ᐅ Removable roof insulation

Dear Insulation Experts,

I’m new here and facing my first major project:

Together with some friends, we want to buy and make habitable three old barns (so-called Rustici) in southern Switzerland. Both the shell and the roofs of these Rustici are made exclusively of gneiss slabs. These roofs are extremely durable and stable, but a few displaced stones can cause leaks. There are only a few specialized roofers left who know how to work with these roofs, but they can make them watertight again by carefully repositioning the stones. To do this, they must be able to access the roof from the inside.

This brings me to our challenge: we want to insulate the roof from the inside, but with a construction that can be relatively easily removed (in case any leaks occur).

I’m very grateful for your ideas. Here’s what I have in mind:

- Place insulation mats between the rafters, directly under the gneiss slabs, then screw OSB boards onto the rafters (also serving as vapor barriers).

- Even neater would be to attach the insulation material directly onto the OSB boards, allowing the whole construction to be removed at once. Which insulation material would you recommend for that?

What do you think of this idea? As I said, I’m not an expert and would really appreciate any advice!

Best regards

Since rustic-style homes seem to be a big topic in Switzerland, I would recommend finding an experienced planner/architect and roofer there. They will definitely have tested and approved concepts available. Anything else is likely to go wrong, especially a solution that is already based on the premise that it won’t work.

Hello Lumpi,
We definitely need an experienced roofer—whether it’s to maintain the roof (i.e., keep it watertight) or to completely re-roof it.
We also have an architect. However, he would only design a project that involves fully stripping the roof and installing a fixed underlayment structure. He said that while some improvisation is possible, he would not design it due to legal reasons.
We could also consider re-roofing completely, but from our point of view, that does not fully solve the problem: we might have about 20 years of peace, but after that, we could still face the issue of the roof no longer being watertight and needing a fixed underlayment.
I’m not expecting any perfect solutions from the community now, but mainly ideas on how to approach the described option. Of course, we would then discuss these further with roofers and architects.

What do you mean by “solutions that don’t work”? Or, what could go wrong?
- The underlayment doesn’t insulate as expected
- Insulation develops mold due to condensation?

What I mean is that the basis of your planning assumes that the roof will eventually leak and everything will have to be torn out again. I wouldn’t plan a house that way.

Your architect agrees: "for legal reasons..." simply means he believes it won’t work and doesn’t want to be liable for the expected damages.

The roof eventually becomes leaky because it is made of "movable tiles" and it easily exceeds the typical lifespan of modern roofs.
The basis of my planning is not that everything has to be torn out when it becomes leaky, but that the underlayment can be removed, the issue fixed, and the underlayment replaced.
If we were to completely rebuild it, we would still have to use natural stone (as required by regulations) and would face the same problem eventually. I understand your point, but I want to plan as far ahead as possible.

What happens if a brick shifts slightly, the roof starts leaking, and you don’t notice? Then the entire insulation is ruined and rot sets in.
Only a professional can give you good advice in this situation.