Insulate roof

[Pappa1986]

Hey hop.

In the next project phase, we will convert the deck into a dining room.
In doing so, we need to insulate the ceiling.
Today, it's truss, felt, battens, and sheet metal.

I'm thinking like this. (from the inside out)
Drywall
Furring strips
Vapor barrier
Truss.
Then I attach battens at the top of all the trusses where I then place masonite, or is there something else? Thinking it might sag?
Then I've created an air gap.
Insulation between each bay, what type of insulation should be used, and how much should there be?
Sheathing.
Felt, battens, batten tiles, or whatever we choose to have.

What I'm thinking is if it can be done in another way? I want as much insulation as possible, and today there are maybe 25 cm wide trusses, so I'll have room for 20 cm insulation.

Feel free to share some ideas

 

[kulle]

Today it is roof truss, felt, battens, and sheet metal.

Tongue and groove boards that the felt lies on?
You can also put a batten in the middle then, which supports the masonite for the air gap.

Edit: I now see that you were also planning to replace the outer roof

 

[Pappa1986]

Boards that the roofing felt is on?
You can also put a batten in the middle in that case to support the hardboard for the air gap.

Edit: I saw now that you are also planning to replace the outer roof

When we think about insulation. Is glass wool or rock wool better? Is 20 cm enough?

 

[kulle]

I prefer glass wool if it is to be insulated in the ceiling from underneath. 20 may be enough but be careful to seal the air gap so there are no air movements in the insulation.

 

[Pappa1986]

I prefer fiberglass if insulating a ceiling from below. 20 may be enough, but be sure to make the air gap tight so there are no air movements in the insulation

Great, many thanks