Put up a heavy-duty floating shelf with hidden rods on a lath and plaster wall

1 each · Pencil

AB-02Confirm the wall really is lath and plaster, and find the timberLath and plaster is always fixed to a timber frame - either studs in a partition wall or battens (grounds) fixed to solid masonry. Tap the wall: it sounds hollow but slightly springy, unlike the dead thud of brick or the tinny ring of metal studs. Drill a 3mm test hole at your centre line: fine lime dust with thin wood shavings confirms lath and plaster; brick or block dust means solid masonry behind battens instead; a flat hollow plasterboard sound could mean dot-and-dab. If a magnet grips the wall or the hole brings out bright steel swarf, you actually have plasterboard on metal studs, not lath and plaster - skip the timber fixing steps below and use the metal-stud fixing instead. Run a detector along the wall to trace the timber and lightly pencil the centres; lath and plaster studs are usually 400-600mm apart.

1 each · Stud and cable detector

1 each · 3mm drill bit

AB-03Do a safety check before you drillCables and pipes can run almost anywhere in a wall, not just in the 'safe zones'. A detector helps, but it can miss deep cables, cables in metal conduit, or anything behind metal-backed board, and a metal stud frame confuses cheap detectors further - always assume something could be there until you prove otherwise. Find your stopcock now, usually under the kitchen sink, and check it turns freely so you can shut the water off fast if you hit a pipe. If you have any doubt at all, isolate the relevant circuit at the consumer unit before drilling.

AB-04Mark and level the rod holesHold the shelf, or a cardboard template the same size, against the wall at the height you want. Draw a level line with a spirit level, then mark the rod hole centres on it, nudging them slightly if needed so they line up with the timber centres you found earlier.

1 each · Spirit level (600mm)

1 each · Pencil

AB-05Choose the right fixing for what's actually behind the plasterLath and plaster on timber studs or battens: drill into the centre of the timber and set a 10mm steel threaded rod with a structural wood-safe resin, embedded 100-120mm. Battens on solid masonry (test hole showed brick or block): drill through to the masonry and use a chemical resin anchor with threaded rod in a 12mm hole, at least 90mm into brick or 100mm into block, avoiding mortar joints. Plasterboard on timber studs instead of lath and plaster: same resin-and-rod method straight into the stud, no plug needed. Plasterboard on metal studs: never use a plain wall plug or an ordinary wood screw - it strips straight through 0.5mm steel. Use a self-drilling metal-stud anchor or a toggle-type hollow-wall anchor rated for the shelf's full loaded weight, and be aware a metal stud alone will not hold a shelf that pulls away from the wall - fit a timber noggin between the studs first, or fix through to masonry behind. Dot-and-dab plasterboard: the fixing must be long enough to pass through the board and the dabs (often 50-70mm) and reach solid masonry behind, so use a long frame fixing or resin anchor into the brick, never just the plasterboard.

1 each · Chemical resin anchor kit

3 each · Threaded steel rod, 10mm x 200mm

Buy:B&QAmazon

1 pack · Metal-stud hollow-wall anchor pack

AB-06Drill the rod holesDrill through your marked centres at a slight downward angle into the wall, following the angle recommended on your fixing pack, usually 10-15 degrees so the rod locks upward under load. Match the drill bit to the fixing size, drill to full depth, then vacuum dust out of each hole before fitting anything.

1 set · Masonry/wood drill bit set

1 each · Handheld vacuum

AB-07Fit the resin anchors and rodsInject resin into each hole following the pack's instructions, then push the threaded rod in with a slight twist to spread the resin evenly. Leave it completely undisturbed for the full curing time stated on the pack, often 30-90 minutes at 20°C and longer in a cold room, before doing anything else.

1 each · Resin applicator gun

AB-08Drill matching holes into the shelfMark and drill holes into the back edge of the shelf at exactly the same spacing as the rods, slightly larger than the rod diameter so it slides on easily, for example 12mm holes for 10mm rods. Dry-fit the shelf onto the cured rods to check the holes line up before you add any glue.

1 each · Wood drill bit, 12mm

AB-09Glue and fit the shelf onto the rodsApply a bead of strong wood adhesive or epoxy inside the shelf holes, then slide the shelf fully onto the rods until it sits flush against the wall. Check it's level along its length and front edge before the adhesive starts to set.

1 tube · Strong wood adhesive/epoxy

1 each · Spirit level (600mm)

AB-10Prop the shelf and leave it to cureSupport the shelf level with a temporary packer or offcut underneath while the adhesive cures fully, usually 24 hours, so it can't droop or twist before it sets. Don't rest anything heavy on it during this time.

1 set · Timber offcut/packers

AB-11Patch and finish around the fixingsOnce the adhesive has fully cured, remove the prop. Fill any gap where the shelf meets the wall, and patch your earlier test hole and any exposed fixing points in the lath and plaster with a fine surface filler. Let it dry fully, sand smooth, then touch up with matching paint.

1 tub · Fine surface filler

Buy:B&QAmazon

1 sheet · Sandpaper, fine grit

1 small tin · Matching paint

Buy:B&QAmazon

AB-12Clean up and test the loadVacuum dust from the floor and wall, and wipe everything down. Before loading the shelf fully, press down firmly on the front edge to check it doesn't move or creak. Only load it up to the weight rating stated on your fixing pack.

1 each · Vacuum cleaner

1 each · Cleaning cloth