A surprising share of fabrication disputes trace back to one event: somebody measured something at the wrong time, and nobody agreed who carried the risk if it was wrong. It is worth five minutes of conversation before you accept a quote.
There are two measurements, and they are not the same
The quoting measurement is approximate. It exists to produce a price — often taken quickly, sometimes from your own figures over the phone, sometimes from a drawing.
The production measurement is the one the item is actually built to. It happens after you accept the quote, on site, by the person who will make the thing.
Trouble starts when a fabricator treats the first as the second. If nobody has visited the site after you placed the order, ask when they are coming. "We have the sizes already" is not a reassuring answer unless they took them in final condition.
Final condition is the whole point
An opening must be measured in the state it will be in when the item is fitted. That means after plaster, after flooring, after any cladding. Measure before plaster and the opening will shrink by the plaster thickness on each side — twenty or thirty millimetres across, which is more than enough to stop a made-to-size frame going in.
A fabricator who refuses to take a production measurement on an unfinished opening is protecting both of you. One who agrees to measure anyway, on your assurance that "plaster is only a little", is agreeing to a problem that will arrive three weeks later.
If the schedule genuinely cannot wait, the reasonable compromise is to measure early and agree in writing that the fabricator allows a tolerance, with a stated process and cost if the finished opening differs.
Who owns the risk
This is the question almost nobody asks and everybody later argues about. There are three honest arrangements:
- Fabricator measures, fabricator owns it. The normal and best arrangement. If it does not fit, they remake or modify it at their cost.
- You supply sizes, you own it. Legitimate and often cheaper, but be clear-eyed: if your figure is wrong, the remake is yours to pay for.
- Measured early by agreement, with a stated tolerance and an agreed cost for adjustment.
Any of these is fine. What causes disputes is leaving it unstated and discovering, with a frame that does not fit, that each of you assumed the other was carrying it.
Site conditions that change a price after agreement
These are the conditions that most often turn into a revised quote. Raise them yourself:
- Out-of-square openings. Normal, up to a point. Beyond it, a frame needs packing or a tapered section.
- A sloping floor or driveway, which changes a gate from a simple swing to something that needs rising hinges, a cut bottom rail or a cantilever.
- What the fixing goes into. Masonry, concrete, stone cladding or hollow block are four different jobs. Chemical anchors into stone cost more than screws into brick.
- Access. Whether material can reach the location at all. A three-metre section and a small lift do not combine, and the alternative is fabricating in pieces and welding on site.
- Services in the way — a conduit, a pipe, a beam crossing the opening.
Take your own measurements anyway
Not to replace theirs, but to sanity-check the quote. Measure the width at top, middle and bottom, and the height at both sides and the centre, and work from the smallest. If your numbers and the quote differ significantly, ask why before accepting — that conversation is free now and expensive later.
Photograph the opening
Before work starts, take a few photographs of each opening with a tape in shot. It costs nothing and settles almost every later disagreement about what the site looked like when it was measured.