How and where to use guide

VELUX Support Trimmer for 18mm Frame Gap - White Roof Windows EBY W27 2000

Typical applications and installation

This trimmer is used during roof window installation to fill the gap between the VELUX window frame and the surrounding roof timber structure. It is particularly valuable in confined spaces where standard trimmers cannot be fitted, such as tight roof angles, narrow rafter bays, or where headroom is limited. Installation occurs after the window frame is positioned and levelled but before final sealing and decoration. The compact design allows it to be manoeuvred into position even in awkward roof spaces where access is restricted.

Install after the VELUX EBY W27 2000 window frame is secured and levelled
Fit into the 18mm gap between window frame and surrounding timber
Use with timber grades F16, F24, and F36 structural members
Suitable for pitched roofs with limited headroom or tight rafter spacing
Provides weather-tight seal to prevent water and air infiltration

Fitting and securing

The trimmer should be positioned carefully into the 18mm frame gap, working from one corner and progressing around the window perimeter. Ensure the window frame remains level and square throughout fitting. The white plastic construction allows for easy visibility during installation, helping you confirm correct seating in the gap. Once positioned, the trimmer should be secured according to VELUX installation guidance, typically using appropriate fixings that do not compromise the weather-tight seal.

Check the 18mm gap is consistent around the entire window frame before fitting
Position trimmer carefully to avoid disturbing window alignment
Work methodically around the perimeter to ensure even seating
Verify the trimmer sits flush with both the window frame and surrounding timber
Secure using fixings specified in VELUX installation instructions

Weather-tightness and maintenance

The primary function of this trimmer is to create a weather-tight seal around the window frame. Once installed, it should prevent water penetration and air leakage at the frame junction. The durable white plastic material resists weathering and maintains its appearance over time. Periodically inspect the seal around the window, particularly after severe weather or high winds, to ensure the trimmer remains properly seated and undamaged. Any gaps or movement should be addressed promptly to maintain weather protection.

Inspect the trimmer seal annually, especially after winter or storms
Check for any gaps, cracks, or movement in the plastic material
Ensure no water is pooling or running behind the trimmer
Clean the white plastic surface with mild soap and water if needed
Address any damage or poor seating immediately to prevent water ingress

Limitations and site considerations

This trimmer is specifically designed for 18mm frame gaps on VELUX EBY W27 2000 white roof windows. It will not be suitable for different window models, larger or smaller frame gaps, or coloured window frames. The compact design, whilst advantageous in tight spaces, means it requires careful handling during installation to avoid damage. Ensure the surrounding timber structure is sound and properly prepared before fitting, as the trimmer cannot compensate for structural defects or poor timber condition.

Only use with VELUX EBY W27 2000 models with 18mm frame gaps
Not suitable for different window sizes, models, or coloured frames
Requires timber grades F16, F24, or F36 for proper support
Handle carefully during installation to avoid cracking or deformation
Ensure surrounding timber is dry, sound, and free from rot or damage