Open-Plan Conversions Forest Hill
Open-plan kitchen, diner and living conversions in Forest Hill, steel, floors, heating and finishes as one job.
- Rated 4.9 from 31 reviews on MyBuilder
- London guide: £3,000 to £8,000+
- Free site survey, itemised quote
GS Renovation creates open-plan living across Forest Hill, turning the compartmented rooms of SE23's Victorian and Edwardian terraces into kitchen-diners and light-filled spaces. We handle the steelwork behind every knock-through, from full open plan to broken-plan layouts with Crittall dividers.
In Forest Hill, a knock-through finished as one room typically costs £3,000 to £8,000 or more, including the steel beam (indicative London ranges, MyBuilder and Checkatrade, 2026). GS Renovation Ltd, a building contractor based in Potters Bar, does the work in Forest Hill: the structural engineer we appoint designs the steel, we install it, and building control signs it off.
Price guide
| Work | Indicative London range |
|---|---|
| Open-plan conversion, steel beam and finishing | £3,000 to £8,000+ |
Indicative London ranges (MyBuilder and Checkatrade, 2026), not a quotation. Prices checked September 2026. Full breakdown: Open-Plan Kitchen-Diner Ideas.
How the job runs
- Free site survey at your Forest Hill address, covering the walls, services and floor levels, and an itemised quote.
- The engineer we appoint sizes the beam, and the work is registered with Lewisham 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 in, opening cut, beam on padstones; then floors, heating and electrics are joined up.
- Building control inspects the steel before it is covered. We finish the room, and the completion certificate follows.
Knock-throughs and kitchen-diners in Forest Hill
The classic Forest Hill layout, two receptions front and back with a kitchen in the closet wing, was never built for open living. Knocking the two reception rooms into one, or opening the rear reception through to the wing, means removing walls that carry the floors and masonry above, so every knock-through here is a structural job with a steel beam at its heart, not simply a matter of taking out brick.
The engineer we appoint sizes the steel for the span and the load, and it bears onto padstones at each end, often with the party wall carrying one side. We prop the structure, remove the wall in safe stages, and set the beam before the props come out. Flush-fitted steel lets us keep ceiling height and, where you want it, the original cornice and picture rails running through the opened space.
Housing in Forest Hill
By the valuation list's count, Forest Hill holds about 11,040 homes, 42% houses and 58% flats; by age, 54% were built before 1919, 13% between the wars and 30% since 1945. Opening up a flat in Forest Hill changes its fire escape route, which building control checks, which matters here because most homes are flats.
Opening a Forest Hill ground floor flat to the garden
An open-plan job in Forest Hill is often in a flat rather than a house: 58% of homes here are flats and 42% are houses. In a ground floor flat the plan can finish at the back wall, with the old window widened into doors so the new kitchen and living room open onto the garden. Inside, taking out the wall is building control work. At the back wall it becomes a change to the exterior, and in a conservation area Lewisham says flats or subdivided houses have no permitted development rights and need planning permission for that change.
That split sets the order of work. The internal steel can be designed while any planning application for the rear opening runs, but both pieces of steel should come from one scheme by the structural engineer we appoint, so the loads meet properly at the corner. Lewisham's fees chart treats support for new glazing, such as a door, as a line alongside removal of an internal wall, and both go on the building control application. We then build the knock-through and the back wall of the Forest Hill flat as one sequence once any consent is in hand.
Broken-plan and Crittall in SE23 homes
Not everyone wants one big room, and in these SE23 terraces broken-plan often works better. We create wide structural openings and then define zones with Crittall-style glazed dividers, so the kitchen-diner reads as one bright space while keeping cooking smells and noise in check. The glazed screen is non-structural, but the opening it sits within still needs a properly designed and installed beam above it.
Every open-plan conversion here is governed by the Building Regulations, so Lewisham Council's building control inspects the beam and its bearings and signs off; this internal work needs building control rather than planning permission. Where the new opening reaches into the shared party wall with your neighbour, the Party Wall Act applies and you serve notice first as building owner. We give you the drawings it needs and run the engineer, the steel, the inspections and the finishing as one job.
- Kitchen island services routed through the new floor
- Beam depth checked against existing ceiling heights
- Utility and boot room space carved out of the new layout
VOA Council Tax stock of properties, March 2025, for Forest Hill West, Forest Hill East and Honor Oak. Counts rounded by the VOA.
