House Extensions in Birkenhead
and Across Wirral

CNR Construction is a Birkenhead-based building contractor specialising in house extensions across Wirral. From rear kitchen extensions on Victorian terraces in Claughton to side extensions on post-war semis in Bromborough and premium open-plan additions in Oxton, we carry out the full range of residential extension work across the peninsula.

This page covers what we do, where we work, what makes a good house extension in Birkenhead and across Wirral, and what the process looks like from initial enquiry to completion. If you are at the stage of looking for a builder and want a free site visit and written quotation, the contact details are at the bottom.

What We Build: House Extension Types Across Birkenhead and Wirral

Rear Extensions

The rear extension is the most common project type in our Birkenhead portfolio. It extends from the back of the property — one storey, into the rear garden — to create additional ground-floor living space. On Victorian and Edwardian terraces across Claughton, Rock Ferry, and Birkenhead's inner streets, the rear is often the only viable direction: shared side boundaries make side extensions impractical, but deep rear plots provide genuine opportunity.

The most requested brief is an open-plan kitchen-diner rear extension. We remove the rear wall of the existing kitchen, install structural steel to carry the load, and extend backwards to create a new kitchen and dining space with glazed doors onto the rear garden. The finished result changes how the house functions every day.

Side Extensions

Side extensions build into the gap beside the house — the side passage or side return that runs between the property and the side boundary. On 1930s semis in Prenton, post-war semis in Bromborough, and Edwardian semis in Oxton, this passage is often underused: a narrow strip that provides access but creates no value.

A side extension converts that wasted width into usable floor area. The most common outcome is a wider kitchen, a utility room and additional storage, or a downstairs WC. The transformation in how the ground floor functions can be disproportionate to the floor area added — a kitchen that gains three metres of width becomes genuinely workable in a way the original plan never allowed.

Single-Storey Additions and Open-Plan Living

Single-storey additions cover both rear and side extensions, and the combination of the two in an L-shaped wrap-around build. The brief that drives most of these projects is the same: create an open-plan living space at the rear of the house, connected to the garden, with natural light from multiple directions.

The key design elements are the rear glazing — bi-fold doors, sliding doors, or large fixed glazing panels — and the internal connection between old and new. The structural work of removing the rear wall and opening the connection is the technical core of most rear extension projects. CNR Construction has structural engineers on our team and handles the structural design and building regulations process as part of every project.

Loft Conversions

We carry out loft conversions across Birkenhead and Wirral alongside our extension work. Loft conversions are often the right answer for households that have already extended at ground floor level and need additional bedroom space, or where preserving the rear garden is important. The three main types — Velux rooflight conversions, rear dormer conversions, and hip-to-gable conversions — suit different property types and budgets. See the full loft conversion guide for costs and planning routes.

Where We Work: Birkenhead and Across Wirral

CNR Construction is based in Birkenhead and works across the whole of the Wirral peninsula. Our core areas include:

• Birkenhead — Oxton, Claughton, Prenton, Rock Ferry, Tranmere, Noctorum, and all inner Birkenhead streets
• South Wirral — Bromborough, Eastham, Bebington, Spital, and New Ferry
• West Wirral — Heswall, Hoylake, West Kirby, Caldy, and Thurstaston
• North Wirral — Wallasey, New Brighton, Moreton, Leasowe, and Upton

Local knowledge matters on a building project. The planning rules that apply in Oxton Conservation Area differ from those governing a standard terrace in Claughton. The structural approach on a 1930s semi with a shallow roof pitch is different from the approach on a Victorian villa with a steep-pitched roof. CNR Construction's experience across all these areas means we bring knowledge that a contractor without local roots cannot.

Planning Permission for House Extensions in Birkenhead

Most single-storey rear and side extensions on Birkenhead properties fall within permitted development rights — they do not require a formal planning application. The key limits are: depth (4 metres for a detached, 3 metres for a semi or terraced property under the standard rules), height (the extension must not exceed the height of the existing eaves), and width (side extensions must not exceed half the original width of the house).

The exceptions:

• Oxton Conservation Area: any work visible from the street requires planning permission regardless of size
• Double-storey extensions: almost always require full planning permission
• Properties where permitted development rights have been removed: some properties have had PD rights removed by a planning condition or an Article 4 direction

CNR Construction confirms the planning position for every property at the initial site visit, at no charge. We manage planning applications on behalf of clients where a full application is needed.

Party Wall Agreements on Birkenhead Terrace Properties

If your Birkenhead property is a mid-terrace — which covers most of Claughton, Rock Ferry, and Tranmere — virtually any rear extension or structural loft conversion will engage the Party Wall etc. Act 1996. This requires serving written notice on affected neighbours before structural work begins.

CNR Construction manages the party wall process as part of the project. This includes serving the notices, coordinating with the party wall surveyor if a dispute arises, and ensuring the legal framework is properly in place before construction starts. It is not an optional extra — it is a legal requirement, and managing it properly protects both the homeowner and the building.

The CNR Construction Process

1. Free site visit: we visit the property, assess the plot and planning position, and discuss the brief
2. Detailed written quotation: a fixed-price quotation covering all construction work, with a breakdown by phase
3. Structural design and planning: where a structural engineer's design or planning application is needed, we manage this on your behalf
4. Building regulations: we manage the building regulations process, including all inspections
5. Construction: we carry out the build with our own directly employed workforce
6. Completion certificate: the building regulations completion certificate is provided on final inspection

Every project ends with a building regulations completion certificate — the documentation that confirms the work was carried out to the required standard and that will be required when the property is sold.

Frequently Asked Questions