ᐅ Insulating the Interior of a Detached Garage: Which Insulation and Vapor Barrier Materials to Use

Hello everyone,

This will be my first post in the forum, and I hope to get some helpful advice.

In short, I want to insulate the inside of my garage.

We built the house new in 2011. It is a detached single-family house. Since we don’t have a basement, the utility room with the heating system was placed inside the garage.
So, in this garage, there is the heat pump, the storage tank, and the utility connections such as telephone, electricity, and water. When the heating system was installed, a small radiator was also fitted in the garage to prevent the temperature from dropping below 0°C (32°F) in winter. After all, the water meter must not freeze.
Last winter, the temperature never dropped below 6°C (43°F) in the garage. However, last winter was not very cold overall.

I plan to insulate the garage from the inside during this year. It will not be used as a living space. I just want to gain a few degrees to protect the water connection from freezing in severe winter conditions. A few extra degrees will also benefit the heat pump and the storage tank. So far, I have not had any moisture problems there.

Now, about the garage. It is a prefabricated garage from Hundhausen.
The walls and ceiling are made of 7–10 cm (3–4 inches) reinforced concrete with a waterproof “Edelplastikputz” (special plastic plaster) exterior coating applied by rolling, and simple paint on the inside.
The roof is sealed with a bitumen/latex emulsion, which will probably be renewed by a professional in 5, or at the latest 10, years.

There is a double-walled sectional door installed, about 3 cm (1 inch) thick. I also want to cover a steel door on the side with Styrofoam from the inside.

I want to insulate the ceiling, one side wall (the other side wall is attached to the house), and the back wall where the door is installed. What is the best approach for that?

I am thinking of gluing 5 cm (2 inches) thick Styrofoam panels directly onto the wall. But I’m not sure if this might cause condensation to form. The garage has stayed dry so far.
Or should I rather build a frame using battens and then install mineral wool insulation with a vapor barrier?

Unfortunately, I don’t have much space at the ceiling because of the door, so the insulation there should not be thicker than 8 cm (3 inches) at most.

Do you have any suggestions on how I can best manage this?

Hello,

Eisenbeisz schrieb:
We built a new detached single-family house in 2011. Since we don’t have a basement, the utility room including the heating system was moved into the garage.
So now the heat pump, the storage tank, and the house connections such as telephone, electricity, and water are all located in the garage. When the heating system was installed, a small radiator was added in the garage to ensure the temperature doesn’t fall below 0°C (32°F) during winter. After all, the water meter must not freeze.
Last winter, the temperature in the garage did not drop below 6°C (43°F). However, last winter was not particularly cold.

I plan to add insulation to the inside of the garage later this year. It will not be used as living space...

I am quite confused...

In all our inquiries about installing house connections and technical equipment in a prefabricated garage, we were refused permission if the designated space was not insulated and fitted as living space. For this reason, prefabricated garages were not provided for such construction projects, but instead, masonry garages were built.

Was your building permit/planning permission approved without conditions, despite placing the utility/technical equipment in the prefabricated garage?

Kind regards

Yes, no building restrictions.
Since we stated directly in the building permit application / planning permission that the garage is heated (it is already heated by a panel radiator) and will also be insulated additionally.
And I am now taking on the insulation work myself.
In that sense, you could say that we imposed the "requirements" on ourselves.

By "not intended to be used as living space," I meant that we don’t plan to sleep or make ourselves comfortable there.

Hello,

Eisenbeisz schrieb:
Yes, no additional requirements ... In that sense, you could say we created the "requirements" ourselves.

Not exactly – the requirement for insulation would have applied anyway; it is standard practice by building authorities to treat spaces outside the main living areas, which are used for the heating system or technical equipment, basically like "living spaces." I think this makes sense even to a layperson.

Thank you for the reply! I’m relieved now again.

One more "curious" question: Was the supplier of the prefabricated garage so affordable all-in that adding insulation later was worthwhile, or why did you not plan a masonry garage from the beginning? From the figures I know, it seems that in the end you roughly break even, but with less effort and stress.

Kind regards

So, the prefabricated garage as it stands now cost about 4500 euros. Insulation will be added on top of that.

A masonry garage, fully insulated, was estimated by the builder at 15000 euros.
We then decided to go with the prefabricated option.

Maybe an idea:

Just isolate the affected area? Like a separate room inside the garage?