Going off the grid with an efficient, remotely located, off the grid cabin, is a huge step, but the principles we will learn in building an off the grid cabin will help us understand construction, and help us start thinking about how to create a home using renewable resources. Our home plan is a bit post apocalyptic in feel because it incorporates high tech and old fashioned ideas side by side, but the idea is to take the best from each time period.
We will learn how the past, present and future of construction vary and how they also remain constant. By considering doing work by hand, we appreciate the modern improvements in construction that make our work easier, and by considering previous standards we appreciate what is good about modern convenience. In addition we can look to the future with confidence that our important conveniences can survive and modern civilization can continue with a limited use of fossil fuels.
Our forefathers entered the vast wilderness in a covered wagon pulled by oxen. They brought with them an ax, and a shotgun. They chopped down their log building materials with an ax, knocked off the bark and hewed them to fit, more or less. They daubed the cracks with mud which dried into clay. They constructed chimneys and fireplaces from collected stones, and created a home out of virtually nothing. They bought single pane glass for windows as soon as they could afford them, which was often years after construction.
For our cabin we will bring our pickup truck, loaded with some five inch thick extruded polyurethane panels, which we precut for windows and doors, and pre-covered in wire mesh. We have Portland cement, sand, a generator, a cement mixer, and the best solar power off the grid system we can find. We have not only an ax, but also a shovel, a little pine lumber, some PEX Pipe and a Franklin woodstove. We also have some assorted fixtures, and appliances. We also have six highly efficient triple glazed windows and two energy efficient doors.
We will also need two helpers, a licensed electrician who understands solar power, and another contractor who is experienced in the use of shotcrete, and interested in affordable housing projects. For this exercise we will assume that we are strong and able bodied, and that we researched our construction art forms for the project rather well.
Our forefathers often built their log cabins on a dirt floor, but they also had problems with their bottom logs rotting, and their furniture didn’t fair any better. For our project we will dig a foundation and build a crawl space. This will take a considerable amount of time with a shovel, so we will keep our cabin small, to save time, and our two helpers will meet us later in the week.
We will dig a trench for the footing of a 16 by 24 foot cabin. The depth of the footing will depend on the depth of the frost line. It is important to pour the footings below the frost line. We will say that the frost line in our area is 16 inches. This means we must dig our footings about six inches deeper for a total of 22 inches.
We will need a level to determine if our footing is deep enough all the way around, because the footing must also be exactly level once it is poured, and we must go down at least 22 inches all the way around, even if the ground isn’t level. That means some of our trench will be deeper, but none shallower than 22 inches… and with a shovel it could take days to dig our trench 8 inches wide. Some soils will require us to build a form, but we will have hard clay soil and it will work fine without building a form.
When we complete the digging we will call our cement expert and together we will mix the cement five gallons at a time and pour them into the footing. This too will take a long time. We are going to have to pay this guy well.
Once the footings are poured, we’ll let our cement contractor go set up his shotcrete spraying equipment, while we start constructing the foundation out of 5 inch thick polyurethane covered with wire mesh. We will also put some lighter supports down the middle of our floor These will not have to be dug down as far, and need not have any sort of concrete footing.
While we are doing this, we can have a well dug. We will need a modern well. Our forefathers dug shallow wells and lived off ground water, but today’s pollution makes that unsafe, and some say it was never sanitary. We will have a modern well dug on our property, complete with an electric pump.
We don’t exactly need a septic tank unless we have a building inspector who insists, and it is certainly unnecessary. One of our fixtures is an incinerator toilet. It will effectively burn the waste to sterile ash. All we need to do is empty the odorless ash pan about once a month. Some would say that the kitchen sink water is black water, and requires a septic. I’ve never really agreed with that point, and consider it gray water. Use gray water from the sinks and tub to irrigate your garden.
Steps to Do before we can spray the floor
• First our cement contractor will bring the concrete sprayer, and spray the foundation walls inside and out.
• During this time we will run PEX pipe from the well and put in rough plumbing for the sinks and shower tub.
• Soon we will also have our electrician install the rough electrical under the house.
• There will be minimal ductwork in a home this size. Two vents should suffice, placed near the midline of the house. Our tiny, efficient heat and air unit can sit between those under the house in the crawl space, or in the yard at the back of our home, depending on the manufacturer specifications. In either case the duct work need not be extensive, and we can probably manage a tiny bit of sheet metal fabrication. It is important however that this ductwork does not leak at all, and that it be insulated properly.
