This is the text and pictures from the original Eco-Cabin Book.
OWNER - BUILDER
|ECO - LOGICAL
ECO - NOMICAL
MINIMUM ECOLOGICAL AND
1976 GREENPEACE EXPERIMENTAL FARM
The eco-cabin is a unique structure, the shape derived from a geometric solid called an icosahedron. The crystalline form is made up of 20 equilateral triangles. If a group o 5 interconnected triangles are removed, the shape of the cabin results. To aid in visualizing the structure, construct the mo del from fig. 1. As evident, the base of the floor is a pentagon 5 sided. It is interesting and convenient that any one side of the base is equal in length to any side of the remaining triangles. In the actual cabin, the roof triangles are extend past the side to form protective eaves.
This shape was chosen for a dwelling because of its simplicity of design, economy, case of construction, great structural strength and maximum utilization of a minimal amount of materials. It has an advantage over 'pure' domes in that placement of windows,doors, and skylights is more conventional. Owing to its simplicity, most of the major components (foundation, floor, and struts) may be prefabricated. This dramatically cuts down construction time on the site. Another 'plus' is that absolutely no power tools are required for construction, suiting remote locations. It is estimated that this well insulated 120 sq. ft. cabin will cost under $600, even in inflationary 1976.
As mentioned before, only hand tools are necessary for construction. the tools required are:
- brace and bit drill with 3/8 bit
- a quality crosscut saw, approx. 8 pts. per inch
- 4 foot level
- chalk line
- adjustable wrench
- 12' tape measure
- staple gun
- carpenter's square
- bevel square
- bow saw (optional)
The most important factor in keeping the cost of your cabin low will be your ability to obtain materials at the lowest possible cost. Although it is desirable to used recycled materials such as those obtained from wrecked buildings etc., many of us lack the facilities or capabilities to do it. An alternative is to scrounge in local lumber yards. Most lumberyards have a section reserved for utility grade lumber. It is usually in bundles of random lengths, although of the same stock size (2" by 4", 1" by 8" etc.). If you can obtain permission to pick through the bundles, you will find enough wood of suitable quality to fit your needs. Remember to keep the bundles orderly, so you can keep a good thing going! Here are some pointers to look for when sifting through the pile. Sight along the edge, and look for warp and straightness of grain. If the grain is very wavy, reject it. The same goes for a bad warp, unless it's near the end where you can cut it off and still have a good size piece of wood left. Then cheek the knots. If they are more than 1/4 the thickness of the wood in depth, reject it, unless it's near the end. This criteria does not apply to sheathing material. Look especially for decay. If it can be cut out, okay, if not reject it. Some lumber may be badly checked (split) on the ends. This is alright if it does not extend too far up the board. Planer skips are okay, un less they visibly weaken the board. Basic Materials list
- 35 5", long, 318" diameter carriage bolts, nuts and washers
- 5 4' by 8' sheets of tongue and grooved 3/s" plywood (approx)
- 15 8' long 2 by 4's construction grade (for wall struts)
- 250 lineal feet of 2 by 4's for roof door etc. (utility)'12' or 16' lengths
- 14 10' long 2 by 6's for foundation
- 1000 board feet of utility grade 1 by 8 shiplap (for sheathing)
- 1 roll of roofing felt
- 2 boxes (1000 each) 518" staples and gun
- 1 qt. of roofing cement 2" and 4" common nails
- chimney jack, vent, door hardware, rope, etc.
- fiberglass insulation for sides and floor
- materials for outer skin
Construction of Foundation
Before you begin actual construction, decide exactly where you want the door and windows to go. If you want a large window oriented south, decide whether you want it slanting in or out. Use your model and sketch in the windows, door and skylight. Then mark the orientation at the construction site.
