Building Works

House Extensions

Single & double-storey extensions, side returns and kitchen extensions.

Overview

Single & double-storey extensions, side returns and kitchen extensions.

From a rear kitchen extension that opens the back of the house to the garden, to a full double-storey side extension that adds a bedroom and bathroom above, Oakline plans and builds extensions from foundations to finish. We handle the build, coordinate structural engineers and building control, and leave you with a space that feels like it was always there.

From foundations to finish

We start at trench depth and finish with paint and skirting. Foundations dug and inspected, brick and block to DPC, cavity built and insulated, structural steels installed, roof formed and weather-tight, then first-fix M&E, plaster and finishes.

Working with your architect — or finding one

If you already have drawings and planning, we'll price and build to them. If you don't, we'll introduce a trusted architect and structural engineer so the whole project is coordinated from day one.

Tying old and new together

Matching brick, mortar colour, eaves detail and roof line takes care and source-matching. We tooth bricks in properly, run damp courses correctly and detail the junction so the extension reads as part of the original house.

Single-storey rear and side extensions

Double-storey extensions and wrap-arounds

Kitchen extensions with bi-folds or sliders

Foundations, brick and blockwork, roofing, glazing

Building control liaison and structural engineer coordination

Case study

Rear kitchen extension, Berkhamsted

Berkhamsted, Hertfordshire

The brief: A dated rear kitchen with a tired conservatory bolted onto the back, no real connection to the garden and constantly cold in winter.
What we did: Demolished the conservatory, dug new trench foundations, built a 6×4m single-storey rear extension in matching brick with a warm flat roof, two roof lanterns and a 4m bi-fold opening onto a new porcelain terrace.
The result: A bright, full-width kitchen-diner that finally talks to the garden — warmer in winter, properly insulated and ready for the next twenty years.

24 m²

Footprint

4m bi-fold + 2 lanterns

Glazing

12 weeks

On site

How we work

Our process

01
Survey & feasibility
Site visit, measured survey, talk through what's realistic.
02
Design coordination
Architect drawings, structural calculations, building control submission.
03
Fixed quote
Itemised quote covering every stage from groundworks to finishes.
04
Build
Foundations, super-structure, roof, glazing, first and second fix.
05
Handover
Building control sign-off, snag walk, aftercare.

Common questions

FAQs

Do I need planning permission?+

Many single-storey rear extensions fall under permitted development. Double-storey and larger extensions usually need full planning. We'll advise at the survey stage and handle the submission with your architect.

How long does an extension take?+

A typical single-storey rear extension is 10–14 weeks on site. Double-storey extensions are usually 14–20 weeks. Weather, finishes and lead times affect this.

Can we stay in the house?+

Yes — most clients do. We seal off the working area, manage dust and noise, and program disruptive stages (knock-throughs, services) around your routine where we can.

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