TWO COUNTRIES separated by a common language; isn't that what somebody once said about the British and Americans?

Construction terms are a rich source of trans-Atlantic ambi-guity, with the term "loft living" being but the latest.

The American word "loft" derives from its 19th-century usage to describe a room in a warehouse, and this is now used to persuade impressionable youngsters to set up home in a disused paintbrush factory down by the canal when, for the same money, they could have got a proper flat in an established residential area - as was pointed out in these pages last week.

In Britain, a loft is more traditionally understood to mean an attic - the pointed bit at the top of the house where the old suitcases, Yardbirds albums and Christmas decorations are kept.

If you suggested to my old Auntie that she might like to try living in the loft, she would not think you were funny at all.

If you have a house with a traditional pitched roof, then making better use of your loft is probably the most cost-effective way of giving yourself some extra space - far cheaper than building a new rear addition, for example. The basics consist of fitting a folding loft ladder and then letting some daylight in through a skylight - with a materials cost of as little as pounds 200.

For anything other than light storage, you will probably also have to strengthen the floor - the existing joists will be strong enough for the bedroom ceilings, but too flimsy for much else. A five metre span needs joists 225mm deep. It is usually simple to lay the new joists alongside the old, and screw them together.

If you want to use your loft as a habitable room then the conversion will need to conform to the Building Regulations, which means a fixed staircase, proper insulation and ventilation, and appropriate fire-safety measures.

Head room can also be a problem, which is why some loft conversions have dormer windows, vertical windows that stick out through the side of the roof, topped with their own little pitched roofs. The Loft Shop, which now has nearly 20 branches throughout the coun- try, has recently published a useful guide to loft conversions and the Building Regulations, which IoS readers can obtain by calling 0870 604 0404.

It is difficult to give hard- and-fast rules about loft conversions, as every situation is different, but in general, people put in skylights, or "roof windows", which are far too big.

This is a waste of money and can result in the place getting unbearably hot when the sun shines. Also, some specialist loft conversion companies use aggressive sales techniques and charge outrageous prices. So if you are planning a serious loft conversion, then getting an architect to draw up a design, and putting it out to tender, may be a better bet.

If you own a more recent house, where the roof was built with timber trusses, then things will not be so simple. These lofts are a jungle of criss-crossing ties and braces, whose removal involves complicated structural work.

It is yet another example of modern construction methods making life easier for the builder, but harder for the owner.