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
[Highest Skill Level]
This is a tip-up toilet, which is flushed by a tip-up wash-bowl. The whole WC unit, including toilet seat and frame, is entirely timber. However the timber toilet tray, is topped by a conventional plastic toilet seat (but without the lid...see notes on using the lid later).
The flush drops into a sloping plastic box, probably a gardener's planter-box (about 160x120) or a paint-roller tray, about 500mm in length. [See notes below for alternatives] This collector has a glued-in conventional U-bend outlet which feeds the disposal pipe system. You should purchase and use the more expensive type of U-bend which allows multiple output directions, and is highly adjustable.
How it all works:
The water added to the Wash-basin is tipped back into the WC unit. Initially it will drop vertically but later large amounts will drop further back, and splash forward from the angled splash board. The plastic toilet seat will probably open automatically against the back liner, but if not, you might screw on a length of PC pipe under the seat near the joint as an easy-to-clean spring.
The toilet tray liner must be flexible because it bends over the planter-box edge every time the toilet is tipped. The back wall liner should be flexible, but it probably has very little flexing. It has been suggested that a short length of white lino would be idea and look very hygenic. The toilet tray plastic could be anything from an old piece of shower-curtin, to a kitchen cutting board. Note also that by putting the toilet seat hinge on the inside of the tray-cavity (not in the tray itself) and on the outside of the plate below it generates a shower-drip ledge that keeps shower-water in the shower-tray area.
Make the main outside frame first, with the two uprights (say, 40mm less than the full raised-room height. This is (2140 - 340 = 1800) which is 1.8m. Then add the top horizontal cap of (700-30) 670mm length between the two sides. Also add the other same-length timbers, and the 200mm wide collector/support which lies behind the planter box to form the collector space.
The face of the WC (including the bottom Collector Cover, Toilet and Washbasin drop doors, and the two vertical doors of the cupboard should be cut from a single piece of 8mm water-resistant ply of 1.8m x 0.7m. Use this ply in its precut full-size (while it is square) to make sure that the whole WC frame remains square.
Turn the frame over and either add a 700x1000mm sheet of plywood as backing to the cupboard area from the top down, say, for the top 1.0m (or so -- you could do the whole back which would help with transport, but be costly since it needs to be water-proof if below basin level).
If you decide not to bother backing this cupboard, screw on two sets of cross-bracing straps made from the 30mm gal iron. This is all needed to hold the unit square.
Note that we have added a 670mm length of 20x15 timber across the unit directly under the cupboards. It only provides some extra rigidity to the WC unit and holds some sort of liner attachments, so it could be a piece of waterproof ply. This liner could be plastic curtain material, but for appearance sake, we suggest something like white linoleum, or some form of heavy-duty sheet plastic. This back liner needs to be the full width of the WC unit, and if possible curve around a little at the sides.
We are now about to cut all the door panels from the single 1.8 x 0.8m sheet of 8mm ply you used to check the frame was square. Measure twice, then cut once. From the bottom:
Leave the rest of the ply intact: Don't cut this last cupboard door panel until everything else is finished, including attaching hinges to what will be the cupboard doors. They can be marked for 'checking in' on the side frame, to sink the hinges in a millimetre or so. You don't want gaps so close to the shower head.
Only when you've checked and fitted the lower-doors should you finish off the cupboard.
You might strengthen up the frame by screwing the bottom Collector Cavity cover in place, but do this only to check that everything is square. Then mark up on both sides where the door junctions are to fit on the side frames.
Originally we planned to support the seat in use by adding some blocks or 'stops' on the back-wall and the Divider Cupboard. Both the WC unit and the shower tray span the same 700mm distance between the back-wall and the Divider Cupboard, so the folded-down toilet tray door could obviously be safely supported this way. You may still choose to do this by adding some external timber blocks to each side. The open Wash-basin unit obviously could easily be handled by this method.
However we now believe that it will be better to keep all elements of the Water Closet unit as a functioning whole; so both the toilet seat door and the wash-basin tray are best supported by diagonal chains. These are attached to the outside triangle tray supports, and back up to the WC 'walls' at an angle of about 45 degrees. You can fix these with heavy screws, but better is with short flat-head 'gutter' bolts and nuts. Note that special chain cavities have been added alongside the seat frames so that the chains have their own droop and storage space.
By making these units self-contained, it's distinctly possible that they present a manufacturing potential for the homeless, because they are suitable for small houses, Granny flats, large caravans and mobile homes. There has recently been a suggestion that they could be considered as flat-pack design for foreign-aid export to India-Pakistan and Indo-China.
