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LABC 2025 Regional Winner ILC Corporate Partner 0800 652 3331

Home extension builders in Hertfordshire. Award winning.

Nationserv is a UK specialist insurance repair contractor delivering end to end building solutions, including award winning home extensions across Hertfordshire and the wider UK. Single storey, two storey, side return and rear extensions, designed and built by our own teams under one project lead.

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LABC Building Excellence Awards 2025 winning home extension at Woodfield Road, Hertfordshire, by Nationserv

LABC 2025

Regional Winner and National Finalist, Best Residential Extension

The two extension types we build

Single or two storey, end to end.

Whether you need a brighter kitchen diner on the ground floor or a full second storey above the existing footprint, the same in house team handles design support, structural work, mechanical and electrical, and final finishing.

Single storey

Single storey extensions.

Rear, side and side return extensions to open up the ground floor. Ideal for kitchen diners, garden rooms, utility runs and home offices. Bifold doors, roof lights, lantern roofs and floor to ceiling glazing all delivered in house.

Rear, side and side return single storey extensions
Open plan kitchen diners with bifolds and rooflights
Garden rooms, home offices and utility runs
Structural openings into existing rooms

Two storey

Two storey extensions.

Adding a second storey above a new or existing ground floor extension to gain bedrooms, bathrooms or a primary suite. Structural calculations, party wall, roof tie ins and external finishes managed end to end.

Two storey rear and side extensions
Wrap around extensions on detached and semi detached homes
Additional bedrooms, en suites and primary suites
Roof tie ins, party wall and Building Control sign off

LABC Building Excellence Awards 2025

Regional Winner and National Finalist for Best Residential Extension.

Our Woodfield Road home extension in Hertfordshire was named Regional Winner at the LABC Building Excellence Awards 2025 and went on to reach the national finals in the Best Residential Extension category.

The LABC Building Excellence Awards are judged by local authority Building Control teams across the UK, the people who sign off every detail of a build to legal standard. Recognition at this level is a peer reviewed measure of design, build quality, attention to regulation, and overall finish, judged by the people closest to the work.

See all accreditations and awards

The Nationserv team holding the LABC Building Excellence Awards 2025 trophy

What is included

End to end, no gaps.

A single line by line specification covering every stage of the extension build. Every core trade you need sits in house. Every approval you need is held within the business.

Design support

Working with your existing architect, or introducing one of our trusted partners. Drawings, planning submissions and Building Control packs handled.

Groundworks

Foundations, drainage, ground stabilisation and underpinning where required. Sequenced to keep the ground floor watertight throughout.

Structure and shell

Steels, masonry, frame, roof and external envelope. Including specialist structural repair where the existing fabric needs reinforcement.

Electrical and gas

NICEIC approved electricians and Gas Safe registered engineers in house. Full first and second fix to current regulations, signed off internally.

Plumbing and heating

New circuits, underfloor heating, radiator extensions and bathroom installations. Coordinated with electrical works to keep the programme tight.

Glazing and openings

Bifolds, sliders, lantern roofs, rooflights and floor to ceiling windows. Sourced and installed as part of the main programme.

Finishes

Plastering, joinery, tiling, flooring, kitchens, painting and decoration. The finishing trades that make or break the perception of an extension.

Snagging and sign off

Formal snagging, Building Control sign off and a documented handover pack. Aftercare available beyond completion.

Project management

One senior surveyor and one project lead from first visit to handover. Weekly progress updates and transparent pricing throughout.

Selected interiors and exteriors

Recent extension work.

Modern kitchen extension at night with full glazing, by Nationserv

Hertfordshire kitchen extension interior portrait by Nationserv

Hertfordshire kitchen extension interior with island by Nationserv

Garden room extension before and after by Nationserv

Home extension before and after exterior by Nationserv

Selected projects

Extension case studies in detail.

All case studies

Residential, Hertfordshire

Greenfield Road full renovation and extension.

New render, kitchen diner, bathrooms, hot tub area and roof works. A multi trade programme delivered in one continuous build.

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Kitchen garden rear extension in London by Nationserv with an architect partner

Residential, London

Kitchen garden rear extension, London.

Rear kitchen extension, design and build with an architect partner. Hand fitted cabinetry and a modern glazed envelope.

Read case study

Heritage, residential

Listed property full renovation.

Full external render, new windows and doors, heritage led internal restoration. Sympathetic finishes throughout.

Read case study

How we work

From first call to final handover.

A clear, four stage path from initial enquiry to project completion. The same surveyor led discipline that runs every insurance repair reinstatement, applied to private extensions.

Stage one

Brief and site visit

A senior surveyor attends, captures the brief, takes detailed measurements and photography, and confirms scope, planning route and constraints.

Stage two

Specification and quote

A fixed, line by line specification with materials, trades and timings. Transparent pricing. No hidden contingencies.

Stage three

Build and project management

Nationserv teams across every core trade, coordinated by a single project lead. Weekly progress updates and a clear site protocol.

Stage four

Snagging and handover

A formal walk through, snagging completion and a documented handover pack. Aftercare available beyond completion.

Common questions

What homeowners ask us.

Do I need planning permission for a home extension in Hertfordshire?

It depends on the size and type of the extension and on whether the property sits in a conservation area or is listed. Many single storey rear extensions sit within permitted development, while two storey extensions usually require a full planning application. Nationserv handles the full planning route as part of the build, including drawings, neighbour notification and Building Control sign off.

How long does a home extension take to build?

A typical single storey extension runs around 12 to 16 weeks on site once foundations begin, depending on size, finishes and weather. Two storey extensions usually run 16 to 24 weeks. The fixed line by line specification we issue at the quote stage includes an indicative programme so you know what to plan around.

Are Nationserv an award winning extension builder?

Yes. Nationserv won Regional Winner at the LABC Building Excellence Awards 2025 for Best Residential Extension at Woodfield Road, Hertfordshire, and went on to reach the National Finals in the same category. The award is judged by local authority Building Control teams across the UK.

What about Party Wall agreements?

Where the extension affects a shared boundary or wall, a Party Wall notice is required under the Party Wall Act 1996. We coordinate with your appointed surveyor, or introduce one of our trusted partners, and sequence the works around the agreed schedule of conditions.

Do you work outside Hertfordshire?

Yes. Nationserv covers 12 UK regions: Hertfordshire, Bedfordshire, Buckinghamshire, Cambridgeshire, Northamptonshire, Oxfordshire, London, Essex, Peterborough, Norfolk, Suffolk and Cornwall. The head office is in Stevenage and most residential work runs across the home counties and London.

Can you work to my architect's drawings?

Yes. We are happy to take on extensions designed by your existing architect, and we work closely with several trusted architectural partners if you do not yet have one. Either way, the build runs under one Nationserv project lead from first site visit to final handover.

Plan your home extension with us.

From first sketch to final handover, Nationserv brings ten years in business and 25 years of combined trade and leadership experience to every brief. Speak to the team and start your extension the right way.

Request a construction quote

0800 652 3331 Speak to the construction team

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