ᐅ Attic Prepared for Conversion – Which Heating System to Choose?

Hello,

we are a family of four and have decided to buy a solid end-terrace house. Underfloor heating will be installed throughout the entire ground floor (except for the utility room) and first floor.
The heat generation will be provided by an air-to-water heat pump.

We have decided to have the attic prepared for finishing, which means a second spiral staircase, an upper hallway, and a door will be installed.

Two low-temperature radiators will be installed in the attic.

Intended use of the attic:
About 50% storage (due to the lack of a basement) and about 50% an occasionally used guest/hobby room.

Does it make sense to also install underfloor heating in the attic?
Personally, I am a bit reluctant. Underfloor heating responds quite slowly, so running it continuously in the attic seems questionable in terms of energy efficiency.

Are these low-temperature radiators suitable to heat the room quickly enough with the low supply temperature of the heat pump (around 35°C (95°F))?

Best regards from Berlin

Hello,

famke_ausb schrieb:

We have decided to prepare the attic for a conversion, meaning a second spiral staircase, upper hallway, and door will be installed.

Why isn’t the original staircase to the loft being continued?

famke_ausb schrieb:

Two low-temperature radiators will be installed in the attic.

What is the total size of the attic?

famke_ausb schrieb:

Purpose of the attic:
About 50:50 storage (due to the lack of a basement) and a seldom-used guest/hobby room.

A pure storage space does not require a radiator but definitely needs ventilation, especially if it is in the attic and that space is finished.

famke_ausb schrieb:

Does it make sense to install underfloor heating in the attic as well?

Primarily, this is a cost issue. If the same underfloor heating system as in the other floors is to be installed in the attic, a concrete slab above the upper floor is necessary. So far, a wooden beam ceiling is probably planned.

Alternatively, the heating “problem” could be solved with electrically operated underfloor heating if you want to avoid the significant cost of a concrete slab. For a space used only occasionally, this is worth considering.

famke_ausb schrieb:

Personally, I’m a bit reluctant. Underfloor heating reacts quite slowly. For that reason, running it constantly in the attic seems questionable from an energy perspective.

That’s a strange comment, especially since the ground floor and upper floor are supposed to be heated by underfloor heating, right?

famke_ausb schrieb:

Are these low-temperature radiators suitable to quickly heat the room with the heat pump’s low supply temperature (about 35°C (95°F))?

That’s exactly why they are called low-temperature radiators, as they are designed for connection to an underfloor heating system. If conventional radiators are to be installed, a mixing valve is required.

Fast or slow always depends on the situation. If guests are expected to stay in the attic, you will probably know in time to heat the room adequately.

Best regards, Bauexperte

@Bauexperte: You can also install a dry screed system with a water-based underfloor heating system, and in that case, you don’t need a concrete slab – as installed for an acquaintance.

Sebastian79 schrieb:
@Bauexperte: You can also install dry screed with a water-based underfloor heating system and then you don’t need a concrete slab – that’s how a friend of mine did it.

I’m aware of that, but it’s not exactly the best solution. However, it is sufficient for temporary use.

Regards, Bauexperte

Sound insulation is better with cement screed.

Regards, Bauexperte

Bauexperte schrieb:
And why isn’t the original staircase continued up to the attic?

I think I didn’t express myself clearly =)
The staircase will be extended directly to the attic, according to the additional agreement with staircase landing and door.

Bauexperte schrieb:
How large is the attic overall?

The usable area is about 52 m² (560 sq ft), the living area just under 31 m² (333 sq ft).

Bauexperte schrieb:
Primarily, it’s a cost issue. If the same underfloor heating installed on the other floors is planned for the attic, a concrete ceiling above the upper floor is needed. So far, a timber beam ceiling is probably planned.

That’s probably correct. I also think a timber beam ceiling will be installed for cost reasons. If underfloor heating is used, a concrete ceiling would be required.

Bauexperte schrieb:
Alternatively, the heating issue could be solved with an electric underfloor heating system if you want to avoid the significant cost of a concrete ceiling. Worth considering, especially if the space is only used occasionally.

Oh no, that would just add another electrical appliance to the household.

Bauexperte schrieb:
A strange statement; especially as the ground floor and upper floor are supposed to be heated with underfloor heating?

True, but the ground and upper floors are occupied around the clock. A constant temperature is maintained there.

Bauexperte schrieb:
Fast/slow is always relative. If guests are going to stay in the attic, in my opinion you’ll have enough time to heat the room properly.

That’s also true.
We will probably just stick with the two low-temperature radiators. That should be enough for occasional guests or whatever.

Thanks for the input