Trusted Open-Plan Conversions in Forest Hill
For open-plan conversions in Forest Hill, GS Renovation delivers one accountable team from first drawing to sign-off. We appoint the engineer who designs the steel, install it, form the openings for your kitchen-diner or Crittall divider, give you the drawings for any party wall notice you serve, and see Lewisham building control through to sign-off. Dust-controlled, sequenced working in your occupied SE23 home is standard, backed by our founder's 30+ years on the tools.
George was brilliant. Lovely bloke, very reasonably priced and a perfectionist to boot. He completed our small kitchen renovation with care and great…
Giorgio is an excellent and intelligent workman, and with very reasonable prices! He installed a kitchen extractor fan in a complicated situation…
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 Open-Plan Conversions Forest Hill
Is the price of open-plan conversion higher in Forest Hill than elsewhere in South East London?
Work on open-plan conversion in Forest Hill is priced from scope, so it costs no more than the same house in Dulwich, typically £3,000 to £8,000 or more (indicative). Costs rise in period stock and with awkward access, both checked at SE23. What neither changes is the order of work: the escape route is resolved at design stage, before the wall comes out. GS Renovation shows each as its own line.
Do I need planning permission to go open-plan in my Forest Hill terrace?
For internal open-plan work, no. Knocking rooms together in an SE23 terrace is governed by the Building Regulations, so Lewisham building control inspects and signs off the steelwork rather than planning. Planning is a separate question for exterior changes, particularly in a conservation area, and a listed home needs listed building consent for internal work too. Where the opening affects the party wall, you serve a party wall notice as building owner, and we give you the drawings it needs.
Does opening up the ground floor of a three-storey Forest Hill house affect fire safety?
Yes. Take away the hall wall in a three-storey house and the stair no longer delivers people to a protected route out, so a fire strategy is agreed with building control first. That can mean keeping an enclosure at the stair foot or other accepted measures. Settle it before ordering steel, since it can move walls.
Will the floors line up when rooms are joined in a Forest Hill terrace?
Not always. Front rooms in these houses usually have suspended timber floors, while a later rear kitchen may sit on concrete, and on the SE23 slopes the difference can be a step. We level before anything is laid, by firring the timber or screeding the lower side, and keep the airbricks feeding the void under the timber clear so it stays ventilated.
How do we keep one big room in Forest Hill warm and quiet?
Design heating for the whole volume instead of keeping old radiators, since one room now has two outside walls and often more glass. Sound carries further as well, and hard floors under high ceilings echo; a partial wall or soft finishes help. With 54% of Forest Hill homes built before 1919, solid walls and old sashes add to heat loss.
What gets done first when a Forest Hill kitchen and dining room are knocked together?
The steel. Props go in, the wall comes out, the beam lands on its padstones and building control inspects before anything is covered. Only then do first fix electrics and plumbing cross the new space, then plaster, then units. Ordering a kitchen before the beam is in risks a downstand clashing with wall cabinets or the extractor route.
What does a Lewisham inspector check on an open-plan job besides the steel?
Lewisham describes its inspectors as checking the build for building regulations compliance, fire safety, energy conservation and access. On a Forest Hill open plan, fire safety can mean the escape route from the rooms above or from an inner room, and energy conservation covers whatever glazing replaces the back wall. We gather the glazing specification and the escape plan with the engineer's calculations, so the inspector sees one complete scheme at the first visit.
How does a pre-1919 Forest Hill house change an open-plan design?
54% of Forest Hill homes were built before 1919, and in houses of that age the two rooms being joined can have different ceiling heights, cornices and a chimney breast each. Joining them makes one room with two sets of period detail. Decide early which cornice runs through and whether a breast stays as a room divider. A beam hidden in the ceiling and one hung below it leave different lines for the cornice, and the structural engineer we appoint sizes the steel for the option chosen.
Can a level threshold to the garden work in a Forest Hill ground floor flat?
Yes, with the detail drawn first. Lewisham Building Control's typical inspection stages include the damp-proof course, and a flush threshold is where that detail is hardest to get right. The paving has to fall away from the door, a drainage channel sits across the opening, and the internal floor build-up has to be known before the frame is ordered. Where a Forest Hill garden slopes up towards the house, the fall may mean lowering part of the patio.
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