House Extension — Add Space & Value to Your Home
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House Extension projects help UK homeowners create additional living space while improving comfort, functionality, and property value. LAMTANS Engineering delivers professionally designed extensions from our Manchester base, combining expert construction, energy-efficient upgrades, and complete project management across the UK.
Why Extend Your Home Instead of Moving?
A house extension is one of the most effective ways to add significant living space and value to your home — without the cost, disruption, and uncertainty of moving. You get to stay in the neighbourhood, the school catchment area, and the home you already know.
Adds Significant Property Value
A well-designed house extension can typically add 10–20% to the value of a UK property. For a £300,000 home, that represents a potential increase of £30,000–£60,000 — often substantially more than the cost of the build itself.
Typically up to 20% added valueMore Cost-Effective Than Moving
Moving house involves estate agent fees, conveyancing costs, stamp duty, and removal — typically £10,000–£15,000 in transaction costs alone, before the premium of a larger property. An extension delivers additional space at a fraction of the total cost.
Stay in the Area You Love
Moving means leaving behind your neighbourhood, established school catchment, local amenities, and community. An extension lets you gain the space you need while keeping everything that made you choose your home in the first place.
Design Exactly What You Need
A bespoke extension is designed around your lifestyle — whether you need a larger open-plan kitchen, an extra bedroom, a home office, or additional reception space. You choose the layout, specification, and finishes to suit how you actually live.
House Extension vs Moving House
Types of House Extensions We Offer
We offer five house extension types across the UK, each designed to maximise space, improve layout, and add long-term value depending on your property type, budget, and planning position. We survey your property first to confirm the most suitable option.
Rear Extension
Most PopularExtends from the back of the property to create additional ground-floor space — ideal for open-plan kitchen-dining rooms, enlarged living areas, or utility spaces. The most widely chosen extension type in the UK, suitable for most property types and often falling within permitted development.
Side Return Extension
Terraced & SemiUses the narrow unused side alley space beside terraced and semi-detached properties to extend the ground floor outward — significantly enlarging kitchen layouts and creating a more open, practical living area without reducing the main garden.
Side Extension
Extra WidthExpands the property width into side land to add extra rooms — an additional bedroom, home office, or integrated garage. Particularly effective for detached and semi-detached properties with sufficient side garden or driveway space to build into.
Two-Storey Extension
Maximum SpaceAdds living space to both ground and first floor simultaneously, maximising floor area and overall value per build pound. Ground floor typically provides kitchen or dining space; first floor adds an additional bedroom, bathroom, or office. The most space-efficient option for the investment.
Wraparound Extension
Full TransformationCombines a rear extension with a side return or side extension in an L-shape, creating the largest possible single-storey ground-floor footprint. Delivers a dramatic open-plan kitchen-living transformation — the most comprehensive single-storey extension type available.
Not Sure Which Extension Is Right for Your Property?
We assess your property at the free survey — checking boundaries, soil conditions, planning position, and your brief — then confirm the best extension type and a fixed-price quote.
House Extension Costs in the UK 2026
House extension costs vary by type, size, specification, and location. The figures below are indicative guide prices — your fixed-price quote is confirmed at the free site survey once we have assessed your property, boundaries, and requirements.
Cost per m² Guide by Extension Type
| Extension Type | Cost per m² | Timeline | Planning Permission |
|---|---|---|---|
| Rear Extension | £1,500–£3,500 | 6–10 weeks | Often permitted dev. |
| Side Return Extension | £2,000–£3,000 | 8–12 weeks | Usually required |
| Side Extension | £1,800–£3,000 | 8–12 weeks | Usually required |
| Two-Storey Extension | £2,000–£3,000 | 12–16 weeks | Usually required |
| Wraparound Extension | £2,000–£3,500 | 12–16 weeks | Usually required |
Typical Total Costs — Real Examples
Additional Specification Costs to Consider
- Kitchen fitting: £5,000–£20,000 (depending on specification)
- Bi-fold doors: £3,000–£8,000 (thermally broken, low-E glass)
- Roof lantern: £2,000–£5,000 (triple glazed)
- Underfloor heating: £3,000–£6,000 (much cheaper installed during build)
All figures are indicative guide prices including labour and materials. Actual costs depend on size, specification, site conditions, and location. Your fixed-price quote is confirmed at your free site survey. Prices exclude VAT.
