01The split, drawn
Draw the line in the right place and prefabrication works. Draw it in the wrong place and the factory ships a perfect item that does not fit.
The boundary is not arbitrary: the left column depends on a machine, the right column depends on the building. A factory that offers to take the site work as well is describing an installation contract, which is a different business with a different liability.
02Measure first, or template first
Two ways to get a prefabricated top to fit, and they suit different sites.
| Method | How | Accuracy | Best for |
|---|---|---|---|
| Drawing only | Dimensions from the design | ±5 mm or worse | New build, carcass not yet in |
| Site measure | Tape and laser on the installed carcass | ±2 mm | Refurbishment with carcass in place |
| Physical template | Hardboard or MDF template of the opening | ±1 mm | Out-of-square walls, older buildings |
| Digital template | Laser scan of the room | ±1 mm | Complex or curved layouts |
A refurbishment in a building over fifty years old should not use drawing-only dimensions. Walls are out of plumb by 10 mm, the floor has a fall, and a top cut to a drawing will be tight at one end and open at the other, which is a problem no tolerance on the drawing can solve.
03Installation sequence, which decides the joint
A prefabricated run longer than the access route has to arrive in pieces, and where the joints fall is an installation decision that has to be made at drawing stage.
- Access first — measure the lift, the door and the corridor before deciding piece length. A 3000 mm top that will not go round the stair is a 3000 mm problem.
- Joint on a support — every joint sits over a carcass divider or a frame member, never over a void.
- Grain continuity — pieces must be cut in sequence from the same sheet, or the grain will step at the joint.
- Joint type — a butt joint with a concealed splice, or an open reveal if the design wants to see it. Both are legitimate; deciding late is not.
We mark the joint position on the drawing and number the pieces on the crate, in installation order, because a crate of six identical-looking tops is a puzzle on site and a labelled crate is not.
04Protection, and why the last trade wins
A prefabricated top is finished when it leaves the factory. Everything after that is risk, and the risk is concentrated in the week between delivery and handover.
Two rules we put on the crate label, because they cost nothing and prevent most claims: do not stick tape to a grained face, and photograph the top before other trades work over it. Our inspection sheet gives the signatory a measured baseline; a photograph gives them a dated one.
05What to send for a prefabricated run
A plan with the access route noted, the carcass height at four points, and the joint positions you would accept. We will come back with the pieces, the crate numbers and the installation order, not just a total.
We build in 5–10 mm plate at ±1 mm on outline and ±0.05 mm on a machined edge, grade 304 or 316L, with the grain direction marked per piece so a sequence can be kept in the factory. Lead time is 15 working days from a confirmed drawing, packing is on-edge in numbered crates with formed edge protection, and each piece carries an inspection sheet recording measured dimensions and grade. That sheet is what a warranty claim is settled against, and it is the only document that survives a fit-out.
Stainless steel manufacturers · The 15-day route from drawing to container · Order terms and packing · Send a drawing for quotation