How to read a planning drawing

A set of planning drawings is usually a location plan, the existing plans and elevations, and the proposed plans and elevations. They were drawn to get permission, not to build from. That difference is the first thing to keep in mind when you price from them.

Start with the title block

The box in the corner tells you the job, the drawing number, the scale and the revision. Check three things:

• The scale. It’s usually 1:50 or 1:100 for plans and 1:1250 for a location plan. It only holds if the sheet is printed at the size it says, usually A3 or A1.
• The revision. A letter or number that changes each time the drawing is altered. Make sure it’s the one the council approved.
• The status. “For planning” means it isn’t a construction drawing.

Look for “do not scale from this drawing” too. If it’s there, trust the written dimensions first. Where a size isn’t written, measuring off the scale bar is an estimate, so treat it as one.

Compare existing and proposed

Put the two floor plans side by side. Whatever changes between them is your job. Walls coming down are often drawn dashed on the existing plan or noted in words. That’s where the breaking through, the steel and the making good will come from.

Read the proposed floor plan

This is where most of your quantities start:

• Overall sizes, for slab, footings and roof area
• Wall lengths and thickness, for footings and brick and block
• Openings, for lintels, steels, doors and windows
• Rooms and fittings, which tell you what the kitchen or bathroom is expected to include

Then the elevations and sections

Elevations give you heights, roof shape, and often the materials in a note (“facing brick to match existing”). A section, if there is one, shows floor build-up, ceiling height and how the roof meets the house.

What usually isn’t there

Planning drawings often leave out the things that move a price most:

• Foundation design and ground conditions
• Steel sizes and the engineer’s calculations
• Where the drains run, and how deep
• Electrics, heating and plumbing layouts
• The specification of the finishes

None of that means you can’t price the job. It means you need to say what you’ve assumed and what you’ve left out, in writing, on the quote.

Check the conditions too

The decision notice is a separate document from the drawings. It lists the conditions the permission comes with, such as materials to be agreed or restricted working hours. Read it before you commit to a price, because some conditions cost money.