House Extensions · Manchester & Greater Manchester
Single-storey rear, side-return, wrap-around and double-storey extensions delivered on a fixed contract — planning, structural, build and finish coordinated by one team so the job actually finishes.
FMB Member · Fully Insured (£2m PL & EL) · Fixed Written Quotes
Service Overview
House extensions covers single-storey rear extensions, side returns, wrap-arounds, double-storey extensions and over-garage builds. We deliver the full job — feasibility, planning drawings via our architect, structural engineering, Building Control, foundations, frame, roof, glazing, first fix, second fix, kitchen install and decoration — on a single contract.
Homeowners outgrowing the kitchen, needing a fourth bedroom, working from home or adding value before sale; landlords improving rental yield; buyers picking up properties specifically to extend. We work both with clients who have drawings already and with those starting from scratch.
When your house no longer fits how you live — open-plan kitchen-diners, utility rooms, ground floor WC, master bedroom with ensuite. Also when you're looking at moving and the cost-to-extend is less than stamp duty plus moving costs (often the case in Greater Manchester).
Extensions live or die on three things: a roof that doesn't leak at the junction with the existing house, glazing that doesn't condensate, and a slab that's flat enough to lay a kitchen on. Those three details are where amateur extensions fail — and they're three of the things we get right by default.
What Happens If You Wait
A bad extension is worse than no extension. It loses value, fails on sale survey and lives with you every single day — the cold patch by the bifolds, the crack above the new opening, the door that doesn't shut after winter.
Our Process
01
Site visit, measured survey, party-wall scoping, drains check, discussion of brief and budget. Honest view of what's possible on your plot.
02
Architect drawings, planning application (or PD certification), structural calcs, Building Control submission — managed for you, with a single timeline.
03
Itemised fixed-price contract, week-by-week programme, payment schedule. Signed before works begin.
04
Foundations, drainage, masonry or frame, steel beams, roof on, windows and doors in. Watertight before any internal work starts.
05
First and second fix electrics and plumbing, plaster, kitchen, tiles, decoration. Snag list resolved, Building Control completion, 12-month defects period starts.
Credentials
£2m public liability and £2m employers' liability cover.
Federation of Master Builders — verified profile.
Carried out by Ultra Build's own team — not subcontracted out.
Handled in-house alongside the main build.
Electrical work carried out by our NAPIT-registered specialist subcontractors, with certification on completion.
Gas work carried out by our Gas Safe-registered specialist subcontractors, with certification on completion.
Around 7 full-time staff, and 20+ including long-standing subcontractors we've worked with for 5+ years.
Why It's Worth It
No managing trades yourself. One contract covers design coordination, build and snag — and one company is accountable if anything fails.
We review architect drawings for buildability before construction starts — catches the clashes (steel into chimney, kitchen against waste run) that derail extensions.
PIR under slab, full-fill cavity, taped membrane junction with existing wall — meets current Part L and stops the cold patch by the bifolds.
Bifolds set on a level threshold with the right cill detail, flashings dressed by hand, no leaks at the upstand on rooflights.
Plaster flat under raking light, skirting mitres tight, tiles set out so cuts go to corners not centres. The difference a sale survey sees.
12 months from handover to call us back for anything that moves or fails. Returned same week, no debate about whether it's our problem.
Workmanship Guarantee
Every Ultra Build Northwest contract carries a workmanship guarantee in writing. It covers defects with the structural build and plumbing issues such as faulty fittings — not just a verbal promise.
10
Years
On Roofs
2
Years
On Extensions
Up To
5
Years
On Internal Renovation Defects
In Detail
Materials, methods and the situations each variation applies to — so you know what you're buying before you buy it.
Working across
Manchester · Cheshire · Oldham · Salford · Stockport · Alderley Edge · Altrincham & Hale
Full Service Area MapThe default Greater Manchester extension — opening up the back of the house for an open-plan kitchen-diner with bifold or sliding glazing to the garden. Typical scope: 3–6m rear projection, beam through the existing rear wall, new rooflight or lantern, full insulation upgrade to existing wall now becoming internal. Programme 10–16 weeks.
