Slipforming a Wilderness Cabin
A work in progress, by Ed Kent
Introduction by Thomas J. Elpel
Ed Kent read my article The Art of Slipforming in the December 1997/January 1998 issue of The Mother Earth News, and later bought an early draft edition of Living Homes. He helped correct some of my chemistry in the book, and we have corresponded ever since.
Ed lives in Idaho, but returns to his family property on Johnston's Lake in Nova Scotia, Canada each summer. It has been his dream to build a stone cottage there for summer use, and he broke ground on the project in 1999. He has kindly given me permission to publish his story and letters here. This is his story-in -progress:
July 4, 2000
Thanks for your postcard, forwarded to me here in the "wilderness". I'm camped at Johnston's Lake, four miles by our new road from the nearest electricity or dwelling at West New Annan. Had seven yards Ready Mix concrete delivered for our footing--cost $371 extra for the truck getting stuck 200 yards from camp. I put in a great 10" x 24" footing with three horizontal runs plus vertical rebar. I am using your 9-1/4 inch walls, and many more of your ideas. I left all my books home on purpose. I read too much--this is time for work.
I'm 66 years old, working alone, often mixing ten 1/2 bag batches per day. I'll be another two weeks finishing the stem walls--then looking forward to the slipform stone work. This place is all rock. I plan to use the pour-in-place tile floor as you have done--no wood for the first floor. I plan a second story, but will wait until I have walls over the windows and doors before I decide that . I thank you for the inspiration your books gave to help make this dream come true.
A Place in the Wild
In 1856 my great-grandfather bought the 650-acre Whirley-wha woodlot in W. New Annan, Nova Scotia, Canada. He built 14 brigantine sailing ships (up to 375 tons) between 1852 and 1866, at his yard in Tatamagouche.
2004: I'm back for the fifth summer of a four-year project, and now predicting three additional summers after this. I weighed 236 lbs. when I started. I am now at 175 lbs. and losing 2 pounds a week, during the summer, but gaining 2 pounds a month during the rest of the year.
We've kept the land in the family ever since, and my mother deeded it to me in 1985. The last logging had been done in 1940, and by 1980 the Balsam Fir was mature and beginning its dying cycle. The cost of building a four mile logging road into the property exceeded the value of the timber until 1999, when I put together a deal with a forest cooperative, and now have a new road to Johnston Lake. It is a three-hour round-trip drive to the nearest town.
Prevailing winds down the lake tend to blow the mosquitoes away, but not the black flies. Since the property has shallow soil and much glaciated exposed bedrock, I had planned on building a summer cabin on bedrock. The best level site I found is on many feet of compacted sand and rock with no clay, and excellent drainage. So much for plans of building on bedrock.
I considered scribe-fit Norwegian Log Building, having taken such a class. Locals tell me log cabins have a short life span in the damp climate. Vandals are also a problem. If they can't break in then they will cut a new door with a chainsaw.
I tolerate two small cabins at Whirley wha Lake, which were built 40 years ago, but are now "community property". Local sportsmen and women camp there year round, and there are many tales as to ownership won and lost in card games , etc. According to my understanding of Canadian Law, it takes 20 years of "adverse possession" before squatters obtain any rights at all. The 20 years would not start unless I objected. My attorney suggested that the goodwill from tolerating the camps will make my own camp safer.
1999: While the excavator and dozer were building the road, I had them dig a rough footing trench for a 24 x 28' cabin, and they took out a few scoops for an outhouse pit. The pit turned out to be so deep and so long I had to build a log structure over it to support the outhouse. I covered the other two-thirds of the pit with logs and brush. Now when you lift the lid and look down, it scares you. I figure I have a 100 year capacity. I built the outhouse in Idaho and brought it up on the rear of my utility trailer. Joanne said she wouldn't go with me if I put the "Y2K COMPATIBLE" sign on it as planned. There was so much rock saved from the excavation work that I didn't have to collect any for building the house. The heavy equipment also dragged in an 8 x 8 x 20' steel cargo container for storage.
2000: After a month of hand digging, setting forms and rebar, I ordered seven yards of concrete for the footings. The truck got stuck 200 yards from camp. Suddenly it looked like I'd own not just seven yards of concrete, but the truck too. With a big 4WD loader we were able to save all, but it cost an additional $371. I had ordered six-sack concrete, and it was green for several days, but finally set up fine. Enough concrete trucks!
I poured 9-1/4" stem walls, 32" high to grade, using a 3-1/2 cubic ft. electric mixer and an old generator. I used air-entrainment and retarder additives to slow down the set time and improve the batch-to-batch flow pattern. One day I made 21 batches, working alone.
Since most of the stem wall would wait a full year before more concrete was poured over it, I left the top of the wall very rough and set in 3" washed stone every few inches , as well as the vertical rebar, to help tie the old and new sections together. I did complete one-eighth of the first floor perimeter in stone. I built the slipforms in Idaho over the winter and hauled them up on the trailer. I used 5/16 x 3 1/2" bolts, plus washers and wing nuts (instead of nails) to tie the forms together horizontally and vertically.
