Structural Alterations Brentford
Structural alterations, new openings, underpinning and floor structures in Brentford, 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 throughout Brentford, whether that is a new opening in a canalside conversion, a supported opening in a post-war flat or replacement joists in a terrace behind the High Street. We build supported openings to the engineer's design, install beams and manage the leasehold consents that riverside flats usually require.
In Brentford, 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 Brentford.
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 Brentford address and an itemised quote.
- The engineer we appoint designs the work, and it is registered with Hounslow Council 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.
Supported openings and new steel in Brentford
Structural alterations in Brentford cover more than a single knock-through. Homeowners come to us to widen a doorway into a spine wall, form a supported opening between a kitchen and living space, replace tired or over-notched joists, or strengthen a floor for a new bathroom in a converted warehouse unit. Each of these changes a load path, so a structural engineer designs the fix and specifies the steel or timber before we lift a tool.
Where a new opening is formed, the engineer sizes an RSJ that bears onto padstones spreading the load into sound masonry or the frame. We prop the structure temporarily, cut back in stages, and set the beam accurately to line and level. In a new-build apartment with a concrete frame the approach differs again, so we always follow the specific engineer's detail for your TW8 property rather than a standard template.
Housing in Brentford
Roughly 13,230 dwellings sit on the valuation list for Brentford. 35% are houses and 65% flats, and by age 15% predate 1919, 24% are interwar and 61% post-war. Structural repair to a block in Brentford usually falls to the freeholder, which matters here because most homes are flats.
When Brentford structural work creates homes or goes underground
Some Brentford structural alterations change the number of homes in a building: a storey added on top of a block, a commercial floor converted to flats, or a house split into flats. Splitting a house always needs planning permission. The first two have been possible under permitted development, but on 4 March 2025 Hounslow confirmed an Article 4 direction removing certain permitted development rights that would result in new dwellings. Check before any design work whether the right a scheme relies on is one the direction removed. The steel, the fire separation and the sound insulation are the same either way, but an application adds a stage to the programme.
Digging down under a Brentford house brings its own rulebook. Hounslow's residential extension guidelines say a basement should be no deeper than a single subterranean floor, and should not extend beyond the main front or side walls of the house. Where a basement is allowed, the developer must submit by condition a Construction Method Statement certified by a suitably qualified engineer. That statement is where the support of the party walls and the street during excavation is set out, so have the structural engineer write it before any digging is priced. Excavating close to next door's foundations also brings in the Party Wall Act, and the building owner serves that notice.
Consents and regulations across Hounslow
Internal structural alterations need Building Regulations approval, not planning permission. That distinction confuses a lot of Brentford owners, so to be clear: planning only comes in where the outside of the building changes, and a listed building also needs listed building consent for internal work. The steelwork, propping and openings inside your flat are signed off by Hounslow Council building control instead.
Because most Brentford homes are flats, and so leasehold, the freeholder's licence to alter sits alongside building control. We assemble the engineer's package for the managing agent, respect the block's rules on noise and shared access, and where any alteration touches a wall shared with a neighbouring flat, you serve the party wall notice as building owner and we supply the drawings it needs. You get one team steering the calculations, the consents and the inspections from start to certificate.
- Trial holes to confirm foundation depth and ground conditions
- Floor structure, joist and beam replacement
- Steel goalpost and portal frames to the engineer's design
VOA Council Tax stock of properties, March 2025, for Brentford Central, Brentford West & Osterley Park and Brentford East. Counts rounded by the VOA.
Why Brentford Homeowners Choose GS Renovation
GS Renovation gives Brentford owners a single accountable team for structural alterations: an engineer-designed solution, freeholder licence to alter and managing-agent coordination arranged, and Hounslow building control inspections booked and passed. We work cleanly around occupied flats and communal areas, and we back every job with our founder's 30+ years of structural experience.
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…
George always kept to commitments and arrived on time. He offered helpful suggestions during his initial visit and promptly provided a reasonably…
FAQ
Frequently Asked Questions about Structural Alterations Brentford
How much should structural alterations in Brentford cost?
Expect structural alterations at a Brentford address to cost £1,500 to £21,000 or more, from a simple opening to underpinning one elevation (indicative), with the property rather than the postcode deciding the figure. At the TW8 survey GS Renovation confirms the detail that matters most, because what each wall and floor carries decides the design. Labour, materials and the Hounslow Council building control fee are then itemised, so another Hounslow quotation can be compared line by line.
Do I need planning permission for structural alterations in my Brentford flat?
For internal work, no. New openings, replacement joists and supported openings are controlled under Building Regulations, and Hounslow building control signs them off. Planning applies where the outside changes, and a listed building needs listed-building consent for internal as well as exterior changes. You will, however, need your freeholder's licence to alter, which we help you obtain.
Can a new doorway be cut through a concrete wall in a Brentford new-build flat?
Sometimes, but the engineer decides. Of Brentford's dwellings, 61% were built after 1945 on the VOA figures, and in a block of that age a concrete wall can be part of the frame carrying the floors above, with reinforcement that cannot simply be cut. The engineer works from the original structural drawings, usually held by the managing agent, and either designs a supported opening or rules it out.
Can the floor joists in a Brentford warehouse conversion carry a new bathroom?
Not until they are checked. Conversion floors in TW8 are often timber joists over the original industrial structure, some notched by earlier pipe runs. A filled bath or stone tiles put a concentrated load on a small area, so the engineer looks at span, depth and notching and may specify doubled joists or steel. That strengthening goes in before first fix plumbing, so the new pipes are routed through sound members.
Is an asbestos survey needed before structural work in a Brentford flat?
Yes, where the building dates from before 2000. Textured ceilings, floor tiles, boxing around risers and old soil pipes in blocks of that age can contain asbestos, and cutting or drilling them releases fibres. The survey comes before strip-out, and anything positive is dealt with by a specialist before our trades open up the structure.
Who has to be told before structural work starts in a Brentford block?
Three parties, in order. The freeholder, through the managing agent, grants the licence to alter. Hounslow Council building control receives the engineer's design and inspects the work. Where the alteration cuts into a wall shared with the neighbouring flat, that owner receives a party structure notice at least two months ahead and can consent or dissent. Missing any one of them can halt the job halfway, with a wall already open.
Does being on Hounslow's local list limit structural work inside a Brentford house?
Not in the way statutory listing does. Hounslow's first local list was adopted in 1997 and was updated in September 2019, and being on it brings no separate consent regime for internal work. A beam, a new opening or replaced joists go through building control as they would anywhere else. The local list matters when the outside changes, because the building's local interest is weighed in any planning decision. Check the address against the current list before designing an external opening.
Can a new basement under a Brentford house be used as a bedroom?
No. Hounslow's residential extension guidelines say basements must not be used as a main living area or as sleeping accommodation, because of flood risk and emergency access concerns. Hounslow also requires a site specific Flood Risk Assessment for any basement development within flood zones 2 and 3, and Brentford lies along the Grand Union Canal. Check the flood zone for the address first, then plan the space as storage, a utility room or a plant room.
Does structural work that creates a new Brentford flat attract the Community Infrastructure Levy?
It can. Hounslow adopted its Borough CIL Charging Schedule on 24 July 2015, and planning permissions granted after that date are liable. Under the Mayor's revised charging schedule known as MCIL 2, liable developments in Hounslow also pay Mayoral CIL, charged per square metre. A new dwelling formed under a planning permission should be checked for liability before work starts, since the levy has its own forms, including notices that have to be lodged before commencement.
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