GSM Builders Ltd offers builders in Greenford and Northolt. Covering UB5 and UB6 including Perivale, Sudbury Hill and the Greenford Broadway and Northolt Village areas. Our base in Hayes is only 10 minutes away along the A40 and Ruislip Road, which makes us one of the most local building companies you can hire here.
Extending and converting Greenford and Northolt homes
Greenford and Northolt were largely built between 1925 and 1939, with terraces of three-bedroom houses and semis laid out around the Grand Union Canal, the Central line and the old Hoover factory. Many still have their original small rear kitchens and separate dining rooms. The two most transformative projects here are a rear or wrap-around extension to create a big open-plan kitchen-family room, and a loft conversion to add a fourth bedroom without losing garden.
We also do a lot of garage conversions on the wide-fronted houses near Northolt Park and Greenford Green, kitchen and bathroom renovations, and full refurbishments of former council homes that families have bought and want to bring up to modern standards. Rewiring, new heating, insulation, replastering and new windows.
Planning in the Ealing borough
Both Greenford and Northolt are in the London Borough of Ealing. There are relatively few conservation areas on this side of the borough (Northolt Village Green is one), so most extensions and lofts can be done under permitted development or the larger home extension prior approval route. Flats and maisonettes always need a planning application. We prepare the drawings, handle the council and arrange Building Control inspections so the work is signed off properly.
Building services we offer in Greenford and Northolt
- House extensions, single-storey rear, side-return, wrap-around and double-storey
- Loft conversions. Velux, rear dormer, hip-to-gable and L-shaped
- Full property refurbishment and renovations
- Kitchen fitting and kitchen renovation
- Bathroom renovation and wall tiling
- Roofing, plastering, flooring and painting & decorating
- 24/7 emergency call-outs, plumbing, electrics, glazing and boarding-up
Why choose GSM Builders Ltd in Greenford?
- Genuinely local. Our base at Leven Way, Hayes UB3 is about 10 minutes by road from Greenford, so site visits, quotes and snagging calls are quick and easy.
- One team from start to finish. Design input, structural calculations, Building Control liaison, all trades and decoration under one contract.
- Building Control approved work. Every structural project is signed off with completion certificates you will need when you sell or remortgage.
- Clear written quotes. Itemised pricing, agreed payment stages and no hidden extras.
- Fully insured with public liability cover and a 12-month workmanship warranty.
Projects we regularly carry out here
- 3 m rear kitchen extension with roof lights on a Greenford terrace
- Rear dormer loft conversion with en-suite in Northolt
- Garage conversion to home office and utility room in Perivale
- Complete two-bathroom refurbishment of an ex-council semi in Northolt
What building work costs in Greenford (2026)
These are the 2026 ranges we quote for Greenford (UB6), excluding VAT. They assume a standard specification and reasonable access; the cost calculator gives a figure for your own project, and a free site survey gives you a fixed written price.
| Project | 2026 price (excl. VAT) | Time on site |
|---|---|---|
| Single-storey rear extension (3 m) | £48,000 to £68,000 | 8 to 10 weeks |
| Side-return extension | £45,000 to £65,000 | 8 to 10 weeks |
| Wrap-around extension | £65,000 to £95,000 | 10 to 14 weeks |
| Rear dormer loft conversion | £38,000 to £48,000 | 6 to 8 weeks |
| Hip-to-gable loft with en-suite | £55,000 to £85,000 | 8 to 10 weeks |
| Whole-house refurbishment (3-bed) | £70,000 to £150,000 | 10 to 18 weeks |
| Kitchen fitting (supply & fit) | £12,000 to £30,000 | 2 to 4 weeks |
| Bathroom refit | £8,000 to £20,000 | 2 to 3 weeks |
Drawings, structural calculations and Building Control fees add £2,500 to £4,500. Where planning is needed, Ealing Council charges £548 for a householder application or £249 for prior approval (fees from 1 April 2026). Our planning guide explains which route applies, and the loft conversion comparison covers which loft type suits your roof.
Frequently asked questions
Do I need planning permission for an extension in Greenford?
Greenford is under Ealing Council and very little of it is in a conservation area, so most single-storey rear extensions up to 3 m and rear dormer loft conversions go ahead as permitted development. A Lawful Development Certificate (£274) is a sensible extra if you may sell within a few years.
What is a build-over agreement and will I need one in Greenford?
If your extension is built over or near a public sewer, common in Greenford. Thames Water needs to agree a build-over. It usually takes 3 to 6 weeks and costs a few hundred pounds. We identify it at survey stage and apply on your behalf so it does not delay the dig.
How quickly can you get to Greenford?
Our yard is on Leven Way in Hayes, about 15 minutes from Greenford, so site visits, deliveries and snagging calls are straightforward. There is no London-wide travel premium in our pricing.
Do you handle Building Control in Greenford?
Yes. Every extension, loft conversion and structural alteration needs Building Regulations approval and a completion certificate regardless of planning. We make the application, book the inspections and hand you the certificate at the end, you will need it when you sell.
Are you insured and do you give a warranty?
Yes, public and employer’s liability insurance, an itemised written quote before anything starts, staged payments against completed work and a 12-month workmanship warranty in writing on every contract.
Nearby areas we also cover
Southall · Hayes · Ealing · Ruislip · Harrow
Get a free quote in Greenford or Northolt
Message us with a few details and photos and we will come out, measure up and provide a written quote free of charge.