Space Odyssey: should you extend your home?

Last Updated on : 17th October 2014

By Zoe Dare HallSpace Odyssey: should you extend your home? - NappyvalleyNET

With long winter nights looming, along with many sofa-bound hours spent watching Phil, Kirstie and the rest showing you how to turn your home into a designer goldmine, your gaze will invariably start to drift around your living space. ‘What if I knock down that wall, dig down here or extend there?’ you may wonder. Or ‘how much do I really need an extra bedroom or subterranean leisure complex?’

There are three main directions we can go when improving our homes and, ideally, adding value in the process. Broadly, we can branch up (into the loft), down (the basement) or sideways (the side return).

“You’ll spend about £50,000 on a loft, between £50,000 to £70,000 on extending into the side return and basements that cover the whole width of the house start at £250,000,” says  Charlie Streatfeild from Marsh & Parsons in Battersea.

Then you need to weigh up the hassle factor versus the payback. It’s tricky to pin down precise numbers on the returns from home improvements, but based on anecdotal estimates of added value, Savills reckon that on a typical London house worth £1m-£1.5m, a basement is likely to add around 10-15% to the value of your house, while a side return extension or loft conversion will add about 5-10%.

“Lofts are the easiest and you’ll make a bit more than it costs. But you do a loft for yourself, not to make millions,” says Streatfeild. “With side returns, you’ll lose your kitchen, which is a pain, especially if you have children. And doing the basement is living hell, especially for your neighbours.”

To that, Tamzin Incledon, associate director of Douglas & Gordon in Battersea, would recommend always getting three quotes as prices can vary enormously from builder to builder. “And don’t necessarily go for the builder that everyone else in the street is using as they may be spreading themselves too thin.”

But let’s get down to the nitty gritty.

Loft conversion

Loft conversions can come in two phases – a main loft that would give an additional bedroom and ensuite bathroom, which costs around £70,000 and in some houses you can extend into the rear loft space. “This is known as a double loft or a pod room and you would spend an additional £40,000 to convert it,” says Incledon. “You always make money on your initial investment as you are adding usable square footage.”

Make sure your loft has a proper purpose. “Lofts are a way to add an extra bedroom so you don’t have to move, so it comes down to whether you have a bedroom with or without an ensuite bathroom. Anything else can end up simply as posh storage, a guest room that is rarely  used or a very expensive playroom,” says Charlie Streatfeild.

Marsh & Parsons have a classic example on Dagnan Road, Balham. The four-bed house has an ensuite bedroom in the loft and is on the market for £1.295m. The house also has a beautifully extended family kitchen with exposed brick wall. click here for details

Space Odyssey: should you extend your home? - NappyvalleyNET

From a disruption point of view, lofts are the least hassle. The works will take about six weeks and you can live relatively unaffected, with the main house only “broken into” in the final week to install the stairs.

You’ll be limited by what planning constraints allow – and without a full mansard extension, you may decide the space isn’t worth spending tens of thousands on. But design options are constantly improving, with many lofts now incorporating far more glass – even entire glass rear walls – to create light at the top.

“We have a house with an open-plan bathroom in the loft bedroom, which is very different,” says Tamzin Incledon. “If you are doing a double loft, you will either extend all the way back to the flank wall, which would create a bedroom and bathroom the same size as you have on the first floor. Or you may only get planning permission for a pod, where you extend only halfway out, giving space for a bathroom, nursery or small study.”

As a gauge of potential value, Douglas & Gordon have a 2,022 sq ft, four bedroom Victorian house WITHOUT extended kitchen or converted loft on Grandison Road, SW11, on sale for £1.425m.  click here for details They have just sold a five-bedroom Victorian house on the same road with extended kitchen and ensuite master bedroom in the loft for £1.75m.


One caveat that applies equally to lofts and side returns is make sure you don’t create a house that’s too big for the street. “No one wants a five-bed house in a three-bed street if there’s a perfectly good street of standard five-bed houses nearby,” says Ed Mead, director of Douglas & Gordon.

And if you’re thinking of moving soon, leave your loft for the next buyer to untap potential. “Always give buyers the option to add value themselves. We can sell it to a much bigger market as those with a small budget can keep it ‘as is’ for the time being and those with bigger budgets can do the work,” says Hamptons’ Jonathan Dyson. “It’s cheaper on agent’s fees and stamp duty too. When we value an unextended house, we simply take the cost of an extended house, deduct the cost of a loft and side return and that’s the price.”

Side returns

The space can make an attractive study or home office, but let’s face it, the main reason people extend into the side return is to build the open-plan cooking/dining/family room that’s a must-have in Nappy Valley. It’s a great use for an otherwise wasted space that’s probably currently used to store bikes and bins – and so common that agents describe such extension projects as “run of the mill”.

“Side returns are worth their weight in gold,” says Tamzin Incledon. And Robin Chatwin, head of Savills South West London, agrees. “Ground floor living space is always at a premium, so often you’ll get the best return on a side extension.”

Costs can start from £30,000, says Jonathan Dyson, but it can be as much as £80,000 if you’re fitting a new kitchen into the space. “People also often incorporate a rear extension into the garden as part of the side return, which adds a further £15,000-£20,000 but would make back what you spend plus about 10-15%,” he adds.

