Skip to main content

Completely London

London property market blog

Property: inside and out

/ by Houzz Experts

How to successfully knock through in a period property

For UK homeowners living in period townhouses, terraced houses and semi-detached homes alike, the notion of knocking through the two ground floor reception rooms to create one larger room is a popular and enduring trend. It offers greater flexibility, a magnified sense of space and enhanced light.

‘We often fit glazed doors between the rooms to make the space more flexible,’ says Natalie Benes of Stiff + Trevillion. Hugo Tugman of Architect Your Home explains that knocking through creates ‘overlapping zones’, in which the distinctions between areas becomes blurred, so each one feels larger when you’re in it.

‘The typical terraced house footprint isn’t particularly wide,’ says Robert Maxwell of Maxwell & Company Architects. ‘Trying to fit a good-sized sofa and dining table into these rooms becomes difficult, but if you remove a wall, the space becomes so much more flexible.’

The process involves knocking a hole through the middle – the size and shape of which is determined by the client (and, of course, what is structurally possible), inserting steel beams to support the structure where necessary, and finally making good, which might involve anything from replastering and painting to adding in steps, laying flooring and relocating radiators and lights. Here, three experts explain the process in more detail.

Professional advice from: Robert Maxwell, director of Maxwell & Company Architects Hugo Tugman, founder of Architect Your Home Natalie Benes, architect at Stiff + Trevillion

Rear Extension
 

Bypass planning permission…

For normal, non-listed properties, knocking through the wall between the two downstairs reception rooms will not require planning permission.

‘Even if it’s in a conservation area, if it’s not listed you still don’t need planning permission,’ explains Natalie Benes. ‘If you want to check, you can contact your local council, but the rule of thumb is that listed building regulations control any renovation to the interior and exterior of the property, while conservation area regulations generally only control external appearance,’ she adds.

See how to make open-plan design work in any property

Croxted Road - Dulwich
 

…unless it’s a listed building

Listed buildings are a whole other kettle of fish and any renovations will likely require planning permission. ‘For listed buildings, planners tend to want to retain the existing plan-form of the house, and the downstairs wall is a key element of that,’ Natalie says. That’s not to say you won’t get planning approval, but you’d need to submit scale drawings of your intended project to your local planning authority and wait to see if they’re accepted.

Transitional living room, London

Fulham townhouse

Photo by Juliette Byrne - Search traditional living room pictures

Decide whether you want to work with an architect

Working with an architect isn’t entirely necessary for a simple knock-through, although going through an architect might help to prevent things going awry later on. ‘If you’re having it done properly, things like whether or not the floors are level will come out in the design process, which will help to give people an accurate idea of budget and timeframe,’ explains Hugo Tugman. Working with an architect from the early design stages might also help you to make use of the space in ways you wouldn’t initially have envisaged.

Clapham extension and refurbishment

Find a builder

If you’re just going for a straightforward knock-through and you have a good idea of what you want, then you may decide you don’t need to consult an architect. You will, however, need a builder to carry out all of the work. Find a reputable one in your area, either through a referral or by checking out the many builders on Houzz. Get expert advice on how to hire the right builder for your project

Town House
 

Consult a structural engineer

It is imperative that a structural engineer is consulted. Many builders will have an engineer whom they work with regularly. ‘We always recommend using a structural engineer, even before you put in your building notice,’ says Hugo. ‘They will provide structural calculations to show what you’re doing structurally to replace what you’re taking out.’

Victorian End-terrace House in Sevenoaks, Kent
 

Notify building control

People often get confused between planning permission and building regulations. ‘They are completely separate departments with separate rules,’ explains Hugo. Building regulations cover things like whether a project is structurally sound, whether the new space is fire safe, and whether the drains work.

‘When knocking through, you would potentially remove the existing corridor that encloses the stairwell from the rest of the ground floor rooms. This in turn removes the safe passageway to the front door in the event of a fire,’ explains Robert Maxwell. You can get around this in various ways, such as installing a fire curtain, an early warning system or a sprinkler system. You can find out more about the regulations on the government’s Planning Portal website.

Remodelling of Victorian House by DHV Architects
 

Get approval

Building regulations can be dealt with in two different ways, explains Hugo. ‘Very simple projects are dealt with under a building notice. You submit the notice – which is typically just one side of A4 – and continue with your project. A building inspector will come along during the works to liaise with the builder. They may also want some structural calculations,’ he adds.

The second way is full plans approval, in which you submit drawings up front and they are then approved and an inspector will come to check throughout the project. Either way, a building inspector will come periodically to agree that the key things have been done as per the regulations.

