire-wall most readily by

using tires cut into half-tire configuration and screwed to adjacent tires (illustration in work). The half-tires are then packed with local earth to 95% compaction, same as other tires in wall. Half-tires should not be used on the end of a bearing wall. The theory here is that the compacted half-tire may be near the "explosion" point, and when loaded by the structure itself, or snow or wind loads, may go beyond. This would result in cracking at the least.

It is necessary to stub-in all pipes, drains, water mains that pass under tire-walls before any tire pounding takes place. This is usually done with trenching for drains and water runs. Access for plumbing lines may sometimes be achieved by passing between tires in a tire wall. Consult a plumber for plumbing design prior to starting tire-walls. It is better to do too much here than too little. Providing these accesses is inexpensive in the early going and costly, at least, later.

12. Concrete Back-fill and Anchor-bolt Installation. Here, my idea is different from Michael Reynolds'. The concrete should extend under the "lip" of the tire containing the bead around the wheel hole. The side view of the concrete looks like a thick "T". With the upper portion of the "T" containing the bead and the lower portion containing the anchor bolt. This way the concrete couldn’t be lifted out of the tire assembly without taking the whole tire along. Install anchor bolts with 2" of threaded bolt above plate mounting surface. An alternative to using the anchor bolts is 5/8" rebar set in concrete at every other tire, as described above, leaving 4-5" protruding from concrete. The sill plate and bond beam are then installed, and the rebar post is bent over to capture the bond beam.

13. Sill Plate and Bond Beam. Install treated 2" X 12" sill plate and non-treated bond beam, as shown in Vol. l, except at the north wall which is as seen in Plans at North Wall Section View. Installation of log beam blocking spacers and shims is per "Earthship".

14. Roof Framing. Choose one of three types of roof beam that may be used. The hand-hewn un-sawn log beam, the I-joist, or other.

a) The log beam will require "grading" (if your building requires a permit), as specified in the UBC, by a certified official log inspector (check with your local building official). You will roll each log while it is inspected. Failed parts may be cut to save the balance of a log. A letter will be sent to you by the inspecting company, and the logs will be stamped to certify them for use as structural members. Hopefully, the value given by the inspector will be higher than the one used by the structural engineer to evaluate the roof loads. If not, there may be a problem if a sharp-eyed inspector picks-up the discrepancy. (1) Log beams are then top-sheathed with rough-cut 1" X 8" pine boards, a layer of 30# asphalt felt paper, two (2) thicknesses of 4" rigid foam insulation are applied over a 6 mil PVC vapor barrier. Selected roofing material is then applied, as required (specific roofing materials may preclude previous assembly procedure). Do not use "rolled roofing" as specified in "Earthship", unless you are poor as dirt and can’t do anything else. If you do use it, you will spend a lot of time on your roof fixing leaks, as long as you live under it.

b) The log beam on 4’ centers requires the same values from the log members but uses 2" x 6" tongue-and-groove sheathing over the logs. The same treatment above the logs as in a). This version requires a more costly sheathing, but uses half the logs. Depends on your situation and the availability of logs. On the normal market suitable logs have run as high as $7 per linear foot, but given independent sources and conditions, may go as low as $10 per log. The tongue-and-groove at local mills can run from $1-$3 per square foot, depending on the market.

c) The I-joist is "off the shelf" and will usually be delivered cut to length, to your site within 48 hours of your order. Engineering information is also "off-the-shelf". These beams are guaranteed by the manufacturer to perform as specified and this takes a responsibility load off the RPE’s calculations. These beams are strong, light, and easy to handle and frame, they are purposely installed "upside down" with the "electrical knock-outs" up. This frame uses plywood or OSB sheathing, per local requirements. The inner cavity is "filled" with a 10" "Kraft" Fiberglas batt (R-38 or more), and an interior sheathing of gypsum board or paneling is applied over a PVC vapor barrier. The resultant space above the insulation batting must be vented. By removing electrical knock-outs and drilling strategic holes (see manufacturer's specifications), a cross flow may be established with minimum exterior appearance. A "whirly-bird" vent as an exhaust is very effective.

d) Other. Here, there are many substitutions for the I-joist beam, i.e., manufactured truss, homemade truss, steel truss, etc. You are on your own here, meaning with regard to engineering, installation, and design standard information is not available, so must be furnished or developed. I'm always open to proven alternatives, tho.

In any case, the "greenhouse" joists must be vented. This is accomplished by leaving a 1/2" space at the top of the joist, between the joist and the horizontal 2" X 12" header. When the roof sheathing is applied, a 1/2" gap is created and A ridge vent is then attached to the ridge, as if a corner flashing. Or, in the case of the one plane roof design, standard soffet venting (under eaves) is utilized.

A one plane roof can utilize standard materials like metal standing-seam roofing.

East to west (or west to east) drainage on these roofs (having a kicked-up greenhouse area) must be provided in the framing. A minimum slope is 3" in 20’. This slope is created by building it into the framing of the main roof section. A cricket is created by overcasting the (slightly angled from east to west) roof sheathing of the main house onto the sheathing of the greenhouse.

15. Roofing Material. Roofing membrane of EPDM rubber, .045 inches thick as a minimum, .060 inches thick if you can afford it. Or, standing-seam metal roofing.

Both of these are the best choices for the tire-house, in my opinion. We used the cheap stuff, like in the book, 90# rolled roofing (NEVER use this!!). Get the best roofing you can afford.

16. Plumbing Drains. Along about now you can start installing the plumbing rough-in. This consists of digging trenches and routing drain pipes. In most counties, this will require an inspection under pressure. Check with your local building official. Don’t even ask about graywater systems, etc. Composting toilets are a valid option, however, in most counties you will still have to install a solids separating tank with a leach field, however. Check on this in your county.

