Hi everyone,
I'm looking for some technical advice on a window-to-wall connection. I’m building with a European timber frame (60x160mm) and a thick layer of wood fiber insulation (Naturheld 140).
The setup:
- Insulation: 120mm wood fiber boards.
- WRB: Isocell Omega 50 Duo.
- Window sealing: Windows will be fitted flush with the insulation layer, sealed (outside) with Illbruck expanding foam tape (Compriband).
- Facade: Ventilated wood cladding.
The Problem: I am debating the best way to terminate the Isocell WRB around the window openings. I see two main options and I’m worried about long-term durability:
- Chemical/Adhesive: Taping the WRB directly to the window frame using high-quality window tape and mastic. My concern is the longevity of the bond—should I expect it to peel off in 10-15 years?
- Mechanical/Structural: Pulling the WRB back to the 60x160mm timber structure (behind the insulation layer), stapling it, and sealing it with mastic there. Then handling the window-to-insulation gap as a separate sealing layer with the Illbruck tape.
Specific Detail - External Blinds (PIR Panel): I have a more complex detail for some windows (see my sketch attached). I’m inserting a PUR/PIR panel in the lintel area to create a pocket for external blind boxes. My plan is to run the Isocell WRB over the PIR panel to create a "black back" for the blind box. This should protect the PIR and keep everything water/wind tight.
My questions:
- Is it better to terminate the WRB on the window frame (adhesive) or the wall structure (mechanical + seal)?
- Does wrapping the WRB over the PIR panel for the blind box seem like a standard/reliable practice?
- How would you handle the transition between the WRB and the Illbruck expansion tape to ensure no water gets behind the insulation?
I've attached photos of the current stage and a sketch of the PIR/blind box detail. Thanks for any insights!