Where to use DPC

To satisfy NHBC and Zurich Municipal technical requirements, Catnic lintels only require a separate DPC in severe exposure zones i.e. zones 3 & 4 of the map and as determined by BS 8104.

NHBC Amendments Oct 1992 require a separate damp proof protection for all lintels in Scotland, Northen Ireland, the Isle of Man and in areas of severe or very severe exposure to driving rain, as defined under BS 5628 Part 3. The map indicates typical exposure categories.

In such cases, a cavity tray/damp proof protection should provide an impervious barrier draining water outwards. It should have an overall minimum upstand of 140mm, returned to the inner leaf masonry, and be so shaped that there is not less than 100mm vertical protection above a point where mortar could collect.

Where exposure conditions or local building regulations demand a separate DPC, Catnic cavity wall lintels not only provide additional protection against the elements but also act as a support and template for the DPC, making it easier to install, and with less risk of damage.

The DPC should project at least 25mm beyond the outer face of the cavity closer and vertical DPC. It should provide drip protection for the door and window heads, and cover the ends of the lintel to ensure moisture is shed clear of the reveals.

For all coastal site applications where the soffit of the lintel is exposed, the use of a soffit cladding in conjunction with a separate DPC is recommended to improve appearance and extend normal maintenance periods.