Installing Floating Shelves in an Awkward Alcove

Why an Awkward Alcove Is Worth the Effort

Almost every older UK home has one: the narrow recess beside a chimney breast, the space between a window reveal and a corner, or the shallow gap above a radiator. These alcoves are usually the last place anyone thinks to put a shelf, because they are never a tidy rectangle. They are also, inch for inch, some of the most useful storage in the house.

A chimney breast typically projects 350mm to 450mm from the wall, and the alcoves either side are often 900mm to 1,200mm wide. That is plenty of shelf space for paperbacks, cookery books, jars and the assorted clutter that otherwise colonises your worktop. The trick is to stop treating the alcove as a problem and start measuring it properly, then build something that fits the space rather than fighting it.

Measure the Alcove Before You Buy Anything

Never assume an alcove is square. Plaster has been skimmed by several generations of builders, and the two side walls are rarely parallel. Take three widths — top, middle and bottom — and three heights on each side. Write them down. The smallest width measurement is the one that governs the shelf, so cut to that figure and allow a couple of millimetres of clearance on each end.

• Check the rear wall for damp patches or blown plaster, especially beside an unused chimney.
• Look for cables and pipework. A radiator pipe often runs up one side of an alcove, and socket spurs are commonly chased into the wall behind.
• Note the depth of the skirting board and any picture rail or cornice. You may need to notch the shelf or finish it short of the profile.
• Check whether the rear wall is brick, blockwork or a stud partition covered in plasterboard — this decides your fixings.

For most alcoves, shelves between 900mm and 1,100mm wide, 200mm to 250mm deep and 18mm to 25mm thick strike the right balance between capacity and visual weight.

Choosing Shelves and Brackets That Will Take Books

Books are heavy and they sit in one place for years, so the shelf must resist sagging. Solid timber or good-quality 18mm MDF works well, but anything wider than about 900mm needs support at the midpoint or a thicker board. As a rough rule, a metre of hardbacks weighs 25kg to 30kg, and a generously filled shelf can creep past 40kg.

Brackets must be rated for that load, not just for the length of the shelf. Look for brackets described as heavy-duty, ideally steel rather than pressed metal, and space them at 500mm to 600mm centres. For a 1,000mm shelf that usually means three brackets, or two brackets plus a central batten fixed to the rear wall. If you are fixing into plasterboard alone, use proper hollow-wall anchors rated well above the load you expect, or better still, screw through into the studs or the masonry behind.

Fixing Battens to Brick or Plasterboard

The most reliable method in an old alcove is to fix timber battens — 50mm by 25mm planed softwood is ideal — along the two side walls and the rear wall at each shelf height. Battens spread the load across many fixings, and they give you a level surface to sit the shelf on, which hides uneven plaster beautifully.

• Into brick or block: drill with a masonry bit, use brown or blue wall plugs depending on hole size, and aim for 60mm to 75mm of screw into the masonry. Avoid drilling into the mortar joints if you can.
• Into aerated block: these are soft and crumbly, so use resin anchors or specialist aerated-block plugs rather than standard wall plugs.
• Into plasterboard: if the board is dot-and-dabbed onto masonry, long screws can reach the wall behind. If it is a stud wall, fix the battens directly into the studs using a stud finder, or use heavy-duty toggle fixings.
• Always check for cables and pipes before drilling. A cheap detector saves an expensive repair.

Level the battens with a spirit level across the alcove, not just along one wall, then mark each shelf height on all three surfaces before drilling a single hole.

Cutting, Fitting and Finishing

Cut the shelf slightly short of the smallest width measurement and test-fit it dry. If one wall bulges, scribe the end with a pencil held against the wall and sand or plane to the line. A snug fit looks far better than a shelf floating in a gap.

Prime and paint or wax the shelf before fitting if you can — it is much easier than working around brackets later. Screw down through the shelf into the battens, or fix brackets to the battens and the shelf to the brackets, countersinking the screw heads so they sit just below the surface. Fill the heads with a little wood filler and touch in the paint.

Load shelves from the bottom up, keeping heavier books lower and lighter items higher. Check the screws once a year, particularly in older plaster, and tighten anything that has worked loose. A well-fitted alcove shelf should hold its shape for decades — and quietly turn the most awkward corner of your home into the most useful.