Structural Alterations Greenwich
Structural alterations, new openings, underpinning and floor structures in Greenwich, designed by the engineer we appoint and inspected at every stage.
- Rated 4.9 from 31 reviews on MyBuilder
- London guide: from £1,500
- Free site survey, itemised quote
GS Renovation carries out structural alterations across Greenwich, from new openings in post-war houses and flats across the borough and Georgian townhouses near the Maritime Museum to replacement joists and underpinning in the Victorian terraces of SE7 and SE18. Our founder's 30+ years of work means we understand how both the post-war and the older stock is built and where it needs proper structural support.
In Greenwich, a simple new opening starts from £1,500, and underpinning a single elevation typically costs £6,000 to £21,000 (indicative London ranges, MyBuilder and Checkatrade, 2026). GS Renovation Ltd, a building contractor based in Potters Bar, does the work in Greenwich.
Price guide
| Work | Indicative London range |
|---|---|
| Simple new opening | from £1,500 |
| Underpinning, single elevation | £6,000 to £21,000 |
| Major structural works | from £15,000 |
Indicative London ranges (MyBuilder and Checkatrade, 2026), not a quotation. Prices checked September 2026. Full breakdown: RSJ & Load-Bearing Walls.
How the job runs
- Free site survey at your Greenwich address and an itemised quote.
- The engineer we appoint designs the work, and it is registered with the Royal Borough of Greenwich building control or an approved inspector. On a shared wall you serve the party wall notice as building owner; we supply the drawings.
- Props and any trial holes first, then the opening, joists or underpinning in the engineer's sequence.
- Building control inspects each stage before it is covered, then issues the completion certificate.
Structural alterations in Greenwich homes
Structural alterations cover far more than a single knock-through: new door and window openings, supported openings between rooms, replacement joists where old timbers have sagged, and underpinning where foundations need strengthening. In Greenwich's Georgian and Regency stock, much of it listed or within conservation areas, these jobs demand a careful, measured approach that respects the original construction rather than fighting it.
Every alteration starts with a structural engineer's assessment and calculations. Where an opening is formed, we prop the structure and install the steel beam the engineer has sized, set on padstones bearing into sound masonry. For sagging floors near SE9 and SE10 we replace joists to the span and grade the engineer specifies, and where movement is a concern we underpin to the depth the engineer designs, always staged so the building stays supported throughout.
Housing in Greenwich
For Greenwich the Council Tax list gives about 125,080 homes; by type 55% flats and 45% houses, by age 60% post-war, 17% interwar and 22% older than 1919. Most homes here are flats, and structural repair to a block in Greenwich usually falls to the freeholder.
Cellars under Greenwich houses and Royal Greenwich's basement rules
In Greenwich 22% of homes were built before 1919, and a house of that age can have a cellar its owner hopes to turn into a room. Where the scheme needs planning permission, for example for a lightwell or other change outside, Royal Greenwich treats that as basement work. It requires a Basement Impact Assessment for developments adjoining homes with new or enlarged basements, including cellar conversions into habitable accommodation, and the Structural Method Statement supporting it must be signed off by a Chartered Civil Engineer or Chartered Structural Engineer. So check that the structural engineer appointed for the scheme holds one of those titles, and the underpinning sequence we build follows the statement.
Two limits come before any design. Royal Greenwich's Urban Design Guide supports only single-storey basement extensions, so a scheme that goes two levels down is not worth drawing. Flood risk is the harder test. Royal Greenwich will not permit basements in flood zone 3, and will not normally permit them in flood zone 2 unless no habitable rooms are proposed. Look up the address on the Environment Agency flood map first. A Greenwich cellar in flood zone 2 may still suit storage or plant, but a bedroom below ground there is a much harder case.
Consents and controls for Greenwich alterations
Internal structural alterations fall under the Building Regulations, so the Royal Borough of Greenwich's building control inspects the propping, the steelwork and the bearings and certifies the finished job. Planning permission is a separate question that arises only with external changes, and those are more tightly controlled in the borough's conservation areas, which cover large parts of central Greenwich, Blackheath and beyond. A listed building is different: internal structural work there needs listed building consent before anything is cut.
Many of these homes share a party wall with the house next door, particularly the terraces of Charlton, Woolwich and Eltham, so forming openings or underpinning near that wall is notifiable under the Party Wall Act and you serve notice on neighbours in advance. We coordinate the engineer, the consents and building control so the alteration proceeds cleanly from first prop to final sign-off.
- Crack repair, helical bar stitching and masonry restraint
- Trial holes to confirm foundation depth and ground conditions
- Temporary works, propping and needling
VOA Council Tax stock of properties, March 2025, for all 35 statistical areas in Greenwich. Counts rounded by the VOA.
