ᐅ Insulation for Garage: Glass Wool, OSB Board, Vapor Barrier, Thermal Insulation

Hello,

we have had a timber frame garage built.

It consists of prefabricated timber studs measuring 8 x 8 cm (3 x 3 inches).
On the outside, an 18 mm (3/4 inch) thick OSB board is attached, which has been plastered.

Now I want to insulate the interior.

I was thinking of putting 80 mm (3 inches) of glass wool insulation between the studs and simply screwing another OSB board on top.

Or should I also include a vapor barrier?

I would appreciate any other suggestions or advice.

Hello,

Is the garage already assembled? OSB on the outside? Will the plaster hold there?
I wouldn’t have thought of that.

Usually, the OSB board is installed on the inside, in the weather-protected area. Relying solely on plaster as weather protection seems risky to me.
If you have an insulated wall, it needs to become more vapor-permeable from inside to outside. Unfortunately, OSB is not vapor-permeable; besides providing structural support, it also acts as a vapor barrier. Therefore: OSB board on the inside and a vapor-permeable plaster base board on the outside.

Regards