ᐅ Counter-battening for Interior Roof Insulation

Hello forum,

and first of all, Merry Christmas to everyone.

I have a question regarding counter battens in my roof insulation work.

In my roof structure, I have installed 200mm (8 inches) insulation between the rafters and sealed it with a vapor barrier foil.

Now, I want to install the counter battens (24mm (1 inch) battens, with the spaces also insulated) to attach the drywall (gypsum board) to them.

What spacing between the battens is recommended?

A 600mm (24 inches) spacing seems too wide to me. Could the drywall sag or possibly warp over time?

I started the first batten at the knee wall and then spaced them every 600mm (24 inches) upwards. At the top, I attached another batten.

Or should I place a batten along the rafters?

Hello,

Merry Christmas to you too.
I would recommend a batten spacing of 31.25cm (12.3 inches). The reason is that the panel is 1.25m (4.1 feet) wide, half of that is 62.5cm (24.6 inches), and half of that again is 31.25cm (12.3 inches). Otherwise, the panels will sag over time. Apart from that, everything looks fine. There is no need for battens on the rafters. Inside, I would possibly recommend using a wood fiberboard instead of plasterboard. These work very well as active heat storage, creating a comfortable atmosphere in the room. Otherwise, make sure to properly seal the vapor barrier. That is the most important thing.

Best regards

I would also prefer to use gypsum drywall panels, as they are excellent at buffering humidity peaks, easy to work with, and (including the joints) create a consistently smooth and even surface.

Regarding the substructure:
If a single-layer timber substructure is to be used, I would follow the installation guidelines of the respective system manufacturer.

The battens to be used should have minimum dimensions of 50 x 30 mm (2 x 1.2 inches).

The spacing between them depends, among other things, on the weight of the cladding. If there are no fire protection requirements, a single-layer cladding with 12.5 mm (0.5 inch) thick gypsum drywall panels arranged parallel to the rafters (i.e., perpendicular to the substructure) might be considered. In this case, the batten spacing should be chosen with a maximum of 50 cm (20 inches), according to the manufacturer’s instructions.

Before installation, you should in any case ensure through a differential pressure–based leakage test that the airtight envelope functions without any gaps. For this purpose, you can commission a full blower door test or alternatively carry out this inspection for leaks yourself. Measurement service providers or equipment rental companies can be found, for example, at luftdicht.de.

With Christmas greetings
KPS

Hello,

I also see the advantages of drywall here. The deflection can vary depending on the material and manufacturer, so I would follow the respective recommendations.

But what do you want to achieve with the thermal insulation placed in front of the vapor retarder?

Best regards

The originally described insulation arrangement in the cavity between the gypsum board cladding and the vapor retarder/airtightness layer undoubtedly reduces thermal bridges in the rafter area and additionally improves the room acoustics in the living space. Therefore, it should definitely be implemented.

@KPS

Why is that? If the condensation from the vapor barrier is absorbed by the insulation, the "thermal bridge" would always be higher than with stagnant air, and the thermal insulation would be almost negligible.

Room hygiene is not even being considered. (especially with gypsum board)