Want an accurate quote for your property? We provide a fixed-price estimate at your free site survey — no obligation.
Get a free quoteHouse Extension Process
Our process is fully managed from free consultation through to building control sign-off. You have a single point of contact throughout — we handle design, planning permission, building control, all structural work, insulation, and every finishing trade.
Free Consultation
We discuss your vision, budget, and timeline. You tell us how you want to use the space; we advise on extension types, rough budget ranges, and likely planning position. No charge, no obligation.
Site Survey & Feasibility
We visit your property to check boundaries, drainage, soil conditions, access, and structural feasibility. We confirm which extension type best suits your property and provide a fixed-price quote.
Design & Planning
Architectural drawings prepared to your agreed brief. Where planning permission is required, we submit the full application and manage all correspondence with the local authority — you don't need to manage any approvals yourself.
Building Control Approval
Building control applications submitted and managed on your behalf. We coordinate all inspections throughout the build to ensure compliance with UK building regulations from the outset.
Groundworks & Foundations
Excavation, concrete strip or raft foundations, damp proof course, and drainage connections completed. All groundwork inspected by building control before superstructure work begins.
Brickwork & Roof Structure
External walls built to match or complement the existing property. Roof structure installed — flat roof, pitched roof, or roof lantern as specified. All structural steelwork fitted where required. Building envelope completed and made watertight.
First Fix — Electrics, Plumbing & Heating
Electrical circuits, consumer unit upgrades, lighting positions, socket runs, plumbing pipework, underfloor heating loops (if specified), radiators, and heating connections completed before boarding and plastering.
Insulation — PAS2035 Compliant
PAS2035 compliant insulation installed to floor, walls, and roof of the extension — meeting building regulation thermal performance requirements as standard on every LAMTANS build. Correctly installed insulation now saves significantly on heating bills for decades to come.
Plastering & Decoration
Walls and ceilings boarded and plastered to a smooth finish. Decoration (primer and paint) applied to agreed specification, ready for your kitchen, flooring, and fitting trades.
Second Fix & Finishes
Sockets, switches, and light fittings connected. Kitchen units, worktops, and appliances fitted (where included). Flooring, skirting boards, bi-fold doors, and roof lanterns installed. All finishes completed to agreed specification.
Final Snagging & Handover
Full snagging inspection completed. Building control issues the completion certificate confirming compliance with UK building regulations — required for property sales, remortgage, and insurance. Your new extension is handed over and ready to use.
We handle everything — planning permission, building control, structural work, all trades, and final certification. One point of contact from free survey to completion. You stay in your home throughout the build.
Do You Need Planning Permission for a House Extension?
Many house extensions can be carried out under permitted development — meaning you do not need to apply for planning permission. Where permission is required, we manage the full application process on your behalf.
Usually No Planning Permission Needed
- Single storey rear extensions within permitted development depth limits
- Extensions that do not cover more than 50% of the surrounding land area
- Extensions with a maximum height of 4m (or matching the original roof height)
- Rear extensions on houses not in conservation areas or Article 4 zones
Permitted Development Size Limits
- Single storey rear: max 4m depth (detached houses) or 3m (all other houses)
- Maximum height: 4m — or matching the height of the original house
- Extension cannot cover more than 50% of the land surrounding the original house
These are cumulative limits — previous extensions and outbuildings already built count towards the total. We check your specific position at the free survey.
When Planning Permission Is Required
- Property is in a conservation area or Article 4 direction zone
- Property is listed
- Extension exceeds permitted development depth or height limits
- Two-storey extensions on most property types
- Front extensions or side extensions visible from a public highway
- Wraparound extensions combining rear and side elements on certain properties
We Handle Planning Permission on Your Behalf
We assess your planning position at the free site survey and manage any planning permission or building control applications required — from drawings and submission through to approval. You don't need to manage any of this yourself.
Book a Free SurveyCombine Your Extension with Energy Efficiency Upgrades
An extension is the ideal opportunity to upgrade your home's energy efficiency at the same time — many improvements are significantly cheaper to install during the build than as a standalone retrofit project afterwards.
Underfloor Heating
Wet underfloor heating is far cheaper and less disruptive to install during an extension build than as a retrofit. Laid before the floor screed, it provides even, efficient warmth across the entire extension floor area — ideal for open-plan kitchen-living spaces with large format tiles.
