Pitched roof over the rafter installation


You will need the following to install the Thermano panels on your pitched roof:

a) sealing tape

  • size: 75 mm or 120 mm wide (50 m/roll).
  • average consumption: 1.5 m for each 1 m2 of the Thermano panel (when sealing on one side only).

You can order your tape with the Thermano panels from Balex Metal.


b) vapour breathing membrane* 

quantity: 1 m2 per 1 m2 of Thermano panels

Balex Metal recommends the Aspira membrane for Thermano. You can order it with your Thermano panels.



c) fastening screws

size, length:

  • min. 185 mm for 100 mm thick Thermano panels
  • min. 210 mm for max. 100–120 mm thick Thermano panels
  • 250 mm for 120–160 mm thick Thermano panels

Calculating the screw length:

Thermano panel thickness + counterlathing (40 mm) thickness + rafter penetration depth (30 mm) + spare for 67° cant (30 mm)
size, diameter: - ø 6 for light shell roofing*- ø 8 for heavy shell roofing*

quantity: depending on the rafter spacing, have 3 to 4 screws per 1 m2 of the Thermano insulation panelwork.



Start laying the panels from the eaves end. Install a verge plank (which goes at the gutter channel) to stop the first row of the Thermano panels. You can fix the first insulation row with several rafter screws to minimise the risk of the wind blowing the panels away.

You can lay the panels on either side (front or back). Remember however, that the next panel rows must be aligned with the TOP lock (overlap) to the top, as shown in the figure:



Seal the panel joints with the sealing tape.



Lay the vapour breathing membrane on the Thermano panel row.
You can tack the membrane, but the final fastening is done with counterlathing*.



Lay the counterlathing on the membrane and fasten it by driving the screws through the Thermano layer and down into the rafters.
Each screw shall penetrate the rafters down to 30 mm. Use 40x60 mm counterlathing on all rafters up to 15000 mm long and 50x60 mm on rafters longer than 15000 mm. Space the screws at ca. 400 mm across the rafters.

The screws must be fastened alternately, i.e. at 90° and 67°. Always begin at the 90° location, see the figure:



Lay the successive panel rows staggered against each other, i.e. by offsetting the joints.
You do not need to pre-fasten the Thermano panels with screws, unless there is strong wind or other conditions which necessitate this.

The panels are very easy to trim quickly. Standard tools, e. g. wood/metal saw will suffice.
Cut with safety glasses.


When the panel layers reach the roof ridge*, join the last rows so that the gap from trimming can be sealed with a low pressure foam and completely closed with the sealing tape.

Keep the gap not wider than 20 mm.



Now cover the ridge with the membrane on both sides of the roof and with an overlap.



The last stage is to fasten the laths.* Lathing is a structural component, so the lath cross section depends on whether the roofing is light* or heavy*.

The standard size is 40x60 mm in cross section. The lath spacing also depends on the roofing type and roofing manufacturer's instructions. Fasten the lathing to the counterlathing with short screws. The screw length must prevent piercing of the membrane, i.e. the screw cannot go through the membrane. Heavy roofing requires reinforcing each lath with a long screw installed in every third rafter. This will increase the screw count from 1 to 2 per 1 m2 of the Thermano insulating layer.



Heavy roofing: made of e.g. ceramic or concrete roof tiles.

Light roofing: made of e.g. trapezoidal profile sheets, sheet metal shingles, or upright seam panels.

Counterlath(ing): substructural members under the roof skin fastened over the rafters or in parallel to the rafters, i.e. along the roof slope.

Lath(ing): substructural members under the roof skin fastened over the counterlathing and in perpendicular to the rafters, i.e. across the roof slope.

Roof ridge: the topmost part of the roof formed by the intersection of roof slopes.

Membrane: a flexible barrier between two media; here the membrane is a wind-proof or vapour breathing/permeable membrane.

Eaves: the bottom horizontal roof edge, which usually protrudes beyond the building shell plane. The eaves are predominantly designed to evacuate rain and melt water clear of the building walls. The rain gutters usually run along the eaves.