How to build under-stairs storage

Inspired by a B&Q how-to. This guide is based on the B&Q video "How to build under-stairs storage" with Kate Hewitt Home, which walks through fitting a proper door and shelving into an awkward triangular opening. Worth watching for the hinge placement detail in particular - it saves a lot of head-scratching on the day.

1. Measure the opening and plan your door

The space under a staircase is rarely square. Measure the height at both ends of the opening and the width at the top and bottom. The floor usually slopes with the stairs, so you need a door that accounts for this - most people use a standard door cut to a raking line along the bottom.

Sketch it out before you touch a saw. Work out where the door hinges will go, whether the door swings into the room or into the cupboard, and how much clearance you have above any skirting boards.

2. Remove or open up the existing stud or plasterboard

Many under-stair spaces already have a rough plasterboard facing with a rough-cut door hole. If that's what you've got, strip it back to the studs and start fresh - it's easier than trying to patch around it.

Check for pipes and cables before you cut. A simple cable checker is worth a minute's effort. Most cables run along the ceiling joists above, but older houses are unpredictable.

3. Frame the door opening

Build a proper door lining from PAR (planed all round) timber - typically 95mm × 32mm. Set the head at the height you want, make sure the uprights are plumb, and fix them back to the existing studs or add noggins to give yourself something solid to hinge into.

The door lining does a lot of work: it's what the door hangs from, what the architrave fixes to, and what keeps everything looking tidy. Get it plumb and square now and the rest is straightforward.

4. Hang the door

A standard internal door cut to the raking line works well. Offer it up to the opening, mark the hinge positions on both the door and the lining, and cut the recesses with a chisel. Two hinges are usually fine for a lightweight door; use three if it's solid hardwood or if the drop is more than about a metre.

Hang the door with the bottom hinge first. Check it swings freely and closes without catching, then adjust the top hinge as needed. A gap of around 2mm all the way round looks right and gives a little movement for seasonal swelling.

5. Line the inside walls and ceiling

Fix plasterboard or MDF sheet to the interior walls and the sloping underside of the stairs. Run it between the studs and noggins, screw off at 300mm centres, and tape the joints if you're planning to paint a smooth finish.

The sloped ceiling inside the cupboard is fiddly but doable. Cut each board to the rake angle, offer it up to the underside of the stairs, and screw through into the joists. If the joists are awkward, batten the underside first and screw the boards into the battens.

6. Fit the shelving

Decide what you're actually storing before you fix anything permanently. Shoes and coats need different shelf heights from an airing cupboard or a meter cupboard. A simple shelf at about 900mm high with the lower section left open for taller items - wellies, a hoover - works well for most families.

Fix shelf brackets to the back wall studs or use adjustable shelf track for flexibility. Shelves of 18mm MDF or ply are solid enough for most household loads without being heavy.

7. Add a door stop and catch

Fit a small rubber or timber door stop to the lining so the door doesn't swing all the way back and damage the wall behind it. Then add a magnetic catch, a ball catch, or a simple lever latch - whatever suits the look you're after.

For a cleaner finish, a touch-latch mechanism lets the door sit flush with no handle at all. Push to open, push to close. Neat, and children tend to find it endlessly entertaining.

8. Fix architrave and make good

Run architrave around the door opening to cover the joint between the lining and the wall. Mitre the corners at 45 degrees, pin them with a brad nailer or small oval nails, and fill the pin holes before painting. Caulk the gap between the architrave and the wall with decorator's caulk - this is what gives it the built-in look.

Sand, prime, and paint the door, lining, architrave, and interior in one go. Two coats of a good satin or eggshell finish is usually enough. That said, if you're going to use the cupboard hard, a gloss on the door face wipes clean more easily.

When to call a handyman

Call Richard if the opening is unusually awkward - very low, very narrow, or involving a structural post - or if the existing plasterboard has damp coming through from below. Fitting the door and lining square is the part most people find tricky; it's worth getting right the first time.