Cost: £3,000–£6,000 — much cheaper installed during buildPAS2035 Compliant Insulation
We install PAS2035 compliant insulation to the floor, walls, and roof of every extension as standard — meeting current building regulation thermal performance requirements. High-spec insulation now locks in energy savings for decades and ensures your extension stays warm in winter and cool in summer.
Installed as standard on every LAMTANS extension buildBi-fold & Sliding Doors
Thermally broken aluminium frames with low-emissivity (low-E) double or triple glazing deliver natural light and indoor-outdoor connection without the heat loss of older glazing systems. Specified and installed as part of your extension package — no need to source separately.
Cost: £3,000–£8,000 depending on size and specificationRoof Lantern
A triple-glazed roof lantern floods a flat-roof extension with natural light while maintaining thermal performance. Far more energy-efficient than older single or double-glazed versions — and when specified during the build, fully integrated into the roof structure and waterproofing system.
Cost: £2,000–£5,000 — integrated during roof buildPAS2035 Compliant Insulation Installed as Standard
Every LAMTANS house extension includes PAS2035 compliant insulation to floor, walls, and roof as part of the build — not as an add-on. This meets current UK building regulation thermal performance requirements and reflects our background as accredited retrofit specialists.
Why Choose LAMTANS for Your House Extension?
We deliver professional house extension services across the UK with a focus on energy efficiency, compliance, and full project management from design to completion.
Full Project Management
One point of contact manages your entire project from free site survey to building control sign-off. We coordinate all trades — groundworks, structural, insulation, electrics, plumbing, plastering, and finishing — so you don't have to.
Planning Permission Handled
We assess your planning position at the free survey and manage all planning permission and building control applications on your behalf — including drawings, submissions, and responses to any queries from the local authority.
TrustMark Registered
Government-endorsed quality mark for home improvement and retrofit work. TrustMark registration provides consumer protection and verified quality throughout your project — backed by a formal dispute resolution process.
Building Control Sign-Off
Every house extension is fully signed off by building control. You receive a completion certificate confirming compliance with UK building regulations — essential for property sales, remortgage, and insurance.
PAS2035 Compliant Insulation
We install PAS2035 compliant insulation to floor, walls, and roof as part of every extension build — not as an optional extra. Your new extension meets current building regulation thermal performance requirements as standard.
Free Survey & Fixed-Price Quote
No-obligation site survey to assess your property, confirm the right extension type, check your planning position, and provide a fixed-price quote. No pressure, no hidden costs — your quote is confirmed before work begins.
LAMTANS Engineering — Retrofit & Construction Specialists
LAMTANS Engineering is a Manchester-based retrofit and construction specialist delivering house extensions, loft conversions, loft insulation, flat roof insulation, pitched roof insulation, cavity wall insulation, external wall insulation, park home insulation, solar panels, battery storage, and heating upgrades across the UK. We combine accredited retrofit expertise with full project management and building control compliance to deliver high-quality, energy-efficient extensions — from free survey to final sign-off.
📍 Based in Manchester — serving Stockport, Oldham, Droylsden, Ashton-under-Lyne, Tameside, and across Greater Manchester, with nationwide coverage.
House Extension — Common Questions
How much does a house extension cost in the UK?
Do I need planning permission for a house extension?
How long does a house extension take?
Will a house extension add value to my home?
Do I need to move out during the extension?
Can I combine an extension with energy efficiency upgrades?
Have a question not covered here? Our team is happy to discuss your property and what's possible — speak to us at a free, no-obligation site survey.
Ask Our TeamSpread the cost of this work with 0% APR finance
Insulation, solar, heat pumps, boilers, windows and doors, kitchens, bathrooms, extensions and full renovations. Finance available through our partner Ideal4Finance: 0% APR over 3 to 60 months, or 10.9% APR over 120 months. A deposit might be payable, and we will agree this before you begin your application.
Representative example: £5,000 purchase over 5 years with a 25% deposit (£1,250); total credit £3,750; 0% APR fixed; 60 monthly repayments of £62.50; total amount payable £3,750; total interest £0. Finance available subject to status.
Ready to Start Your House Extension?
Book your free, no-obligation site survey today. We assess your property's suitability, confirm the right extension type, check your planning position, and provide a fixed-price quote — all at no cost. We aim to provide your quote within 72 hours following your free survey.