News – Building above the garage: Time to extend yourself

Converting the space above a garage can add substantial value to a home, reports Cherry Maslen.
By Cherry Maslen
Last Updated: 5:47PM GMT 24 Mar 2009

How would you like the value of your house to go up by £100,000? Not by a sudden property boom, obviously – I think we can forget that for some time – but by adding an extra bedroom and bathroom above your garage. This enticing scenario is entirely possible if you happen to have a double garage attached to your house, or even detached from your house, live in a fairly high-value area, and can raise £10,000 – £15,000 to pay for the work.
“Building above a garage is one of the quickest ‘wins’ in terms of adding value because you’re working with what you’ve got and you don’t need to dig new foundations,” says Simon Thomas, managing director of Bristol Architectural Services. “People don’t always think about it as an option, but 30 per cent of what we do involves above-garage extensions.”

Jason Orme, editor of Homebuilding & Renovating magazine, agrees that adding a storey on top of a garage and creating an extra bedroom and en suite bathroom could add 10-20 per cent to the value of a house.
“If you’re in London or other areas where values are high, this can amount to up to £100,000,” he says. “The biggest rises are if you go from three to four bedrooms. A four-bedroom house is expected to have two bathrooms these days, so if you add the en suite you will push the added value to the maximum.”
Simon Thomas adds that houses built in the last 20-30 years are prime candidates because many have double garages attached, although he’s also worked with much older properties.
Of course you can gain an extra room by extending into the garage itself instead of building above, but what if, bizarrely, you still want it for the car? Or, like most of us, find it’s the only place to put the bikes/garden furniture/table tennis/barbecue/skis? And if it’s an extra bedroom you want – still the best way to send house prices upwards – the ground floor off the kitchen may not be the ideal spot.
Extending above a double garage should give you enough room for a decent-sized bedroom and ensuite, but what if yours is a single garage – is it still cost-effective?
“There isn’t a huge cost difference – a double will only add 30-40 per cent to what you’ll pay, so you’re obviously better off with a double,” says Orme. “But singles are still worthwhile. You could make it into a single guest or child’s bedroom with a shower en suite at one end. I’d go for a small wetroom to make it more modern.”
Orme says a basic build with no complications could come to as little as £10,000 without the cost of the bathroom suite or decorating.
But it may not be that simple, he warns. “Though the foundations are likely to be good enough to support an extra storey, the garage walls may not be. If they are single skin they will probably need upgrading to match the rest of the house.”
You’ll also have to consider whether you’ll need an extra staircase, depending on access from the main house. And you may be blocking off a window on the existing house with the extension.
Detached garages, says Orme, can be easier to work with because there are no implications for the rest of the house. Be careful what you spend, though, as there will be a slightly more limited market when you come to sell. Anyone needing an extra bedroom for a child may not be that keen on one in a separate building. Rooms above a detached garage do make an ideal guest suite, though, or an office, granny or nanny flat, or teenager’s bedroom/study/place to play loud music.
James and Lauren Stinton, both 38, have grown their four-bedroom house into a five-bedder with the addition of a fabulous guest suite above their detached garage in Harpenden, Hertfordshire. Their home is one wing of a lovely old 1906 stable block built for a grand house nearby, itself now split into separate properties.
The double garage is reached by a stone path from the back door, and now has a spacious double bedroom plus en suite above it. The Stintons have two girls – Ava, five, and Grace, three – do a lot of entertaining and frequently have friends and family to stay.
“We’re really pleased with the way it’s turned out,” says James, who runs a corporate hospitality company. “We only finished it last summer but it’s already been well used. It’s nice for guests to have their own space and not get woken up by the children in the morning. When Lauren’s parents stay we don’t see them till they come over for breakfast at 10 in the morning.”
The Stintons live in a conservation area and the project wasn’t without planning hitches. “Our first lot of plans were turned down flat by the planning department,” says Lauren. “It’s so frustrating because they don’t tell you exactly why or what they would give permission for. So I rang up and persuaded the planning officer to come out.”
In this Lauren was lucky since planners don’t always enter into discussions or make home visits, but her persistence paid off. It turned out the objection was to the spiral staircase and mini balcony the Stintons had wanted on the outside.
“We wanted the staircase outside so as not to lose space inside,” says James. “But they said it would look too fussy. It turned out to be a big help getting them here, though, because they told us we could extend the garage two metres at the back to give us the space we wanted. We had no idea we could do that.”
That meant digging new foundations and adding to the cost, but it was worth it to the Stintons. The wooden staircase (they ditched the spiral idea) opens straight into the bedroom, and the extra two metres meant they could fit a small kitchen on the ground floor behind the garage itself, making the guest accommodation self-contained.
The other problem was height. “My father is 6ft 5in and James is 6ft 4in, so we didn’t want a low ceiling,” says Lauren. “The planners wanted us to lower the height on our drawings by two metres, but in the end they agreed to one. My dad can stand up comfortably in there, so it’s OK.”
They also insisted on “conservation roof lights” which are completely flush with the sloping roof instead of jutting out. “If you stand at the front of the garage you can’t see any windows at all,” explains Lauren. “But these are expensive – it cost £3,000 for the rooflights alone.”
Fortunately the Stintons didn’t have to stick to a strict budget. “We wanted the best of everything and we did get a bit carried away,” says James. “We spent twice as much as we originally planned and it took twice as long. But even so I reckon we’ve doubled the money we’ve spent on it in terms of adding value.”
“We added architectural features to the exterior to make it look more like a coach house, such as arches over the garage doors, and we put Travertine tiles in the bathroom and had the staircase handmade,” adds Lauren.
The cost of the build was around £40,000, but Lauren agrees you could pay a lot less if you were doing a straightforward conversion using an existing garage footprint. The couple used a builder who had worked for them before and an architect recommended by the builder, but there are also specialist companies dealing solely with garage conversions.
The Cloisters is under offer, with the Harpenden branch of Strutt & Parker (01582 764343). The last time the house was valued, in January 2007 before the garage work began, it was £995,000 – £1.05 million. It was on the market at £1.3 million.
Above board
The garage foundations will need to be checked to prove they can take the extra load. They must be at least 450mm wide and 750mm deep.
You’ll need planning permission because of the extra height and alteration to the roof line.
Do the sums before you start. Compared to the cost, find out from local agents how much value the extra room is likely to add to your home.
At least disruption during the build is limited, especially with a detached garage.