Specification desk

WillScot specifications freeze the loads before a module is cut

The desk writes a design basis in one pass: destination country, design wind speed, ground snow load, seismic design category, storey count and the foundation interface the site will actually build. Production does not start on a blank wind cell.

A 75 mm PIR sandwich panel and a 100 mm rock wool sandwich panel can share the same cold-formed frame and still fail different tests. The sheet names the core, the thickness, the target U-value and whether the fire note is a panel coupon or a wall assembly with joints and doors.

Engineer marking a module elevation beside a wall panel sample

Four checks that sit on every specification

01 Load basis

Wind, snow and seismic values are copied from the project brief or left open. ASCE 7 or the local equivalent is cited as the reference the engineer will use, not as a pre-approved result.

02 Envelope

EPS, PIR and rock wool are compared on mass, U-value and the fire strategy. A thermal bridge at the steel skirt is drawn, because a mid-panel U-value hides the frame.

03 MEP split

MEP preinstallation lists what is factory-terminated and what is a site tail: power, data, HVAC interface, sanitary. Medical gas and fire pumps stay off the standard line.

04 Packing method

The container loading plan states volumetric set-down or bolted knock-down. A 40HQ count from one method is not reused for the other.

Two specification records, written as scope not slogans

PIR wall sample measured with a thickness gauge

Heated classrooms, Ontario, 2021

Background: twelve swing-space rooms needed a winter U-value target of 0.35 W/m²K and a snow note of 1.5 kN/m². Process: the desk locked 75 mm PIR for external walls, called out skirt thermal breaks, and moved inter-room partitions to mineral wool after the acoustic brief arrived. Result: the issued sheet separated the wall U-value from the partition fire note so a single coupon could not be read as the whole room.

Bolted module corner with a torque mark

Bolted clinic frames, Gulf coast, 2023

Background: eight outpatient rooms had to share shipping with a narrow port window. Process: frames were specified as bolted knock-down with Z275 galvanized coating mass, wet areas called out for cut-edge repair, and sanitary stacks stopped at a marked site coupling. Result: wall sets shared a 40HQ plan while floors traveled on a second booking, and medical gas was written as excluded scope.

Welded volumetric frames keep lug coordinates fixed in the plant and consume more deck space. Bolted frames raise the site hour count and depend on the torque record. WillScot prices both when the road and the crane rule are known. Neither method removes the need for a local structural check.

0.35 W/m²K sample U-value target on the 2021 school sheet
Z275 Coating mass named on cold-formed camp frames
60 min Fire minute mark used when an assembly test is attached
2016 Year the rock-wool line was added beside the PIR line

Send the basis, not a mood board

  • Destination country and whether the module is temporary or a permanent reading.
  • Plan size, storeys, and the crane or road limit if you already know it.
  • Wind, snow and seismic numbers, or a note that they are still open.
  • Fit-out inclusions and the items you want kept on site.

ISO 9001 does not replace this list. A management certificate does not state a member size or a fire minute.

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