A design for small, low-cost demountable homes with full facilities (cooking, washing, shower and toilet).
© Plateau Group
This H4H design is available to any volunteer groups for non-commercial use, but please make a formal request.
H4H Fabrication Details
Both side-frames (mirror images)
See separate sides for the lining, shelving and fit-outs.
Fabrication details:Main Frame:
All wall studs are the same height so the roof is flat. Outdoors in weather it will need the floor to be slightly raise on scrap-wood chocks under the front of the floor-panel to provide some rain run-off.
Overall length of these frames are 3.6 metres - the length of the top and bottom plate timbers. The side walls are all 70mm thick and insulated for 2/3rds of length with glass-wool insulation. We have not included any noggins, mainly for reasons of simplicity in the fabrication, and the need to nail, etc. We doubt that they are necessary in such a low-height wall.
The outside height of the frame is 2.14 metres (2100 mm ply height + 40mm for exposed top and bottom plate width) This leaves 10mm of overlap top and bottom for tack-gluing the ply. The same for both Stud 1 and Stud 5 (10mm of overlap).
We suggest cross bracing (using 30mm flat gal strips) on outside across the unlined back section from studs 5 to 7. The exterior cladding will be in contact with these braces, but the cladding is probably not strong enough to stop flexing in some circumstances.
The two stub legs are made from 700x30mm timber off-cuts. They would be ideally made in two parts, screwed (but not glued) together. The main leg timber would be 325mm of 70x30, with a small 'pad' of 15mm timber 15mm screwed to the bottom to extend the overall length to 340mm.
The idea here is that:
These Stub legs add on 70mm of height -- the thickness of the floor frame -- since the floor panel is about 600mm shorter than the side panels. And since the 15mm thick pad is screwed to the end it is easy to remove on uneven ground, or outdoors where the whole unit will be tilted back to provide for water run-off.
These two floor sections are almost the last components added during erection, so all underfloor fittings and utility connections are accessible until the final stage (adding the Divider Cupboard, and water-sealing around the shower-tray junction.)
In Revision 3 we have abandoned the more elaborate idea of cutting and bending corner angle-iron in favour of a simple system which only uses gal iron hold-down straps when and where needed. The previous approach was complicated through trying to do too many things, using one length of iron, by bending and cutting the angle.
When the panels are being erected on-site there must be a very simple and quick way of locking them together at right-angles without needing more than two men. The joints need to be both strong and air-tight and held together by just a few screws.
We now use 2.1m and 1.8m lengths of moderately thick (1.2mm), 30x30mm galvanised angle-iron which are pre-drilled and attached to the sides of both the front and the back panel. This iron is strong yet it gives the joints a small amount of flexibility, and it also allows the addition of short tie-down metal straps for the roof and floor panels when the units are erected outdoors. To handle severe weather conditions, the angles can also be linked to ground stakes (short star pickets driven into the ground)
Hold-down straps are best made in bulk, because, while only a few are used during the panel-fabrication process, a few will be needed during the erection, and a few spares should be included in the Step-Box for later-date erections. They will be lost, and they are often need.
These straps would be very simple sections of flat 20mm or 30mm gal iron cut to lengths of 70+30 = 100mm. They would all be drilled with 5mm holes in the straps centres at distances of 15mm from each end, and with a mid-point hole 50mm from the ends. [Note that the screw would now be in the center of a 30mm wood face, and allow two screws in any 70mm wood face.]
A strap can be looped back on itself (screw through one end hole, then through the middle) to create a ring through which strong fencing wire can be used to tie the sides to the floor, and then tie the floor to a couple of short star pickets driven into the ground.
See also the note about adding corner straps to the back roof frames at the time the ceiling interior lining is being installed. These straps needs to emerge through saw cuts in the lining, and extend downwards for wall attachment during erection.
Plateau Group Convenor: Stewart Fist
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