The WC unit must look more clean, sterile and finished than the other components in the unit, so if you are making chain links to the drop-down doors, then use the nut-and-bolt type with some chrome nuts if you can. Also the same for the WC's door handles; they need to look clean and sterile even though blocks of wood or off-cuts from a broom handle would work OK.
The Wash Bowl
The bowl is nothing more than a cheap plastic portable basin (rectangular or oval in shape ... see discussion on flushing). It can be fixed to its plywood hinge-down door by nothing more than a single gutter-bolt through the door ply (it won't leak).
The tray on which the basin sits is just a single 700x300mm piece of 8mm water-proof ply (or just water-tolerant ply). Cheaper ply can be well lacquered and perhaps covered with a glued-down plastic sheet surface, mainly to protect it from soap, which will inevitably be left on the flat top.
It is best if the drop-down wash-basin tray is hinged on two timber blocks screwed to the WC side timbers as illustrated here, with the hinge fixed UNDER the block, but OVER the door, and with the pivot projecting into the gap between.
Perhaps you could also screw a small plastic food tray down to these blocks on both sides, and add a toothbrush holder here (Angle-gal with large drill holes?) while you are finishing the unit off.
Overhang for drips
The idea behind this hinging suggestion is that the basin's door can project out a little at the base, yet fold back to a vertical position slightly more than upright (the basin weight keeps it closed). This then leaves a slight ledge overhang between each door which gives any shower-water draining off the door surface a way of dropping away from the door edge below.
A few drips probably don't matter much with the raised floor and air circulation, but we should try to keep all splash and surface water within the shower-tray area if we can. We are not over-concerned about completely water-sealing every component of the toilet-shower area; it is exposed a little to the weather outdoors anyway, and a few drops under a raised floor is not going to be a problem.
Since the toilet unit door will be closed to flush it, and the soiled tray vertical, the basin's flush water will probably always clean the tray relatively well. However, by adding a horizontal/angled splash timber (100mm wide) the majority of the falling water will be deflected against the soiled surface.
As the user progressively tips the basin, the water will pour out from a point which will initially be fairly close to the hinge face, then the flush will move progressively across the 200mm depth of the WC unit as it strengthens. By adding some angled baffles to the side of the splash board you can concentrate the strength of the flush even more in the central tray area (as we suggested in the toilet-tray area).
These units are going to be used for personal, clothes and food washing, so there is no reason why they shouldn't be kept as clean and hygienic as a conventional porcelain type.
The Toilet Seat Frame
Essentially the seat unit is just four triangular supports screwed and glued to the drop-down door made from 8mm ply. The basic units have a 20mm gap in the front, and 180 height at the back. The door will be hinged to the cover-plate (hiding the collector and U-bend) below ... BUT with the lower arm of the hinge on the outside of the cover-plate, and the upper arm on the inside of the door, so as to create a drip-ledge for any shower-water run-off.
The aim is to leave space on each side of the toilet seat for the supporting chains -- then provide two triangular supports for each side of the seat -- and have a solid cross-timber at the back to which the plastic seat will be hinged.
The interior width of the WC is 700-30=670mm, allowing 15mm each for side timber thickness. The suggested dimensions for the seat unit:
At this stage with the toilet tray and wash-basin hinged and spaced correctly, you should complete the top cupboard with its shelves, upright, and two doors.
Ideally, have the top cross timber for the WC wide enough extend out forward over the cupboard doors to stop any water penetrating there. If you only have 200x15 timber then set the top cross timber forward, leaving a gap at the back where it doesn't matter.
You should only separate the two top doors after you've fitted the door hinges on the back of the doors, and made sure that everything is square.
You will probably need to notch the centre shelf of the cupboard to accommodate the 25x15 mm vertical which is needed behind the vertical door gap to stop any shower splashes entering between the two doors. This vertical timber could be notched into all three horizontals of the cupboard if you think of it early enough. This would probably make the whole cupboard slightly stronger (since it lacks a ply backing).
Fix four small cupboard hinges to the ply and then mark and 'check-in' (set in) the hinges on the WC uprights, and do this before you separate the two doors. With this approach, everything should finish square, and only then, with clean and even saw slots, you can saw between the doors, all horizontal and vertical doors. It just needs a sanding and some lacquer or paint (make it bright) with a good paint finish. Then add a couple of handles. It's worth spending time on this unit.
