Stanmore · Harrow
House extension architects in Stanmore
Rear, side-return and wrap-around extensions in Stanmore (HA3), designed in 3D around how you live and around Harrow Council's planning expectations.
What do I need to know about extensions in Stanmore?
Many single-storey rear extensions in Stanmore 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 Harrow 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 Harrow
Harrow's suburban character policies steer extension design towards subordination, pitched roofs and matching brick.
Harrow's guide sets out depth, height and roof-form rules for extensions on its largely suburban 1920s–30s housing. We design to the Harrow Residential Design Guide SPD.
Typical housing we see in Stanmore:
- Period terraces and semis around Stanmore centre
- Post-war infill closer to the HA3 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 Stanmore 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 Harrow Residential Design Guide 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.