Through-lounge knock-throughs · Westminster
Through-lounge knock-throughs in Westminster
Through-lounge knock-throughs in Westminster, from free survey to completion certificate.
- Price fixed in writing once scope is agreed
- Building control arranged
- Temporary works and making good included
- Free survey visit
- Engineer's calculations arranged
- Building control handled
- Fixed written price once scope is agreed
- England, Wales, mainland Scotland & NI
Planning through-lounge knock-throughs in Westminster
Our through-lounge knock-throughs service in Westminster covers everything from the first visit to the completion paperwork. The wider London area is covered as well. Postcode districts we cover here include SW1, W1 and WC2.
Many period terraces and semis were built with a front parlour and a back sitting room divided by a solid brick wall. Opening them into one through-lounge brings light from both ends of the house, but that wall commonly carries the floor joists, the wall between the bedrooms above and sometimes part of the roof load too.
Key points for your project
- Ornate cornicing often runs around both rooms and stops at the wall being removed. Where practical, the run is extended across the opening by matching the profile, either run in place or cast, so the joined room looks original rather than patched.
- Minor hairline cracks can appear in plaster upstairs as the structure takes up the new support. This is common after a knock-through and is usually filled at decoration stage, but wider or growing cracks should be reported so they can be checked.
- Many owners leave short nibs of wall at each end of the opening rather than going fully wall to wall. Nibs can give the beam a bearing, line up with the chimney breasts and keep the feel of two linked rooms, but the engineer decides whether they are adequate.
- Radiators, pipe runs and sockets on the dividing wall need relocating. Older houses sometimes have heating pipes running under the floor along the wall line, so these are traced and moved by a heating engineer before the wall comes down.
- Period ceilings are often lath and plaster, which can crack or sag when the wall below is disturbed. Props are set to spread load gently, and damaged areas are repaired with lime plaster or overboarded, depending on the condition and your preference.
How the job runs in Westminster
Look and measure
We check the wall, the span you want and what the wall is carrying, and photograph anything the engineer needs to see.
Design and price
Calculations come back from the engineer and we confirm your fixed written price, line by line.
Building control
We submit a building notice or full plans application to the local council's building control team, so approval is in place before the wall is touched.
Fit, inspect, finish
The work is propped and the steel installed and packed tight. After inspection the opening is boxed, plastered and left clean.
What do through-lounge knock-throughs cost in Westminster?
As a guide, budget £3,200–£7,050 including VAT for through-lounge knock-through in Westminster, based on published UK cost guides adjusted for London prices (+28%).
| Job | Typical guide range | What it usually covers |
|---|---|---|
| Through-lounge knock-through | £3,200–£7,050 | Wall between front and back reception rooms, steel beam, approvals, plastering and floor infill |
| Plastering and making good | £380–£1,540 | Boxing the beam, bead and skim, reveals, floor infill where the wall stood and tidy-up |
| Party wall surveyor (agreed surveyor, per neighbour) | £1,150–£2,550 per neighbour | Schedule of condition and award where a neighbour dissents; serving notice alone, where the neighbour consents, costs far less (England and Wales only) |
| Kitchen-diner knock-through | £3,200–£7,700 | Internal structural wall between kitchen and dining room, steel beam, approvals and making good (kitchen fitting extra) |
Figures include our approximate regional adjustment for London prices (+28%) and are rounded. How these figures are worked out.
Building control and neighbours in Westminster
Structural openings in English homes need building regulations approval before work starts. The local council's building control team can deal with it, or you can use a registered building control approver. Either way the steel is inspected before it is covered, and a completion certificate is issued at the end. Keep it safe for when you sell.
If the beam bears into a wall you share with a neighbour, the Party Wall etc. Act 1996 applies, and a party structure notice must be served at least two months before that work starts. We arrange this through a party wall surveyor.
Questions about through-lounge knock-throughs in Westminster
What happens at the survey visit in Westminster?
We look at the wall, the floor and ceiling either side and what sits above, measure the opening you want, and note cables, pipes and access for the steel. It usually takes under an hour and there is no charge.
Can you work on older or listed homes in Westminster?
Yes. Older homes often have lime mortar, timber lintels or shallow footings, which the engineer allows for. Listed buildings need listed building consent for internal structural changes as well as building regulations approval, and that must be in place first.
Should I keep the chimney breasts when knocking through?
Most people do, because the breasts frame the opening and support the stack above. Removing a chimney breast is a separate structural job needing its own design and approval, and it affects your neighbour if the stack is shared. Keeping them usually simplifies the steelwork and preserves the character of the room.
Do I need a party wall agreement for a through-lounge?
In England and Wales, yes, if the beam end will be cut into the wall shared with your neighbour: a party structure notice must be served at least two months before that work. Your neighbour can consent or dissent. Scotland and Northern Ireland have no Party Wall Act, so title deeds and the general law apply instead.
How long does a through-lounge knock-through take?
The structural part usually takes three to five working days, covering needling, propping, removing the wall, fitting the steel and packing it. Party wall notice periods, plastering, period repairs and drying time sit around that, so the overall timeline depends mostly on notices and the finishing work.