Trusted Structural Alterations in Greenwich
For structural alterations in Greenwich, GS Renovation gives you a single team responsible from the engineer's design to building control's completion certificate. We commission the engineer, install steel on padstones, underpin or replace joists as designed, and book every building control inspection through to sign-off. Where a party wall is involved, you serve the notice as building owner and we supply the drawings and programme it needs. Work is staged so your period home stays supported and lived-in throughout, backed by our founder's 30+ years on the tools.
Reviewed jobs near Greenwich
1 MyBuilder review from Woolwich, with each customer's own job title:
- Replace kitchen extractor hob, Woolwich, 27 Apr 2024 (5 out of 5)
Read all 31 on our reviews page.
We loved working with George and Ibrahim and would highly recommend them. They have done splendid job on our new kitchen refurb which including new…
Built a new extension at rear of property. Laid foundations, drainage, raised floor, new roof and completed all fixtures and interior decoration…
Giorgio is an excellent and intelligent workman, and with very reasonable prices! He installed a kitchen extractor fan in a complicated situation…
FAQ
Frequently Asked Questions about Structural Alterations Greenwich
What does the structural alterations quotation for a Greenwich home cover?
A Greenwich quotation for structural alterations sets out scope, programme and price on one document, within £1,500 to £21,000 or more, from a simple opening to underpinning one elevation (indicative). It shows what is done, in what order and at what cost, and the order is not arbitrary: underpinning is dug in controlled bays, never all at once. Exclusions are stated plainly rather than left to be discovered once work starts at the SE10 property.
Does underpinning my Greenwich house need party wall notices?
Usually, yes. Underpinning close to the shared party wall with a neighbouring property, common in Greenwich's terraces and semis, is notifiable under the Party Wall Act, so you serve notice as building owner (or your surveyor does) before work begins, and we give you the drawings and programme it needs. The underpinning itself is also controlled under the Building Regulations and signed off by the Royal Borough of Greenwich's building control, and we handle that application as part of the job.
What goes above a new doorway cut through a solid wall in a Greenwich house?
A lintel or beam sized by the engineer for what that wall carries, never a stock item picked off a shelf. Needles are threaded through the brickwork above and propped, the opening is cut beneath them, and the lintel is bedded onto sound bearings at each end. Old lime-mortar brickwork can hide timber lintels or infill, so bearings are checked first.
Is a listed Greenwich house treated differently for internal structural work?
Yes, and the order changes. For an unlisted home, Building Regulations approval through the Royal Borough of Greenwich covers an internal opening. Where the building is listed, internal structural alterations also need listed building consent, and that consent has to be granted before anything is cut, because the fabric itself is protected. The engineer's drawings then serve both applications, so they are prepared first.
Can sagging floor joists in an older Greenwich house be sorted from above?
Usually, yes. Lifting the floorboards exposes the joists without disturbing the ceiling below, which matters where there is original plasterwork. The engineer specifies whether each joist is strengthened with a new timber bolted alongside or replaced outright at the right size and grade for the span. Past plumbers and electricians have often notched the tops of joists deeply, and those cuts are what the survey looks for first.
Does removing a wall upstairs in a Greenwich house affect the roof?
It can. An upper-floor wall may look like a partition yet carry struts or binders from the loft, so the engineer climbs into the roof space before calling it removable. Downstairs walls pass load to the foundations; upstairs ones sometimes rest on floor joists that were never meant to take them. Tracing that path in both directions comes before any design.
Does demolishing a rear outbuilding in a Greenwich conservation area need planning permission?
It can. In Royal Greenwich conservation areas planning permission is always needed for total or large demolition of a building measuring more than 115 cubic metres. A detached garage or workshop can pass that size, so measure the volume from drawings before booking the skip. Below that threshold the demolition may still involve building control where it affects a drain, a shared wall or the structure left standing.
Is a Greenwich house on the local heritage list treated as a listed building?
No. Royal Greenwich keeps a local heritage list of buildings of local architectural or historic interest, with over 500 entries, and local listing is a planning consideration rather than statutory listing. Listed building consent applies to statutory listed buildings, and Royal Greenwich charges no fee to apply for it. For a locally listed house, a structural change that shows outside is weighed against its local interest when planning is needed. Internal work there stays a building regulations matter.
Can underpinning a Greenwich house go in under a building notice?
It can. Royal Greenwich lists mass concrete underpinning among its building notice charges, so the route exists for it. The exception is drainage. Royal Greenwich requires a full plans application to build over or within three metres of a public sewer, and a shared run behind a terrace can pass that close to a rear wall being underpinned. A drain survey before the notice goes in tells you which route applies, and the structural engineer we appoint designs the bases around what it shows.
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