What is an as-built drawing?
An as-built drawing is a construction drawing that shows how the work was actually carried out, with every deviation from the original design incorporated. In Dutch it is called a revisietekening; the terms record drawing and as-built record are also used.
On site the execution almost always differs from the drawing in detail: a pipe runs around an unexpected beam, an opening shifts, a wall ends up ten centimetres over. Those deviations are marked up as the work proceeds and then worked into a new, valid set of drawings.
When are they produced?
- At handover — the contractor issues the as-built set as part of the operation and maintenance file
- After each completed stage — for instance straight after the foundations are poured or the services are installed, while everything is still visible
- For an existing building with no drawings — the building is measured up as found; that is also an as-built drawing
What goes on it
- Actual dimensions, levels and thicknesses
- The position and depth of services: drainage, water, gas, electrics and data
- Openings as built, load-bearing walls and any structural changes
- A clear date, revision number and the name of whoever prepared it
Practical tips
- Measure services before they are covered. A photograph with a tape in shot, referenced to two fixed points, is worth its weight in gold later
- Use a revision colour. Changes marked in red on a print of the original avoids confusion
- Make the as-built set contractual. Specify that handover is not complete without it; otherwise it rarely happens
- Keep it digitally and on paper, and pass it on when the property is sold
For a later alteration, a new installation or an investigation into a defect, a good as-built drawing quickly saves a day of searching and opening up.
Related terms
- Renovation
- Reinforcement
- Formwork
- Crawl space
- Facade
Want to learn more about construction terms? Visit our knowledge base at fredsdiyplans.com.