Get those jobs done with a little help from DIY guru Julia Gray. This week: how to increase the value and look of your house using mezzanines.

Really high ceilings are a fantastic architectural feature and can also be used to create an extra room, something that's useful day-to-day and will add instant value to your home. With a mezzanine level (an internal balcony overlooking the space below), you can add a room more easily and - usually - for less money than converting your loft or cellar or building an extension.

A mezzanine can have all sorts of uses - a dressing room, home office, studio, spare room, bed platform or play area in a child's room (bed platforms are also popular in high-ceiling studio apartments). However, there are lots of practical considerations. To start with, if you want to stand up comfortably in both the mezzanine and the space underneath it, the room should have a ceiling height of at least 4.2m (13ft 9in), unless it's a small child's room.

Whatever you use the mezzanine for, you'll also need something to enclose it. A balustrade or half-height wall are popular choices because you still get a feeling of space, although you do, of course, lose some privacy. You'll also need a staircase up to the mezzanine. Ladder-style ones are fine for kids, but not ideal for adults, and remember spiral staircases save space. For another clever use of space, tuck things under a (conventional) staircase, such as a built-in home office or storage, or even a wet room or kitchenette.

One thing you don't want to do without is adequate soundproofing, because this could affect your enjoyment of the mezzanine and the room below. Don't forget the importance of natural light either. Depending on where and how tall the room's windows are, the mezzanine could lack daylight, so you'll need bright artificial lights that can be operated from both levels of the room.

Because a mezzanine level is an internal structure, you shouldn't need planning permission to build one, unless you live in a listed building, in which case consent may be required from your local council's conservation department. If your home's leasehold, you may need the freeholder's permission to add a mezzanine, depending on the terms of the lease.

Using an architect to design the mezzanine is a good idea, as they will know how to make the most of the space and may come up with ideas you haven't thought of. The architect can also advise you if you need the services of a structural engineer and, if necessary, will be able to put you in touch with a party-wall surveyor and a building regulations approved inspector. Alternatively, a builder may be happy to design and construct the mezzanine for you, or build it to a design you've done.

Costs for a mezzanine level start from hundreds of pounds (for a small, simple platform in a child's room), but can cost thousands, depending on the structure's size and the work involved. Compared to most types of building work though, this is a quick and inexpensive way of adding a bright and functional room to your home.