Screws

Screw fasteners should be long enough to give adequate penetration into the supporting structure. Generally, 30 mm embedment is required for screws into timber or three threads engagement for screws into steel. Refer to roofing manufacturers for specific recommendations.

Fasteners should be:

• a minimum of Class 4 for Severe Environments,
• Class 5 for Very Severe Environments,
• manufactured and coated with materials compatible with the material being fastened, and
• fitted with low-carbon, non-conducting sealing washers.

Profiled washers should have an EPDM sealing washer.

Screw Points

Screw points

 

Screw Heads

Screw heads

 

 

 

Screw Gauge

ScrewGauge

 

Threads per Inch (TPI)

ThreadsPerInch.

 

Screw fasteners are identified by their length, gauge pitch (threads per inch) and their drill point. The drill point may be type 17 for driving into timber or drill point for driving into steel. Reduced diameter drill points, which can be used for either function, are also available.