Structural Alterations Dulwich
Structural alterations, new openings, underpinning and floor structures in Dulwich, 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 Dulwich, from forming new openings in the period villas to replacing tired joists and underpinning in the bay-fronted Victorian and Edwardian terraces of SE21. Our founder's 30+ years on the tools taught one habit: find which way the joists run and what the foundations sit on before promising any opening.
In Dulwich, 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 Dulwich.
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 Dulwich address and an itemised quote.
- The engineer we appoint designs the work, and it is registered with Southwark 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.
Structural alterations for Dulwich period homes
The Victorian and Edwardian terraces around Dulwich come with their own quirks: rear closet wings, side returns and original timber joists that have carried a century and a half of use. Whether you want a wider supported opening into a side-return infill, replacement joists where old ones have sagged, or a new doorway punched through solid masonry, we start with an engineer's design so every alteration is calculated, not chanced.
New openings get a properly sized steel lintel or beam bearing onto padstones, with temporary propping while we cut and safe staged removal of the masonry above. For subsidence or a settled bay, we underpin in short, sequenced bays to extend the foundation down to firmer ground. Each of these is a distinct structural operation, and we sequence them so the house stays fully supported at every stage of the work.
Housing in Dulwich
For Dulwich the Council Tax list gives about 14,360 homes; by type 55% flats and 45% houses, by age 30% post-war, 11% interwar and 56% older than 1919. Where most homes are flats, structural repair to a block in Dulwich usually falls to the freeholder under the lease, so it is agreed with them before anything is opened up.
New openings in outside walls in the Dulwich Village Conservation Area
The Dulwich Village Conservation Area was designated on 7 September 1968 and was one of the first in Southwark. Inside it, structural work behind the plaster of an unlisted house is still a building regulations matter. Outside, a house there keeps fewer permitted development rights: cladding, a side extension or a rear extension of more than one storey needs planning permission. Southwark's Householder SPD goes further and says its route to a single storey rear extension without planning permission is not available to homes in a Conservation Area. National rules still allow a modest single storey rear extension to a house there unless a direction removes the right. Where a new opening grows into a small rear room, a lawful development certificate from Southwark settles the position before work starts.
For a listed Dulwich house the order changes again. Southwark's fees and charges schedule sets a separate pre-application fee for householder listed building development, covering extensions or internal alterations. Listed building consent covers work inside the house as well as outside, and internal structural changes need it even where nothing outside moves. The engineer's outline scheme is worth taking to pre-application advice before the calculations are finished. At that stage the beam position, the size of the opening and any historic fabric that would be lost can still be adjusted.
Consent and sign-off across SE21
Structural alterations inside your Dulwich home are controlled under the Building Regulations rather than planning, so this internal work needs building control, not planning permission. Southwark's planners matter only if the outside changes within a conservation area, or if the house is listed, when listed building consent is needed for internal work too. We tell you plainly which route your project takes so there are no surprises and no work that has to be undone later.
Where an alteration touches the party wall shared with your neighbour, common in the tightly packed East Dulwich terraces when beams bear into it or foundations are underpinned close by, the Party Wall Act applies. You serve the notices as building owner (or your surveyor does); we give you the drawings and programme they need and build to any award. Southwark Council's building control inspects the steelwork, propping and any underpinning at the key stages and issues the completion certificate once satisfied. We arrange every inspection for you.
- Building control applications, inspections and the completion certificate
- Trial holes to confirm foundation depth and ground conditions
- Lintel replacement and repair over failed openings
VOA Council Tax stock of properties, March 2025, for North Dulwich, East Dulwich, Herne Hill & Dulwich Park and Dulwich Hill. Counts rounded by the VOA.
Trusted Structural Alterations in Dulwich
For structural alterations in Dulwich, GS Renovation gives you a single accountable team from engineer's drawings to final certificate. We install the steel to the engineer's sizing on padstones, prop and cut in safe stages, underpin sequentially where needed, and handle Southwark building control. The engineer sets the sequence; our founder's 30+ years on the tools keep us to it.