The book Why Buildings Fall Down by Levy and Salvadori (Norton & Company) talks about the lack of redundancy in failed structures. No question that my 18" pilasters and corner posts are redundant, as well as more work. The pilasters are faced on the inside for appearance. If this cabin is not still standing in 200 years, I will be very upset.
In 2000 the snow depth reached 5 feet. I plan the roof to be able to support 10 feet of snow, and to have little structural damage if a 60 foot tree falls on it. I plan a salt box roof line with a 5/12 pitch, since I don't want to work on a steeper pitch than that. I'll be using about 20' flattened logs for roof rafters, to include some overhang. Several feet of snow is pretty good insulation, if someone wants to be there in winter to run a maple syrup operation. An insulating roof could be added later. Fuel wood is plentiful, and the beech stands have little other value. I'll have a truss beam support the long rafters at 12' run, supported by the center post and side pilasters, and use collar ties for redundancy.
2001: Arriving the first week of May was a big mistake. The snowmobile groomer packed down the snow, then more drifted in. I had to wait 10 days for it to melt. The road was bare through the maples and birch, but the snow was hip-deep in the shade of the spruce and fir trees.
For an easier method of wire-tying the slipforms, I switched to 17 gauge electric fence wire, which is much stronger, stiffer and cheaper than some sources of wire. It is convenient to place the reel of wire on a rebar, have the wire run under a heavy rock to straighten it, and peel off about 50 feet or so before cutting it into 2 foot lengths.
To tighten the wire ties I used 2 x 2 levers, 16 inches long, with a 1/8" hole drilled 4" from one end. There are two 1-1/4" drywall screws set into the wood about 1/4" and 3/4" inches from the hole, leaving a gap between them. After threading the proper amount through the hole, the wire is gripped with pliers and wound around the first screw, then in figure-eights around both screws. A similar lever is attached on the other side of the wall. The short end of the first lever is propped up onto the 2 x 4 framework of the forms when the wire is pulled through to put the second lever in place. Raising both ends of the second lever up onto the framework usually provides plenty of tension against the spacers. If it is too tight, then a small block of wood can be placed under the long end instead.
All this can be done from one side of the forms, and the single wire reduces conflicts with rock placement compared to the two-wire system. Only half as many wires need to be cut when the forms are removed, and the lever arms are returned to the bench to remove the old wire ends with pliers. I found this method quicker and more convenient than the twisted wire system, and it uses about half the wire.
For security, I embedded 1/2" PVC pipes in the concrete outside the window frames. Plywood shutters will be affixed with 8" bolts into the holes. A grid of 3/4" rebar across the openings will give additional security, and provide extra strength to the lentils above the windows. The quality thermopane windows will be installed from the inside. Exterior storm doors will be installed with cheap locks to keep out the honest. A removable sandwich panel of steel and plywood will frustrate thieves. Inside that will be a conventional front door. In that area a rash of Vandalism happens about every 10 years--never by snowmobilers, but by kids in pickup trucks or ATV's.
For a center post I chose a 15" diameter red spruce. Working alone I cut, trimmed, and dragged it to the cabin with my 4WD Ford. I used a dull, cheap machete as the chief tool for peeling. I then erected a 20' A-frame, looped a 100' logging cable through sheaf, and bolted on four guy wires, and tied on poly rope and come-a-longs for side and back stays. With the butt secure in a steel fixture set in concrete, and using a 3 ton chain fall, the post was slowly pulled to the sheaf. That was pretty stable, but then it was important to keep the post moving in an absolutely vertical plane, by sighting it with a plumb bob, and adjusting the side stays. The A-frame slid down the cable, and the post was drilled and bolted to the 1/4" steel fixture with four bolts of 1" threaded rod, with washers and nuts. Although there is now a beam notched in and affixed in the wall, the 4 guy wires are adjusted to equal tension--sort of a triple redundancy.
By the time I left in September, most of the first floor was completed to the top of the windows. I used up all the cement before quitting, since cement left from the year before was partly ruined by spring.
2002: I stayed at home in Idaho until mid June, thereby avoiding the snow, mud season, black flies, and most of the mosquitoes. Besides, five months last year was too long to be alone with just my 3 and 12 year old Australian Shepherd dogs for company.
I spent only three months in Canada this year, but I did complete the first floor exterior of an 8-foot diameter circular tower containing a 12-inch diameter concrete post and eleven spiral, rough concrete stairs to be finished later with terra tiles. I greatly appreciate all the good ideas you have shared through your book Living Homes.
