Area guide · WD6
House Extensions in Borehamwood (WD6)
Planning a house extension in Borehamwood? We design, gain planning permission and build extensions across the WD6 family-house belt — the 1930s semis, the postwar terraces and the larger detached homes up on the Elstree side. Borehamwood is one of the few corners of south Hertfordshire where local agent guides still put typical sales around the half-million mark, which makes it exactly the town where a well-judged extension beats a move: the same money that barely covers stamp duty and fees on the next house up buys a kitchen-diner across the back of this one. Applications go to Hertsmere Borough Council, and the everyday schemes move through without drama.
Live planning data
What Hertsmere Council is actually approving right now
Borehamwood answers to Hertsmere Borough Council — the same authority as Radlett and Elstree — and the borough's register is moving. The most recent pull shows thirteen residential consents in the window: rear extensions and loft conversions out in front, side and double-storey schemes plus a garden building behind them. That is, almost line for line, the list of what a Borehamwood house wants doing.
The town's briefs are the practical ones, and Hertsmere treats them accordingly: a rear extension that respects the neighbouring pair, a hip-to-gable loft that matches materials, a garage conversion that keeps the front elevation tidy. Where Radlett schemes are argued on design flourish, Borehamwood schemes are won on good-neighbour fundamentals — daylight, overlooking, matching brick — and we draw them to pass those tests the first time. Elstree & Borehamwood Town Council is a consultee on applications, and a tidy, well-explained scheme gives it nothing to push against.
Figures drawn from Hertsmere Borough Council's published planning register — a read on the borough's approvals weather rather than our own project list. Each application turns on its own merits.
Recent extension approvals near Borehamwood
We tracked 13 residential extension and loft approvals in the WD6 area, most decided by Hertsmere Council. Most are single-storey rear extension, loft conversion, outbuilding / annexe. Here are some recent examples that secured approval — useful context for what tends to get through on Borehamwood homes:
Islip House Mildred Avenue Borehamwood Hertfordshire
Use of house and outbuilding to teach Pilates, ancillary to primary residential use. Certificate of Lawful Development (Existing)
WD6
1 Rowley Lane BorehamwoodHertfordshire
Single storey rear extension Depth: 4.50m, Height: 3.00m, Eaves: 2.90m
WD6
30 Berwick Road BorehamwoodHertfordshire
Single storey rear extension Depth: 4.80m, Height: 3.00m, Eaves: 2.88m
WD6
34 Northfield Road Borehamwood Hertfordshire
Construction of first floor rear extension
WD6
36 Northfield Road Borehamwood Hertfordshire
Full width first floor rear extension
WD6
28 Whitehouse Avenue Borehamwood Hertfordshire
Construction of part single, part two storey side and rear extension, and rear outbuilding for office and gym use with 1x rooflight to front and rear
WD6
Source: public local-authority planning decision records. Approvals shown are recent examples of schemes granted in the area to illustrate what is achievable locally — they are not necessarily projects undertaken by us. Planning outcomes depend on your specific property and proposal.
Local knowledge
Borehamwood's housing stock, street by street
Borehamwood grew in three pushes — with the railway, with the studios, and with the postwar expansion — and each generation extends differently.
The interwar semis off Shenley Road. Either side of the high street and through the older streets around Furzehill Road and Cranes Way, the classic 1930s semi rules: bay front, side passage, kitchen at the back too small for how families now live. This is prime rear kitchen-diner territory (£45,000 to £90,000, or £55,000 to £110,000 with a mid-range kitchen in), and the side passage often carries a side-return or wrap-around where the plot allows. The loft above usually takes a hip-to-gable conversion with rear dormer (£55,000 to £90,000) — the most-approved loft scheme in the borough.
The postwar family streets. The town's larger postwar neighbourhoods — up towards Well End Road and east of the centre — trade bay-window character for solid structure and wider plots. These houses take extensions simply and economically: straightforward foundations, uncomplicated roof junctions, and garage conversions (£18,000 to £35,000) that turn an unused single garage into a study or playroom in weeks.
Deacons Hill and the Elstree side. South-west of the town, towards Deacons Hill Road and Barnet Lane, plots widen and values climb past £1 million into proper Elstree territory. Briefs here scale up with the houses — wide glazed rears, double-storey additions (£75,000 to £160,000), whole-floor reworks — and the green belt begins to shape what the edge plots can carry.
The green belt edges. Borehamwood's core is unconstrained, but the town is belted on nearly every side — towards Well End, Shenley and the Elstree fringes. Edge plots extend within the proportion rules; our guide to extending in the green belt explains the test, and we establish your plot's headroom before design begins.
Every street is different. That's the point.
