Structural engineering for two-storey extensions in Greater Manchester
Looking for help with structural engineering in Greater Manchester? Here's what's involved, the rules in England and what it typically costs.
Greater Manchester at a glance
- Nation
- England
- Price region
- North West England
- Postcode areas
- BL, M, OL, SK, WA, WN
- Towns covered
- 67 listed below, plus surrounding villages
- Site visits
- Free, no obligation
What a structural design involves
Structural engineering for a two-storey extension involves calculating how the new floors, walls and roof carry their loads down to the ground, and designing the beams, lintels, foundations and ties into the existing house to suit. The engineer's calculations and drawings form part of the building regulations approval. They also tell the build team exactly what steel and foundations to install.
The main places we list in Greater Manchester are Manchester (M1), Oldham (OL1), Wigan (WN1), Bolton (BL1), Stockport (SK1) and Salford (M5). We cover the villages in between too.
Fees
A structural engineer (calculations and beam design) is a guide of £750–£2,200, priced in writing once the design is known.
Rules in England
In England, structural engineering is part of building regulations approval under Part A rather than planning. The engineer's calculations go to council building control or a registered building control approver with the full plans application. Where more than one contractor is involved, the Building Safety Act dutyholder rules also apply.
Approval in England: Householder planning application: £548 (or £575 for applications made from 8 December 2026). Lawful development certificate: £274 (about £288 for applications from 8 December 2026). Councils should decide householder applications within 8 weeks of validation.
Building regulations: Building regulations approval (full plans recommended) from the council or a registered building control approver, with a completion certificate at the end.
The Party Wall etc. Act 1996 applies, so notices may be needed for work on or near a shared wall or boundary.
Getting the design right
Tying into the house
The new walls and floors are tied into the existing house with wall ties, restraint straps and joist hangers. The engineer also considers movement between the old and new foundations and where a movement joint may be needed.
Beams and padstones
Steel beams carry the first floor and roof over openings, and they sit on padstones that spread the load into the walls. The engineer sizes each beam and checks the walls can take the point loads, which affects ceiling heights and where posts can go.
How we work in Greater Manchester
Free site visit
We visit your home in Greater Manchester, look at the structure, access and boundaries, and talk through what you want the new rooms to do.
Choose the approval route
Some designs fit permitted development, most need a householder application. We decide which applies in England before drawing in detail.
Price it properly
Once the engineer's calculations are in, we fix the build price in writing, with a clear list of what's included.
Build it
The new structure goes up first, then we open into the house, finish inside and get the completion certificate.
Towns we cover in Greater Manchester
- Manchester
- Oldham
- Wigan
- Bolton
- Stockport
- Salford
- Rochdale
- Sale
- Bury
- Altrincham
- Middleton
- Ashton-under-Lyne
- Leigh
- Stretford
- Urmston
- Chadderton
- Eccles
- Tyldesley
- Hyde
- Walkden
- Prestwich
- Radcliffe
- Cheadle Hulme
- Heywood
- Denton
- Stalybridge
- Ashton-in-Makerfield
- Westhoughton
- Farnworth
- Saddleworth
- Hindley
- Droylsden
- Whitefield
- Swinton
- Royton
- Atherton
- Old Trafford
- Dukinfield
- Failsworth
- Hazel Grove
- Irlam
- Horwich
- Manchester City Centre
- Bramhall
- Ramsbottom
- Bredbury
- Hale (Greater Manchester)
- Longsight
- Didsbury
- Fallowfield
- Littleborough
- Burnage
- Little Hulton
- Marple
- Cheetham Hill
- Lees
- Hollinwood
- Crumpsall
- Timperley
- Uppermill
- Ince-in-Makerfield
- Blackley
- Kearsley
- Little Lever
- Abram
- Mossley
- Hale Barns
Structural engineering for two-storey extensions in Greater Manchester: questions
How deep do foundations need to be for a two-storey extension?
There is no single depth. It depends on the soil, nearby trees, drains and the loads. On firm ground foundations may be around a metre deep, while clay near trees can need much deeper trench fill or piles. Trial holes and the engineer's design set the depth, and building control inspects the trenches.
Do I need a structural engineer for a two-storey extension?
Almost always. Building control needs calculations showing that the foundations, beams and walls can carry the loads of two storeys and a roof. A two-storey extension usually involves removing part of an outside wall and new steel, which needs an engineer's design.
Can a steel beam be hidden in the ceiling?
Often, yes. A beam can sit within the floor depth so the ceiling is flat, but that may mean a deeper steel section or a different floor structure. Otherwise it shows as a downstand below the ceiling. We discuss the options with you and the engineer before the design is fixed.
Neighbouring areas
- Structural engineering for two-storey extensions in Cheshire
- Structural engineering for two-storey extensions in Lancashire
- Structural engineering for two-storey extensions in Merseyside
- Structural engineering for two-storey extensions in West Yorkshire
All extension services in Greater Manchester · About structural engineering for two-storey extensions
Ready to see what a second storey could do for your home?
Book a free site visit. We'll look at your house, talk through options and explain the approvals you'd need, then price the design stage in writing.