Glass box extensions in Harlow: design, approvals and build
From the first sketch to final sign-off, we plan and build glass extensions in Harlow and the surrounding Essex area.
- Guide price in HarlowFrom £31,500 inc VAT
- PlanningSame limits as single-storey rear; glazing checked for building regs
- Build time10–16 weeks on site
- Postcode districtsCM17, CM18, CM19, CM20
Guide prices for Harlow
For Harlow we adjust our national guide rates by ×1.06, the factor we use for East of England. Figures include VAT; your written quote after the survey replaces them.
Typical rates in Harlow: £3,180 to £6,150 per m² including VAT, depending on specification.
| Size | Essential | Standard | Premium |
|---|---|---|---|
| 2 m × 4 m 8 m² | £31,500 – £38,500 | £31,500 – £40,000 | £36,000 – £49,500 |
| 3 m × 4 m 12 m² | £38,000 – £46,000 | £44,500 – £56,000 | £54,500 – £74,000 |
| 3 m × 6 m 18 m² | £57,000 – £69,000 | £66,500 – £84,000 | £82,000 – £111,000 |
For a figure based on your own dimensions, use our guide-price tool.
What we take care of
- Steel or glass beams and slim-frame glazing
- Planning drawings that show the glass detail
- Whole-house energy calculations where needed
- Solar-control and low-energy glass specification
Do I need planning permission in Harlow?
In England a glazed or orangery-style extension follows the same size limits as any single-storey rear extension: 3 m or 4 m without an application, or up to 6 m and 8 m through prior approval. Building regulations limit glazing to about a quarter of the new floor area plus the openings it replaces, unless whole-house calculations show the design still performs.
In a conservation area, national park, National Landscape, the Broads or a World Heritage Site the permitted development limits are tighter (no side or two-storey extensions without an application). Listed homes need listed building consent, and if permitted development rights have been removed, any extension needs an application.
If the work involves a shared wall, building on the boundary, or digging foundations within 3 m (sometimes 6 m) of a neighbour's building, the Party Wall etc. Act 1996 applies and notice must be served before work starts: two months for work to a party wall, one month for new walls on the boundary and for excavations.
Building over or within 3 m of a public sewer needs the water company's consent, usually through a build-over agreement, before the foundations go in.
Applications are decided by the local planning authority (your district, borough or unitary council).
Extensions in and around Harlow
Site visits are available across Harlow (CM17, CM18, CM19, CM20). We also work in nearby Waltham Abbey (8 miles), Brentwood (14 miles), Chelmsford (16 miles), Billericay (17 miles).
Across the East of England many houses sit on generous plots, and single-storey and wraparound extensions are a natural fit.
From first visit to completion
Site visits are free and there is no obligation. Where drawings are needed, the design stage is priced in writing before it starts.
Free site visit
First, a site visit: we look at the house, garden, access and drains and listen to what you need.
Design and approvals
We produce the drawings and structural design, and manage the approvals so they are in place before work starts.
Fixed written price
You receive a written, itemised price and programme. Nothing starts until you are happy with it.
Build and sign-off
Our team builds the extension, keeps you updated weekly and finishes with building control sign-off.
Glass extension questions answered
Do you cover all of Harlow?
Yes. We cover Harlow and the surrounding parts of Essex. Site visits are free and there is no obligation.
Can I see a price before committing to anything?
Yes. The guide prices on this page are adjusted for Harlow, and the guide-price tool gives a range for your own size. After the survey you get a written price before anything is agreed.
Do I need building regulations approval in Harlow?
Yes. Almost every extension needs it, whatever the planning route. We prepare the drawings and book the inspections.
Are glass extensions cold in winter?
Modern double or triple glazing with warm-edge spacers and underfloor heating keeps them comfortable. They are not as warm as a solid room, and we explain the trade-off honestly.
How much does a glass extension cost?
Our guide range is about £3,180 to £6,150 per m² including VAT, because structural glass is made to order. A 12 m² standard-spec glass extension is typically £44,500 to £56,000 in Harlow.
Book a free site visit in Harlow
We will measure up, check the planning position and give you honest guide figures.
- Free, no-obligation site visit
- Planning route checked before you spend on drawings
- Written price once the design is agreed
- Building control sign-off at the end
Prefer to talk? Call 0800 088 6341 or .
Book a free site visit
Tell us a little about the project and we will arrange a time.