Building supply
Building supply
Roof Underlay
The second line of defence.
- Fixing
- Component
- Category
- Building Supplies
Breathable underlays and vapour control layers for ventilated and unventilated roof build-ups.
Profile cross-section — schematic, not to scale
Overview
A metal roof keeps water out. The underlay keeps the roof out of trouble: it catches wind-driven snow that gets past a ridge, it manages the condensation that forms on the underside of cold steel, and it protects the structure during the days between felting and sheeting.
Which underlay depends on the build-up. A ventilated cold roof and an unventilated warm roof need different membranes, and getting that decision wrong is the most common cause of a roof that drips on a clear February morning.
Applications
- Ventilated cold roofs
- Unventilated warm roofs
- Re-roofing over existing cover
- Temporary weather protection
01
Build-up specific
Breathable and vapour-control grades for the roof you are actually building.
02
Condensation management
Handles moisture forming on the underside of cold steel.
03
Site protection
Weatherproofs the structure between felting and sheeting.
Technical data
Specifications
All VANKKA data is metric. Values are confirmed for your project at quotation and issued with the technical documentation.
Verified technical data for this product is being finalised. The data sheet structure below shows exactly what will be published — request the full technical documentation and our team will send the current figures for your project.
Specification
Documentation
Everything you need to specify it.
Data sheets, installation guides, CAD details, declarations of performance and warranty terms. Documents not yet published can be requested directly and will be sent by the technical team.
- RequestTechnical data sheet
Technical data sheet
Data sheetPDF
- RequestInstallation guide
Installation guide
Installation guidePDF
Gallery
Roof Underlay in use
Photography of this product in production and on completed buildings.
Roof Underlay on a completed building
Roof Underlay profile detail, raking light
Roof Underlay in production on the roll-forming line
Roof Underlay installed — junction and trim detail
Completes the system
Trims and accessories designed for this product
Ordered with the profile, these come from the same coil and the same batch — so they match exactly.
