Survey Drawing Scales Explained — 1:50 vs 1:100 and When to Use Each

What Does Drawing Scale Mean?

A drawing scale tells you the relationship between the size of something on paper and its actual size in the real world. A scale of 1:50 means 1mm on the drawing represents 50mm (5cm) in reality. A scale of 1:100 means 1mm on the drawing represents 100mm (10cm) in reality.

The higher the second number, the smaller the drawing — a 1:200 drawing of a building will be smaller than a 1:100 drawing of the same building. Larger scale drawings (smaller second number) show more detail; smaller scale drawings (larger second number) show less detail but cover more area.

Standard Scales for Measured Building Surveys

In the UK, measured building surveys are conventionally produced at the following scales:

What Does Each Scale Look Like in Practice?

1:50 Scale

At 1:50, a typical 4m × 5m room is represented as an 80mm × 100mm rectangle on the drawing — roughly the size of a large postage stamp. Wall thicknesses of 300mm are shown as 6mm lines on paper — clearly visible and measurable.

1:50 is the standard scale for floor plans because it provides enough resolution to show all the detail that matters for architectural and engineering design — wall thicknesses, reveal depths, stair geometry and room dimensions — while fitting a typical residential floor plan onto an A1 drawing sheet.

1:100 Scale

At 1:100, the same 4m × 5m room becomes a 40mm × 50mm rectangle — half the size of the 1:50 version. Wall thicknesses of 300mm are shown as 3mm lines, which is still clearly visible but carries less drawn detail.

1:100 is standard for elevations because an elevation covers the full height and width of a building face. A typical two-storey house elevation at 1:50 would be too large for a standard drawing sheet — at 1:100 it fits comfortably on A1.

1:200 and Smaller

Scales of 1:200 and smaller are used for site plans and location drawings where the context rather than the detail of the building is what matters. A topographical survey of a 1-acre site is typically drawn at 1:200 or 1:500 depending on the site size.

What Does Your Planning Authority Require?

Most local planning authorities in England and Wales follow the requirements set out in the National Planning Policy Framework and associated validation checklists. Standard requirements for a householder planning application typically include:

• Existing and proposed floor plans at 1:50 or 1:100
• Existing and proposed elevations at 1:50 or 1:100
• A site/block plan at 1:500
• A location plan at 1:1250

Individual planning authorities may have specific requirements that differ from these standards. Always check your local authority's validation checklist before commissioning your survey to make sure the scale you specify will be accepted. If in doubt, 1:50 for plans and sections and 1:100 for elevations is almost universally accepted.

What Scale Should I Specify for My Survey?

For most residential and small commercial projects, the answer is straightforward:

• Floor plans — specify 1:50
• Elevations — specify 1:100
• Sections — specify 1:50

If your project involves a very large building — a large commercial property, a multi-storey building, a building with an unusually large footprint — 1:100 floor plans may be more practical to fit on drawing sheets. Discuss this with your surveyor at the quote stage.

Can the Scale Be Changed After the Survey?

Yes — scale in CAD is simply a display setting. A 1:50 DWG drawing can be plotted at 1:100 without any change to the underlying drawing. However, if you need drawings plotted at a specific scale for a planning application, confirm this with your surveyor before issue so the sheet layout and annotations are set up correctly for that scale.