ᐅ Which level of finishing is appropriate for an attic reserved for future expansion?

Make sure to install the plaster on the gable ends right away. You’ll regret it if you don’t.

Can’t you have the underfloor heating installed now? It doesn’t have to be connected yet. Having two systems side by side could reduce the efficiency of the underfloor heating later on.

How are you handling the stairs? Are you leaving just an opening at first, or installing a full staircase immediately? If the latter, I’d suggest considering the railing placement in the upper floor plan so the railing isn’t too short or too long later on.

allstar83 schrieb:

and insulate the ceiling below

What exactly do you mean?

If you place the insulation ON the screed, you won’t have a proper floor again. If you put it under the screed onto the concrete slab, the thickness won’t meet the energy saving requirements. Installing it below the concrete slab in a suspended ceiling becomes a complex building physics challenge.

Once the screed is laid, you can/should also install underfloor heating right away. For an attic of about 40m² (430 ft²), that should hardly cost more than 1500€. Upgrading the heating system alone to run radiators (e.g., adding a mixing valve) will cost about the same, and the pipes and radiators themselves probably about the same amount again. Plus, you will have permanently higher heating costs. In short: financially, that would be a big mistake.

In the end, this approach only “saves” the extra costs that arise if you insulate the roof instead of the ceiling (which is a slightly larger area). But considering that the insulation both on top of the screed and below the ceiling also needs to be finished or covered, while insulation in the roof slope could remain exposed for now (with vapor barrier), and drywall could be done later as a DIY project after moving in, I just don’t see any real savings potential.

pffreestyler schrieb:

Can’t you have the underfloor heating installed now? It doesn’t have to be connected yet. Having two systems running side by side could later reduce the efficiency of the underfloor heating.

How are you handling the stairs? Just an opening at first or a full staircase? If the latter: I would plan the railing based on the upper floor layout, so the railing isn’t too short or too long later.

It’s possible, but any potential expansion (if it even happens) is still far in the future. It’s also somewhat a matter of budget.

We will have a proper staircase since we intend to use the attic floor as a basement equivalent—for storage and as a hobby space (e.g., rehearsal room, etc.).

Dr Hix schrieb:

What does this mean?

If you place the insulation ON the screed, you don't have a "proper floor" again. If you place it under the screed on the concrete slab, the thickness is not sufficient to meet the energy saving regulations.

Thanks for the hint.
That was the plan from the general contractor. However, the insulation was supposed to be thicker than usual. I will ask about it.

Walls built later will then rest on the screed, which is not ideal in terms of sound insulation.