The most fool-proof form of door locks are cheap strong magnets (about 8x8mm) from the hardware store (often sold by the dozens) which can be superglued into a drill-hole in the timber directly behind a metal counter-sunk screw or a glued-on metal plate.
There are three liners.
Waste & Flush
With our model building, it quickly became evident that the toilet-flush system would probably benefit from baffles to channel the water spilling from the wash-basin out to the sides was ineffective. The more the flush-water could be deflected from the sides towards the centre, the better. The WC unit is 700mm wide while the whole tray area is only 300mm, and the waste soiled area of the tray is most likely to be only 100mm.
We believe there are three (all effective) ways to do this, and all of them defy my three-dimensional drafting skills, so I'll describe them instead. If you build a unit it will quickly become obvious to you which is the easiest way to do this ... or maybe find none of them are necessary. All can be added after the unit is fabricated.
The toilet seat unit (with or without these triangular baffle/concentrators) now has a number of hollow cavities, and inevitably there will be some splashing of solid wastes from the collector tray. There are three ways to handle this:
Collector Tray and U-bend
The ideal Collector Tray turned out to be a gardener's planter box of about the dimensions we needed (500x150x150) but when we returned to buy, all of them at that size were already sold. Others were all perforated in the base. You could use paint-roller and wallpaper-hanger trays also. Another alternative is a length of plastic guttering with two end pieces. The width of the Collector Tray is not really important, and you can chock on the sides of the tray if the one you buy is less than 150-170mm wide.
The tray needs to sit on an angle to maintain a reasonably strong flow, and it is important not to have an obvious obstruction where it enters into the U-bend (this is obviously important).
Buy a reasonably good, adjustable U-bend. They come with swivel joints so that the output pipe can face in any direction, as well as up or down. The pipe department at your hardware store will also have a range of pipe fitting (which might just be a short length of pipe, or a standard pipe-joiner). You won't want to cut the U-bend itself, it will be expensive. Note that rain-water down-pipes and fittings may be much cheaper the sewerage fittings, but generally they are of a thinner plastic (which doesn't matter here since the pipes aren't underground).
Fitting the U-bend:
We need to add the U-bend to the low end of the collector box by using a good, strong plastic glue (and self-tapper screws). Don't cut the U-bend; cut the connector as illustrated here.
This was the original way of mounting a U-bend to the end of a planter-type box.
You can use an electric drill with a side-cutting 'hole saw' to create the pipe-size hole in the end of the planter.
You must cut this hole as close as you can get to one side of the box, because you will need to strengthen the joint by adding a couple of self-tappers, as well as using quite a lot of plastic glue which will create the main joint bond. You should then drill and screw the fitting onto one side so as to lock it hard into the planter. Remember that the other side of the planter has a 70x30 timber underneath. Which side this will be? depends on which way you want the output to flow.
You may need to strengthen the fitting vertically by adding a small L-shaped bracket to the top of the pipe, and lock it back against the planter box.
Important: You will need to block the small gaps (red) underneath and to the sides of the planter box. The gaps may need to be plugged with glue and some softened pipe offcuts.
Warning: You probably should not add screws from beneath the box to strengthen the fitting because their projecting thread will emerge in the middle of the flow and certainly catch toilet paper.
You can now fit the U-bend itself. The importance of the U-bend lies in the fact that the water in the pipe will sit below the connection level.
The outside width of the WC unit should be 700mm to allow it to fit between Stud 6 and 7 (We have set these 708 apart). The uprights of the WC are made from 200x15 dressed pine. This timber is generally cut and dressed to fairly accurate dimensions but it shrinks with age. The space between studs can easily be a couple of millimetres wider or narrower than anticipated also (there are some angle-iron joints here), so our working dimensions for the WC should be no more than 700 mm as an outside width, and an inside width of 670. (allowing 15mm each for the two sides.) The horizontal timbers should be cut accurately to this 670 length: you will need:
You should purchase:
We are surprised to find recently that AA grade 8mm Marine Ply in 1220 x 2440 sheets was only twice as expensive as lower grades in structural and BC grades (with only one surface with first-class veneer). Unfortunately a single sheet gives you the 700mm wide face material for the WC and leaves only 400 for the back of the Divider Cupboard which obviously needs the same grade of water resistance. However the cut patterns here get good value out of the sheets.
