ᐅ Roof construction and insulation

Hello everyone,

I am having a house (E70 energy-efficient house) built with a simple gable roof without windows.

I am responsible for the roof construction as a DIY task. I will receive the roof truss and take care of the rest myself.

I have not done this myself before, but some relatives have done similar work on their own.

Since I am not entirely sure about the roof structure, I could use some advice.

The roofing company advises me to proceed as follows: breathable underlay membrane, counter battens, then roof battens, and finally the tiles... with insulation installed between the rafters later. So, no sheathing with boards or panels. When I asked if this would be sufficient for an E70 house, they answered yes.

However, I am considering including roof sheathing and possibly an additional insulation layer above the rafters. This seems more reasonable to me.

Or at least sheathing made of OSB or MDF panels, then the breathable underlay membrane, then the counter battens and the roof battens.

Does anyone have experience or expert opinions on this?

Hello,

RoughRider schrieb:

Underlay membranes, counter battens, then roof battens, and then the tiles on top... later the insulation between the rafters.

This is basically a valid approach.

RoughRider schrieb:

So no sheathing with boards or panels. My question about whether this is sufficient for an E70 house was answered with YES.

Who answered this question with YES? The roofer? Your designer?

How thick are your rafters? 20cm (8 inches)? 24cm (9.5 inches)?

Regards

thank you for the response...

the question was answered with YES by the developer (Town & Country partner)...

i don’t know how thick the rafters are yet, since the roof frame hasn’t been installed...

but i assume they are not thicker than 20cm (8 inches) because of the higher costs for the developer

Hello,

RoughRider schrieb:
...The roofing company told me to do it this way: .....
However, I am considering using boarding and possibly additional insulation above the rafters. That seems more reasonable to me.

I don’t fully understand the question 😕
There is an energy saving regulation certificate for this construction project! Therefore, the structure for the component "roof" should be clearly defined. Just take a look at the documents 😉
Of course, better solutions are always possible, but they must be properly executed.
In the case of the rafters, the insulation layer is about the "height," not the "thickness." For modern constructions, the height is determined less by structural requirements and more by heat transmission losses (insulation between rafters)! The costs for the roof can also be optimized.

Hopefully, the heating system sizing is not just as unplanned.

Best regards.

What do you mean by "without a plan"?

I already explained how it is specified in the documents...

==> The roofing company tells me to do it like this: underlay membranes, counter battens, then battens, and then the roof tiles... with the insulation between the rafters installed later.

I am also considering adding a sheathing made of wood-based panels...

The second option would be to install continuous insulation above the rafters and skip the insulation between the rafters altogether...

Hello,
there are many ways to achieve a good insulation value. You can use insulation between rafters or exterior (above-rafter) insulation. However, exterior insulation tends to be more expensive. If you have never done this yourself before, I would think it over carefully.

The sizing of the beams (beam height) and the properties of your insulation material (thermal conductivity class) are important.

How is it calculated in your structural design or energy performance certificate (thermal insulation calculation)?

Regards