The first step is to prepare the skids. The skids are two logs of equal length, on which the foundation is attached. Locate two logs approximately 15" long and over 6" in diameter. They should be peeled so no destructive insect s are harboured. Next,adze or flatten one side to provide a level surface. Then snap two parallel chalk lines 4" apart. Use an axe to chip away the wood between the lines, sighting along the log as you go. When this is done, lay the skids on the ground, surface side down. Divide the skids into thirds. At each third point, cut notches about 6" wide and 2" deep. These are to accommodate the upright posts that keep the cabin off the ground. The next step is to raise and level the skids. First, decide the height you want your cabin floor to be off the ground. Don't forget to take into account the thickness of the floor and joists (6Y4"). Then take two pieces of scrap boards and nail them to the end of one of the skids as shown in fig. 2. Swing them apart until you have the desired height then repeat the entire proceedure to the other side, making sure the skid is level. When that i@ done, dig two holes directly under the notches, deep enough to remove the sod layer and a large enough to accommodate a rock with a flat surface at least 6" in diameter(cement pier blocks can be substituted). make sure the rock is at least 2" above the surface. Then measure the distance between the rock and the notch and cut and peel a post about equal to the width of the notch. If you find that the skid isn't perfectly level, shim the post at the notch (a wood shingle works well). Repeat the entire operation to the other skid, making sure that the center of one skid is exactly 4' 8" away from the other and that they are mutually level.
The next step is to prepare the perimeter floor joists. Select 5 ten foot long 2 by 6's that are relatively straight. Set your angle protractor square to 540 and lay out five 9' lengths with 54(angles at either end. Place the joists as shown in the floor plan (fig. 4), fastening the end lightly, with 2" nails. juggle the@joists around until they form an accurate pentagon, then dig holes under the three points shown, and lay rocks and posts as was done on the skids. When this is done, secure the ends with 2 4inch nails each (Fig. 3). Make sure the joists are level with respect to each other. A little precision and time here will save hours of frustration later.
Next, position the floor joists as shown in Fig. 4, and nail securely with two 4 inch nails. Notice that most of t 'he joists (the five longest) are two pieces of wood joined at a skid. Here again, take time to level accurately.
Fabrication of Hubs and Struts
Cut and drill the hubs and struts as shown in Figs. 5 and 6. Two people can reduce preparation time here. The hubs can be drilled five at a time if they are clamp ed together Note: a hole should be drilled through the centre of the roof hub for a safety rope (which will be explained later). Two people working in harmony should be able to prepare all the hubs and struts in about 2 hours. The next step is all fun. Assemble the struts and hubs according to your model (Figure 1).
Place the lower wall hubs on the floor. Do mt tighten the nuts until all the struts are connected and the hubs are straight. To connect the frame to the floor, first find the centre of the floor as shown in Fig. 16. You must spot the lower wall hubs accurately in order for all the angles to be true. To do that, measure exactly 851/2 inches from the centre to all give points. Place the inside edge of the lower wall hubs centred on that mark, and nail them to the floor. Then block both sides of the hub with 5 inch long 2 by 4's and nail them too A way to cheek the whole assembly is to cheek the top struts for level. Twist the hubs until levelling is achieved evenly around the perimeter.
Loosely bolt the five roof struts to the roof hub. COt a pole exactly 137 3/4 inches long and nail a 2 inch nail halfway into the centre of one end. Insert the nail into the We in the centre of the roof hub. Then hoist the entire assembly, fitting the roof struts into the notches of the top wall hobs, up until the butt of the pole rests exactly on the centre mark on the floor. Temporarily nail the pole into the floor, remembering that it will have to be removed later. Nail the struts to the hubs, then tighten the nuts at the peak. The overhang from the struts forms the basis of the caves. Measure, cut and nail the 'rafters' as shown in (fig. 8 & fig. 9). When that is done, the support pole can be safely removed
Normally, one starts the sheathing with the roof, the reason being that once it's finished, it doesn't matter whether or,:not it rains, you can still work on the walls. However, we did just that, and when it came to sheathing the very top of the walls, we found the space between the over hang and the wall was not large enough to swing a hammer! So, before you start on the roof, nail one b g around the top of the
Before you begin to sheath the roof, nail a board of shiplap around the very perimeter of the roof struts to provide a nailing surface for the very ends of the sheathing boards. It should be mentioned that, in the interest of safety, a panic rope should be installed. Tie a 1/4 inch rope about 12' long, to a 7 inch long stout stick. Pass the free end through the hole in the roof hub, then nail the stick into the hub (to counter gravity). This rope should always be near the person working on the roof so that it can be grabbed at in a hurry. Start sheathing the roof from the centre of each section of the roof, working out to either side. Here again, two people working together should be able to sheath the roof in 2 days. Our method was to have one person on the roof marking the angles and nailing the boards, the other person marking the lengths and cutting. If rain seems imminent, you should waterproof the roof as soon as possible. First cut holes for the stovepipe 'jack' assembly, skylights and vents as required, then nail the above on. A vent might be desirable during the summer but during the winter, it just lets out heat. An off-on divide would be ideal. Install insulation if you want it (see section on insulating). A serviceable one season temporary roof can be made with two layers of roofing paper. Start by sealing all the nails used to secure the vent, etc, with roofing cement. Staple the two layers of roofing material, star ting from the bottom, overlapping 6 inches. When you get to ak chimney jack or whatever, cut an oversized hole, not so big that it extends over the flange. Then liberally cement the paper to the flange. If you get confused while roofing, just 'pretend' that you are a drop of failing water.
