Counter battens in the interior area for roof insulation

@parcus,

so far there has been no talk of a vapor barrier in the strict sense.
The previous discussion only assumed a vapor retarder.

If the Sd value of the vapor retarder foil is chosen correctly, the roof structure works without condensation forming on the vapor retarder foil.

Best regards
KPS

@KPS

correct, I also meant vapor barrier, as shown in the photo
and the values for the visible foil.

The membrane visible in the picture is the moisture-variable Vario KM Duplex with an Sd-value between 0.3 and 5.0 m.

The manufacturer's datasheet states:

"The variable sd-value of the Isover Vario KM Duplex can only be captured using a dynamic calculation program (e.g., according to the literature reference [10] in DIN 4108-3: 2001-07). Therefore, the Fraunhofer Institute Holzkirchen has determined that when calculating according to a static method (DIN 4108-3: 2001-07 section 4.2. or A 6.2, e.g., the Glaser method), a fixed sd-value of 2.5 m must be assumed for the Isover Vario KM Duplex."

The individual layers of the roof structure must be arranged so that the Sd-value decreases from the inside to the outside. Since it was not specified how the roof structure above the rafters is designed, I assume an underlay membrane with an Sd-value of <= 0.02 m, battens, counter battens, and tiles or roof shingles.

In this case, no condensation is to be feared in the area on the room side in front of the vapor control layer.

In any case, it is advisable to have both the thermal and moisture-technical calculations as well as the airtightness testing carried out on site by specially trained professionals.

If it is a new build, a "steam bottleneck" can still occur. Since drywall panels are not very thick, the sd value is also low. Depending on the paint coating (type and thickness), the sd value is between 1 and possibly a maximum of 10 m.

However, I only know the aforementioned system as Vario with fleece.

Hello,

first of all, thank you for participating in my post.

Unfortunately, I have only now found the time to read the articles.

The question was asked why I fill the space between GK and the foil with insulation.
Well, I want to achieve that the entire construction does not sound "hollow."

I have shortened the batten spacing to 300mm.
So I added another batten in the middle of the already existing battens.

The GK boards are then screwed vertically onto the battens.
I use the "1-man" boards 600 x 2250. This fits exactly in length between [Kehlbalkenanschluß] and [Drempel].

I will have the [Blower-Door Test] carried out after completing the insulation work.

I have posted a diary about my house construction online.

Have a nice evening.

Hello,

especially with a new building, the risk would be way too high for me.
Is it really specified like this in the layer structure?

With a simple GK cladding, an sd-value of μ8 x 0.0125 m/μ = 0.1 m results.

As KPS correctly writes, the individual layers of the roof structure must be designed so that the sd-value (diffusion-equivalent air layer thickness) decreases from the inside to the outside. Thus following the absolute moisture content of the air.

In addition, the counter battens should follow the rafters with at least 24 mm thickness, even if the DIN does not provide this for interior finishing as it does for exterior battens.

Best regards