As-built drawings are detailed plans that show a building as it actually exists, including every change, addition or deviation from the original design. If you are planning a renovation, a basement conversion, a second suite or an addition in the Toronto area, they are often the starting point, because anyone designing new work needs to know what is really there, not what a decades-old set of plans says should be there.

This guide gives you a plain-language definition of as-built drawings, explains how they differ from record drawings and existing condition drawings, and walks through the situations where you genuinely need them and the ones where you may not.

What Are As-Built Drawings? A Plain-Language Definition

As-built drawings (sometimes written “as-builts”) are detailed documents that reflect the final, built condition of a structure, capturing changes made from the original construction documents. Put simply: design drawings show what was planned, and as-built drawings show what was actually built. That is why they are considered the most reliable record of a building as it truly exists.

The meaning matters because buildings rarely end up identical to their plans. Walls shift during construction, a duct gets rerouted around a beam, a previous owner finishes a basement or removes a partition. Every update or modification made since the original plans becomes part of the building’s real condition, and as-builts capture it.

In construction, as-builts typically fall into three categories:

• Architectural: layout, room dimensions, wall locations, windows, doors, floors and ceilings.
• Structural: beams, columns, bearing walls, foundations and framing.
• MEP: mechanical, electrical and plumbing systems.

For a typical house project, the architectural set is usually the core deliverable, with structural and service information added where the project demands it.

As-Built vs Record Drawings vs Existing Condition Drawings

These three terms are often used interchangeably, which causes real confusion when you are requesting a quote or reading a contract. They overlap, but they describe slightly different things.

Redlines are marked-up plans used during construction and technically differ from the final as-built drawings. Beyond that, definitions vary: some professionals treat record drawings as the formal close-out set, while others use “as-built” and “record” as synonyms. In practice, the useful move is to stop arguing about the label and state what you need in plain terms, for example: “measured drawings of the existing house, including the basement, to use for design and permit plans.”

When Do You Need As-Built Drawings? (Renovation, Permits, Second Suites, Sale, Close-Out)

The honest answer is that it depends on what you are doing. There is no single rule that says every homeowner must hold a set of as-builts. In short: you can usually skip them for cosmetic work that leaves walls, openings and layouts untouched, and you generally need them when a project changes the structure, layout or floor area, because the design cannot be done well without accurate existing information.

Renovations and additions

Designers rely on as-builts to understand existing conditions before making decisions. Without them, renovation plans can clash with what is actually in the building: a wall that is not where the old plan says, a ceiling height that is lower than assumed, a bulkhead hiding ductwork. Documentation commonly gets created before a renovation and again after construction is complete, so the second set reflects the finished work.

Building permit drawings

Permit drawings for alterations are typically drawn on top of the existing building, so they generally need an accurate base. Confirm submission requirements with the City of Toronto or a qualified designer rather than assuming. What is consistently true is that permit drawings built on guessed dimensions invite problems. For background on the drawings themselves, see what building permit drawings in Ontario require.

Second suites and basement conversions

Converting a basement into a second suite means working within the existing envelope: ceiling heights, window locations, stair geometry, mechanical rooms and structural elements. These are exactly the details that decide whether a layout works. Accurate measured drawings of the existing basement are the foundation of the design, and it is worth reading about second suite design and permit plans if this is your project. Confirm current requirements for your address with the City of Toronto.

Selling, buying or refinancing

Owners need as-built information to do pretty much anything with a building, from renovating to selling it. For a typical home sale, you are not generally required to produce a drawing set, but accurate plans can help when undocumented renovations are involved or when a buyer plans to renovate. This is a situation where the need is situational rather than universal.

Project close-out

On a new build or major renovation, the final as-built or record set is part of handover. It documents how the building was actually constructed, including concealed items such as plumbing runs or electrical routing, which become very hard to trace once walls are closed. If you are the owner on a project with a contractor, make sure close-out documentation is agreed in the contract up front.

What Should a Good Set of As-Built Drawings Include?

Quality varies widely, so know what a useful set contains. For a typical house, look for:

• Floor plans for every level, including basement and, where relevant, attic or crawl space access.
• Accurate dimensions with consistent scale and clear labelling rather than vague descriptions.
• Wall thicknesses, openings and windows/doors with sizes and locations.
• Ceiling heights and notable changes in level, bulkheads and stairs.
• Key structural and service elements that affect design, such as visible beams, columns, mechanical equipment and stacks, as scoped.
• Elevations and sections when the project involves additions or changes to the exterior or to heights.
• Notes on assumptions and any areas that could not be accessed or verified.

That last point is easy to overlook. Hidden or inaccessible systems are the weak spot of all documentation, so a good provider tells you what was not captured instead of silently filling the gap.

How As-Built Drawings Are Created: Manual Measurement vs 3D Scanning

There are two broad approaches, and the right one depends on the building and the project.

The traditional workflow is to visit the site, measure each room manually, sketch the layout by hand, and transfer the measurements into CAD software. Digital capture methods such as laser scanning and other 3D scanning tools are also used. Neither method is automatically better: a careful manual survey of a simple house can be perfectly adequate, and a scan is only as useful as the drafting that follows it.

What to Check Before Hiring Someone to Prepare As-Builts in Toronto

Architects and designers who originally designed a project are often the ones who prepare its as-builts, since they know the original intent. For an older house with no original designer on record, specialist measurement and drafting providers commonly fill that role. Either way, ask these questions before you commit:

• What exactly is the scope? Which floors, exterior elevations, sections and systems are included?
• What method and tools will be used, and how is accuracy checked?
• What will you receive? PDF only, or editable CAD files your designer can build on?
• How are inaccessible areas handled, and will they be flagged on the drawings?
• Can the drawings be used for permit plans, and will the same team (or your designer) be able to work from them directly?
• What is the turnaround, in writing, for your property size and complexity?
• Who verifies the drawings before delivery?

Be cautious of vague quotes that do not state scope or deliverables. Two quotes that look similar can describe very different levels of detail.

Next Steps: Getting Accurate As-Builts for Your Project

Start by clarifying your goal. If you are planning an addition, basement conversion, second suite or major renovation, gather any original plans, past permit records and renovation notes you have, then arrange measured drawings before design begins. Using them as the base saves your designer from guessing, and it reduces the risk of costly surprises once work starts.

If you want measured drawings of your property, you can read more about as-built measurement and drafting services in Toronto. If your project involves a lower level, there is also a related guide on what is as-built measurement and how it fits into a basement-to-second-suite project. When you are ready to talk through your property, reach out through the as-built measurement service page above.