Drawing Extension Plans: What to Include for Planning Permission 

Drawing Extension Plans: what “good” looks like for planning

When homeowners talk about Drawing Extension Plans, they’re usually trying to do one (or more) of these things:get planning permission, confirm Permitted Development with a Lawful Development Certificate, or give a builder enough information to price accurately.

For planning permission, “good” drawings are not about fancy graphics. Instead, they’re about clarity.A planning officer should be able to answer these questions quickly:

• What is currently there?
• What are you proposing to build?
• How big is it, and where does it sit on the plot?
• How will it look from outside?
• Will it affect neighbours (light, privacy, outlook) or the street scene?

If you want the wider context of how drawings fit into a full householder submission, our pillar guide is a good companion read:our complete application checklist.

Planning drawings vs Building Regulations drawings

One of the biggest stress-points we see is homeowners assuming “drawings are drawings”.In reality, planning and Building Regulations serve different purposes, so the information level is different.

Planning drawings (what the planning department uses)

• Focus on size, siting and appearance.
• Show how the proposal relates to boundaries, neighbours and the street.
• Typically include existing/proposed plans and elevations, plus a site/location plan.

Building Regulations drawings (what Building Control uses)

• Go into construction detail (structure, insulation, fire safety, ventilation, drainage, etc).
• Often coordinated with structural calculations (Part A) and energy requirements (Part L).
• Used for inspections and compliance sign-off.

If you’re unsure what you’ll need for Building Control, this guide explains it in plain English:what’s required for Building Regulations approval.It’s also worth understanding how inspections work in practice viaour Building Control overview.

What to include in Drawing Extension Plans for planning permission

Although councils vary slightly, most householder submissions in England expect a familiar “core set” of drawings.Below is the checklist we use when helping homeowners prepare a clean, easy-to-assess pack.

1) Location plan (usually OS-based)

• Shows your property in context (nearby roads/landmarks).
• Typically includes a red line around the application site.

2) Block / site plan

• Shows the plot boundary, the proposed extension position, and key site features.
• Usually includes adjacent buildings, access points, and sometimes trees, sheds or hardstanding.

3) Existing and proposed floor plans

• Clear “before and after” layouts, labelled as Existing and Proposed.
• Walls removed/added should be obvious, and room uses should be labelled.
• Where helpful, add key dimensions so the proposal can be understood at a glance.

4) Existing and proposed elevations

• Usually the most important drawings for neighbour impact and appearance.
• Show window/door positions, external finishes, and ridge/eaves heights where relevant.
• Make sure the elevations match the floor plans (openings line up, projection depth is consistent, etc).

5) Roof plan (often needed)

• Helpful where roof forms change (flat roof lanterns, parapets, pitched roofs, dormers).
• Can prevent “back and forth” questions about drainage falls and roof shape.

6) Sections and levels (when your site isn’t flat)

• Particularly useful for sloping gardens, stepped floor levels, or where neighbour relationships are tight.
• Shows floor-to-ceiling heights, roof build-up intent, and how the extension sits relative to ground level.

7) Notes that quietly improve approval chances

Planning officers are assessing impact, not construction detailing. However, a few short notes can make your proposal easier to support:

• Materials: a short note like “brick to match existing” / “grey aluminium bi-folds” / “roof tiles to match”.
• Obscure glazing: if a side window could affect privacy, specify it early.
• Boundary treatment: if you’re adding screening or a new fence, show it on the site plan.

If your project is specifically a house extension, this deeper guide is helpful for the pre-submission stage:how the extension permission process usually works.

Who can produce your drawings (and when DIY is risky)

Homeowners often ask us: “Can I draw my own extension plans?” In many cases, yes — councils don’t require you to use an architect.That said, “can” and “should” aren’t always the same thing.

When DIY drawings can work

• Your proposal is simple (for example a straightforward single-storey rear extension).
• You can measure accurately and draw to scale.
• You understand that the planning officer needs consistent drawings, not just a sketch.

When DIY becomes a false economy

• You’re close to boundaries or neighbours’ windows.
• The design includes unusual roof shapes, level changes or large glazing.
• Your home is in a conservation area or is listed (or near a listed building).
• You expect to move windows/doors multiple times during design.

If you want a quick sense-check of what’s normally included for a typical householder pack, this PME guide is useful:what most homeowners include for house extension submissions.

How to draw extension plans step-by-step (practical checklist)

If you’re trying to work out how to draw extension plans (including “how to draw extension plans free” or “draw extension plans online free UK” searches),the process below is the safest way to avoid inconsistencies.

Common mistakes that delay approval

Even when the design is perfectly acceptable, small document issues can slow things down.Here are the problems we see most often with extension submissions.

Mistake 1: Drawings that don’t agree with each other

• Plans show one window position, elevations show another.
• Extension depth differs between plan and elevation.
• Roof height is unclear or inconsistent.

Mistake 2: Missing context for neighbours

• No clear boundary lines or neighbour windows shown where relevant.
• No section drawing where level changes create uncertainty.
• Side windows that could affect privacy, but no note about glazing type.

Mistake 3: Treating planning drawings like construction drawings (or the other way round)

Planning officers don’t need every insulation layer or steel beam location.Meanwhile, your builder and Building Control often do.If you try to use one pack for everything, it can create gaps in the next stage.This guide explains the “next stage” documents clearly:how councils typically assess an application pack.

Related homeowner searches (and what they usually mean)

If you’re searching phrases like “drawing for extension”, “drawing house extension plans”, or “free software for drawing extension plans”, you’re normally trying to solve one of these problems:

• Speed: you want something you can submit quickly.
• Cost control: you want to avoid paying twice for rework.
• Confidence: you want to know you’re including what the council expects.

A quick rule of thumb: the cheaper or faster the method, the more you must personally manage the risk (accuracy, revisions, and “missing sheet” issues).If you want us to take that stress off your plate, we can help you package everything properly first time.

FAQs: Drawing Extension Plans

Next steps & useful PME guides

If you’re moving from “rough idea” to a real submission, these PME guides usually help homeowners avoid expensive detours:

• How to check if you need permission at all
• The typical extension permission journey
• A plain-English overview of compliance requirements
• What Building Control does (and what they’ll look for)
• What timelines tend to look like in real life

Key facts snapshot: Drawing Extension Plans

External references

• Planning Portal guidance (national resource)
• GOV.UK overview of planning permission

Final thought

The best extension submissions are the ones that remove uncertainty.If your drawings are consistent, properly labelled, and show neighbour relationships clearly, you give your application the smoothest possible run.That’s exactly what good Drawing Extension Plans should do.