How and where to use guide
VELUX Insulation Collar 78x140cm BDX MK08 2011
Typical applications
This insulation collar is used in loft construction to seal the interface between bulk insulation materials and timber frame components. It is particularly valuable in retrofit loft insulation projects where existing roof trusses and timber frames create thermal bridges and air gaps that compromise insulation performance. The collar is also suitable for new build loft installations where maintaining a complete thermal envelope around structural timbers is essential for meeting building regulations and energy efficiency standards.
- Retrofit loft insulation upgrades around existing roof trusses
- New build loft construction with timber frame systems
- Sealing gaps between insulation batts or rolls and structural timbers
- Creating continuous thermal barriers in pitched roof spaces
Installation and positioning
Position the insulation collar around timber frame members and roof trusses before or during insulation installation. The fibreboard construction allows it to be fitted snugly against structural timbers, creating a seal that prevents insulation from settling away from these elements. Ensure the collar is positioned to bridge the gap between the insulation material and the timber surface, maintaining contact on all sides. The 78 x 140cm dimensions are designed for standard loft bay widths and truss spacing, though you may need to cut or overlap collars to suit your specific roof geometry.
- Fit collar around timber members before laying bulk insulation
- Ensure full contact between collar and both insulation and timber
- Overlap collars where necessary to maintain continuous sealing
- Check that collar does not compress or restrict insulation placement
Performance and limitations
The BDX 2011 grade fibreboard provides durable, long-lasting performance in loft environments. However, this collar is a gap-sealing component only and should be used as part of a complete insulation strategy that includes appropriate bulk insulation materials, vapour control layers, and adequate ventilation where required. The collar does not provide structural support and must not be relied upon to support insulation weight. Ensure your loft design includes proper ventilation to prevent moisture accumulation, particularly in pitched roof spaces with breathable insulation systems.
- Use alongside appropriate bulk insulation materials
- Do not use as a structural support element
- Maintain adequate loft ventilation to prevent condensation
- Check building regulations compliance for your specific application
On-site handling and storage
Store the insulation collar in a dry location on site to protect the fibreboard from moisture damage before installation. Handle carefully to avoid crushing or deforming the collar, as this will compromise its sealing effectiveness. Keep the product away from damp conditions and ensure it is installed promptly after delivery. Once fitted in the loft space, the collar will be protected by the surrounding insulation and roof structure, but take care during installation to avoid tearing or puncturing the fibreboard surface.
- Store in dry conditions away from moisture and weather exposure
- Handle carefully to prevent crushing or deformation
- Install promptly after delivery to avoid prolonged storage
- Inspect for damage before fitting