Why Building Regulations Drawings Exist
Building Regulations drawings are not the same as planning drawings. Where planning drawings show what a development will look like from the outside — its form, size, and position on the site — Building Regulations drawings show how it will be constructed, to demonstrate compliance with the technical standards of the Building Regulations.
They form the basis on which Building Control inspectors check the work during construction. Understanding them helps you verify that the structure being built matches the approved specification.
Types of Drawing in a Building Regulations Package
Location Plan
A 1:1250 or 1:2500 scale map showing the site in context. It confirms the address and property boundary. Required as part of the application but contains limited technical information.
Site Plan / Block Plan
Shows the site layout at 1:500 or 1:200 scale — the position of the proposed building within the plot, drainage runs, access, and levels. Drainage details often appear on or alongside the site plan.
Floor Plans
Floor plans (typically 1:50 scale) show each floor of the building from above. For an extension project, you will see:
- Room layouts and dimensions
- Wall thicknesses and construction types
- Positions of windows and doors
- Structural elements (beams shown in dashed lines where overhead)
- Thermal breaks, cavity widths
- Floor build-up notes
Elevations
Elevations show the building from each external face — front, rear, and sides. On Building Regulations drawings, elevations show:
- Materials specified for external walls
- Window and door positions and sizes
- Heights (eaves, ridge, overall)
- Relationship to ground level
Sections
A section is a cut through the building — imagine slicing through the structure vertically and looking at the cut face. Sections are the most technically useful drawings for understanding construction because they show:
- Floor build-ups (screed, insulation, concrete slab, DPM)
- Wall construction layers (brick, cavity, insulation, blockwork, plasterboard)
- Roof construction (rafters, insulation, boarding, tile)
- Foundations (type, depth, width, concrete specification)
- Junctions between elements (eaves, parapet, floor-to-wall junction)
- U-values noted alongside insulation specifications
Detail Drawings
For complex junctions or elements, detail drawings (1:10 or 1:5 scale) show exactly how a particular connection or construction should be built. Common details include:
- Cavity wall insulation at window reveals
- Roof eaves and overhangs
- Flat roof edge and parapet details
- DPC positions at foundation level
- Beam bearings and padstone details
Key Symbols and Notation
| Symbol | Meaning |
|---|---|
| Dashed lines | Elements above the cut plane (beams, lintels) |
| Hatching | Cross-sectional material fill (brick, concrete, insulation) |
| U-value noted | Thermal performance of the element |
| NTS | Not to scale |
| Revision clouds | Areas changed from a previous issue |
| N/A | North arrow on site and floor plans |
What to Check
When reviewing Building Regulations drawings for your project:
- Dimensions: Do the rooms and spaces match what you understood to be proposed?
- Insulation: Are U-values specified? Are they consistent with your discussions on energy performance?
- Foundation depth: Is the foundation shown deep enough for the site conditions (especially in London Clay areas with trees nearby)?
- Drainage: Where does the drainage connect? Is there a sewer conflict?
- Structural elements: Are steel beam positions and sizes clearly shown?
Revisions and Issue History
Drawings have an issue history — the first issue is typically for Building Control application. Revisions are made as queries arise. Always check that the drawings your contractor is working from match the approved revision issued by Building Control — outdated drawings on site are a common cause of compliance issues.
RCB Design & Build
RCB reviews Building Regulations drawings with clients at the pre-construction stage, helping them understand what has been approved and what it means for the build programme and specification. We flag any discrepancies between approved drawings and the proposed construction sequence before work begins.