We design to Borehamwood'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 a house extension costs in Borehamwood in 2026
Borehamwood builds at the standard North London baseline — one of its genuine advantages over the premium villages next door. Realistic all-in build ranges, excluding VAT, professional fees and kitchen fit-out:
| Extension type | Typical Borehamwood cost | On-site time | Usual planning route |
|---|---|---|---|
| Side-return extension | £35,000 to £65,000 | 2 to 3 months | Often permitted development |
| Single-storey rear | £45,000 to £90,000 | 3 to 4 months | Often permitted development |
| Kitchen extension (incl. mid-range kitchen) | £55,000 to £110,000 | 3 to 4 months | Often permitted development |
| Hip-to-gable loft + rear dormer | £55,000 to £90,000 | 6 to 10 weeks | Usually permitted development |
| Wrap-around extension | £70,000 to £140,000 | 4 to 6 months | Full application |
| Double-storey rear | £75,000 to £160,000 | 5 to 7 months | Full application |
| Garage conversion | £18,000 to £35,000 | 4 to 6 weeks | Usually permitted development |
Work to £2,800 to £4,200 per square metre. The full framework — what's in a build price, what sits on top, how to compare quotes — is in our North London cost guide. Our pricing method is the same here as everywhere: a free design visit, then a fixed quote itemised line by line, and the figure you sign is the figure you pay.
Permissions, handled
Planning permission in Borehamwood: what you need to know
Hertsmere decides, the town council comments. Householder applications take roughly eight weeks to determine. We prepare the drawing set to Hertsmere's requirements and manage the consultation end to end.
Permitted development does most of the work here. A semi in WD6 can push 3m out the back with no application at all, or 6m via the larger-home prior-approval route — detached houses get 4m and 8m — and the loft allowance holds on most streets. Anything we build under PD gets papered with a Lawful Development Certificate: it's the document your buyer's solicitor will one day ask to see.
Party walls matter on the semis. Most Borehamwood extensions are built against a shared boundary, so the Party Wall Act usually applies. Where neighbours consent in writing the cost is nil; where surveyors are appointed, budget £1,000 to £2,500 per affected neighbour. We serve and manage the notices as standard — see the party wall guide.
Green belt: an edge issue only. The centre of town carries no green-belt constraint; the fringes toward Well End and Shenley do, measured against the original building. One check at the first visit settles which rules your plot plays by.
How it works
How it works
- Free design visit. An hour at the house: what's feasible, what it'll realistically cost, and which consent route fits.
- Design and drawings. Drawn to clear Hertsmere's good-neighbour tests — daylight, overlooking, matching materials — at the first attempt.
- Consents, managed. We run the submission and the town-council consultation and field every officer question until the decision lands.
- Fixed-price build. One project lead, building control sign-off, and a finish we're happy to put our name to.
Questions, answered
Borehamwood extension FAQs
Which council covers Borehamwood extensions?
Hertsmere Borough Council decides planning applications in Borehamwood, with Elstree & Borehamwood Town Council consulted on schemes. A standard householder application takes around eight weeks to determine, and we manage the whole process.
How much does an extension cost in Borehamwood?
Budget £2,800 to £4,200 per square metre in 2026 — the standard North London baseline. A single-storey rear typically lands between £45,000 and £90,000, a kitchen extension between £55,000 and £110,000 including a mid-range kitchen, and a double-storey rear between £75,000 and £160,000, all excluding VAT and fees. Every project gets a fixed, itemised quote after a free visit.
Can I extend without planning permission in Borehamwood?
Often, yes. Semis carry 3m of rear extension under permitted development, extendable to 6m with prior approval, and most lofts convert under PD too. We still obtain a Lawful Development Certificate so the consent is in writing.
Do I need a party wall agreement for a Borehamwood extension?
On a semi or terrace, usually yes — most rear extensions and lofts notify at least one neighbour. Written consent costs nothing; appointed surveyors run £1,000 to £2,500 per neighbour. We handle the notices as part of the job.
Is a loft conversion worth it in Borehamwood?
Very much so. The 1930s semis take a hip-to-gable with rear dormer for £55,000 to £90,000, adding a double bedroom and bathroom that the local market values well beyond the build cost — and most qualify as permitted development.
How long does a Borehamwood project take?
A few weeks of survey and design, roughly eight weeks in planning where an application is needed — many schemes skip it under PD — then three to four months on site for a single-storey extension, six to ten weeks for a loft.
What clients say
Rated 5.0 on Google
“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.…” read the full review
“Really impressed with the entire project. The side extension and conservatory have been finished to a very high standard and the team made the process straight forward and stress-free. It’s transformed the space and added so much value, would definitely recommend.”
“Brilliant experience with the extension company, transparent from the word go. Completed a double story extension for me and I couldn’t be more pleased. Thank you”
“I got the extension company to do a bathroom refurb for us a January they done a great job they managed to fit in a large shower as well as a bath”
Reviews shown word for word from our Google profile. Read all 12 reviews on Google
Free site visit
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