17. Electrical Wire. All wires that will be buried in adobe must be Type UF. Obey all the local and national electrical requirements (NEC). If you aren’t an electrician, see one now. If you don’t have electric on your property, call for an estimate from your local provider.

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.

18. Insulation. Install insulation in greenhouse areas (and in the balance of cavities in "I-joist" houses) after electrical installation and inspection. These "batts" of insulation should be the "Kraft" (foil facing inside the house, for fire retardation). A glued moisture barrier goes up next (6 mil PVC). Next is the paneling or sheet rock.

As an alternative to the expensive hardboard urethane "alloy" (required by the log beam roof), which is high yield (R-60 for 8") but has very poor moisture resistance, I'd suggest using high density expanded polystyrene (EPS) sheets (8" total thickness) for it's low cost, reasonable insulation yield (R-36 for 8") and excellent moisture resistance.

19. Tire In-fill. Filling the interior spaces between the tires with adobe and cans as shown in the book is a VERY big job. There is some controversy about this item. In my opinion, the only spaces that need to be filled are in tires that are exposed to exterior moisture, and these not with adobe, but reinforced cement mortar and fill (cans, rocks or whatever). Otherwise, all interior tire-walls may omit adobe and can in-fill process by screwing or nailing metal lath or tarpaper & chicken-wire (stucco mesh), directly to the tires and coating with the three coat stucco process (achieving 1 inch thick). Yes, this does leave a space, but every tire is still in intimate contact with the room air or sunlight and will act as mass-storage. This process is much less work, and a little more expensive.

Even less work and time too, with no "loss" of thermal mass, is the "shot-crete" process. This system comes from the swimming pool industry. A high volume "mist" of cement mortar is "blown" onto the wall and then troweled smooth. A large house can be done in a day or two using this method, but may cost $5,000-8,000. This may seem expensive, but comes out to be a wash in terms of money/time with hand techniques, if you can afford it in the first place.

20. Flooring. Flooring may be as desired, flagstone, slate, concrete, Spanish tile, adobe, etc. Wall-to-wall carpets are a "no-no" as they insulate your thermal mass from the ambient temperature of the house. Throw rugs are OK, but, keep in mind, the floor is your connection with the largest chunk of mass-storage in the house.

21. Windows. Windows are the "heaters" in the passive solar home. If you want to grow plants in the summer, they should be slanted (and, some say don’t use "low E" glass, as the plants don’t want any rays filtered from the sunlight, but I can't be sure on that, as some say it's fine). If you don’t want to grow plants for food, they can be vertical, but "sun-space" will be minimized. I have only one client that has used it, and they use shades to keep the sun out. Could be, not enough "E", or not enough ventilation.

Two critical points when mounting these windows in a slanted window array. 1) Both panes of the double-pane insulated glass panel MUST be supported equally. Hard rubber blocks, (2) 1/4"x 1"x 2", should be supplied with each window pane (ask for these in advance). 2) When buying windows, specify that silicone adhesive compound (not butyl rubber) must be used for seals. Non-compliance with either of these points will result in window failure due to slow sliding of glass, causing breaking of the laminar seal and subsequent condensation opacity.

SOLAR NOTE: The amount of double glazed insulated windows should be a minimum of 25% of the available floor space. A house located at 9400’ altitude above Colorado Springs, CO, having a percentage of 37% glass/floor space with slanted glass, has not been below 70 degrees since it’s first "close-in". This house requires shades to keep cool (an option would be more ventilation). It’s better to have too much heat, than not enough. It’s easy to let heat out when it’s too hot, but it’s hard to put heat in when there isn’t enough.

WARNING: Michael Reynolds' mullion design for slanted glass panes (external window 'clamp' metal), as presented in "Earthship" Vol. 1, not only leads to leaks into the house but will continually require maintenance, do nothing to alleviate condensation drips, AND they're ugly.

After some research into a functioning design, we've settled on (and suggest to our clients) two suppliers of leak free and beautiful window hardware. Both provide extruded aluminum channeling and mullions that are anodized in any color for a long last finish that is not only attractive, but practically impervious to the elements. It is a bit pricey, but the long-term results warrant the expense.

This hardware automatically drains any water, such as condensation, that reaches the inside surface of the glass, to the outside of the house. This clever design also assures continued leak-free function, even if the extruded EPDM seals (included) were to leak.

22. Heating. Some counties will require a "back-up" heat source. Check your county’s requirements. This subject requires extensive discussion, including: window area/active floor space ratio; ceiling heights; mass directly available to solar energy for passive storage; total mass available for passive storage; window coverings; type of alternate heat source; personal temperature comfort zone desired, and so on. A properly functioning passive solar home using these principles should maintain a minimum of 65 degrees in the winter and maximum of 75 degrees in the summer.

23. Egress. Due to fire requirements, all bedrooms require immediate alternate (other than the way in) access to the outside. This can be accomplished by an egress window (check local requirements on egress windows), or a door. You may not pass through another room (hallway included) to achieve this access.

24. Skylights. My experience with skylights is that 1) they should represent the equivalent ventilation at the "top" of the house as the awning/opening windows at the front of the house, 2) they should be easy to open and close. Click to see easy-open, no counterweight design. And 3) they present a prominent potential for the development of condensation. To resolve these criteria we have recommended (and used ourselves) a 4' x 4' skylight in each room, with the equivalent of openings on the solar window wall (two awning windows, as seen above in the photo in para. 21). Skylights should be triple pane with thermal-barrier frames, to stop the condensation from forming.

Good luck with your project. There's nothing as frustrating or satisfying as building your own house. We wouldn't have it any other way, or live in any other kind.