Proper Window & Door Installation
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Go to categoryWindow & ETICS Integration: Installation Guide
The simultaneous installation of new windows and an External Thermal Insulation Composite System (ETICS) is the ideal opportunity to eliminate thermal bridges. This guide analyses installation positions, RAL-standard sealing methods and provides comparative costing.
1. Window Installation Position
Select the installation position relative to the masonry to see the steps. The choice decisively affects the isotherm trajectory.
Step by Step (Middle Position)
- Preparation: Create a clean, flat, levelled substrate (trowelling/plastering around the opening if the wall is uneven).
- Fixing: Level and mechanically fix the frame with direct screws or brackets. Attention: Avoid permanent wooden wedges that break insulation continuity.
- Joint Sealing: Apply the chosen sealing method (e.g. RAL tapes or foam/silicone) in the gap between frame and wall (see Section 2).
- ETICS Application (Reveal Turn): The most critical step. Because the window sits inside, a reveal is created. The ETICS insulation (usually thinner here, e.g. 2-3 cm XPS or EPS) must turn into the reveal and overlap the frame by 1-2 cm to break the thermal bridge.
- ETICS Termination: Use a purpose-made plastic drip/connection profile (window connection profile with integrated mesh) between the turned ETICS and the frame, for elastic connection and crack prevention.
Evaluation
- Traditional, familiar aesthetic.
- Easy and robust mechanical fixing.
- Creates a thermal bridge at the reveal if not insulated properly.
- Reduces the useful opening due to the ETICS reveal turn.
Step by Step (Outer Face)
* The ideal choice per building physics (RAL). The frame aligns with the insulation layer.
- Preparation: Flatten the outer edge of the masonry.
- Fixing (Special Requirement): Because the window sits flush (or even beyond) the wall face, special brackets are needed. Install purpose-made metal angle brackets (consoles) around the perimeter or create a thermally insulating subframe (e.g. Purenit, Compacfoam or Triotherm).
- Installation & Sealing: Screw the frame onto the brackets. Apply a sealing system between the frame and the wall/subframe. Here, a multifunctional tape (Trio) is often the easiest solution.
- ETICS Application: The ETICS boards (e.g. EPS 7-10 cm) are bonded to the wall and lap over the outer face of the frame by 1-2 cm. There is no reveal to insulate. Thermal insulation is continuous.
- ETICS Termination: As before, use a window connection profile between the main ETICS board and the frame.
Evaluation
- Excellent isotherm performance (zero thermal bridge).
- The daylight opening is not reduced by coatings.
- Requires specialised, expensive fixing materials (brackets/Purenit).
- More demanding installation for the technician.
2. Joint Sealing Methods (RAL Standards)
The joint between frame and wall must satisfy the principle: "More airtight on the inside than on the outside" (3 levels). Choose the method based on budget and skill level.
METHOD A (The "Classic" RAL)
Tapes & Elastic Foam
The 3 sealing levels are achieved with 3 separate materials:
- Inside: Airtight / vapour-barrier tape (Vapor Barrier).
- Middle: Elastic PU foam, low-expansion, for thermal/acoustic insulation.
- Outside: Vapour-permeable / waterproof tape or cord tape (BG1).
Prerequisites: Requires time and care at corners. Ideal for uneven surfaces (foam fills voids).
Premium
METHOD B (The Modern Solution)
Multifunctional Tape (Trio)
A single self-expanding tape (impregnated foam tape) that handles all 3 levels simultaneously.
- Dense inside (vapour barrier).
- Insulating in the middle.
- More open outside (vapour-permeable, rain-resistant >600 Pa).
Prerequisites: Absolutely flat and levelled wall reveals. Very fast installation.
METHOD C (Alternative/Economical)
Flex Foam & Liquid Membranes
Foam at the centre and brush-applied pastes/mastics (liquid membranes) instead of tapes.
- Inside: Brush-applied liquid vapour-barrier membrane.
- Middle: Elastic PU foam.
- Outside: Brush-applied liquid vapour-permeable waterproof membrane.
Prerequisites: Good for renovations where tapes struggle to adhere. Requires drying time.
3. Comparative Costing & Performance
| Method | Estimated Material Cost (per linear metre)* | Labour (Index) | Best Use |
|---|---|---|---|
| A. Tapes & Foam | ~ €4.00 – €6.00 / m | High (requires thoroughness) | New builds, uneven joints |
| B. Trio Tape | ~ €8.00 – €12.00 / m | Low (1 step) | Perfect surfaces, speed |
| C. Flex Foam & Liquid | ~ €3.50 – €5.00 / m | Medium (drying time) | Renovations, difficult spots |
| * Prices are indicative for comparison. If "Outer Face" installation (Scenario 2) is chosen, add the cost of special angle brackets/Purenit (~€15 – €30 per linear metre). | |||
The data are estimates based on average Greek market prices (2026). Every installation is unique and requires individual assessment by a specialised technician.