As-Built vs As-Designed Drawings, Explained

By Salar Kiabi, Founder, FIMIT · 7 July 2026 · 5 min read

Last reviewed 17 July 2026

The two most important words in building documentation are "as-designed" and "as-built", and confusing them is expensive. As-designed drawings show what the architect intended before a brick was laid. As-built drawings show what actually got constructed — and, ideally, what stands there today. For anyone managing a building rather than designing it, the second one is the version to plan from.

The difference in one line

Per-wall, door and window dimensions captured from an iPhone scan in FIMIT. — An as-built record carries the measured dimensions of the detected walls, doors and windows — as the space actually is today.

As-designed: the intended layout and dimensions from the design phase.
As-built: the layout and dimensions as actually constructed, capturing on-site changes.
Current as-built: the as-built record kept up to date as the building is altered over its life.

Why the gap costs money

Buildings drift from their drawings the moment they are occupied. Walls move, partitions go up, service risers get boxed in, tenancies subdivide space. Plan a maintenance job, a fit-out or a cleaning contract from an as-designed drawing and you are quoting against a building that no longer exists — which means change orders, wasted visits and disputes.

The real problem: as-built records go stale

Most organisations do have as-built drawings somewhere. The problem is they were accurate on handover day and have quietly decayed ever since, because updating them traditionally meant commissioning a measured survey. So the drawings sit in a drawer, trusted less each year.

Keeping as-built current without a survey crew

FIMIT lets a facility team keep as-built records current themselves: walk a space with an iPhone or iPad Pro whenever it changes, and get an updated to-scale 2D floor plan and 3D model in minutes. Re-capture only what changed, keep one shared record organised by building and room, and plan from reality instead of intent.

Frequently asked questions

What is the difference between as-built and as-designed drawings?

As-designed drawings show what the architect intended before construction; as-built drawings show what was actually built, capturing the changes made on site. For anyone managing rather than designing a building, the as-built version is the one to plan, quote and budget from, because it matches the space that actually exists today.

Who is responsible for producing as-built drawings?

As-built drawings are usually produced by the contractor or design team at project handover, recording any changes made during construction. But keeping them current afterwards falls to the building owner or facility team — and that ongoing upkeep, not the original handover, is where most as-built records quietly fall out of date.

When do you need as-built drawings?

You need as-built drawings whenever you plan work on an existing building — maintenance, a fit-out, a cleaning contract, a compliance audit or a move. Quoting or scheduling from an as-designed drawing risks planning against a building that no longer exists, which leads to change orders, wasted visits and disputes on site.

Can you create as-built drawings from the original design drawings?

No — you cannot reliably create as-built drawings from as-designed ones, because the whole point of an as-built is to capture the changes the design drawings do not show. You have to measure the space as it stands, which a LiDAR iPhone scan now makes quick enough to do whenever a building changes.

About the author

Salar Kiabi, Founder, FIMIT

Salar Kiabi is the founder of FIMIT, which turns a single iPhone LiDAR walk-through into an accurate, to-scale 2D floor plan and 3D model for property and facility teams. He writes about measurement accuracy, capture technique, and getting a floor area from a phone that you can actually stand behind.