It's common to want a tweak after permission is granted — a different window, a rooflight, a change of materials, or a slightly different size. Some changes are straightforward to handle; others aren't. Here's how to change an approved design without undermining your permission.
In short
Once you have planning permission, the work should generally follow the approved drawings and conditions. Small changes may be handled through a non-material amendment; bigger ones may need a fresh application. Whether a change counts as 'non-material' is the council's judgement. Don't just build something different — check first. SC Design prepares the updated drawings.
Not sure which route applies to your property? Send Sean your postcode, a few photos and a short description for an honest first view — with no obligation.
Reviewed by Sean Corser, SC Design & Construction. Sean Corser helps Wirral homeowners with architectural design and drawing packs for extensions, loft conversions, planning and building regulations.
Last reviewed June 2026
Planning permission is granted for the specific scheme shown on the approved drawings, subject to any conditions. Building something materially different can put you outside your permission, which causes problems later — including when you sell.
So the starting point is simple: the build should follow what was approved, unless a change is properly handled.
A non-material amendment is a route for minor changes that don't conflict with the permission or its conditions. Planning Portal notes these applications may require revised drawings and details of exactly what's changing.
There's no statutory definition of 'non-material' — it's for the local planning authority to be satisfied a change is minor. Decisions should usually be made within 28 days of a valid application.
Changes people often ask about include moving or resizing a window, adding a rooflight, swapping materials, or small dimensional changes. Whether each is 'non-material' depends entirely on the specific permission — a change that's minor on one scheme can be material on another.
Listed building consent, where it applies, can't be altered through the non-material amendment route, so listed properties need particular care.
If a change isn't minor, a non-material amendment won't cover it and a new or different application may be required. The honest answer is often 'it depends', so it's worth checking before building rather than after.
We prepare the updated drawings and clearly set out what's changed, which is exactly what an amendment or fresh application needs. We won't advise anyone to just build something different and hope.
A few details are enough for an honest first view — with no obligation:
Need planning drawings? We can prepare them — clear, coordinated and ready for builders and building control.
External links open in a new tab. Always confirm your specific project with the relevant authority.
Send Sean a few photos and a short description of what you'd like to do. You'll get an honest first view with no obligation.