Planning of a roof renovation from 1963

Proposal Isover, U=0.197



Hello everyone,

I recently purchased a house from 1963 and now want to insulate the roof structure. (currently no insulation, only plastered bamboo mats)

The roof construction consists of rafters measuring 130x100mm, with a cross battens and concrete tiles on top.

Step 1: (currently -> goal: Energy Saving Ordinance)
- Insulation between rafters
- Insulation below rafters
- Interior drywall

Step 2: (in 3 years)
- Insulation above rafters (alternative to roof sheathing)
- Replacement of roof tiles

Current limitations:
- Due to the ceiling height in the 1st floor living area, rafter doubling is not possible (length of roof slope: 2.20m)
- In the attic, rafter doubling would generally be possible (length of attic beam to ridge: 3.10m)
- Thus, insulation between rafters max. 120mm with 10mm ventilation gap to cross battens/tiles

Current questions:
- I have planned ISOVER as insulation material according to the manufacturer's proposal - are there alternatives? (better, cheaper)
- Does anyone have experience with the variable vapor barrier "ISOVER Vario KM Duplex UV"? Alternatives? (better, cheaper)
- Can the insulation below rafters also be done with Styrofoam? Reason: cheaper and easier to install

I have already planned the setup on u-wert.net as described above - what do you think about it?

Thank you very much in advance for your effort,
Feder

I would ask the local building materials dealer which manufacturer they carry. I just bought the material from Knauf and URSA cheaper than Isover. But that always depends on the dealers.

I do not consider Styrofoam easier to install since the cutting effort will be quite high. In addition, Styrofoam also has a poor sound insulation value. This material therefore seems rather unsuitable to me. If you want to implement an above-roof insulation later, why then an internal insulation?

Hello,

thank you very much in advance for the answers.
From a cost perspective, Isover currently seems to me to be the most affordable option.

What raises the biggest questions for me at the moment is the connection to the roof tile level. Is the planned ventilation gap of only 10mm without a sub-roof structure sufficient there, or does a sealing against external influences still need to be applied?

A roof insulation is only planned to take place in Step2 with the planned renewal of the roof covering - this may still be delayed for some time. Since I need a cross battens and an installation level anyway for the ceiling construction with gypsum boards, I can just insulate these accordingly right away.

Best regards

Are you aware that foil and adhesive tapes do not last forever? Then moisture enters the thermal insulation. Do you have information from manufacturers about the service life?

Jochen

So commercially available films will certainly last a few decades. Weak points are certainly adhesive tapes and adhesives. However, one should be aware that such insulation basically is no longer modern after 20-30 years, or that after this period a renovation/replacement may simply be necessary. Especially when it comes to the roof. Hardly anyone probably expects it to last 100 years, and even if it would last that long, you would probably take it out beforehand and replace it with something new. I hardly know any houses and apartments where nothing has been done for 50 years or more and everyone is still satisfied.