Alcove shelving that stays straight

Span is the number that matters

Deflection increases dramatically with span. Doubling the width of an unsupported shelf increases sag far more than doubling the load on it. That is why a shelf that is fine in a narrow alcove sags in a wide one built from the same material.

Three ways to stop the sag

Any of these work; the right one depends on the look you want.

• Increase thickness, or build up a thicker front edge to give an apparent thickness with more stiffness.
• Add a front edge stiffener — a solid timber lip acts as a beam along the shelf.
• Reduce the effective span with a central divider or a rear cleat plus side bearers.

Fixing into what's actually there

Alcove walls vary wildly: solid brick, lath and plaster, dot-and-dab plasterboard over masonry, or stud. Each takes a different fixing, and dot-and-dab in particular fails when fixings only grip the board. Establishing the wall build-up is the first job, not an assumption.

Setting out around a chimney breast

Alcoves are rarely the same width, rarely square and rarely plumb. Good alcove joinery is scribed to those irregularities so the finished front line is straight even though the wall behind is not — and where both alcoves are visible together, matching the shelf heights across the breast is what makes the pair look intentional.

Questions we're asked about this