If the prospect of living without a kitchen for a few months is too much to bear, there are plenty of properties with amazing extensions on the market. In Wakehurst Road, this four-bedroom house on sale for £1.495m has a beautifully light, bright extended kitchen and family room, plus a master suite with wet room in the converted loft. click here for details


And on Eglantine Road, Wandsworth, Savills are selling a five-bed house for £1.850m. A stunning terraced house refurbished to a high standard, with the benefit of a beautiful kitchen opening onto a 54ft landscaped garden. click here for details

Eglantine Road

On Nicosia Road, just off Wandsworth Common, a five-bed house on sale for £2.8m through Hamptons has seen extensive renovation, including curved folding doors across the rear of the house. There’s still development potential, though, as the basement hasn’t yet been converted. click here for details

Nicosia Road

Plenty of buyers are happy to put in the graft – to add a room of their specification and bump up their property’s value. “For about £80,000, you’ll gain more square footage and instantly increase the saleability of the house,” says Tamzin Incledon, who has a three-bed Victorian house on Wakehurst Road, in need of all works, on sale for £1.350m. click here for details


There’s also a rare opportunity in Wandsworth’s ‘Toast Rack’ – a six-bed period house on Baskerville Road, in the same family since it was built and with direct access onto Wandsworth Common. On for £3.5m through Hamptons, it needs modernisation and is ripe for extension. click here for details


And on Broomwood Road between the Commons in Clapham, a large semi-detached house on sale for £1.5m through Hamptons is calling out for a side return and has a large, unconverted basement currently used for storage. Contact Hamptons International Northcote Road for more details.


Style-wise, glass concertina doors across the back of the kitchen are a must to bring the outdoors in and give a great sense of light. They don’t get much lighter and brighter than this all-white specimen on Chelsham Road, Clapham, on sale for £1.75m through Marsh & Parsons. click here for details


“Absolutely no pillars or posts will be left in a new kitchen these days. Lines are simple and steels are sunken in to the ceiling so you have a completely flush finish,” says Tamzin Incledon. Living roofs sewn with wild plants and grass are also becoming more popular in South West London, says Robin Chatwin.

So, a few months of hassle and eating out the microwave (in the living room) versus having a sparkling new family hub where you’ll spend 90% of your waking hours – and being quids in? Worth it? Almost certainly.   


The big daddy of home improvement projects, with works taking anywhere between six months for a small basement to two years for a major one, this is the one that’s likely to cause the most noise, dirt, dust and possibly neighbourly fall-out if you decide to create a subterranean lair befitting of a Bond baddie.

There are plenty of recent examples of basements gone wrong due to over-ambitious plans or under-qualified builders leading to subsidence, floods, or complete collapse. So is it worth it? “It costs a minimum of £400 per square foot to do a basement, so you need to be living in an area where you are going to get that back,” says Ed Mead. “Certainly ‘nappy valley’ falls into that category and in fact you’d get back at least double what you put in with resale values of more than £1,000 per square foot.”

Then it depends on how you do it. The crucial thing is ceiling height. And light. The added space can be valuable – London agents reckon subterranean living space is worth about 50% of the square foot value of above-ground living space – but not if you’re merely adding dark, dingy bedrooms or entertainment dens that no one wants to venture into.

“The houses we see are top heavy, usually with four bedrooms, or five if they’ve converted the loft. There’s not enough living space and the dining room that no one uses is usually a compromised play room, so a basement can be a great place to chuck the kids. People’s main reason for doing it is so they don’t have to move,” says  Marsh & Parsons’ Charlie Streatfeild.

If you want to convert your basement to improve your own standard of living, then do it, advises Tamzin Incledon. But given the expense and disruption, don’t do it if you are seeking an immediate payback. “I would look at all the recent plans on Wandsworth Council website for an idea of different basement layouts. I would also get in three basement companies – Estbury, Minale and Mann and RMT Ltd – and see what suggestions they come up with,” she recommends.

“A media/playroom is generally a must. Most families want a place where toys can be stored without encroaching on ground floor level space. A large utility room is also expected. And if you do the full basement, another bedroom and bathroom is generally desirable, perfect for a nanny or additional guest room.”

Don’t be tempted by gyms or saunas, she suggests. “Buyers don’t generally rate them as they feel they are paying for something they won’t necessarily use.” And the biggest financial tip for basement conversions? “Don’t let it take you over the £2m mark at the moment. People are spooked at the higher end because of mansion tax talk.”

To spare yourself renovation hell – though possibly not the mansion tax – there’s a six-bed house in Orlando Road in Clapham, on sale for £2.75m with a 35’ family/playroom in the basement, plus a bedroom and utility room. click here for details

orlando rd

On Foxmore Street, Battersea, Savills are selling a five-bed house for £2.995m whose full basement conversion includes a bedroom and media room. click here for details

Foxmore Street

Just about sparing you from sleepless nights over mansion tax – for now anyway – is a six-bed house on Wroughton Road, Battersea, with a large converted basement with a playroom, wine cellar and bedroom, and a fully extended kitchen. It’s on the market with Marsh & Parsons for £1.975m. click here for details

woughiton rd

And there’s even a property with a basement conversion that slips in under the £1m mark. The two-bed maisonette in Cautley Avenue in Clapham – on sale for £929,000 through Marsh & Parsons – has a large bedroom with an ensuite bathroom and dressing room on its stylishly renovated lower ground floor. click here for details

Cautley Avenue

So, to summarise:

Lofts: minimum disruption, a six-week job and with good head height and a clear purpose (ie. a bedroom), definite added value.

Side return: A few months of dust, rubble and takeaways. Worth it for the wow kitchen, which Nappy Valley buyers expect. Definite added value too.

Basement: At least a year’s disruption. Dirty, noisy, expensive and you’ll need to do a lot of neighbourly appeasement. Done well, it’ll add value. But no one wants to feel they’re sleeping in a cave.

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