Filling in the side return of a Victorian or Edwardian terrace, often combined with a rear extension to create an L-shaped open-plan space. Critical detail: roof junction with existing back addition, party-wall awards with both neighbours, and floor levels matched across the join.
Adding a bedroom or ensuite above the new kitchen, or extending up and out to the side. More steel, more party-wall implications, more value added. Programme 16–24 weeks.
Converting an integral garage to habitable space and adding a bedroom above, or building over a flat-roof extension. Structural survey of the existing slab and walls is always step one.
Aluminium bifolds (Origin, Smart, Schüco), sliding doors, slim-frame steel-look windows, flat or pitched rooflights and lanterns. Specced for U-value, frame depth and threshold detail so they sit flush with the floor finish.
Most extension work is residential. Commercial extensions (shop, café, salon expansion) are handled under our commercial building works page — same standards, scoped around trading hours and customer access.
What Clients Say
Single-Storey Extension
Craig and the Ultra Build team did a fantastic job throughout the process of our single-storey extension — they minimised the disruption to our daily life and the job was completed on schedule to a really high standard.
Jake Lee
Extension
Super experienced and helpful team! Very happy with our extension project and would definitely recommend to anyone dreaming of natural light and lots of space in their home.
Nara Bayaraa
Single-Storey Extension
I had the pleasure of working with Craig and his team at Ultra Build last year, and I can't thank them enough for making our house into a home for my family. We had a single-storey extension built on the back of the house.
Kieran Herbert
Extension
Amazing team. We absolutely love our extension — it's completely changed the house and how we live in it. Thanks again.
Andrew Holsgrove
Questions
Cost, timeline, guarantees, lifespan, emergency availability — the questions everyone asks, answered before you call.
Ask YoursTypical 2026 prices in Greater Manchester: single-storey rear extension £2,200–£2,800 per m² for shell; with kitchen and bifolds in scope, £2,800–£3,800 per m². Double-storey is more economical per m² (shared foundation and roof) at £2,000–£2,600 per m² for shell. Every quote is fixed and itemised.
Many rear and side extensions fall under Permitted Development and don't need full planning — but rules on height, depth, materials and previous extensions apply, and a Lawful Development Certificate is strongly recommended. Larger or front extensions need full planning. We confirm at feasibility.
Single-storey rear: typically 10–16 weeks on site. Side-return wrap-around: 14–20 weeks. Double-storey: 16–24 weeks. We issue a week-by-week programme with the contract.
Yes — any extension that opens the existing rear wall, adds steel or alters loads needs structural calcs. We organise this through our engineer and the cost is included in the design package.
For single-storey rear extensions, yes — the existing rear wall stays in place until structure is ready, so you keep a working kitchen for most of the programme. Double-storey or major reconfiguration may need 2–6 weeks elsewhere depending on scope.
If you're excavating within 3m of a neighbouring wall, or building on the boundary, the Party Wall Act 1996 applies. We flag it at feasibility and recommend a surveyor — most awards are agreed without dispute when handled early.
Full scope of works against the drawings — substructure, frame, roof, windows, first and second fix, plaster, kitchen install (PC sum), tiling, decoration, external make-good. Variations are priced against the original rates in writing before any extra work starts.
Yes — 12-month defects period as standard from handover, plus material warranties on roof, glazing and boiler. Anything that moves, leaks or fails in year one, we come back and fix.
Yes — full submission, inspection bookings (foundations, DPC, drainage, insulation, completion), photo file of concealed zones, completion certificate handed over at end.
Yes — Manchester, Salford, Stockport, Oldham and Cheshire. See service-areas page for full coverage.
Next Step
Free site survey across Greater Manchester, fixed written quote — no obligation. FMB member, fully insured with £2m public liability and £2m employers' liability, Manchester-based.
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