When the roofing is in place, cut shingles out of the scraps about one foot square, and staple them to the intersecting edges of the roof sections, from the bottom up, overlapping 6 inches. When you are all done, no staples should be exposed except at the top. This temporarily roof has proved itself through one Vancouver Island rainy season on two cabins, with out leaking a drop. When installing a permanent roof, just use the roofing paper covered over by the roofing material. To waterproof the peak, cut an oversized hub (about 1' on an edge) out of 1/2 inch plywood, and bolt it on to the existing roof hub, using extra nuts and washers. Cement the nuts with roofing cement. The safety rope should be passed between the two hubs so it can still be used. Cover the whole cap with a layer of 4 mil. polyethylene film. A note about snow. The roof has been designed to withstand 40 pounds per square foot. We have measured 24 inches of snow on the roof without adverse effects. (1 inch of snow=1 lb. per sq. ft.). .
Before you start to sheath the walls, decide exactly where you want the windows and door. The door must be put in one of the triangles with the base on the floor, not the point. Leave one side open (not the door side) to sheath last, so you can conveniently use the elevation of the floor as a sawhorse in the event that you don't have one. It should be mentioned that any acceptable sheathing material can be used instead of shiplap. Shiplap was chosen because when it shrinks, you don't have to look at tarpaper between the cracks. For water proofing purposes sheath so the lap is under the board above it. Sheath from the top, where you nailed the first board earlier,'Crom the bottom, on the other sections. Hacksaw the hub bolts just above the nuts so the sheathing will fit properly. A fast way to sheath the walls is to have two people hold up the board, one on each side. Each person is responsible for marking, cutting and nailing, his/her side. When you get to where you marked the windows, either leave a hole or build a window frame out of 2 by 4's and nail sheathing to it. One word of caution: never cut into the supporting struts! They are all that holds the roof up. The outside of the walls should be covered with one layer of roofing paper. Although the caves are long enough to protect the walls from rain, there might be a wind which could blow moisture onto the walls. just roll the paper out, over lapping 6 inches and working from the bottom up. Cut it and staple it in place. This also serves as a vapour barrier for the insulation.
There are two ways a door may be installed. One is to fit two parallel uprights in the triangle and hang a door from them. The only problem is that the door is hung at an angle, so it closes with considerable force. This could be remedied with a hydraulic screened closer, but who wants to look at that? A better way is to build an upright frame and hang the door vertically. Because of the triangular shape of the doorway, a rectangular door wouldn't fit the frame. So, a door must be built to fit the frame. A serviceable door can be made out of shiplap lumber. Trace the outline of the door and transfer it to a few boards laid together. Make two thicknesses, one vertical and one horizontal, and nail them together. A little extra work and you can make a Dutch door. (fig. 10)
The holes that are left for windows can be temporarily covered with 4mil poly reinforced with lath strips, or permanent windows can be installed. Used rectangular windows will fit into the wall sections that originate at the points of the floor. They can be installed in the other sections as well, but they would have to be rather close to the floor or very small. Instead, triangular windows can be installed.
If you have chosen the location for windows before you started sheathing, the following is for you. If you have already sheathed the cabin and decided to put a window in where none previously existed, please see the section on alternate window installation.
To install rectangular windows a 2 by 4 works well as shown in figure 11, you will have to build an outer frame to set the windows in. Use two bevel squares to get the needed compound angles. One for the angle of the wall strut in relation to the ground, the other angle is for the strut in relation to the sheathing (twist). After determining these angles, mark and cut the 2 by 4 lower horizontal, stud, making sure it is as long as the window you want to put in. Level it and nail it. Measure the height of the window, and add 1/2" to 1/4", then measure and cut the upper horizontal strut that distance away from the lower horizontal stud. In stall it, again making sure that it is level. Note, the entire frame should be square to the sheathing. Next measure the width of the window, add 1/2" to 3/4", then cut and install to upright studs, that distance apart. Sheathe the wall triangle with shiplap. Now nail a 1" by 2" blocking frame to the inside edge of the 2 by 4, (fig. 12). If you want windows that open, simply hinge the window in any direct ion to the 2 by 4 frame. Line the outside edge of the blocking frame with weather stripping. To finish up a permanent window installation, cut 3 pieces (top and 2 sides) to the measurements of the inside blocking frame. Place the window in the opening and shim it in tight with some scraps of shingles (Figure 13). Stuff insulation in the cracks to keep the drafts out. To make a sill for the permanent installation, cut a 1 " by 4" the length of the window. Place a 1/2" shim next to the window, on the outside, to give the sill a tilt (away from the window) to shed water. Place the sill next to the window and nail it.
