Area guide · EN6
House Extensions in Northaw (EN6)
Extending a house in Northaw? Cuffley's quieter neighbour is a proper Hertfordshire village: a conservation-area core around the church and green, lanes of substantial detached houses on deep plots, and the green belt with Northaw Great Wood holding it all in place. The postcode says EN6 but the council does not say Hertsmere or Enfield: Northaw applications go to Welwyn Hatfield Borough Council, a detail that catches out builders who do not work here. The projects the village generates are exactly our kind: sensitive village-core additions, big glazed rears on the lanes, and extension-plus-remodel programmes on the plots that can carry them.
Planning in Northaw
What wins approval in Northaw
Welwyn Hatfield's approach here is consistent: the staples clear when the design respects the setting. Around the green and the church the conservation area raises the materials-and-massing bar; on the lanes the green belt proportion test frames the bigger schemes, measured against the original building. Neither stops good projects. What they reward is preparation: designations read before design, the original-building baseline calculated, and a scheme composed to pass rather than argued through afterwards.
The plots are the village's quiet advantage. Along Northaw Road East and West, Judges Hill and Vineyards Road, gardens run deep enough that a substantial rear addition disappears from the lane entirely, and several of the larger houses carry the full premium brief, a double-storey rework or whole-house programme, comfortably inside the arithmetic. That scale of work is what our luxury extensions service exists for, and the policy side is unpacked in our green belt guide.
Every application is decided on its own merits; we build the case for yours before submission.
Local knowledge
Northaw's stock, lane by lane
The village core. Cottages and period houses around the green, inside the conservation area. Work here is crafted and quiet: matched brick and tile, traditional joinery, additions that keep the street scene intact. PD narrows in the core, so most schemes go to full application with the heritage case built in.
The lanes. The detached houses along Judges Hill and Vineyards Road are the classic Northaw brief: deep plots, mature screening, room for a wide glazed rear (£50,000 to £110,000) or wrap-around (£85,000 to £170,000) that the lane never sees.
The edge plots. Where gardens meet the fields and the Great Wood, siting decides schemes: additions behind the building line, dark rooflines, planting that ties the garden back to the landscape. Officers notice when a scheme respects why the green belt is there.
The larger houses. Northaw has a scatter of properly big homes where the conversation is reconfiguration plus extension, planned as one programme rather than a string of projects.
Every street is different. That's the point.
We design to Northaw's stock and to what the council demonstrably approves — not to a template. A free site visit tells you what your house can take.
Get my free estimateHonest numbers
What an extension costs in Northaw in 2026
All-in build ranges, excluding VAT, professional fees and kitchen fit-out:
| Extension type | Typical Northaw cost | On-site time | Usual planning route |
|---|---|---|---|
| Side-return extension | £45,000 to £80,000 | 2 to 3 months | Often permitted development |
| Single-storey rear | £50,000 to £110,000 | 3 to 4 months | PD outside the conservation core |
| Kitchen extension (incl. mid-range kitchen) | £65,000 to £130,000 | 3 to 4 months | As above |
| Hip-to-gable loft + rear dormer | £60,000 to £105,000 | 6 to 10 weeks | Usually PD outside the core |
| Wrap-around extension | £85,000 to £170,000 | 4 to 6 months | Full application |
| Double-storey rear | £90,000 to £200,000 | 5 to 7 months | Full application |
Work to £3,000 to £4,900 per square metre by setting and specification. The larger programmes are banded in the luxury extension cost guide, and the price you sign after the free visit is the price you pay.
Permissions, handled
Planning in Northaw: read the layers, then design
Welwyn Hatfield decides. Not Hertsmere, despite the EN6 postcode, and not Enfield. Householder applications take roughly eight weeks, and we prepare the file to Welwyn Hatfield's policies from the start.
Conservation core, green belt ring. Inside the core, PD narrows and design expectations rise; on the lanes, the original-building test sets the envelope. We map which layers touch your plot before any drawing.
PD where it survives. Outside the core, the 4m and prior-approval 8m rear allowances and loft volume usually hold, and everything built that way gets a Lawful Development Certificate.
Party walls. Deep plots make disputes rare, but boundary excavation still triggers the Act; budget £1,000 to £2,500 per affected neighbour where surveyors are appointed.
How it works
How it works
- Free design visit. Layers mapped, baseline calculated, honest advice on what the plot can carry.
- Design and drawings. Composed for the village setting and the policy tests together.
- Planning, handled. Managed through Welwyn Hatfield to the decision notice.
- Fixed-price build. One itemised figure, delivered properly, handed over immaculate.
Questions, answered
Northaw extension FAQs
Which council covers Northaw?
Welwyn Hatfield Borough Council, despite the EN6 postcode shared with Potters Bar and Cuffley. We prepare applications to Welwyn Hatfield's policies and manage them through to decision.
Can I extend in the Northaw conservation area?
Yes, with design that respects the village core: subordinate massing, matched materials and traditional detailing. Permitted development narrows inside the core, so expect a full application, prepared with the heritage case built in.
How does the green belt limit my project?
Extensions are measured against the original building, so the headroom depends on what previous owners added. We calculate your baseline at the first visit; on Northaw's larger plots the answer is often more generous than owners expect.
What does an extension cost in the village?
Plan on £3,000 to £4,900 per square metre in 2026. Glazed rears typically run £50,000 to £110,000 and double-storey schemes £90,000 to £200,000, excluding VAT and fees, with the larger programmes banded in our luxury cost guide. Quotes are fixed and itemised.
Do you cover Northaw?
Yes: the village sits just beyond Potters Bar, and we cover Cuffley and the rest of EN6 too. Site visits are free and unhurried.
How long will the project run?
A few weeks in design, roughly eight in planning, three to seven months on site by scale, with honest programme dates given alongside the quote.
What we build in Northaw
The same team designs, gets planning and builds — one fixed, itemised price whichever route your Northaw project takes.
Nearby areas we cover
What clients say
Rated 5.0 on Google
“The Extension Company built a 5m single storey rear extension on our Victorian terrace in Crouch End. Went down the permitted development route so no planning application needed, which they explained up front and saved us months. Kitchen-diner now opens onto the garden with sliding doors. £87k all in, matched the quote.”
“From the initial site visit onwards to my property in Barnet, we felt that the team actually listened to what we wanted. They suggested a few changes to the layout that we hadn't considered, and those changes have made a huge difference. Would definitely use again and recommend”
“Used The Extension Company for a loft conversion on our semi detached in Barnet and couldn't be happier. They explained what was possible at the first visit, sorted the planning side, and gave a fixed price with no surprises at the end. The hip-to-gable and rear dormer gave us a big double bedroom with an en-suite. Tidy, professional and finished on schedule. Would recommend to anyone in North London thinking about a loft conversion.”
“We had been putting off our loft conversion for years because the whole process felt overwhelming. The team made it much easier than expected and handled the drawings, planning and build for us. We now have a lovely extra bedroom and shower room.”
“Our wrap-around extension has completely transformed the ground floor. We now have the open plan kitchen and family space we wanted without losing all of the garden. Thanks to everyone involved.”
“Really pleased with the work from The Extension Company. We had our extension done in Hampstead and the whole experience was excellent. Great communication from start to finish, The quality of the finish is excellent and we’re really happy with the result. Would definitely recommend them if you’re thinking about an extension.”
Reviews shown word for word from our Google profile. See 9 more client reviews · Read all 16 reviews on Google
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Free site visit anywhere in Northaw, honest feasibility advice and a fixed, itemised price — design, planning and build handled end to end by the Pine Grove team.
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