RAPID Top-2-Roof Screws for On-Roof Insulation

Schmid RAPID® Top-2-Roof screws are long structural fixings for securing counter battens through on-roof insulation into the supporting timber. Their twin-thread arrangement supports the batten and helps transfer forces without relying on the insulation as the structural fixing point.

Why on-roof insulation needs a specialist fixing

In an on-roof or warm-roof build-up, the counter batten is separated from the rafter by the insulation layer. The fixing must pass through this non-structural depth before achieving the required anchorage in timber.

The connection may need to resist roof loads, wind actions and forces acting down the roof slope. A long general-purpose wood screw is not automatically suitable simply because it reaches the rafter.

How RAPID® Top-2-Roof works

The main thread anchors into the supporting timber. A second threaded section beneath the head engages the counter batten and holds it at the designed position. This arrangement helps the fixing transfer compression and shear forces while limiting unnecessary compression of softer insulation.

• Long lengths for insulated roof build-ups
• Suitable for hard and soft insulation within the approved system
• Secondary thread to secure the counter batten
• Cylinder head intended to reduce surface splitting and sink flush with the batten
• Coarse thread and friction section for lower driving resistance
• Follower-thread tip for a quick bite without routine pre-drilling

Typical applications

Fixing angle and layout

Warm-roof screw arrangements may include fixings installed square to the rafter, at an angle, or in a calculated combination. The correct layout depends on the roof geometry, loads, batten, insulation and supporting structure.

Do not assume a standard angle or spacing from another project. Use the project fixing schedule or a calculation based on the relevant design rules and current product data.

Choosing the correct screw length

Insulation thickness is only one part of the length calculation. The selected screw must pass through the counter batten, insulation and any other layers in the fixing path before achieving the required effective embedment in the supporting timber.

• Confirm the counter-batten depth.
• Measure the complete insulation and board build-up.
• Allow for the specified fixing angle, which increases the distance travelled through the build-up.
• Use the effective timber embedment required by the design.
• Check that the upper and lower threaded sections will sit in the intended components.
• Select an approved available length rather than rounding up without verification.

A screw can be long enough overall but still be unsuitable if its thread positions do not match the roof build-up. Site tolerances should be included in the design rather than corrected by overdriving the screw or changing its angle.

Installation checks

1. Confirm the specified screw diameter, length, angle and centres.
2. Locate the supporting rafters accurately through the roof build-up.
3. Keep counter battens aligned and adequately restrained during fixing.
4. Use the correct drive bit and a suitable installation tool.
5. Drive on the specified line and angle into the centre of the supporting timber.
6. Avoid overdriving and crushing the insulation beyond the designed condition.

Frequently asked questions