Use 8mm AA grade Marine Ply for the main door surfaces, and we would strongly suggest the use of solid 200x15 planks of good quality pine should be the main structural material for the Water Closet. You'll need a small amount of 150x15 (total 1.2m) for the actual toilet seat supports (or use a piece of structural ply cut out into a U-shape).
Note that the sides of the plastic seat support projects back beyond the supporting triangles about 50mm to accommodate the hinge-points of the toilet seat. We could have left the seat lid intact but there doesn't appear to be much point unless it acts as an efficient water deflector (you make up your own mind), and it is a large surface that will be constantly wet when people want to use the toilet.
The toilet seat support:
The toilet seat frame uses four (almost) triangles cut diagonally from two pieces of 200x15 dressed pine. The long diagonal-cut sides screw onto the drop-down Marine Ply door. The top has two 250mm lengths of 75x15 which provide the plastic seat's side supports, and a cross-ways "H" of the same material (but now 600 in length ) provides the hinge point for the toilet seat across the back. You will need some battens under these joints to create a single U-shaped seat support.
One suggestion worth exploring is to use a short (600mm) length of a large sewerage pipe, which has been cross-cut half-way through, then longitudinally slit between these two. You can then open the two sides of the pipe out, using the plastic bending technique discussed below (using a length of copper water pipe as a heat-transfer)
PVC Drain pipes come in 10mm variations, so you can get 90, 199, 150 mm in 6mm grade, and lighter grades for stormwater.
Start with the 200x15mm pieces of timber. Square cut two lengths of 410mm (for the triangular supports) and another two for the side seat support of 335mm ????CHECK.
Using both lengths of 410mm, mark 20mm down on one side corner, and 20mm up on the other. Then by join your two opposite points you will have marked a cut line, which gives you two 'triangles' out of each piece. You need all four.
Check dimensions before cutting (you may have slightly narrower timber ... the the 410mm seat line is the dimension which matters. The diagonal cut line length at 410mm should be the right dimensions for the toilet seat (but don't worry if it is 10mm or so out). The seat support planks can be slightly longer or wider to take up any discrepency.
Check:The uncut tray length will be 410mm, and each will have right-angle ends of 20mm and 150mm. The diagonal length of the cut doesn't matter all that much, but since it attaches directly to the drop-down door you need it not to overhang at the front. A little at the back is probably OK, but all four triangles should be the same, so check these dimensions before you saw.
You'll need to cut off the lid of the purchased item, you don't want this in use, then you can assemble the unit with the plastic seat (and its hinge) on top. You can best figure out how to do this, however couple of screw-eyes, with a larger screw into the plastic and used as the pivot is a good place to start.
Check that the seat is not projecting too far forward for door closure before you fix the hinge position. The whole toilet seat unit should be about 410mm or so front-to-back . The plastic seat will be about 380mm wide, (and it will sit 15mm above the timber).
When in the tipped-up closed flushing position, the seat should now fit into the space between the WC's front and the lining and outside cladding wall with a minimum of spare space. If your unit ends up a bit thicker than this, it will still close and fit since the WC can be moved forward a bit from the wall before being fixed with screws into Studs 6 and 7 (both top and bottom).
There may be a problem with the flush-water not hitting the pan strongly enough to wash it clean. This may arise from your selection of liner type, or it may be a case of the water not being deflected strongly enough onto the tray surface. Generally it will be OK. Anyway, the whole toilet is relatively easy to clean, and the output collector tray below can also be easily cleaned and unclogged.
If your toilet seat doesn't automatically open when tipped, it may not allow the full flush to reach the tray. If so, you may want to screw a 30cm length of standard transparent PVC or other flexible tubing under the plastic seat (back near the hinge) to act as a spring. The seat should then lift a little when the weight is removed.
We suspect that this spring is not necessary and that the flush water flowing over the vertical seat will cause it to open enough automatically.
The restThe ideal way to line the tray: 1. flexible heavy duty builders' "carpet saver" in rolls 2. A white plastic kitchen waste unit. It stands 45mm high, with a square cross section, and a slight taper about 25-30cms across. The L-shaped opener in the lid can be used as a water deflector. How to bend plastic. Mostly you will want to bend to produce clean straight bendpoints' The way to do this is to clamp a short length of copper water pipe to a bench-top gas jet, leaving a foot or so projecting out into the room. Turn the gas on and hold the plastic sheet in contact with the pipe. It won't take long for the line of contact to soften a very straight line in the plastic, which is easy to bend. Need to paint Two different hinge systems Add wirebasked soap tray pivot over chain space' 20 offcuts