For the triangular type windows (Figures 11 & 14) the principle is the same except you have to make the window frames. Mark the angles, measure and cut a 2 by 4 horizontal stud to complete an outer frame (the other two sides are made up by the wall struts). In figure 11, an upper stud is shown. This is not necessary for strength or window installation, so it may be omitted. To build the actual window, take exact opening dimensions and angles. Construct a simple frame by mitering 1 by 10 pieces of wood to fit the opening. Before you nail the thing together, rip two one inch strips off the pieces of the frame. These rippings will serve to block the glass in from the inside and the outside. Take one set of the rippings and nail them flush to the inside edge of the window. Use a straight edge to make sure the blockings are in the same plane, for the glass doesn't bend. Take the nailed together window frame to the local glass shop and have them fit the type of glass you want into the frame. If you happen to have the glass on hand you could cut it your self. If you get it from the shop, let them do it, they don't usually charge for cutting. Don't, however, let them permanently install the glass in the frame as the window has to be nailed in place. Fit the window in to the opening, bringing the inside edge flush with the lower horizontal stud and wall struts. Shim if necessary and nail in place. The cracks should be filled from the outside with scrap bits of ungulate. Next, fit pieces of wood on the inside to 'join the window to the outside frame. (Figure 15) The finished exterior should come right up to the window frame itself on the outside. When the hammering is all over, fit the glass into place and nail the outside set of window rippings into place.
Alternate Window Installation
We devised a very simple window installation method to install windows on a wall that has already been sheathed. Build a 2 by 4 frame 3/4" larger (inside dimensions) than the window you want to install. To keep this frame square, nail two lath strips diagonally across it. Hold the frame at the desired height while levelling the bottom edge. Now scribe a line along the inside of the frame taking care the frame doesn't move off level. Remove the frame. At each scribed corner, drill a 1 " or larger hole. Start cutting along the line with a keyhole saw until the cut is long enough to finish with a crosscut saw or a ripsaw as required, (Figure 16). When the cutting is completed, hold up the frame again, bracing it against the sheathing firmly, and have another person (or yourself) nail it from the inside using 3%" nails, (Figure 17). Remove the lath strips, Nail 1" by 2" strips along the inside edge of the frame to provide a surface for the window to rest against. Place the window into the frame against the 1 by 2 strips., (Figure 18). Shim the window in tight with some shingles. Nail a moulding to the outside of the win- dow to hold it permanently in place. Apply some form of caulking around the outside frame (Figure 19). Use weather stripping on the inside blocking to keep out drafts and water. The caves of the roof should protect the windows from direct rain. The raw cuts through the sheathing on the inside may be dressed up by nailing up pieces of 1 by 2 mitred like a picture frame through the sheathing and into the outside frame.
First, decide what size skylight is desired. Remember, it has to fit between the roof rafters. DO NOT CUT INTO THE RAFTERS! We find that a 16" by 24" skylight is quite adequate. Using 1 " by 6", build a simple box frame the overall size of the glass. Take the box to the local figure 16 sheet metal shop and have them bend a "ZIP type flashing over it. That is, a continuous water-tight flashing, ripping over the top edge of the box, going down the side to the bottom of the box then flaring into a 6" flange. The shop may already know it as a "skylight flashing" but don't count on it. Cut a hole in the roof to the INSIDE dimensions of the box. Place the box with the flashing over it on the outside of the hole, line it up and nail the flange to the roof sheathing. Gum over the nails and edges of the flange. Place the roofing around it the same way the chimney jacks were done as described elsewhere in this article. The best way to attach the glass (auto safety glass is recommended because it doesn't shatter) is to apply a bead of silicone adhesive such as Dow Corning 781 around the top edge of the flashing. Then place the glass over the adhesive and press down. The glass may tend to slide until the adhesive sets. If so, tack two finishing nails at the bottom of the glass and into the frame. Apply silicone to the nails too, (Figure 20).
