Standards Development

Scope

Existing scope below, further consideration tbc.

"This Part of the Code deals with zinc roof covering and gives recommendations based on accepted good practice in the United Kingdom for laying zinc roofs on the Roll Cap System. In this system the sheets are fully supported and have their sides turned up against shaped wood rolls spaced to suit the width of the sheets. The rolls are covered with an independent capping which completes the joint. Joints between the ends of sheets are made either by means of drips or welts depending on the pitch, see Figure 1 and Figure 2.

Recommendations are given for the whole of the roof covering above the upper surface of the constructional base for both flat and pitched roofs.

Flashings and gutters are also dealt with in so far as they are integral parts of the roof covering."

Purpose

CP 143-5 has been proposed for a full revision and to be published as a British Standard.

Reasons for revising are: 

• Still in imperial measurements

• The underlays recommended are not appropriate

• Mainly addresses roll cap whereas since 1990, 90% of zinc roofs and walls use the standing seam joint

• The roof pitch of 1:60 is not recommended, the minimum is 1:20

• Substrates have changed dramatically in 60 years (including warm roof construction)

• Fire protection has also changed

• Detailing really needs more in-depth information