Civil Engineering Reference
In-Depth Information
Chapter 6
Truss Plate Systems
Most users of trussed rafters will first come into contact with the name of one of the plate
system manufacturers on receipt of a set of computer printed calculations. If these are not
asked for, it is possible that the user may never know which brand of plate has been used
in the manufacture of the trussed rafter supplied to him.
The plate manufacturers or 'system owners' supply both plates and design information to
trussed rafter manufacturers who, clearly, are free to choose which system they prefer. The
choice will be made on plate price, but more importantly (and increasingly a deciding
factor) on the degree of design information and technical backup available from the sys-
tem owner.
Whilst at first sight the type of plate used on the trussed rafter may seem of little import-
ance to the end user, because his contract to purchase trussed rafters is with the trussed
rafter manufacturer, it can affect both the quality of service and product supplied and more
importantly the precise construction form used on the roof.
The purchaser should be interested because the system owners, through their various man-
ufacturers, can offer different forms of roof construction, some of which may appear very
competitive on first sight but may involve a significantly higher site labour input than an
alternative offer. The quality of the fabrication of the trussed rafter is another factor and
this, to some extent, will be affected by the machinery and cutting data made available by
the system owner to the fabricator. The purchaser is advised to ensure that his supplier is a
member of the BM TRADA certification scheme and that the trusses are marked accord-
ingly (see Fig. 5.3j and 5.3k).
Systems Available
Changes involving the producers of the punched metal plates or system owners continue.
Gang-Nail, the original in the UK, is still producing. MiTek Industries Ltd, a combination
of Bevplate and Hydro-Air, is still a major producer but has disposed of its builder's fix-
ings to Simpson Strong-tie. Wolf Systems Ltd was a newcomer when the
