The NZ Metal Roof and Wall Cladding Code of Practice is a comprehensive design & installation guide, and a recognised related document for Acceptable Solution E2/AS1 of the NZ Building Code.
It is not possible to install metal roof cladding and accessories to acceptable trade practice without the specialised tools required to cut, fold, position and fix them in an acceptable manner, and where these tools are not available, trades-people can make their own to enable a particular joint to be made.
Some of the tools may require a vice, but most hand tools are portable and can be used on site. Portable lightweight folders are now available that can bend from 2 .000m to- 4.400m m steel of up to 0.95 mm thick.steel.
(see drawing 14.8.D)
These machines can also slit the material for flashings so that they can be measured, cut and bent on-site, and fitted without the delays associated with off-site manufacture.
All metal joints that are to be sealed should be mechanically joined. Seaming is one acceptable method of joining two pieces of metal.
The two pieces are folded so each hooks into the other and then they are locked together by the means of a hand seamer or groover. (see drawing 14.8.F)
The material allowance depends onis dependent on the hook dimension, but it is usually 6 mm. That means the extra allowance for the is 18 mm, because there are four thicknesses of material.
This type of seam can be used on a flat surface or round surface.