Fixing Types and Pull-Out Loads by Wall Material

For light loads (up to 5 kg per fixing), use standard nylon wall plugs screwed into the plasterboard. For medium loads (5-20 kg), use spring toggles, gravity toggles, or self-drill plasterboard anchors. For heavy loads (20-50 kg), use metal plasterboard fixings like Grip-It or Hollewand anchors. For very heavy loads (TV mounts, heavy shelves), always fix through the plasterboard into the timber stud or use a mounting board.

Tap the wall: a hollow sound indicates plasterboard on studs or dry-lined masonry. A solid sound suggests brick, block, or solid plastered masonry. Drill a test hole: red dust = brick, grey dust = concrete or dense block, white/cream dust = aerated block (Thermalite/Celcon), fine white dust with hollow feel = plasterboard. Check the depth to find what is behind the surface layer.

Ultimate (or characteristic) load is the maximum force at which the fixing fails (pulls out or the wall material crumbles). Safe working load (SWL) is typically the ultimate load divided by a safety factor of 3-4, giving a comfortable margin of safety. Always use the safe working load for design purposes. The values in reference tables are for ideal conditions — reduced loads apply in cracked masonry, close to edges, or in poor-quality substrates.

Standard nylon wall plugs have very poor pull-out strength in aerated blocks (typically only 50-100 N). For meaningful loads, use fixings designed for aerated concrete: nylon frame fixings (Fischer SXR, Rawlplug UNO), special aerated block screws (Turbobolt AB), or resin anchors (chemical fixings). Resin anchors provide the highest pull-out loads in aerated block, typically 1.5-3 kN per fixing.

A typical TV (15-30 kg) on a full-motion mount exerts significant leverage forces. In solid brick or concrete, use M8 or M10 sleeve anchors or throughbolts — each providing 3-5 kN pull-out. In plasterboard on studs, fix into at least two timber studs using 75 mm or longer coach screws or lag bolts. In aerated block, use resin anchors (M8 or M10 threaded rod) for adequate strength. Never rely on plasterboard alone for TV mounts.