Survey before
you cut
The structural drawing is what someone intended. The survey is what exists. On custom metalwork, only one of them can be cut to.
Drawn from jobs run in 304 and 316L on our own factory floor in Foshan, not from a style guide.
- Reading time
- ~6 min
- Typical deviation
- 10–20 mm
- Worst we measured
- 38 mm
- Survey time
- 1 day
How much deviation is normal
On a cast concrete column, 10 to 20 mm from the structural drawing is ordinary. On a blockwork wall with plaster, the finished face can be 15 mm from where the drawing says.
We have measured fourteen columns in one lobby ranging from 4 mm to 38 mm off. None of them were defects. They were all within structural tolerance, and all outside cladding tolerance.
What to measure
- Width and height at multiple heights, not once
- Plumb, in both directions
- Wall thickness, if a reveal is involved
- The finished face — plaster, stone, tile — not the substrate
- Floor level at the base, because gaps hide there
If you are measuring for us, four points per opening is the minimum. Photographs of the tape against the surface are worth more than a tidy table.
Who should measure
Either us, or you with a clear method. What matters is that the measurements exist before cutting and that the shop drawing is re-issued against them.
The failure mode is not "nobody measured". It is "someone measured and the drawing was not updated" — which is worse, because everyone believes the number exists.
What it costs to skip it
A survey takes a day. Re-making a set of column casings takes two weeks plus a plating batch, and the plating batch is the part that moves the delivery date.
Survey is the least expensive step in the whole job and the one most often reduced to "we will check on site".
Got a drawing
that contradicts
one of these notes?
Send it. We will tell you what we would do with it, whether you order or not. The 48-hour question list is free.