As-Built Scan-to-BIM for a Victorian House Renovation in the Annex, Toronto

Overview

When a client of MG Design, a Toronto design-build firm, bought a detached 2½-storey Victorian in the Annex, a house well over a century old on a deep lot, the renovation was going to be designed by an architecture practice based overseas, with offices in Australia and the UK. The architects would never stand in the house. Everything they knew about it had to come from the drawings.

There were no reliable existing drawings. So before any design work started, MG Design asked iScano for 3D as-built plans in Revit: the whole house, inside and out, plus the garage and the backyard. The as-builts had two jobs: give the remote architects a true model to design in, and give MG Design a base for the permit set covering underpinning and structural work in the existing house.

Fifteen months later, with the house underpinned and the interior walls removed, MG Design came back for a second scan to bring the floor plans up to date on the stripped structure.

How it was done

1. Scope

We agreed the capture area with MG Design’s project manager: the full interior, the exterior envelope, the garage and the backyard, so the architects would have the site context as well as the house.

2. Capture, phase 1: terrestrial inside, mobile outside

A day and a half on site in December, a full day and a Saturday morning, with the listing agent present. Inside, we used a high-precision terrestrial scanner, because the interior detail was the point: trim, ceilings, the stair, wall thicknesses and the basement, all of which the renovation design would depend on. Interior surfaces were captured at 2–3 mm. Outside, the exterior envelope, the garage and the backyard were captured with a mobile scanner: faster to walk than to set up station by station, and accurate enough for site context, elevations and the yard, where millimetre trim detail was not the requirement. Both datasets were registered into one coordinate system.

3. Processing and staged delivery

The registered point cloud was ready five days after the scan and shared with MG Design for a walkthrough on screen. MG Design wanted to start work before Christmas, so we released the ground- and first-floor plans first and completed the rest of the set with the model. Everything was in the architects’ hands under three weeks from the day we arrived on site.

4. The model

The Revit existing-conditions model was built at LOD 250: enough geometry for design and permit drawings without over-modelling a house that was about to be gutted. Because the architects were on Revit 2020, we delivered the model in that version, with AutoCAD and PDF exports and confirmation that it would carry into SketchUp. The point cloud itself (about 9 GB) went to them too, with a viewer, so any question about the house could be answered by looking at it rather than by flying someone over.

5. Drawings

Elevations, plans and sections were produced from the model and dimensioned from the scan. On a Victorian, that is where the value sits: arched window openings, the door surround, the turret and the roofline are all irregular, and the drawings describe them as they are rather than as a catalogue detail.

6. Permit

MG Design used the as-built set as the base for the permit application covering underpinning and structural work in the existing house, reviewed and stamped by their building envelope consultant.

7. Capture, phase 2: mobile

Just over a year later, after the underpinning was done and the interior walls were out, MG Design asked for the floor plans to be re-issued on the new structure. This time a mobile scanner was the right tool: the building was open, only the plans were needed, and speed mattered more than millimetre trim detail. We scanned the stripped interior and updated the floor plans so the next stage could be set out on what was actually there.

What the interior designer gets

Renovations like this one are designed as much by the interior designer as by the architect, and the same as-built set serves both. From a measured model an interior designer receives:

• Reflected ceiling plans with true ceiling heights, drops and bulkheads, not nominal ones
• Wall thicknesses as built, so cabinetry, built-ins and tile layouts land on the real wall
• Stair sections with riser, tread and handrail data, the detail that usually gets re-measured three times
• Window and door openings to the millimetre, for millwork and window treatments
• A model to drop kitchen and bathroom layouts into without a site visit, and a point cloud to check any detail against

Why it mattered

The architects designed a full renovation of a house they never visited, on a model they could trust. The design-build team applied for permits on measured drawings instead of assumptions, and when the structure changed, the drawings changed with it. That is the point of as-built documentation on a residential renovation: one measured baseline at the start, and a quick re-measure when the building moves on.

Project facts

Location	The Annex, Toronto
Building	Detached 2½-storey Victorian, over 100 years old; 4+1 bedrooms; garage and backyard on a 47 × 138 ft lot
Client	MG Design, Toronto design-build firm
Designer	Overseas architecture practice with offices in Australia and the UK
Phase 1	Phase 1: terrestrial scanning inside, mobile scanning outside; 1.5 days on site; point cloud in 5 days; full set in under 3 weeks
Phase 2	Mobile scan after underpinning and demolition; updated floor plans
Accuracy	2–3 mm interior (terrestrial); mobile exterior for context and elevations
Model	Revit existing-conditions model, LOD 250, delivered in Revit 2020
Deliverables	Point cloud + viewer · Revit model · floor plans, RCPs, sections, elevations · AutoCAD · PDF · site photos
Used for	Renovation design by a remote architect and interior designer; permit set for underpinning and structural work

Planning a renovation on a house with no drawings? See our as-built documentation service, Scan-to-BIM services and 3D laser scanning in Toronto, or read our guide to 3D scanning for Toronto building renovations and the difference between static and mobile LiDAR.