Vapour Control

Vapour Check - Technical Note

It is important to recognise and address the need for including a Vapour Check or perhaps a breather paper if the roof being refurbished cannot be adequately sealed.  This is an essential consideration to avoid the problem of interstitial condensation. Old buildings and the construction details they employed, were by their nature very 'leaky' with air and vapour movement not controlled. Over-cladding or over-sheeting will generally require the introduction of a vapour control layer (VCL) above the internal sheet and below the insulation to keep internal moisture out of the roof void and prevent air leakage in line with current building regulations.

What about rooflights? - Technical Note

The refurbishment of roofs with existing rooflights can be a problem, and generally the client would have to accept a reduced level of light through the rooflight as a result of the introduction of a VCL. Cutting and sealing the VCL around every rooflight could overcome this but can add considerably to the overall cost.