‘One thing to be aware of is that building regulations don’t have to be done by the local authority, and there’s an increasing number of private surveyors who are approved by the government,’ says Hugo.

Cardigan
 

Tell your neighbours

If you’re in a terraced or semi-detached property, you’ll likely be subject to something called the Party Wall Act, which is entirely separate from both planning permission and building regulations. It’s to do with any works that will affect the party (shared) wall. ‘If you are removing any main walls that have a structural loading in a terraced or semi-detached property, you’ll need to obtain party wall agreement with either or both of your neighbours,’ explains Robert.

‘It’s a relatively simple process that can be carried out directly by the homeowner, as long as they adhere to the guidelines specified on the government website,’ he adds. ‘You would need to send a party wall notice to your neighbours, give them a chance to respond to the works you intend to carry out and, if necessary, appoint their own surveyor. For more complex party wall issues, I would recommend appointing a party wall surveyor to deal with this on your behalf.’

‘It’s good to remember that nobody can stop you as long as what you are doing is within regulations,’ says Hugo, ‘but they can cause delay. The best way to go about it is to deal with it professionally and it’s likely your neighbours will make the party wall process very easy for you.’

Finlay Street

 

Check whether the wall is structural

A common mistake people make is to assume that just because a wall sounds hollow, it’s not structural. ‘A structural wall is one that’s there for a purpose, either to support the walls on either side or the floor above it,’ explains Natalie.

In a row of terraced houses, the wall between the living and dining room is often bracing the walls either side to keep them vertical. ‘These walls are almost always structural, even if they’re not carrying a load,’ says Hugo. ‘It’s a very dangerous misconception to assume that hollow means it’s OK to remove without the relevant precautions.’ Similarly, not all brick walls will be structural, so check with someone who knows what they’re doing.

Period House Tunbridge Wells


Preserve period features with a downstand

There is always the danger that knocking through the two rooms will destroy some of the original features. But carefully considered and executed knock-throughs can be very effective. ‘To preserve cornicing, you just leave a little downstand from the ceiling, so the cornice can continue. It also gives you an idea of how the house was originally structured,’ explains Hugo. So you can still do a knock-through without losing the detail.

Edwardian Terrace, Lounge/Dining Room


Prepare for a couple of weeks of disruption

A knock-through is a pretty straight-forward procedure. ‘There’s no reason why it should affect any of the services, such as electricity and gas,’ says Hugo. Although, of course, if there are any wall lights or radiators on the wall, they will need to be moved and the wiring dealt with. After that, it’s a simple case of actually making a hole and putting in any of the necessary beams, which needn’t take more than a week. The making good can take a while longer, though.

‘Chances are, the floors will need to be replaced or changed, as it’s rare they run through both rooms,’ advises Robert. ‘It really depends on how complicated the project is and how many walls you are removing. Knocking through the two reception rooms shouldn’t be overly complicated,’ he adds. ‘It’s worth also checking with your insurance company, as living in the property while structural work is going on might not be advisable.’

Pembridge Crescent, Notting Hill, London, W11
 

Combine with redecorating for cost efficiency

The simple task of making a hole in the wall isn’t the expensive part. ‘Expense comes in the moving of radiators, of electrics, replastering and redecorating,’ says Hugo. ‘If you’re doing lots of work anyway, the additional cost might only be between £3,000-£10,000, but if your house is pristine, then to knock through and refinish it will more likely be between £15,000-£20,000.’

‘This really depends on the complexity and level of finish,’ says Robert. ‘I would imagine just to install a new beam between the two reception rooms would be around £5,000, but if you want to change the whole space and the electrics, flooring and lighting, it could easily go up to £20,000-£30,000,’ he adds.

Things like having a downstand can make a project cheaper. ‘If the beam can go underneath the ceiling in the downstand, it’ll be cheaper than having to knock up into the ceiling,’ explains Hugo.

Similarly, creating a larger hole where the ceilings and walls of both rooms are totally flush will cost more than if you have a frame, just as knocking through in a narrower house will be cheaper than in a wider house. Again, the quality of finishes specified by the homeowner will greatly determine the final price.

Graeme Wilson, Houzz Contributor

About our expert View all posts by this expert

Houzz Experts

Houzz is the leading platform for home renovation and design, providing people with everything they need to improve their homes from start to finish – online or from a mobile device. From decorating a small room to building a custom home and everything in between, Houzz connects millions of homeowners, home design enthusiasts and home improvement professionals across the country and around the world.

Read more testimonials Leave a review