Architects Joseph and Lesley Logan transformed a decaying Victorian mausoleum with the modern virtues of air and space. Oliver Bennett explains how to give your old house new life
Vintage buildings are as eternally fashionable as vintage clothing. But no-one, unless they were a heritage freak, would want to live exactly like the Edwardians, Victorians or Georgians, just as no-one would want to look like a replica bobby-soxer. While old buildings can have that quality estate agents call "character", they often need making-over to be compatible with late 20th-century life. That usually means creating more light and space, sometimes by simply knocking through a wall, but occasionally by attempting something more substantial.

Just such an opportunity to revamp and restore was offered to architects Joseph and Lesley Logan, both graduates of Strathclyde University's architecture department. Their conversion of a house in Glasgow has bought a contemporary sense of space to an 1830 building without sacrificing its essence and integrity. A Victorian town house, it was built for a timber merchant in Glasgow's West End. It is matched by a symmetrical twin across the road and towers grandly over the sturdy tenements that characterise Glasgow's 19th-century housing.

When the Logans discovered it, the building was in a serious state of neglect and had been colonised by bedsit-land. The couple had to "take the house apart and put it back together again" before it was marketable. Feeling the effects of recession, which was particularly cruel to architects, they opted to develop it into six flats, including one for themselves and baby daughter Victoria. "It was a way of creating work," explains Joseph. Fortunately, he has made a profit from the scheme, and has become an advocate of small-scale, architect-led development.

Local estate agents were unenthusiastic. Although the flats are wonderfully spacious, they were designed with only one bedroom. "Estate agents value a property in terms of the number of doors in it," Joseph says. "It's really quite frightening." That they are stuck with an idee fixe about a Victorian house-conversion is hardly surprising, but it does indicate a somewhat stagnant relationship with period property. "Our development is not about creating rooms, but space," says Logan. It is an approach that has obviously been well-received by Glasgow's returning urbanites, because the flats sold almost immediately.

Each apartment has a dramatic mezzanine floor opening out onto the full 4.4m height of a Glaswegian ceiling. The Logans created a contemporary feel by playing with the flats' interior volume, but also nodded at the local building vernacular by using traditional crafts such as stonemasonry. "We were lucky in that traditional craftsmen still exist up here," says Joseph. New stone steps were cut, cast iron and plasterwork elements were rebuilt, and, finally, the Logans added small classical sculptures to the front of the house. With architectural precision, they even attended to the invisible details. "The leadwork is very good quality," says Joseph, "even though no-one can see it."

The Logans also updated the Victorian detailing, freshening up the context so that the Grade II-listed house appears at one with its softly modernist makeover. By using living building and decorative traditions they have avoided a heritage industry feel.

"There's something about old buildings that architects are seduced by," explains Joseph. "It's a context that you can respond to, not a blank page." He is inspired by the feeling of passing time implicit in the old building, which reminds him of the continuity of family life. Therein lies the appeal of his house: it is at once ancestral and forward-looking.

You don't need to spend a fortune to bring your old house into the late- 20th century. Jonathan Darke of London architects Stillman Eastwick Field, says one relatively inexpensive way of doing this is to take the walls (or just one wall) back to the brick to get that bare, industrial look. Or replace pendant lights with recessed lighting, which emphasises the planes of ceiling and wall in a manner which instantly reads "modern". But restoration itself, he adds, is well-served as never before. "It was almost impossible to get mouldings 10 years ago, unless you got them made up," he says. "Now you can buy them off-the-shelf."

There are restrictions in house listings and conservation areas which should be observed. But, as Darke says: "You can do what you like to most Victorian buildings, provided that you observe structural and environmental criteria." The classic way in which many householders have updated their properties since the open-plan Sixties is to knock two downstairs rooms together. Indeed, this is now a mass-market convention. But householders are often afraid of making even small improvements like this. "It's often very simple work, but people think 'I can't do it'," says engineer Neil Thomas of Atelier One, who is perhaps best known for engineering 'House', Rachel Whiteread's temporary East London art object. "It is often simpler and cheaper than people think." And the cost can usually be passed on in the house price.

Thomas is currently working on a pounds 3 million project in London's Mayfair. Improbably, they are having a whole new storey built in the basement of the house. Alternatively, you can replace a section of non-loading wall with glass bricks, or take down a stud wall to open a living room out onto the staircase. Older terraced houses were often built very well, and they can withstand a fair amount of change, although one should be cautious of subsidence. Thomas, who has gutted houses so that only the facade remains, also warns that tighter building legislation has had an impact on just what we can do to old houses.

In any scheme, one has to get past that uniquely British feeling that the past should be faithfully preserved. A morbid sentimentality affects our relationships with old houses. Developments like the Logans' can show that the new and old need not be mutually exclusive.