What to Put Under a Click Panel Roof?
Click panels are a modern type of metal roofing that visually resembles a traditional standing seam roof. However, for the roof to perform properly over the long term, choosing high-quality sheet metal alone is not enough. It is equally important to consider what goes underneath it.
1. Flat and Stable Substrate
Click panels have a relatively flat surface, which means that any unevenness in the substrate can be more visible than with profiled roofing.
The substrate should be:
• flat,
• stable,
• sufficiently strong,
• properly prepared for the specific type of panel.
Full-surface timber decking or suitable structural boards are commonly used.
2. Breathable Roofing Membrane
Condensation can form under metal roofing, so it is important to protect the roof structure from moisture.
This is why a suitable breathable roofing membrane or secondary waterproofing layer is used. Its purpose is to help direct any water toward the eaves and protect the insulation and timber structure.
However, not every membrane is suitable for direct contact with metal roofing.
3. Separation or Ventilation Mat
With Click and standing seam roofing, a separation or ventilation mat is often used between the substrate and the metal covering.
It helps to:
• remove moisture,
• create a small gap between the metal and the substrate,
• reduce long-term contact between the metal and moisture,
• partially reduce noise during rainfall.
For example, some Click panel systems are specifically designed to be used together with this type of ventilation layer.
4. Proper Roof Ventilation Is Essential
Even a high-quality membrane is not enough if the roof is not properly ventilated.
Air should be able to enter near the eaves and carry moisture upward toward the ridge.
Proper ventilation:
• reduces condensation,
• helps dry the roof structure,
• extends the service life of the roof.
5. What Goes Under a Click Panel on an Insulated Roof?
On a standard insulated roof, the build-up may look like this:
interior → vapour barrier → thermal insulation → roofing membrane → ventilation layer → solid substrate → separation layer → Click panel
The exact build-up always depends on the roof design and the specific roofing system.
6. What Goes Under a Click Panel on a Carport or Garage?
On an uninsulated carport or garage, the roof build-up is simpler, but condensation can still form on the underside of the metal sheet.
It is therefore important to provide:
• sufficient ventilation,
• proper moisture drainage,
• a suitable substrate,
• and, if necessary, a separation or anti-condensation layer.
7. Most Common Installation Mistakes
The most common mistakes include:
• uneven substrate,
• unsuitable roofing membrane,
• missing separation layer,
• insufficient ventilation,
• poorly executed details,
• overly rigid fastening of long panels without allowing for thermal movement.
Metal naturally expands and contracts with temperature changes, so the roofing must be installed correctly.
Summary
There should not be just “some membrane and metal sheet” under a Click panel.
A correct roof build-up must provide:
• a flat and stable substrate,
• protection against moisture,
