You've done your upstairs, you've done your downstairs, so what's next to do in your house? Why, the stairs themselves, of course. A new, sweeping, open-plan stairway disappearing into the upper reaches of your dwelling-place. Perfect for impressing the guests.
Trouble is, when you contemplate any kind of alteration to a conventional up-and-down staircase, it feels as if you've got a real mountain to climb. I mean, where exactly do you begin? You could perhaps change the carpet, or paint the banisters a different colour. But as for making it do a stylish zigzag, or suddenly go spiral, it's surely not possible, is it? And if you tamper with the stairs, doesn't the whole house fall down, anyway?
Beset by such worries, I stumbled through the door of Stairplace, in south-east London, conceivably the only high-street shop in the United Kingdom devoted to stairs. Here, in the heart of West Norwood, you can not only try out real staircases, rather than just reading about them in brochures, but you can also immerse yourself in the whole dizzying world of stairs, in particular, its rich linguistic heritage.
The "string", for example, is the diagonal plank into which the individual stairs (or "treads") are fixed. The "nosing" is the projecting, rounded edge of the stair, while the "bullnose step" is the wide step at the foot of staircases. Also, "winders" (rhyming with "minders") are steps that incorporate a 45- or 90-degree turn (not to be confused with "winders", rhyming with "cinders", which is what workmen call the glass things you look through).
And that's just the start of it. Having got your lips around the terminology, it's then the turn of your eyes to be opened to the abundance of possibilities available to the staircase connoisseur. Not only can you choose between straight and spiral, but you've got helical, too, which revolves around an open stairwell rather than just a pole (ie, spiral). And even if you go for straight, you've got the option of doubling back when you're halfway up, which is called a "dog-leg".
"A basic rule of thumb is that a rectangular space lends itself better to a straight staircase, while a square one suits a spiral," says Stairplace's resident expert Jon Wallace, who joined the parent firm The Loft Company from school just eight years ago, and has already reached the top of the career ladder.
"Then, once you've decided on the shape, your next question is whether you're going to go for a standard staircase (£1,500), custom modular (£2,000) or custom-made (£4,000)."
It should, however, be stressed that, whichever of these you choose, the component parts all arrive in a large crate, which all but the most adept DIY-ers are advised not to try to assemble. "Unless you really know what you're doing, you can come badly unstuck," testifies Jon. " With spirals, for example, you have to make your mind up whether you want to go clockwise or anticlockwise. Get it wrong, and you can end up at the top of the stairs, walking straight into a wall. And if you don't followed the guidelines correctly, you may find that you've put up an illegal staircase."
Illegal? Yes, as if Britain's prisons weren't full enough, there's a danger that if you make a miscalculation on your measurements, you could end up doing a stretch at Her Majesty's pleasure. Or, at least, have your house declared uninhabitable by the council building inspectors.
The main factor in determining a staircase's legality is whether a child could get its head stuck in it - either through the banisters or between the stairs (if it's open-plan).
Any gap wider than 100mm is deemed to be an irresistible invitation to infants, and is thus outlawed. Adults, too, are protected from the perils of rogue stairs - by law, each tread has to be a minimum of 220mm deep (ie, able to accommodate the very biggest feet), while the gap between wall and handrail must be at least 800mm, in case someone fat needs to get downstairs in a hurry (eg, in the event of a fire).
However, there are exceptions; if it's just a staircase up to an attic room, you can get away with some rather dodgy-looking cutaway stairs, which are shaped like rudders and are strictly forbidden in regular homes - unless you want to hear the heavy tread of the stair police.
As for banister technology, we haven't even touched upon whether you should get the kind of banisters that you can bend by hand; that you bend with the help of a hammer; or that you bend by heating over a flame and then fixing into position before it has cooled down.
"If you want to read some more about the subject, you should get hold of Building Regulations - Approved Document K, from the Office of the Deputy Prime Minister," says Jon, sensing my enthusiasm.
"Then, if you want to take it further, you can get British Standard BS 5395 for Stairs, Ladders and Walkways - though it does cost £172," he adds.
As it happens, I'm already saving up. You get a lot of nutcases and sad cases in this world, but I am now proud to consider myself a fully signed-up stair case.
The next step
* Stairplace, 86 Knights Hill, West Norwood, London SE27 (020-8761 8844; www.stairplace.co.uk). A local stair shop offering advice, installation, and staircases to try out. Open Mon-Wed 8.30am-5.30pm, Thursday 8.30am-8pm, Friday 8.30am-4.30pm, Saturday 10am-3pm.
* Bisca (01439 771702; www.bisca.co.uk). For designer staircases - wood, glass, metal, you name it.
* Richard Burbidge (01691 678201; www.richardburbidge.co.uk). Specialists in stair furniture and accessories - spindles, banisters, handrails, newels.
* The Loft Shop (0870 604 0404; www.loftshop.co.uk). No-frills straight and spiral staircases, branches across the South and the Midlands.
* Building Regulations - Approved Document K ( www.odpm.gov.uk). All you need to know about stairway specifications.