An extension in Maidenhead needs two approvals rather than one: planning, and building regulations. We build the extension and coordinate both, and we appoint a structural engineer for the calculations rather than producing them. This page sets out what the town's planning framework has asked for since April 2026, what the ground under the town is, and what the council's own charges come to.
The Maidenhead Neighbourhood Plan now helps decide your application
The Maidenhead Neighbourhood Plan was formally made, meaning adopted, by the Royal Borough of Windsor and Maidenhead on 21 April 2026. It now forms part of the statutory development plan used to decide planning applications in the town. An extension designed against the borough plan alone is no longer designed against the whole of the plan that applies to it.
Policy DE-2 requires development proposals to demonstrate full regard to the key characteristics of the relevant character area, and to follow the design guidance and codes for that area set out in section 4 of Appendix 1. That means identifying your character area before the drawings are produced rather than after. We raise it at the first visit.
The council will not let you correct an application after it is validated
The council's published position is not to seek or accept amendments to a planning application after validation. It states that it will not accept unsolicited amendments, and that where an amendment is accepted at officer discretion it will allow only one round. There is no comfortable second attempt built into the process.
The Royal Borough of Windsor and Maidenhead also adopted its National and Local Validation Requirements on 5 February 2026, and an application that does not meet them cannot be made valid. Getting the submission complete first time is therefore the whole game. We work through the buildability questions before anything is sent rather than after a refusal.
Foundation design in Maidenhead depends on which side of town you are on
British Geological Survey 1:50k mapping shows Seaford Chalk and Newhaven Chalk Formation, undifferentiated, as the bedrock across a long list of Maidenhead addresses. Those include the town centre, Boyn Hill, Castle Hill, Furze Platt, North Town, Ray Mill, Oaken Grove, Altwood Road, Pinkneys Green and the northern part of Cox Green. That is a different foundation problem from the clay ground further into London.
The same mapping shows Lambeth Group clay, silt and sand as the bedrock beneath the southern part of Cox Green and the Larchfield Road area. It also underlies the Lee Lane and Pinkneys Drive end of Pinkneys Green, and the southern fringe of Braywick towards the A308. Lambeth Group clay is shrinkable, so tree influence and seasonal ground movement matter on those sides of town. Braywick Road, Braywick Park and Desborough Park sit on chalk.
The building control charge for a single storey extension is published
From 1 April 2026 the council's building control charge for a single storey extension of 10 to 40 square metres is a £432.00 plan charge plus a £558.00 inspection charge on full plans, or £1,138.50 as a building notice, inclusive of VAT. That is separate from the planning fee, the engineer's fee and the build cost, and it is shown separately in your quotation.
The council asks for two days' notice before commencement of work, and one day's notice for stages including excavations for foundations, foundation concrete, damp proof course laid, first floor joists and roof timbers before covering. Those inspections are what a completion certificate rests on. We book each one as the build reaches it rather than afterwards.
- Steel goalpost frames where the rear wall opens up
- Flat and pitched roofs with rooflights or lanterns
- Trial holes to set foundation depth near drains and trees
- Planning applications and permitted development assessments
- Full fit-out, finishing and making good
Why Choose GS Renovation in Maidenhead
An extension here is decided against the Maidenhead Neighbourhood Plan as well as the borough plan, and the council does not accept unsolicited amendments once an application has been validated. That puts the effort at the front of the job, where it is cheapest. We identify the character area, appoint the structural engineer, coordinate the planning and building control applications, and book each inspection as the build reaches it. You deal with one point of contact from the first survey to the completion certificate. GS Renovation Ltd is fully insured, registered in England, company number 14611254, and quotations are free and without obligation.
- Paperwork and certificates handed over for when you sell
- Free follow-up visit after completion if anything needs attention
- Waste cleared as we go, not left piled in the garden
- Drainage diverted or built over with the right approval in place
- Permitted development checked before you pay for a planning application
- Site left safe and secure at the end of every day