An extension in Luton runs on two tracks: the planning route first, then building control. Luton Borough Council handles both, and it publishes exactly what it will inspect and what it will charge. We coordinate the applications, appoint the structural engineer and build to the calculations issued.
The eight inspections on a Luton extension
Luton Borough Council lists eight inspection stages for an extension to a house, shop or office, beginning with commencement and ending with completion of work. Stage 2 is inspection of the new excavation for foundations, so the trench is seen before any concrete goes in.
Stage 4 covers new walls, damp proof course and below ground drain pipes for falls and line. At the end, the council states that once the extension is approved and installer certificates are received, the completion certificate follows within five working days.
What building control charges
A single storey extension under 100 square metres carries a charge of £1,045 on a full plans combined payment, or £375 plus £700 if you split the payment. Those figures apply from 1 April 2026.
A two storey extension under 100 square metres is £1,245 on a full plans combined payment and £1,530 under a building notice. Full plans is the cheaper route in both cases, and it also gives you a checked design before the groundworks start.
The planning route, and the fast track
Luton offers a fast track householder application for £250, with a guaranteed decision within five working days of the end of the consultation period. It is not available if the property sits in a conservation area, and the request must be stated in the proposal description when the application is submitted. Only two of Luton's five conservation areas are primarily residential: Rothesay, designated on 7 July 2003, and Luton South, designated on 19 April 2010.
Six Article 4 directions are in force in Luton, and none of them removes permitted development rights for house extensions or alterations, so ordinary householder rights apply across the borough. Check which council you are dealing with before anything else, because an LU postcode does not mean Luton Borough Council. The LU1 outcode spans Luton, Central Bedfordshire and Dacorum, taking in Caddington, Slip End, Markyate and Flamstead.
What is under the new foundation
Luton sits on Chalk bedrock, not London Clay, so the shrink and swell subsidence pattern that dominates north London is not the default assumption for foundations here. Above the chalk, the cover changes by area.
Clay with flints, described by the British Geological Survey as unsorted sediment with flint gravel in a sandy mud matrix, is mapped over the chalk at Stopsley, Round Green, Stockwood Park, Farley Hill and Wigmore. The Environment Agency's flood map for planning records Flood Zone 2 along the River Lea at Leagrave and through Wardown Park. Both change what the foundation and drainage design have to answer.
- Full fit-out, finishing and making good
- Steel goalpost frames where the rear wall opens up
- Bi-fold, sliding and French door openings to the garden
- Building control inspections at foundation, damp course and steel stages
- Single and double storey extensions
The GS Renovation Difference in Luton
An extension is where planning and building control have to be run in step, and Luton publishes enough detail to plan both properly. We coordinate the applications, appoint the structural engineer, build to the calculations issued and hold the programme against the council's eight inspection stages. The excavation stage and the drainage stage cannot be worked around, so the groundworks are booked with them in mind rather than in hope. Fully insured, with free no obligation quotations.
- Photographs kept at each stage for your records
- Honest updates if a date or a detail has to move
- Free follow-up visit after completion if anything needs attention
- Insulation and thermal detailing to current regulations
- Drainage diverted or built over with the right approval in place
- Scaffolding and site set-up planned for tight London plots