Ace Alfa Construction London
House extension builders London - Ace Alfa Construction rear extension project

Ace Alfa Construction · London

House extensions across London - rear, side return and double-storey

Ace Alfa Construction designs and builds house extensions across all London boroughs. Whether you need a rear extension to open up your kitchen, a side return to recover dead space, or a double-storey addition for an extra bedroom, we manage every stage - planning permission, structural work, and final finishes.

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Overview

Extension types we build

Every property is different. We build all main extension types across London and advise on the right option for your home and budget.

  • Rear ExtensionThe most common extension type in London. Extends the back of your home - typically used to create an open-plan kitchen-dining space or larger living area. Single or double storey.
  • Side Return ExtensionFills in the narrow passage that runs alongside many Victorian and Edwardian terraces. Adds width to your ground floor kitchen and often includes a rooflight to bring in natural light.
  • Wrap-Around ExtensionCombines a rear and side return extension into one L-shaped addition. Creates the largest possible ground floor space without a double-storey build. Popular in semi-detached and terraced houses.
  • Double-Storey ExtensionExtends both ground and first floor simultaneously - the most cost-efficient way to add significant square footage. Requires planning permission in most cases but adds maximum value.

Why us

Why choose this service

  • Add space without the cost of movingA well-designed extension can add significant living space and increase your property value - often at a fraction of the cost of upsizing in London.
  • Planning and structural work fully managedWe handle planning permission applications, party wall agreements, and structural engineering so you do not have to deal with councils or consultants.
  • Minimal disruption to your daily lifeOur site team works to a structured schedule and keeps your home as liveable as possible throughout the build. We set clear timelines before work starts.

How we work

Our process

  1. Extension type selection and technical planningWe assess your property, advise on the right extension type for your space and budget, and prepare technical drawings and planning documents.
  2. Structural work and envelope constructionFoundations, brickwork, steelwork, roofing and windows are installed by our experienced structural team to building regulation standards.
  3. Internal finishing and snaggingPlastering, flooring, electrics, plumbing connections, and decoration are completed and signed off through a thorough snagging process before handover.

Scope

What's included

  • Structural engineering and calculationsAll structural elements - foundations, steelwork, load-bearing changes - are designed by a structural engineer and signed off by building control.
  • Party wall agreement supportWhere your extension is close to a shared boundary or wall, we advise on party wall obligations and can recommend a party wall surveyor.
  • Full build - groundworks to finishingFoundations, drainage, brickwork, roofing, windows, internal plastering, flooring, electrics, and decoration. Everything to a move-in standard.
  • Building regulation sign-offWe manage all building control inspections throughout the build and obtain your completion certificate on handover - essential for future property sales.

Recent work

Case studies

Open-plan kitchen extension with island and garden glazing in London

Chelsea

Rear Kitchen Extension

Full rear extension in Chelsea adding an open-plan kitchen and dining space. Structural steelwork, bi-fold doors, underfloor heating, and full internal fit-out completed in 10 weeks.

Side return kitchen transformation with rooflights in London

Central London

Side Return Transformation

Side return extension in Central London recovering a narrow passage to create a wider kitchen and utility room. Included rooflights, structural steelwork, and full replastering.

Answers

Frequently asked questions

Will we still be able to live in the home during extension works?

In many cases yes. We phase works to reduce disruption and explain access, dust control, and timing from the start.

Can you help us choose the right extension type?

Yes. We help compare rear, side, and wraparound options based on your property layout and budget goals.

Do I need planning permission for a house extension in London?

Many rear and side extensions fall under Permitted Development rights and do not require planning permission, as long as they meet size and design criteria. However, properties in conservation areas, listed buildings, or flats are subject to stricter rules. We assess your property at the initial consultation and advise you before any work begins.

How long does a house extension take in London?

A typical single-storey rear extension takes 8-12 weeks on site once planning is approved. Double-storey extensions usually take 12-16 weeks. Planning and design adds 8-12 weeks before site work begins. We provide a full project timeline in your written quote.

How much does a house extension cost in London?

Costs vary depending on size, type, specification, and location. We provide a full written quote after visiting your property with no hidden costs.

Explore

Related services

Many extension projects combine with other works. Explore related services.

Loft ConversionsAdd a bedroom above while extending below.Kitchen RenovationMost rear extensions include a full kitchen refit.Full RenovationCombine your extension with a whole-house refurbishment.