Conversion kicks

By Alex Brooks

Transforming roof space into a living or storage area can be a worthy challenge.

The roof space in most houses is ready-made for converting into either extra living or storage space. And it all costs a fraction of the price of a typical renovation or extension. A conventional renovation can cost between $3000 and $4000 a square metre but converting roof space costs just $1500 a square metre, says Charles Heydon, general manager of roof converters Attic Ladders.

Most attic conversions involve adding skylights, insulation, floors and a dormer window. Maintaining natural ventilation is important and roof lines can be raised to accommodate the tallest members of the household. Also, the attic is usually the largest space in a house, especially if you're lucky enough to live in an older-style bungalow, semi or terrace where the roof pitch is high. Not all attics can be converted, however.

"In a space-poor house like a terrace, the attic conversion offers an extra 25 or 30 square metres of space for a very low price," Heydon says. "But if you live in a modern house with roof trusses (triangular-shaped support beams), you can't convert the space."

Architect Yvonne Haber says attic conversions are a "grey area", depending on whether the room is considered habitable under the Building Code of Australia.
"Typically, the room has to have at least 60 per cent of the space with a height of 2.4 metres for it to comply," she says. "Then you need a proper fixed staircase."

Attics in houses with hipped roofs - a roof with sloping ends and sides - make it difficult to create staircase access with adequate head space. A storage room is much easier to create and needs only a pull-down ladder for access. But to get the most use out of an attic room, install a fixed staircase.

"Usually, you will lose at least three or 3.5 metres of [floor] space on the ground floor to create a proper staircase," Haber says. "And that's building a 750 millimetre-wide staircase [that] won't have any space to get furniture up and down it."

Even if you can't convert your roof space into habitable living space, extra storage space always comes in handy. Those nifty pull-down attic ladders, which cost between $400 and $1300, can be cheaper than creating a built-in wardrobe. Structural engineer Salim Dalla, from Complete Consultants, says it is important to get attic areas checked for load-bearing capacities before storing heavy things such as boxes of books.
"The older style houses usually have good capacities - the hardwood joists are typically one-and-a-half times stronger than the treated pine joists used in most houses today." Each square metre needs to be able to bear up to 400 kilograms of weight, he says.

Dalla warns that timber joists will "deflect" under too much weight - and the first sign is cracks in the ceiling beneath the weight.
"When the loads are too great, you get deflection in the [roof] members first," he says. "That means the timber will bow. Then you can get a sudden failure."

This "sudden failure" equates to the roof crashing down, so Dalla suggests getting a professional engineer to check an attic before hijacking it for do-it-yourself storage.

Did you know?

Structural engineer Salim Dalla says cracks in the ground-floor brickwork of a house can be minimised by a first-floor addition. "A lot of people think if they have reactive movement and cracking that they can't put a second floor on," he says. "But the addition will tie the tops of the walls together and restrain the movement, alleviating the cracking."