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 was brilliant. Lovely bloke, very reasonably priced and a perfectionist to boot. He completed our small kitchen renovation with care and great…
FAQ
Frequently Asked Questions about Structural Alterations Dulwich
What is the going rate for structural alterations around Dulwich?
Structural alterations around Dulwich typically costs £1,500 to £21,000 or more, from a simple opening to underpinning one elevation (indicative), but scope varies more than the market does. Two Dulwich jobs of the same size can be different work, because the ground and existing foundations decide whether underpinning is needed. GS Renovation surveys and prices each on its merits at SE21, with the Southwark Council building control fee shown separately.
Do I need planning permission for structural alterations in my Dulwich house?
For internal structural work, no. Forming openings, replacing joists or underpinning inside your SE21 home is controlled under the Building Regulations, so it needs building control sign-off rather than planning permission. The exceptions are a listed house, which needs listed building consent for internal work as well as external, and exterior alterations inside a conservation area, which can need planning permission. We confirm which applies before we start.
Who designs a structural alteration in a Dulwich house, and at what stage?
A structural engineer does, and before anything else. The engineer visits the SE21 house, traces where joists and walls above land, then issues calculations and a drawing fixing the beam or lintel size and its padstone bearings. Building control assesses the work from those documents and the neighbour's notice describes it. Pricing steel without them is guesswork, so the calculations come before a firm figure or a start date.
Can I form a new opening in an outside wall of my Dulwich terrace?
Usually, but an external wall behaves differently from an internal one. Period walls in SE21 are solid brick, so the opening needs a lintel or steel sized for the masonry above plus any floor it carries, with proper bearings each side. Because the elevation changes, check first whether your street is in a conservation area, where exterior alterations may need consent from Southwark Council as well as building control approval.
Is taking out a wall upstairs in a Dulwich house easier than downstairs?
Often, because less sits on it. A first-floor wall in a Dulwich house may carry only ceiling joists and part of the roof, though some upstairs partitions support a purlin or an old water tank and do more than they look. The engineer checks from the loft down. On the ground floor, the same wall line usually carries the whole floor above plus that upstairs wall, so the steel section grows accordingly.
What if opening up my Dulwich floor reveals rotten joist ends?
They are cut back and the joists properly supported before any new opening goes in. In solid-walled Dulwich terraces, joist ends built into damp brickwork decay out of sight and are only found once boards come up. Common repairs are bolting new timber alongside or hanging the joists on steel hangers. The engineer confirms the detail, building control sees it, and the source of damp is dealt with before plaster closes it in.
Can a Dulwich cellar be dug deeper to make a usable room?
Only with planning permission. Southwark's Householder SPD says permission is required for all homes to create a new basement or extend an existing one, and a Basement Impact Assessment (BIA) has to go in with the application. The SPD also limits basement extensions to no more than a single storey below ground. Lowering a cellar floor usually means underpinning the walls around it, so the engineer's underpinning sequence and the BIA are prepared together before anything is excavated.
Does a new window in the outside wall of a Dulwich flat need planning permission?
Assume so until Southwark confirms otherwise. 55% of homes in Dulwich are flats, and flats have narrower permitted development than houses: Southwark's Householder SPD, for example, says the single storey rear extension route without permission is not available to flats or maisonettes. A new or enlarged opening that changes how the building looks is normally a planning matter for a flat. The freeholder's consent is needed as well, since a lease commonly keeps the outside walls with the freeholder.
Can a new window go in the flank wall of a Dulwich semi?
Sometimes, but the boundary distance matters. 16% of homes in Dulwich are semi-detached or detached, and their flank walls are external walls that can take an opening where a terrace cannot. Part B of the building regulations limits unprotected areas, such as windows, in a wall close to a boundary, and under permitted development an upper floor side window has to be obscure glazed and fixed shut at low level. The engineer sizes the lintel, while building control confirms how much opening the flank can have.
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