Bonded lining is the fastest way to insulate a straight, sound internal wall: a sandwich panel (insulation + plasterboard) fixed with adhesive mortar, no frame. A room is lined in a day. But the technique has strict conditions.
Conditions of use
- Wall flat (defects < 15 mm, absorbed by the dab thickness), dry and solid (a chalking render = forbidden without primer).
- Common max height: 3.50 m in a single panel.
- Forbidden on: walls with rising damp, salt damage, flaking paint, old wallpaper.
Dab bonding (diagram)
The method in 5 moves
- Adhesive mortar dabs on the back of the panel, roughly every 30 cm both ways (about twenty per panel).
- Panel set on 10 mm packers, pressed on, then tapped in with a straightedge to align with the chalk line and plumb.
- Check plumb on every panel AND alignment between panels — the first 10 minutes allow any correction.
- 48 h drying before joint taping.
- Heavy loads do not hold in a bonded lining without a through-fixing — see fixing heavy loads on plasterboard.
EPS or polyurethane?
- Graphite EPS (grey): the standard, λ 0.031, good value — 13+120 mm gives R ≈ 3.85, subsidy-eligible.
- Polyurethane: λ 0.022, the thinnest at equal performance — precious when every centimetre counts, dearer.
- Old breathing or irregular wall: prefer the frame system with wool.