Fixing and buying guide
VELUX Underfelt Collar 55x98cm BFX CK04 1000
What this product is and who needs it
This underfelt collar is designed specifically for CK04 VELUX roof windows installed on pitched roofs with underlay. It sits between the window frame and the roof underlay to create a weathertight barrier. If you are installing a CK04 VELUX window on a pitched roof with standard underlay protection, this collar is an essential component you must purchase and fit.
- For CK04 VELUX roof windows only
- Pitched roof installations with underlay
- Creates weathertight seal at frame-to-underlay junction
- Part of the complete flashing system
Sizing and compatibility
This collar is sized at 55x98cm and is manufactured specifically for CK04 VELUX windows. Before ordering, confirm your window size is CK04 by checking your existing window or the product documentation. Using the wrong size collar will compromise the weatherproofing of your installation. This product is compatible with standard pitched roof constructions where roof underlay is present.
- Size: 55x98cm
- Window compatibility: CK04 only
- Check your window size before purchasing
- For pitched roofs with underlay
What is included and pre-installation checks
You will receive one underfelt collar measuring 55x98cm. Before installation, inspect the collar for any damage and ensure your CK04 window frame is clean and free from debris. Check that your roof underlay is in good condition and properly positioned. Confirm that you have all other components of your VELUX flashing system to hand, as this collar works as part of a complete installation.
- Pack contains one underfelt collar
- Inspect for damage before fitting
- Clean window frame and underlay area
- Ensure all flashing components are available
Installation overview
The underfelt collar is positioned between the window frame and the roof underlay to create a weathertight seal. It must be installed as part of your complete VELUX flashing system during window installation. The collar prevents water from penetrating the critical junction between the window and roof structure. Follow the VELUX installation instructions supplied with your window to ensure correct positioning and fixing of this component.
- Fits between frame and roof underlay
- Essential for weathertight installation
- Part of complete flashing system
- Follow VELUX installation instructions