Install roll felt / blanket felt in the attic

Hello forum readers,

I plan to cover the unused attic with a roll felt or blanket felt to achieve better insulation in winter and summer.
I did some research and came across this page on the web, among others:

[MEDIA=YouTube]yB2dFg8uFvs[/MEDIA]

In it, you can quite well see how the matter should be approached and laid. Since the video apparently comes directly from ISOVER, I simply assume that everything is correct as described.
My questions:

[*]Has anyone had good/bad experiences using these materials and can recommend or advise against it?

[*]Does the insulation bring the hoped-for improvements regarding heating cost savings and insulation?

[*]What thickness of insulation material would you recommend? Area approx. 80 sqm; year of construction approx. 1965; otherwise, it really looks like in the video in my case

[*]To what extent can costs be saved when purchasing the materials? Does anyone know a good and inexpensive building materials dealer where you can order online and that delivers reliably?

[*]The installation does not seem to require any special knowledge. I would install it together with a neighboring craftsman from the construction trade. Do you have any other tips and recommendations?

I am grateful for any tips and further information!

Regards

Hi, according to official statistics, this is a very profitable measure. To achieve the current insulation level, you should choose at least 16 cm insulation thickness.

I would be cautious with the vapor barrier foil underneath – the result can either improve or cause a mold problem, depending on what kind of ceiling you have underneath. Better have an independent energy consultant take another look. Check the [BAFA list].

You can also simply roll out the insulation material without foil and nothing on top, so that any moisture vapor that occurs can escape.

If you also want it cooler in summer, light materials are not optimal, then look among natural insulation materials (wood fiberboards) or recycled: cellulose = newspaper flakes.

One more tip: if you apply 24 cm insulation thickness, you will probably reach the funding level of the [KfW] and can get a 10% investment grant – you need to calculate that in relation to the additional costs. You also file the application through an energy consultant – this time only those from the [Energy Efficiency Experts list].

Happy working
Susanne Junghans