The first floor interior of the tower will include a structurally separate masonry stove, bake oven and the corner of a massive Rumford-style fireplace. Above the fireplace smoke shelf/damper I plan a 6' x 6' x 8" forward leaning steel radiating surface, with flue connections at the top and also just above the smoke shelf, dampers, etc. This won't be started until the year 2005, and the design will permit easy changes to mistakes.
In the mean-time, I've started installing floor joists (flattened logs using Alaskan small log mill), and I am developing some composite log/concrete walls for the second floor. At age 68 I feel I have lots of time to complete and enjoy this camp.
Hurricane Juan took down about 10,000 fir and spruce trees September 28th. I'm fortunate to have a good woods crew who works on windfall. It can be more dangerous than taking down standing trees. Most of the Balsam Fir is 60+ years old, over mature, and sometimes rotten inside.
The upper deck will be 8 x 20 feet with the central half covered by a roof. The picture with the 55 gallon drum and steel form (1/8" thick x 2' high x 6' wide) shows the approximate location for the 6 x 6 foot fireplace. I plan to line the lower two feet with firebrick and then proceed with steel. I will build a masonry stone firebox inside the steel drum and build a colonial type bake oven above-- but have each of the three fixtures structurally independent in case they don't work as planned, or need service.
Since I might not ever be here in winter, this project is more for fun than practicality. As with this entire project I have no firm plans, and may change my mind on the heat fixtures.
The terratile covered concrete steps, and a few tons of rock packed around the masonry stove steel flue pipe-- about 8feet of horizontal run-- will provide a sizeable heat sink. The thermal conductivity of steel is something like 1,000 times that of masonry. Want to talk me out of this?
I hate the burned dust problem of steel stoves, and I plan to apply a thin coat of wire mesh/mortar cement around the rock to prevent dust, and hopefully to avoid the cracking typical of masonry stoves.
You can see in that photo the two 1' diameter vent holes (well above the snow level). One is to provide air to the fireplace. The other is to let bathroom fumes out.
I am still using the split log technique on 2nd floor walls, with 4 1/2 to 5" of concrete between. Three trees have fallen on the walls with no effects.
I'll plan to get some good pictures to you at the end of the summer--with 1/2 the roof on, which will include your rainwater collection system.
I get additional inspiration every time I pick up your books.
2005 - 2006: I made lots of progress in 2005 and 2006, but have stopped trying to predict how much longer it will take to finish. Trees loosened by hurricane Juan continue to fall each year, and I've salvaged another thirty or so for floor joists, roof rafters and siding.
A year ago we visited the famous Winchester House in Palo Alto, California, and I had a "Eureka Moment". When the Winchester Arms heiress was crippled with arthritis, she had stairs built with 2" risers to enable her to go from the first to second floors. This idea solved my problem of how to get from the tower to the ten-foot second floor without having to bend over. I transitioned from the concrete circular stairway with 8" risers to 4" risers with 18" treads. So another problem of not having proper plans is solved by the luck on which I rely heavily. It sure is a lot easier to carry fifty-pound buckets of concrete up the stairs than the homemade ladders.
I've changed plans a bit on the stove/bake oven system, and may decide the 8 x 16 foot third floor sleeping room should be added later. Getting the rest of the roof on seems more important now.
I now have a well supplying good water via a 12-volt pump, a propane/wood burning combination cookstove, a large propane refrigerator/freezer, a shower, and can finally get regular cell phone service via a Yagi directional antenna. Sleeping in my hanging queen size bed is far more comfortable than the steel shipping container, and the 9" of stone/concrete definitely reduces day/night temperature fluctuations.
In early May I may pick up an old friend in Minnesota, via Silver Star, and buy a few more of your great books. I'll call when I have the date.
2007: Too bad we missed connecting in May, but I did enjoy admiring your fine new building, and the scenery on the way.
In 2007 I worked five months on the cabin, installed twelve windows, 300 square feet of roof, a 3rd floor sunroom, and footings for the 6 x 6 Rumford fireplace.
Over the winter I'm reworking my antique wood fired steam engine to be safer and to produce 12 volts. I am also building a 64" diameter, 12 volt system.
In 2008 I expect to complete the slipformed, eight-foot diameter "castle" tower to its final height of twenty-eight feet. I hope to complete the roof and on rainy days I will work on the fireplace. I continue to read your books for ideas and inspiration, have used your "terra tiles" technique for the cold part of the fireplace hearth, and will use it for the circular tower step and first floor final surfaces, perhaps countertops.
2008: Just a note to send along with our Christmas letter, card, and a few pictures. I completed the concrete arches and beams supporting the castle tower floor, the floor itself with openings for chimney and hatch for ship's ladder and one merlon to final height, about twenty-six feet from the ground.
I also completed the shed roof section for firewood storage, a bit more on the fireplace, and the slipformed wall with three slot windows up to the roof level. I'll carry the merlons and crenels about four feet above the roof line after figuring the best way to dispose of rainwater.
Check out Living Homes: Stone Masonry, Log, and Strawbale Construction.