Roof Window: Creating a watertight seal

Integrating a roof window into an ISOLINE LOW LINE sub-roof roof requires careful attention to your roof pitch and a "double weathering" technique to guarantee a completely watertight seal.

Follow these guidelines for a successful installation:

1. Check Your Roof Pitch Requirements

Your choice of window depends entirely on the angle of your roof:

• Pitches between 10° and 10°: You must use a specific low-pitch roof window model engineered to operate safely at low angles.
• Pitches 15° and above: You have the flexibility to use standard roof window models.

2. Implement Double Weathering Around the Frame

To ensure absolute water tightness, you need to achieve "double weathering" by sealing the window at both the sub-roof (Isoline) level and the external tile level:

• Sub-Roof Level (First Line of Defence): Use an ONDULINE APRON PIECE positioned at the top of the roof window Seal the ISOLINE LOW LINE sheets directly to the roof window frame using a high-quality adhesive flashing band.
• Tile Level (Second Line of Defence): Install a standard tile flashing kit (chosen specifically to match the profile of your roof tile) to weather the window at the external tile layer.

3. Fixing & Membrane Protection

When securing the components on site, ensuring you do not damage underlying layers is crucial:

• Fixing Length: Use 75mm fixings for your batten setup. This specific length provides structural security without penetrating or compromising the existing breather felt membrane underneath.