AR-08Fix the architrave — method depends on the wall behind itNail into the timber door lining first with 40mm lost-head or oval nails every 300-400mm, about 15-20mm from the edge. Run a bead of instant-grab adhesive along the back of the wall-side edge, then add the right fixing for what's behind it: into solid brick or block, drill a 5mm hole through the architrave and wall, fit a red or brown wall plug, and drive a 40mm countersunk screw or masonry pin. Into plasterboard on a timber stud, drive a 40mm oval nail or panel pin straight into the marked stud centre; the adhesive holds the rest of the run. Into plasterboard on a metal stud, don't nail it — the pin bends and the steel just dents. Use the grab adhesive plus a self-drilling metal-stud screw only where you've marked a stud, and never a plastic wall plug or wood screw, which strips straight through 0.5mm steel. Over dot-and-dab plasterboard, nails between the dabs won't hold, so rely on the grab adhesive along the whole length; if you need a mechanical fixing, use one long enough to pass through the plasterboard and dab into the solid masonry behind, typically 60-75mm. Onto lath and plaster, avoid hammering pins as they can crack the old plaster keys — use grab adhesive and hold the architrave with masking tape or props until it cures, pinning lightly only into the door lining side.