When the foundation wall is dry, probably in two days, we will place sheets of poly urethane across the floor. We should have two holes for the vents, and ask our shotcrete worker to spray that as well. This will have to cure for several days before we can continue.
Our shotcrete expert has decided to infuse the shotcrete with a lovely golden colored dye so that it will resemble yellow adobe. This means that we will never need to paint our cabin either inside or out, and it will require virtually no maintenance for the next few hundred years.
When the concrete floor has cured, we can build our walls out of the 4 by 8 foot polyurethane sheets covered with wire mesh. Since our panels are precut we must match them to the right place on our home. We have faced our cabin to the east, where there are two windows and a door. We also have two windows and a door on the back, and two windows on the south side. There are no windows to the north, but there is a hole for a stove pipe. There are a few small holes for plumbing and wiring to fit through the walls and floor as well.
We will connect the walls to each other with metal fasteners attached to both the foam core and the wire. The eves on top of the two narrowest walls are made of a single panel cut diagonally, making it four feet high at the center and placed across the top. We will fasten that to the walls and continue.
We will place an additional wall near the center of the home, to help support the ceiling. This wall will be made of thinner polyurethane, perhaps only 2.5 or 3 inches thick. When we have all four walls up and our eves in place, our cement contractor will spray the walls with shotcrete and allow it to dry.
In a couple of days we will cover the roof with panels, and apply the shotcrete, both to the interior, and to the exterior. We may need to use pieces of lumber to help prop up the roof during this time. We can take the supports down later. Once the concrete is dry nothing will ever be able to knock it down.
Now our shell is complete. The exterior looks like lovely golden adobe or stucco, and so does the interior. There is no painting or wallpaper necessary, but we may want well padded carpet to soften the hard concrete floor, and vinyl floor covering will make the kitchen seem nicer, but it isn’t necessary. Our vaulted ceiling is lovely and the home is just the right size to be extremely efficient for two people.
• We will install an on demand hot water heater, which is very efficient. We could probably get away with two or three inexpensive point of use hot water heaters.
• If we prefer, we can build cabinets out of very thin polystyrene or Styrofoam sheets and more shotcrete. Even our countertops can be made this way. If we do not prefer this continuation of our shotcrete theme, we may install cabinets and countertops from a home improvement store.
• We will install on our kitchen cabinets, a lovely copper sink. This will be our one luxury. The copper sink stays clean and germ free due to the nature of copper. It will patina, but not stain. That can be very attractive. We will never need to scrub our sink, simply wipe it out with a soft cloth.
• We will also install the shower and tub combination of our choice. We may tile over the concrete to create shower walls if we like, or buy an enclosure.
• Plumbing is easy with PEX pipe, and without that toilet to plumb we should be able to handle the drain lines to the sinks and tub as well.
• If we selected the most efficient refrigerator and range we could find, then it will be easy to keep the power on with fewer solar panels. A microwave can also save power, more than the most efficient oven, by reducing cooking times, and warming things up without having to use the oven or a burner.
• We will now install our Franklin Stove for emergencies and to supplement a small, efficient heat and air system, on cold rainy days.
• Our home’s electrical system will support computer equipment, televisions, and electric lights just like every other home.
Now our electrician will come out and install our solar powered off the grid system. We will rely on batteries, similar to car batteries and an inverter to power our home. If our home were in the city we could attach it to the power grid, and omit the need for batteries. While self sufficiency increases the price of a solar system, it also gives us freedom. We could though, make a little extra money selling electricity to the power company if we were on the grid. Unfortunately in the city or in a subdivision our special little house might not pass all the regulations. After all it is way ahead of its time.
We will have to keep our generator handy for emergency battery recharges which will only take about an hour a day, during extended bad weather. Our generator may burn a little bit of gas, during extended cloudy weather, but we will never again pay a utility bill.
Eventually we could add a porch or another bedroom or two to the home, but for now this home will do nicely for a young couple. Remember to leave a door where you intend to add on, especially with insulated concrete, because making a hole in it can be very difficult once it has been poured or shot with concrete.
So now you can see the different steps to building a small insulated concrete home, discover the benefits of building a smaller home, appreciate the hard work involved in doing things yourself and learn about efficient water use. We also see how our homes can be adapted to be more energy efficient, and more environmentally friendly. While I admit, building an off the grid cabin is an extreme prototype, the knowledge gained from our golden home in the wilderness, will serve us well as we build larger homes, with more modern equipment.