Whetstone · Barnet
House extension architects in Whetstone
Rear, side-return and wrap-around extensions in Whetstone (N20), designed in 3D around how you live and around Barnet Council's planning expectations.
What do I need to know about extensions in Whetstone?
Many single-storey rear extensions in Whetstone can be built under permitted development (up to 3m deep for semis/terraces, 4m for detached, or 6m/8m with prior approval), but flats, conservation areas, Article 4 areas, side extensions over half the house width and two-storey schemes need planning permission from Barnet Council.
The rules at a glance
- Single-storey rear: 3m (attached) or 4m (detached) under permitted development
- Larger Home Extension prior approval: up to 6m / 8m
- Side extensions: single storey, no wider than half the original house
- Conservation areas and flats: planning permission usually required
General national guidance; every address is checked individually before design.
Planning in Barnet
London Borough of Barnet planners are focused on suburban character, garden depths, and rear-extension precedent under Barnet's Residential Design Guidance SPD.
Barnet officers look closely at rear projection, garden depth and the character of suburban streets, especially in Hampstead Garden Suburb and other conservation areas. We design to the Barnet Residential Design Guidance SPD.
Typical housing we see in Whetstone:
- Period terraces and semis around Whetstone centre
- Post-war infill closer to the N20 boundary
- Larger detached stock on the leafy northern edge
- Mixed-use frontages along the main high street
How we work
We start remotely: a Matterport scan gives an accurate 3D model of your home, we design options you review on video calls, then produce concept drawings. Planning and Building Regulations drawings follow only if your project needs them.
FAQs
Questions
Everything you need to know about working with DOR Architects.
Build costs depend on size, glazing and finishes. Most Whetstone single-storey extensions we see fall broadly in the £2,500–£3,500 per m² range for build with a mid-range finish, excluding VAT, fees and the kitchen; see our North London extension cost guide for the full breakdown. Our Stages 0–2 (survey, existing drawings and concept design) are offered as a fixed estimated fee; planning drawings (Stage 3) and Building Regulations drawings (Stage 4) are optional add-ons only if you need them.
No architect can guarantee approval. We design to the Barnet Residential Design Guidance SPD and recent local decisions to give your scheme the best chance.
We start remotely: a Matterport scan produces an accurate 3D model of your home, so we can design and review options with you on video calls.