ASSY^® isotope timber screw

Roof application 1

• With soft insulation < 0.06 N/mm²

For soft insulation with a pressure resistance below 0.06 N/mm², such as fibreglass, mineral wool, animal and plant eco-insulation = use an alternating screw-in pattern at an angle of 60° to the rafter axis.

Roof application 2

• With pressure-resistant insulation > 0.06 N/mm²

For non-slip insulation with a pressure resistance above 0.06 N/mm², such as hard polyurethane (PUR) or polystyrene (PDS) foam = parallel screw-in pattern at an angle of 60° to the rafter axis.

Calculation of the required screw length:

• Thickness of securing battens in mm


• + thickness of insulation in mm


• + thickness of boarding in mm


• + 60 mm screw-in depth

Intermediate result in mm x a factor of 1.15

• Final result in mm


• Use the next longest screw length

Additional product documentation:

• Würth timber dimensioning software, (available online or as a download for offline work)


• Timber dimensioning software, load tables and detailed processing instructions can be found on the service page www.wuerth.de/assy.


• Data sheet for over-rafter insulation