The ground rules of extending upwards: plan your extension before you start

Converting an attic space is a great way to gain extra living space and add value to your home. But there are a few things you need to consider before embarking on this kind of project.

First, determine if you have sufficient headroom in the attic for a good living space. For your attic to qualify as a habitable room – in other words, for you to be able to call it an extra bedroom when selling your home – it will need to have a floor-to-ceiling height of 2.4m/94in in at least 50 per cent of the usable space.

You should also check if the works you are proposing will need planning permission. The rule of thumb is that if you are planning on raising the roof or adding any window to the front or side, you will probably need planning permission. Skylights to the rear of the property will not need planning permission, but a dormer window will.

You should get a structural engineer to check what kind of structural alterations will need to be made to support the new room. You will also need to get a certificate of compliance, which certifies that the work has been carried out in accordance with building regulations. This encompasses all building-control issues on site, such as structure, ventilation, insulation, safety, access, electrics, and so on. You will require the documents if and when you come to sell.

When it comes to the internal layout, there are a few design principles that you need to consider, starting with the design and layout of the staircase up to the attic. You want these stairs to feel as much like a continuation of the existing staircase as possible, which will make the attic feel more like a proper additional storey rather than an afterthought.

Use every bit of space

Make sure you use every available bit of space. A successful design should eliminate awkward leftover areas. Use low, under-eaves space for storage and try to ensure that it is as accessible as possible. For example, instead of putting in doors to provide access under the eaves, we built in drawers, which made access far easier. Window seats in smaller dormer windows are a great idea as not only are they a lovely feature but they also provide additional storage space.

If you are planning an en-suite, think carefully about your headroom. Toilets and baths can be placed in the lower part of the space, but basins and showers will need good headroom. Opting for wall-hung basins and WCs rather than standard floor-mounted fittings is a good idea as they need to be built out, allowing for recessed storage above as well as giving the illusion of more space.

Disguise unsightly elements, such as pipework and plumbing, by building out in front of them to create useful areas, such as alcoves for storage.

Finally, think about your lighting. With sloping ceilings, lighting can prove to be a challenge, so opting for wall lights in place of overhead spots or pendants is a good idea.