If you’re thinking about extending your home in Manchester, the first question most homeowners ask is a simple one — how much is it going to cost?
The honest answer is that it depends on several factors: the type of extension, the size, the specification of finishes, and the condition of your existing property. But that’s not particularly helpful if you’re trying to plan a budget, so in this guide we’ve broken down the typical costs for each type of extension in Manchester, along with the key factors that will influence your final price.
Single-Storey Rear Extension Costs in Manchester
A single-storey rear extension is the most common type of home extension in Manchester and the most straightforward to plan and build.
For a typical Manchester terraced or semi-detached property, you can expect to pay:
- Small single-storey extension (up to 15m²): £18,000 – £28,000
- Medium single-storey extension (15–25m²): £28,000 – £42,000
- Large single-storey extension (25m²+): £42,000 – £60,000+
These figures cover all structural work including foundations, brickwork, roofing, windows and doors, insulation, and basic internal plastering and finishing. They don’t typically include kitchen fitting, flooring, or decorating, which are usually agreed separately.
Double-Storey Extension Costs in Manchester
A double-storey extension adds space on two levels and offers significantly better value per square metre than a single-storey build, since you’re sharing the cost of foundations and roofing across twice the floor area.
Typical costs for a double-storey extension in Manchester:
- Small double-storey extension: £40,000 – £60,000
- Medium double-storey extension: £60,000 – £90,000
- Large double-storey extension: £90,000 – £130,000+
Double-storey extensions almost always require full planning permission, and the design process typically adds 8–12 weeks before work begins on site. We manage the full planning application on behalf of all our clients — find out more about our house extensions and new builds service.
Wrap-Around Extension Costs in Manchester
A wrap-around extension combines a rear extension with a side return, creating a large L-shaped addition that dramatically increases ground floor space. These are particularly popular on Manchester terraces where the side passage is currently wasted space.
Typical costs for a wrap-around extension:
- Standard wrap-around extension: £55,000 – £95,000
- Large or premium wrap-around extension: £95,000 – £150,000+
Wrap-around extensions are complex builds requiring careful structural planning and almost always require planning permission. The results, however, can be transformative — particularly for open-plan kitchen and dining room projects.
Loft Conversion Costs in Manchester
A loft conversion adds usable space without extending your footprint, making it one of the most cost-effective ways to gain an extra bedroom or home office.
- Velux loft conversion: £18,000 – £28,000
- Dormer loft conversion: £30,000 – £55,000
- Hip-to-gable loft conversion: £35,000 – £60,000
- Mansard loft conversion: £45,000 – £70,000+
Loft conversions that create a habitable room always require building regulations approval, and some types require planning permission. They also typically involve significant roofing work — our Manchester roofing team works alongside the extension team on all loft projects to make sure the roof structure, insulation, and weatherproofing are done properly.
What Affects the Cost of a House Extension in Manchester?
Beyond the basic size and type, several factors can push the cost of your extension up or down significantly.
1. Specification and Finishes
A basic extension with standard windows, plain plaster walls, and no fitted furniture sits at the lower end of the price range. Add bifold doors, underfloor heating, a fitted kitchen, or premium materials and costs rise accordingly. It’s worth deciding early on where you want to invest and where you’re happy to keep things simple.
2. Ground Conditions
Manchester’s clay-heavy soil can cause issues at foundation stage. If a structural engineer recommends deeper or wider foundations than standard, this adds cost. We carry out a thorough site assessment before quoting so there are no surprises once work begins.
3. Brick and Material Matching
Manchester has a huge variety of housing stock — Victorian terraces, Edwardian semis, 1930s houses, and post-war builds all use different brick types and mortar styles. Matching new brickwork to your existing property takes skill and the right materials. For harder-to-match period properties, reclaimed bricks may be needed, which adds to material costs but is essential for a seamless finish.
4. Planning Permission and Building Regulations
Many single-storey rear extensions fall under permitted development and don’t require full planning permission, which saves both time and money. Larger extensions, double-storey builds, and properties in conservation areas almost always require a full application. Building regulations approval is required for all extension work regardless — we handle both processes on your behalf.
5. Roofing Type
The type of roof on your extension affects cost. A simple lean-to roof is the most economical option. A pitched roof that matches your existing property costs more but looks better and adds more value. Flat roofs using modern systems like GRP fibreglass or EPDM are a popular middle ground — particularly for extensions at the rear where the roof isn’t visible from the street. Our roofing team advises on the best option for each project.
6. External Landscaping
Once the extension is built, the surrounding outdoor space often needs attention — broken paving, disturbed garden areas, or a new patio to make use of the extra space. Our paving and hard landscaping team can lay a new patio or driveway as part of the same project, saving you the hassle of bringing in a separate contractor.
How to Get an Accurate Quote for Your Extension
Online cost guides — including this one — give you a useful starting point, but the only way to get an accurate figure is to have a builder visit your property and assess the project properly.
At Reliable Builders, we offer free, no-obligation site visits across Greater Manchester. We’ll look at the ground conditions, discuss your vision, and provide a fully itemised written quote that covers every aspect of the build — no hidden costs, no vague estimates.
We cover extensions across Stretford, Sale, Altrincham, Chorlton, Didsbury, Salford, Trafford, Wythenshawe, Eccles, Stockport, and the surrounding areas.
As builders in Manchester with over 50 years of experience, we cover all of these areas and more
Get in touch today to arrange your free quote.
Frequently Asked Questions
Does a house extension add value in Manchester? Yes — a well-built extension typically adds between 10% and 25% to a property’s value depending on the type and size. A kitchen extension or additional bedroom has the strongest impact on sale price. The key is quality of build — a poorly finished extension can actually put buyers off.
Do I need an architect for a house extension in Manchester? Not always. For straightforward single-storey extensions, many builders — including us — work from detailed drawings produced by an architectural technician rather than a fully qualified architect. This is perfectly acceptable for planning and building regulations purposes and is often more cost-effective. For complex or large projects, a full architect may be recommended.
How long does a house extension take from start to finish? From initial enquiry to completion, allow 4–6 months for a single-storey extension — this includes the planning and design stage plus the build itself. Double-storey extensions typically take 6–9 months in total. We provide a full programme of works before starting so you know exactly what to expect at every stage.
Can I live in my house during the extension build? In most cases, yes. We work carefully to maintain access to key rooms and secure the site each day. For larger projects where structural work affects the main living area, we’ll discuss the build sequence with you in advance to minimise disruption.
Reliable Builders Ltd are Manchester-based construction specialists with over 50 years of experience in house extensions, brickwork, roofing, and paving. Contact us for a free, no-obligation quote.