Skip to content
Review.Live

Quality

Mock-ups and samples: agreeing quality early

By Review.LivePublished 3 min readHow we write

The architect stops at the library's east wall during the owner's walk and says the mortar joints are too wide and the colour is off. The mason says the wall matches what was approved. The mock-up panel was demolished two months ago to make room for a loading area, and nobody photographed it.

A brick wall in a blend of buff and orange bricks laid in running bond with even grey mortar joints.
Photo: Jon Moore on Unsplash

Appearance and workmanship are hard to specify in words, so specifications use physical references: samples of the materials, and mock-ups that show them assembled. Owners' specifications often make the approved mock-up the standard by which the finished work is judged, require approval before the work starts, and ask for the mock-up to be kept undisturbed until its removal is allowed. That protection works only if the approval is recorded and the reference still exists when the question comes.

A mock-up sets the standard before production; the first-installation inspection then checks the real work against it.

  1. List every sample and mock-up the specifications require at the start, with who approves each, and schedule them well ahead of the work they govern.
  2. Build the mock-up with the crew that will do the work, in the location and size the specification states, from approved materials.
  3. Get the approval in writing, with any conditions, and note what the mock-up covers and what it does not.
  4. Photograph the approved mock-up and samples wide and close, with a tape in the frame, and label each sample with its approval date.
  5. Protect the mock-up until the specification or the consultant allows removal, and record when and on whose instruction it came down.
  6. Show it to every new crew before they start, and compare the production work with it on your walks.

Common mistakes

  • Building the mock-up with a different crew from the one doing the work.
  • Approving by conversation, with no written record or conditions.
  • Demolishing the mock-up for space before the work it governs is finished.
  • Keeping approved samples in a box nobody can find.

Checklist

For each required mock-up or sample

  • Scheduled well ahead of the work it governs
  • Built by the crew that will do the work
  • Approved in writing, with conditions
  • Photographed wide and close, with a tape in the frame
  • Protected until removal is allowed, and the removal recorded
  • Shown to each new crew before they start

Check your understanding

The consultant approves a cladding mock-up but asks for tighter joints. What should the written approval say?

Show the answer
That the mock-up is approved with a condition, what the condition is — which joints and what change — and the date. Without the condition in writing, the mock-up as built becomes the standard, including the joints the consultant wanted changed. The crew should see both the approval and the condition before production starts.

Sources

  1. Section 01 4000, Quality Requirements (design guidelines, issued 2017-03-29)Northwestern University, Facilities · Northwestern University projects, United States (an owner's specification, shown as an example) · accessed
  2. Section 01 45 00, Quality Control (design standards, 2022-03-28)Missouri State University · Missouri State University projects, United States (an owner's specification, shown as an example) · accessed
  3. Section 01 45 00, Project Quality Control (design guidelines and construction standards)The University of Texas at Dallas, Facilities · University of Texas at Dallas projects, United States (an owner's specification, shown as an example) · accessed

Related articles