Existing Drawings for a Scottish Building Warrant or Planning Application: What You Actually Need

Almost every project on an existing building in Scotland starts with the same requirement: accurate drawings of the building as it is now. Planning officers, conservation officers and building standards verifiers all compare what you propose against what exists, and if the “as existing” drawings are wrong, incomplete or plainly drawn from a sketch, the application is delayed, returned or — in the worst case — approved against a building that isn’t there.

This guide explains which existing drawings the Scottish system expects, at what scale, and how to get them produced properly.

Two separate consents, two sets of drawings

Scotland runs two distinct processes, and most projects need both:

Planning permission deals with the principle and appearance of what you are doing — the extension, the change of use, the new windows — and is decided by the council’s planning department under the Town and Country Planning (Scotland) Act. Listed building consent and conservation area consent sit alongside it.

A building warrant deals with how the work is built — structure, fire, energy, ventilation, accessibility — and is issued by the council acting as verifier under the Building (Scotland) Act 2003. It is required for most alterations, extensions and conversions, whether or not planning permission is needed.

Both applications are submitted through the eDevelopment / eBuildingStandards portals and both require existing and proposed drawings. The good news is that the same measured survey feeds both.

The existing drawings a planning application needs

For a householder or full planning application on an existing building, the council will typically expect:

• Location plan at 1:1250 or 1:2500, based on an Ordnance Survey map, with the site outlined in red
• Site or block plan at 1:200 or 1:500 showing the building, boundaries, neighbouring buildings and access
• Existing floor plans at 1:50 or 1:100 of every level affected
• Existing elevations at 1:50 or 1:100 — usually every elevation, not just the one you are changing, so the proposal can be read in context
• Existing sections where levels, roof form or height are relevant to the proposal

Proposed drawings are then produced at the same scales and, crucially, on the same base — so the “before” and “after” are directly comparable. If the existing drawings are inaccurate, the proposed drawings inherit every error.

For listed buildings and conservation areas, expect the bar to be higher: existing elevations and sections need to record the building’s features faithfully — mouldings, string courses, chimney heads, window patterns, roof coverings — because the consent is judged on the effect on those features. Historic Environment Scotland and the council’s conservation officer will want to see them drawn, not described.

The existing drawings a building warrant needs

A building warrant application is assessed against the Building Standards technical handbooks, so the verifier needs to understand the existing construction as well as the layout. The existing drawings normally include:

• Existing floor plans at 1:50 (1:100 for large buildings), showing room uses, wall thicknesses, door and window positions and widths, and floor levels
• Existing elevations where the external envelope changes
• Existing sections showing floor-to-ceiling heights, floor and roof construction where known, stair pitches and headroom, and any changes in level

The proposed drawings then show the work in enough detail to demonstrate compliance — structural alterations, fire compartmentation, insulation, ventilation, drainage — and the existing set is what those details are drawn against. Wrong floor-to-ceiling heights, mis-drawn stairs and missing level changes are among the most common reasons a warrant application bounces back for more information.

Why the existing drawings are the part that goes wrong

Existing drawings are often produced quickly, from a walk-round with a tape measure and a laser disto, by whoever is designing the scheme. That works for a simple, modern, rectangular building. It does not work for the buildings most Scottish projects involve: sandstone tenements with bay windows and split-level closes, Victorian villas extended three times, Georgian townhouses in Edinburgh’s New Town, farm steadings that have never been square.

The usual failure modes:

• Walls drawn parallel that aren’t, so the extension doesn’t fit
• Floor-to-ceiling heights assumed from one room and applied to all
• Roof structure guessed from the outside
• Level changes between rooms missed entirely
• Elevations reconstructed from photographs, with windows in the wrong place

Each of these shows up either in the application (as a query or a returned application) or on site (as a variation, a redesign and a delay).

The fix: a measured survey drawn from a laser scan

A measured building survey produced from a LiDAR scan records every surface of the building in a single visit — inside, outside, roof and site — as a dense, measurable point cloud. The existing plans, elevations and sections are then drawn directly from that record, at the scales the application needs, and supplied in DWG and PDF so the designer draws the proposals straight over them.

Because the drawings come from the scan rather than from a sketch, they carry the building’s real geometry: the out-of-square rooms, the true ceiling heights, the fall across the floor, the roof as it actually sits. That is exactly what the planning officer and the verifier are comparing your proposals against.

For listed buildings the scan is also a permanent record of the historic fabric, captured without touching it, which is useful evidence in its own right.

What to ask for

When you commission the survey, tell the surveyor:

1. What the drawings are for — “existing drawings for a householder planning application and building warrant” is enough for them to scope the right set
2. Which drawings and scales the council’s validation checklist asks for (most councils publish one)
3. Whether the building is listed or in a conservation area, so heritage detail is drawn to the right standard
4. Your CAD standards — layering and title block — so the set drops straight into the proposed drawings
5. That you want the point cloud too — it answers the follow-up questions during design without another visit

Typical turnaround is a site visit within the week and drawings one to two weeks later. Costs are covered in our measured building survey cost guide.

Where we can help

Kanna produces scan-derived existing drawings for architects, architectural technologists, designers and owners across Glasgow, Edinburgh and the rest of Scotland. The practice is led by a Chartered Architectural Technologist, so the drawings are produced by someone who has prepared planning and warrant applications and knows what the council will look for.

Request a fixed-price quote or call 0141 260 0115.