When as-built drawings are needed for completion
At the end of construction, the approving authority inspects the building before issuing completion. If the house matches the approved plan, the process is straightforward. If it does not, the authority may ask for revised or as-built drawings and may apply its rules on deviations.
Authorities treat deviations differently depending on their nature. Some may be regularised; others may need to be corrected on site. Ask your architect to review the as-built set against the approved plan and confirm the current position with the authority before you apply.
As-built survey: what gets measured
A careful as-built survey covers more than room sizes. It records levels between floors, ceiling heights, stair dimensions and how the building sits within the plot. On older houses, walls are often not square, so surveyors take diagonal measurements to draw the shape correctly.
Hidden elements such as foundations, reinforcement and pipes inside walls cannot be measured without opening up the structure. If an engineer needs those details, they may recommend investigation such as exposing parts of the structure or other testing.
- Room sizes and diagonals
- Floor-to-floor and ceiling heights
- Door, window and ventilator openings
- Stair rise, going and width
- Plot boundary and setbacks
Using as-built drawings for renovation and extra floors
Before planning a new floor or a big renovation, you need a reliable base drawing. Designing on top of guessed dimensions leads to clashes on site. An as-built set gives your architect a correct starting point and helps the structural engineer judge what the existing frame can take.