Tips/Insulation concept for my garage/attic renovation? Including sketch

Hello everyone!

Wonderful that this forum exists. So I'll just get started right away .

I have a wooden garage that is free-standing on every side. The garage is built as shown in the sketch. That means on the left there is a small annex directly connected to the garage room – thus making the 'original garage' larger. On top of that is a gable roof .... see sketch. The roof is directly connected to the garage room – so it is 'one big room' – there is no separate 'attic' dividing the garage into two rooms!

The goal: I want to be able to work in my garage in winter/autumn without freezing . That means the garage needs to be insulated. That's not a problem – I was thinking of using 100mm thick Neopor. The heat source would be a medium-sized stove with chamotte bricks.

Now the question:

Option 1: I leave the garage exactly as it is and insulate it completely: exterior walls + roof. Now I have an 84m³ room that I have to heat – the heat rises first under the roof and then slowly comes down.

Option 2: I build a classic attic floor – i.e. a floor that separates the roof from the garage room and then insulate this normally – so you would only have a 73.5m³ room to heat.

-> It is clear that option 2 is better in terms of energy! The air does not first 'pointlessly' collect under the roof + it gets warm faster -> But option 2 is also much more expensive because the attic floor has to be built first. So, with option 1, can you just say "Yeah, you just have to wait 5 minutes longer until it gets warm" or is the difference really significant? That means, is the installation of the attic floor worth it?

I am very grateful for any tips and especially experience!

Sketch:


Best regards!

Wait five minutes. Seriously, that is way too expensive for the purpose. Karsten

We built an insulated and heated garage directly (connected to the house gas, second high flow). The insulated floor slab is also important. In total, the ~35sqm garage cost us about 40,000 EUR.

If then, I would go with Var. 2. You also have nice storage space upstairs.

If then I would go with Var. 2. You also have nice storage space on top.

Sure, that's true of course! Maybe I should have specified my question a bit more: I'm purely interested in thermodynamics. So how does the effect improve through Variant 2? Maybe someone has a rule of thumb? Or can throw around a bit with physical quantities? Like how much more energy would be needed to basically heat the roof first and then the garage space, or how long would it take for the heat to move down.....

-> Unfortunately, the floor is not insulated - unfortunately! As mentioned, it's an old wooden garage......

Thanks and best regards!

Compared to the walls and the fittings of your garage, the air volume has only a low heat capacity. The air warms up quickly. Especially when heating up, there is stronger convection due to the initial temperature differences, meaning the warm air mixes more with the cold air, and the warm air does not remain "standing" at the top. On the other hand, with the roof space you also get more external surfaces, and especially the roof might be the least insulated.

I would generally advise against insulated garages. If you can get wood for heating cheaply, it probably isn’t worth it. The thermal insulation brings risks elsewhere, such as condensation in the summer.

We built a directly insulated and heated garage (connected to the house gas, second high supply). The floor slab being insulated is also important. In total, the ~35sqm garage cost us about 40,000 EUR.

With you, everything is always 30 or 50% more expensive than one would expect. We also paid that much, but our garage is significantly larger and also built with a double-shell construction with core insulation and facing brickwork.