ᐅ Rooms cold on the floor – is insulating the basement ceiling a good idea?

Our living room (ground floor) feels extremely cold underfoot. Even after heating for hours (standard radiator), your feet still feel cold—the floor temperature measured with an infrared thermometer is between 17 and 18°C (63 and 64°F).
The basement room below has a temperature of about 13°C (55°F), and the basement ceiling is bare concrete.
My question is: Would insulating the basement ceiling help? If so, what materials would you recommend?
Regards,
N

1. I assume the basement is unheated?
2. Is there open access to the basement, or is it closed off with stairs and a door?
3. What is the ceiling height in the basement?

Insulating the basement ceiling is one of the energy retrofit measures with the best cost-performance ratio.
Depending on the ceiling height in the basement, you can use various materials. I would recommend aluminum-coated PIR insulation and simply glue it to the ceiling (there are special adhesive foams for this). You can also use all other common materials (which may be cheaper but offer less insulation) and glue them to the ceiling, such as EPS, XPS, or wood fiber insulation.

In terms of cost, for a typical single-family house, you should be well below 1,000,000 euros (approximately 1,000,000 USD).

Thanks for the quick reply!
- Yes, the basement is unheated.
- Open access directly through the stairwell
- Ceiling height approximately 2.15m (7 ft)
These PUR panels come in a wide range of thicknesses. How do you determine which one is suitable for your specific purpose?

This can theoretically be calculated. For simplicity, I would suggest using two layers of 50mm (2 inches) insulation, applying one layer lengthwise and the other crosswise. Although it requires more effort, this way you reduce thermal bridges.

Nanopixel schrieb:

- open access directly through the staircase

That’s obviously inconvenient since a lot of energy is lost. But it can’t be changed.

Nanopixel schrieb:

These PUR boards come in endless thicknesses. How do you determine which one is right for your purpose?

You can do some calculations. Another question is what might already be installed under your screed.
In my renovation, 2cm (0.8 inches) PUR below the underfloor heating and 10cm (4 inches) PUR under the basement ceiling provided insulation performance comparable to a KfW 55 new build. Whether you need that is another question, but from around 50mm (2 inches) thickness upward, a noticeable improvement should be possible based on experience.

Just to avoid any misunderstandings, the basement access is indeed open, but the room we’re talking about here (under the cold-floor living room) is of course fitted with a door ;-)

This raises a question regarding the implementation: In this room (storage area), there are large wooden shelves that reach up to the ceiling and are fastened there. I assume it would be better to modify those rather than stick panels around them?

As for the living room: If the floor covering is ever replaced (currently an aging parquet), is it possible to install insulation underneath, even if you can’t allow an additional 2cm (about 0.8 inches) in height?