Insulation is installed on the walls by nailing spacers or dividers to the outside of wall. These may be either horizontal or vertical as required for your choice of finished exterior. They should be the thickness (or slightly less) of the insulation you want to use. e.g. 2" by 2" for 2 1/2" or R7 insulation. Space the stringers as determined by the width of the insulation, e.g. 16" for 1 5" fiberglass batts. Assuming you have already covered the walls with building paper (as a vapour barrier) nail the dividers along the outline of the wall triangles from the outside. Then measure and cut the horizontal (or vertical) spacers and nail them from the INSIDE, through the sheathing and into the spacers. Next, friction fit, staple or nail the insulation in between the dividers. Loose insulation such as "Fiberfill" should not be attempted as it will settle, leaving cold spots. Fill in the empty pockets with scrap bits of insulation (Figure 21 ). Cover the insulation with 1 5 pound perforated roofing felt, starting from the bottom, horizontally overlapping 6". The walls are now ready for the finished exterior. (Figure 22)
Finished Exteriors, 'Clapboard Style'
To achieve the 'clapboard effect shown in (fig. 23) it is necessary to install the insulation with vertical spacers. Shiplap boards are then nailed horizontally with the upper boards lap set into the lower boards lap, not meshed as usually done. Remember that the upper boards should overlap the lower so that the wall sheds water.
Start at the bottom, pre-cutting the ends the same way the initial sheathing was done, making sure that the first board is level. Nail 2 - 2" nails into each vertical insulation spacer. Repeat the pattern, making sure to set the lap into the board below it. When you get to the top board, you may have to rip the board length wise to get a suitable fit. Try to butt the adjacent wall triangles as close together as possible.
A 1/2" to 1 " space is okay, but the closer they fit the easier they are to waterproof. since the boards lap over each other the only way to for water to enter is from the joints, simply spread a thick layer of roofing gum into and over the gap. this forms a channel for the water to run down.
When the gumming is completed, apply your choice of finish to the shiplap boards. Stain preservative, paint or varnish may all be used with good results. When the stuff has dried, rip ten 10 foot long shiplap boards in half to cover the gummed edges. Nail them with the ripped edges facing away from the joint, and the lapped edges mating directly over the centre. This will totally conceal the roofing gum. Any water getting behind this moulding will just follow the channel formed by the roofing gum and exit at the bottom. Apply the finish coat to the shiplap and admire your handiwork.
Finished Exteriors, 'Shakes'
The problem with shaking the outside of the Eco-Cabin is the question of what to do at the edges of the wall triangles. This was solved by nailing 1 by 2's
on edge to the 2-by stock that was used to outline the wall triangles for insulation, (fig. 24). This acts as an edger to butt the shakes to . After you nail them up, seal the joint where it meets the wall with roofing gum or other suitable chalking.
16"horizontal spacing is used for the insulation spacers to accommodate 20" shakes nailed in a double course pattern. Start from the bottom, laying the shakes side by side making sure the bottoms are even with the 2 by 6 joists. Nail them with 2" hot dipped galvanized box nails. Cover the spaces left by the first 'coarse' by a second row of side by side (1/2" to 1 ") thus forming the second 'course'. The first course does not have to be fitted to the edger too accurately but the second course, the 'show' course, must be fitted as closely as possible. To do this, set the un- cut shake over the edger flush to the bottom. Sight along the nearest edge and mark the shake. Because of the angle of the cut, use a ripsaw, cutting with the waste side TO THE RIGHT OF THE SAW. The reason for this is that cedar will almost always split below the saw cut on the side with the least angle. If the waste doesn't split, it can be used on the next course, Measure exactly 16 inches up from the bottom of the first completed course of shakes. Tie a string at that height, perpendicular to the bottom. This will be the bottom line for the next series of courses. Repeat this pattern until the top is reached,
then proceed to the next wall triangle. When you get to the top of the wall triangle with the wide edge to the top you must cut each shake to length in order to keep the spacing equal. Around the windows and doors bring the shakes right to the edge or nail an edger around them so that you can butt the shakes as at the edges. Standard single coursing could be tried for a different effect. (fig. 25)
There are many kinds of roof coverings. Try to utilize materials that are available, plentiful and cheap. Roll roofing is the cheapest commercial roofing around and is easily applied. Asphalt shingles and wood shingles and shakes may be used. The latter aren't particularly cheap unless you split your own. The methods for installing these are amply covered in traditional building literature.
