GRP pods

How does GRP pods work, step by step?

1. 1

   Step 1: Standardise the bathroom before anything else is fixed

   The pod route starts with a decision by the client and the designer to reduce the number of bathroom layouts to as few as the brief will bear. Every distinct layout is a distinct mould, and moulds are the dominant tooling cost. The design team works through the accessible units, the mirrored handings, the units with a window in the bathroom and the units with a sloping ceiling, and either brings them into the standard family or accepts them as separate types built another way. This is not a detail exercise. It is a briefing exercise, and it happens before the general arrangement drawings are anywhere near complete.

2. 2

   Step 2: Design the pod as a component, not as a room

   The manufacturer takes the agreed layouts and develops them into a mould design. The internal dimensions, the position of every drainage and supply connection, the electrical entry point, the ventilation route and the door swing are all fixed in that geometry. The designer sets what the pod has to achieve and the manufacturer decides how the shell delivers it. Everything the building needs to give the pod - the structural opening, the connection points, the tolerance the pod sits within - is written down at this stage, because once the mould is cut the pod is no longer a variable.

3. 3

   Step 3: Build and sign off a prototype

   The first shell out of the mould is a prototype, and it is inspected as one. The design team, the client and often the eventual end user walk into it, use it and mark it up. Reach, door clearance, shower spray pattern, the position of the mirror against the light, the feel of the floor fall - these are things drawings do not settle. Changes are cheap at prototype stage and expensive afterwards, because they may mean altering or replacing the mould. The signed-off prototype becomes the benchmark against which every production pod is checked.

4. 4

   Step 4: Mould the shell and fit it out

   Production runs to a repeating factory cycle. The shell is laid up in the mould and released, then moves along a fit-out line where the sanitaryware, taps, screens, pipework, wiring, extract, lighting and accessories are installed by people working at bench height in good light with parts to hand. This is the part of the process that produces the quality difference, and it has nothing to do with the material. A person fitting the fiftieth identical shower valve in a warm factory, with the right tool already in their hand, does better work than the same person doing it once on the eleventh floor.

5. 5

   Step 5: Test every pod before it leaves the factory

   Each completed pod is tested as a finished assembly. Pipework is pressure tested, drainage is filled and checked, the electrical installation is inspected and tested, the extract is run, and the wet areas are flood or spray tested. Defects are corrected in the factory with full access and no programme pressure from other trades. A tested pod arriving on site should need nothing but its connections, and that is the whole commercial argument for the method - it moves the finding and fixing of faults into the cheapest place to find and fix them.

6. 6

   Step 6: Protect, transport and move into position

   The pod is wrapped, its openings sealed and its vulnerable corners protected before it leaves. Delivery is sequenced to the site programme rather than to the factory's convenience, because a pod delivered early has to be stored somewhere dry and secure, and pods are awkward things to store. Moving the pod into position is a planned lifting or handling operation designed by the appointed person for the project, taking account of the route, the weights involved and the state of the structure at that time. The route into the building is checked physically, not on a drawing, before the first delivery arrives.

7. 7

   Step 7: Set, level and connect

   The pod is set down on its bearing, levelled and packed to the level the design requires, and fixed as the designer has specified. Services are connected at the pre-set interface points, the door threshold and any surrounding construction are made good, and the fire-stopping around the pod and at every service penetration is installed and recorded as a separate, inspected operation. Fire-stopping around pods is a recurring source of defects precisely because it is the one part of the assembly that is still built on site by hand.

8. 8

   Step 8: Commission, hand over and protect until completion

   The pod is retested in place, because a unit that passed in the factory has since been lifted, transported and connected to a building. Water is run, drainage is checked under load, the extract is tested against the ventilation strategy and the electrical connection is verified. The pod is then locked or sealed and left alone. On most projects the pods are complete rooms sitting inside an unfinished building for months, and the damage they suffer in that period is done by other trades using them for storage, for shelter or as a convenience.