Instructions for improving the thermal insulation on a sloping roof following damage by a marten.


Over-the-rafter thermal improvement of a sloping shingle roof.

Roofing based on shingles, especially aspen wood shakes, gives a building an eye-catching look. These types of roofing are also perfect for irregular roof slopes. In the example shown here, the aspen underlines the beauty of the “eyebrow” on both sides of the roof.

The project used in the instructions is located in the heart of the picturesque land of Kashubia, in Poland. The aspen roofing was installed 10 years ago, and has since suffered some heavy weathering. It was not properly waterproofed, and must now be removed. However, removal reveals a much bigger problem underneath the roof, with the glass wool thermal insulation having been heavily damaged by a marten, which made its way into the attic and built its lair there.

To ensure great thermal comfort throughout the year, the owner wants to have Thermano thermal insulation panels installed, which are made from rigid polyurethane. Thermano boast the highest thermal insulation class, A++, and resists infestation by vermin, forest creatures (including martens) and birds.

How much does thermal roof insulation replacement cost?

Currently, 125 mm is the Thermano layer thickness for roofs, in compliance with the Polish Ministry of Construction (to achieve a heat transfer coefficient U=0.18). 
This thickness will increase to 150 mm (to achieve U=0.15) from the year 2021.

Indicative gross price of materials:

  • Thermano sandwich panels: from 100 zł m2


Step-by-step improvement of thermal insulation damaged by a marten

1. The work should commence with the removal of the old covering. It is recommended to secure the place of the shingle or wood chip drop area with film, because there are a lot of nails among the debris.

2. The next stage involves the removal of old battens and counter battens. After the disassembly of the shingle or wood chips and the substructure, the existing vapour breathing membrane was exceptionally left in place.

3.The next step is the preparation of appropriate battens and counter battens. In this case the Investor chose to use the same cross-section – 40 x 60 mm – for both the battens and counter battens in order to ensure proper venting of the substructure and covering with a new wooden shingle.

4.Next, you can begin the standard over-rafter installation of Thermano panels on the flat roof surfaces, starting from the eave. Obviously, all possible gaps wider than 3–4 mm must be filled with low-pressure foam and all the joints between the Thermano panels must be secured with 50 micron thick aluminium tape.

5. More attention should be paid to the preparation of Thermano panels for the protection of the “eyebrow”. Due to the roof curvature on this element, the installation of Thermano is quite specific. In the roof presented here, the Contractor decided to use a technique characteristic for the assembly of plasterboards on curved surfaces. Thermano panels were cut from top and shaped on the “eyebrow” curvature. The gaps that were formed in this process were filled with low-pressure foam and sealed with aluminium tape. It is worth noticing that thanks to this solution the bottom cladding of the Thermano panels remained intact and retained its airtightness.

6.The subsequent stages of roof covering installation are the same as in the case of a standard over-rafter thermal insulation. The following elements are placed on the Thermano panels in this order: vapour breathing membrane, battens and counter battens as the substructure for the new wooden shingle. 

The counter battens should be attached to the rafter through Thermano panels using long screws, every 40 cm or so, alternately, one perpendicularly to the rafter and the next at a 67o angle. Because 100 mm thick Thermano panels and counter battens of 40 x 60 mm cross-section were chosen for assembly and the roof covering will be lightweight, ⌀6 screws were used with a minimum length of 200 mm. Also due to the lightweight roof covering made of aspen wood chips, battens are attached to the counter battens using short screws. In this case it is important to select appropriate screw length in order not to unnecessarily puncture the vapour breathing membrane. Because both the counter battens and battens have a cross-section of 40 x 60 mm, the screws should be 70–75 mm long.

7.The next stage is the assembly of the new roof covering of wooden shingle or aspen wood chips, which will be impregnated at appropriate time and protected against weather conditions. According to the manufacturer, a properly installed and protected roof covering of aspen wood chips should retain its technical and visual parameters for at least 30 years. The building modernised in the way presented here perfectly protects the interior from the impact of both low and high temperatures, facilitating a full-year usage of the house. Moreover, the roof is now inaccessible to forest animals.

Thermal improvement with the Thermano system provides high thermal insulating power from the low lambda Thermano panels.


If you install a Thermano thermal insulation system...

  • You will save on power bills for heating or cooling the house.

  •  You go green. Reduced energy usage means a lower footprint of airborne pollutants.

  • You will no longer have to worry about the protection of your roof. Thermano resists infestation by vermin, including rodents, martens and birds.


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If you have any questions, please contact our Thermano technical consultants:

+48 801 000 807