ETICS external insulation — the full installation
External insulation is a system, not a product: board adhesive, then boards, then anchors, then a mesh-reinforced base coat, then the finish. Each layer protects the one beneath, and any shortcut in the order shows on the facade within two winters. This guide walks the order that cannot be shortened.
Bonding the boards: bead and dabs
On the board's back: a continuous adhesive bead around the perimeter + three dabs in the middle, so that after pressing, adhesive contacts at least 40% of the board. The perimeter bead is not cosmetic — it stops air circulating behind the boards, and back-flow cancels half the insulation's value. Press and straightedge each board to its neighbours immediately.
Boards go up half-bonded like brickwork, interlocking at building corners, and a board joint never lands on the line of a window or door reveal — opening corners take L-cut boards. Gaps between boards are filled with insulation slivers or foam — never adhesive: adhesive in a joint is a thermal bridge that draws its own lines on the facade later.
Rasping and anchoring
After 24–48 hours rasp the boards flush to erase steps between neighbours — any small step now becomes a permanent shadow on the finished facade. Then the anchors: 6 per m² as the base pattern (more at corners and upper storeys per wind load), each head set flush with the board face, not sunk.
Base coat and mesh: the heart of the system
Apply the base coat 3–5 mm with a notched trowel and embed the glass-fibre mesh in the outer third of the fresh coat — never against the board: mesh buried deep reinforces nothing. Overlap runs by 10 cm and close with a pass that hides the mesh completely. Opening corners take diagonal 45° mesh patches before the general mesh — facade cracks start at window corners before anywhere else.
The finish
Once the base coat dries (typically 3 days, weather depending) comes the finish primer and the final layer — a textured render or flexible facade paint. Work each elevation "wet on wet" without stopping mid-face, or the break line shows forever.
The insulated-facade mistakes
- Dabs with no perimeter bead — air circulating behind the boards.
- A board joint on a window line — the famous diagonal crack.
- Adhesive in board joints: thermal bridges that draw the board grid on the facade.
- Mesh laid against the board instead of the outer third.
- No diagonal patches at opening corners.
- Anchoring before the adhesive sets, shifting the board.
Frequently asked
Can adhesive replace anchors, or anchors replace adhesive?
No: adhesive carries the weight and stops air rotation; anchors resist wind suction. On low buildings over very sound substrates anchoring can theoretically be dropped, but the practical rule in our market is both, always.
How long between boarding and the mesh coat?
24–48 hours for the adhesive to set, then rasping and anchoring, then mesh. EPS left in the sun for weeks yellows and degrades at the surface — do not leave the facade bare for long, and if it happens, rasp the degraded face off before continuing.
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Last updated: 2026-08-09