Before you run out and spend your hard earned bread on sorry looking asphalt products, consider an alternative that is really 'dirt cheap', that is sod. Consider its virtues. It gives the Eco-cabin added weight in a severe wind storm. It deadens sound, and insulates the cold from outside. An important safety feature is that it is not, combustible, serving as protection from roof fires. Sod is available everywhere, and where it isn't, it can be grown right on a dirt filled roof. It is also.very durable, lasting at least as long as conventional roofing, with the added-feature of being able to mend itself. It also looks kind a neat. Here is the way we put ours on.
Sod itself is not inherently waterproof. Consequently water passes through it until it reaches a waterproof barrier installed underneath the sod. The function of the sod, then, is to protect the barrier from erosion by the elements. This enables the use of relatively cheap materials like 6mil polyethylene sheeting This plastic, when protected from the ultraviolet rays of the sun, will last almost indefinitely. Rather then remove the temporary roof described earlier lay the poly right over it. We used 6mil poly that came in 10 ft. by 100 ft. rolls. One roll was good for two cabins. We found the 10' width too wide to handle, so we slit it lengthwise.
Start installation from the eave edge, fastening the plastic to the roof with a roofing gun. Do not staple! Overlap the top and sides at least six inches. Cut slots around roof jacks, skylights and vents that are no greater in area than covered by the metal flanges of the above. Cement the edges of the poly to the metal with the roofing gum. When the top is reached, cut an oversized section of plastic then use liberal amounts of gum to fasten it down. When this operation is completed,fill a five gallon bucket with water and dump it all over the roof. This should enable you to find any leaks. The next step is to install rough sawn cedar 2 by 4 (or equivalent) sod retainers, These literally keep the sod from sliding off, due to the slope of the roof. Measure the distance between the extremities of the roof struts. Then cut the 2 by 4 to size and neatly fit the mating ends.
Install the sod retainers by employing 1 5 pieces of angle iron 1Y2" on a side and 10" long. They should each be about 118" thick. Drill two 318" holes on each leg, then paint each angle piece with a rust preventative primer.Place three sections of angle iron to each edge of the roof, evenly spaced, with the up-turned edge away from the middle of the cabin (fig. 26)
. Drill 318" holes through the eaves so that they correspond with the holes in the angle iron. Then with 2" by 318" carriage bolts, bolt the angle iron to the eaves, nuts and washers on top. Then rest the precut 2 by 4 on the lip of the angle iron, centre it on the eave, and $crew it to the angle iron with 2" by 318" lag screws. The space under the 2 by 4 is for water draining off the roof. Repeat the entire operation to the remaining four sides. Now for the sod. You may use any type of sod available. If no sod is around, it can be grown right on the roof. To do that, lay a fine mesh chicken wire over the plastic, taking care not to puncture it. Then place soil over it to a depth of 4", and plant whatever i desired.
The best way however is to use ordinary field sod. cut it into 1 ft. square blocks using a SHARP spade. It is best to wait for a time when the sod is moist and only cut a small quantity(a wheelbarrow load) at a time -to avoid dry-out. It is convenient 'to employ one person on the ladder and one person to pass up the sod. The person on the ladder has to carefully place the sod in intimate contact with the poly to avoid spaces. The person on the bottom should closely scrutinize the bottom of each piece for sharp rocks and remove them. Beginning from the retainer work your way up, one roof section at a time. Try to butt the corners as closely as possible by breaking pieces off with your hand to suit. The same goes for roof jacks skylights,etc. No need to be overly picky, just cover the bald spots. The vegetation will grow together in a few months.
When completely sodded you can walk on the roof as much as you have to. The sod may be watered through the dry spell is to keep it green or you can let it follow the same natural cycle as its cousins in the fields. If there is a lot of rain where you live you might consider fertilizing the sod once or twice a year because all the water passing through the earth washes out most of the nutrients.
Because of the angles involved with the hubs the bord nailed into the floor should be cut at the same 65° angle as the hubs, were they meet the floor. How ever it should be noted that eventhough these hubs work fairly well on the floor the hubs at the top of the walls are very dificuld to keep from twisting and deforming the traingle which is what the whole point of how this structure works.
© Ragnar Torfason
2006 May 8