THE LOWDOWN ON… BUILDING A LOFT EXTENSION

LOOKING TO ADD MORE FOOTAGE TO YOUR HOME? ARCHITECT KIM LODDO REVEALS THE KEY FACTORS TO CONSIDER WHEN CONVERTING YOUR ATTIC SPACE

If you need extra space in your home, an attic conversion may be the answer. The term ‘loft extension’ is a catch-all phrase for increasing the space in the roof volume you already have, but there are several ways to create one depending on your style of house. Here are the key elements that need to be considered.

1One of the first things to check is whether you have enough head height for a loft extension. Take some measurements to ascertain how much space you have from the floor to the ridge beam. If you haven’t got enough room to stand in that space, you may not be able to proceed. The most valuable space you’re going to get in the loft is standing space, so it’s important to understand how much of this the build will create.

2Typically, the most straightforward way to create a loft extension – especially if you live in a terraced house – is to add a dormer window at the back. This will lift the roof of the loft over a new vertical window, creating a flat roof overhead that gives you more room. The pitched roof at the front stays the same. If you live in an end-of-terrace house, another option is to extend to the side of the property’s roof by doing a hip-to-gable extension. It’s all about getting more volume without building above the existing ridgeline of your roof. The best thing to do is to get an architect to look at your roof to see what’s possible – sometimes the biggest extension isn’t necessarily the best one.

3As well as a designer, you’ll want a structural engineer on your team to check the existing structure. They might need to dig a trial pit to check the foundations are deep enough to take the load of the extra floor. Plus, the new structure is likely to enclose, rest on or require the raising of the party wall with your neighbours. This means you’ll probably need to bring in a party wall surveyor to handle this side of the project, too.

4When creating a design brief for your architect, the first thing is to explain what problem the loft extension will solve. Do you want an extra bedroom, for instance? Or more storage space? Would you like another bathroom? Once your designer knows what you’d like to establish in terms of the space’s function, they can factor this into the plans not only for the loft, but also how the rest of the house works in relation to that space.

5It’s difficult to say how much space a loft extension can add to your house in terms of square footage – it all depends on the height of the ridge beam. It’s more useful to think about the size of the loft as proportional to the rest of your house. As a rough guide, you might be able to achieve between half and three quarters of the area of the floor plan on the level below. In terms of cost, based on the design-led loft extensions we have carried out, a couple of years ago we’d have suggested a ballpark cost of £3,500 per m2. However, costs are rising post-covid, as there’s been lots of issues with material availability and labour shortages. Current costs are therefore much more difficult to predict.

6The access staircase leading up to your loft is almost as important as the room you’re building there. According to Building Regs, it should have a minimum head height of 2m. Spend plenty of time working out how the structure will connect to the rest of the house, too. For example, if it’s too steep or you feel as though you might bang your head when you use it, getting up to your new loft will feel awkward.

7Typically, dormer extensions at the back of the house fall under what’s known as Permitted Development, which means you don’t necessarily have to apply for planning permission. But if you live in a listed building or a conservation area, PD rules don’t apply. For more information about what’s covered under PD rules, head to planningportal.co.uk.

8You don’t necessarily need to move out during construction. If you can put scaffolding up at the front and back of the house, contractors can get in and out through the scaffold without too much disruption. Then they can knock through at the last minute and build the staircase up. The amount of time it takes ultimately depends on what you’re putting up in the loft – a new bathroom, for instance, will add to the timeline. For a typical bedroom and en suite in the loft, I’d say about three or four months – though this could easily rise to six months or more for complex schemes.

Kim Loddo is a director at IBLA (ibla.co.uk), a London-based architecture practice that has worked on bespoke renovations and extensions in and around the city for more than 20 years.