Extension Drawings for Planning Permission

Do you need planning permission for an extension?

Usually, yes. Most home extensions need full planning permission from the local authority, and the authority would very much like to see the thing drawn properly before you go anywhere near a brick. That application has to be supported by a particular set of scale drawings — not a sketch on the back of a quote from your builder, however confident he was about it.

Some smaller extensions fall under permitted development instead, meaning you can build without a full application. You will still usually want that in writing, because the person buying your house in nine years' time will ask, and “the bloke said it was fine” is not a document. Our PD Compliance Pack checks eligibility first and produces a Lawful Development Certificate that proves the work was lawful.

What extension drawings you actually need

A householder application needs your house drawn as it currently is, and again as you intend it to be. That is the whole job. The Standard Planning Pack is that full set:

• Location & site plans
• Existing elevations
• Proposed elevations
• Existing floor plans
• Proposed floor plans
• Reasonable revisions within the original agreed project brief

The first draft is normally issued within 7–10 days once Plan Pros has received the completed self-survey and all project information reasonably needed to start, and either you have expressly requested early commencement or the 14-day cancellation period has ended. The drawings are delivered digitally for the planning stage and marked not for construction unless an expressly different written scope applies. What the council then does with them is, regrettably, outside our control.

The wording varies depending on who you last spoke to — house extension drawings, extension planning drawings, planning drawings for an extension. They are the same drawings, under the same fixed fee, whichever phrase you arrived with.

What extension plans cost

£650 covers one straightforward single-storey extension with up to 50 m² of new or materially altered floor area. It includes one agreed proposal and one planning route at one existing house. That keeps the published price fair for the normal project without making a small customer subsidise a much larger brief.

Architects commonly charge a percentage of your build cost, which quietly means the more ambitious your extension, the more your drawings cost — despite being, in every meaningful sense, the same drawings. We have never managed to make that add up either, so we do not do it.

If measuring your own house does not appeal — and for most people it genuinely does not — the Enhanced Planning Pack at £899 sends us out to measure it instead, plus fast-track drafting and 3D imaging so you can see the proposal before you commit to it. The survey covers 25 miles around Retford.

Larger and combined extensions

Two-storey and wrap-around extensions, more than 50 m², combined extension-and-loft schemes, multiple design options and unusually complex roofs, levels or sites take more survey information and drawing time. We quote those projects individually once we have seen the brief. The same applies to new dwellings, flats, HMOs, commercial work, listed buildings and specialist supporting reports. Send the project for a scope and price check before ordering a fixed pack.

What happens next

You send measurements and photographs. We draft the set and include reasonable revisions during the active design and review stage, provided they remain within the original agreed project brief. Please provide written approval or, where reasonably possible, one consolidated revision list within 7 calendar days of each complete drawing pack issued for review. A project may be placed on hold if there is no response, can be reactivated without charge within 30 calendar days of the most recent drawing issue, and may be administratively closed after that. Silence is not approval, confirmation of factual accuracy or authority to submit drawings. There is more on turnaround and what you receive, and the FAQs handle the questions that come up most often.