We design, plan and build house extensions across Balham and the wider Wandsworth borough — one team, one fixed price, one project manager from sketch to handover.
Typical scope +18 to +60m²
Cost guide From £2,500 / m²
Build time 12–22 weeks
Consult Free 1–2 hour visit
BUILDING IN BALHAM
Balham is known for its tree-lined streets full of family-sized Victorian terraces. Most families solve space constraints by extending to the rear or converting the loft.
Rear extensions with French doors and rooflights create open kitchen-diner spaces; two-storey extensions add bedrooms.
Balham projects include a two-bedroom loft conversion and a two-storey rear extension with a first-floor terrace.
Local advantage
Why Balham homeowners choose DPS for house extensions.
01 · PLANNING HANDLED
We handle the permission side in-house.
Planning drawings, building-regulations and party-wall paperwork are prepared and submitted by our own team —
including for conservation-area or listed properties where extra consent is needed. One point of contact owns
both the approvals and the build, so nothing falls between an architect and a separate contractor.
02 · ONE TEAM
Architects, builders, project managers — all in-house.
No subcontractor juggling. From the first sketch through structural engineering to final snagging, your project moves
through people who all sit in the same office and answer to the same project manager.
03 · TRANSPARENT PRICING
From £2,500 / m² — itemised and fixed.
You pay in stages, only after each stage is signed off. Variations only happen when scope genuinely changes — and
they go through written authorisation, never a verbal "while we are at it".
Yes — Balham (SW12) is well within our Wandsworth working area. We typically deliver several house extensions projects across this borough each year.
How long does a house extensions project take in Balham?
End-to-end (consultation → handover) usually 12–22 weeks. Build phase alone is shorter — most house extensions sites complete in 8–18 weeks depending on scope and finishes.
What does house extensions cost in Balham?
Typical range: From £2,500 / m². Our online calculator gives you a tighter figure based on your house type and ambitions; the fixed quote follows a free site visit.
Will I need planning permission in Balham?
It depends on the property. Many house extensions fall under permitted development, especially in Wandsworth. Where planning is needed (conservation areas, listed properties, larger schemes), we handle the application end-to-end.
Do I need planning permission for a house extension?
Many extensions fall under permitted development. We assess your property and tell you exactly what you need on the first visit.
How long does a typical extension take?
A single-storey extension takes 12–16 weeks from breaking ground to completion. Double-storey runs 16–22 weeks.
Can we live in the house during the build?
For most rear extensions, yes. We dust-seal the working area and maintain access to your kitchen and bathroom.