ᐅ Underfloor heating installed over a vaulted ceiling with a low installation height
Created on: 24 Nov 2025 12:36
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HolzpaarWe bought a cavity wall house with a vaulted ceiling on the ground floor and basically gutted it to start fresh with a proper construction.
We want to install a hydronic underfloor heating system.
Now we plan to level the vault with Bituperl (loose fill) to about 10mm (0.4 inches) above the steel beams at the highest point.
After that, we have a maximum build-up height of 60mm (2.4 inches) before applying thin impact sound insulation and vinyl flooring.
Do you have any practical suggestions?
Best regards, Holzpaar
We want to install a hydronic underfloor heating system.
Now we plan to level the vault with Bituperl (loose fill) to about 10mm (0.4 inches) above the steel beams at the highest point.
After that, we have a maximum build-up height of 60mm (2.4 inches) before applying thin impact sound insulation and vinyl flooring.
Do you have any practical suggestions?
Best regards, Holzpaar
Hi,
with only 60 mm (2.4 inches), the available space is very tight, especially if you have an old vaulted ceiling that is probably far from perfectly level. Before making any decisions, have you had the load-bearing capacity and the maximum additional load of the vault checked? Some surprises only become apparent when it’s too late...
Using Bituperl as a leveling layer is fine, but for a water-based underfloor heating system, you either need an extremely low-profile system (studded or velcro panels of about 20–25 mm (0.8–1.0 inches) plus 20–25 mm (0.8–1.0 inches) of screed) or a dry construction system, which works more easily with limited height. Calcium sulfate or cement-based flowing screeds are basically ruled out at your height. A dry screed system with integrated underfloor heating would probably be the most practical combination, even though it may initially be more expensive.
with only 60 mm (2.4 inches), the available space is very tight, especially if you have an old vaulted ceiling that is probably far from perfectly level. Before making any decisions, have you had the load-bearing capacity and the maximum additional load of the vault checked? Some surprises only become apparent when it’s too late...
Using Bituperl as a leveling layer is fine, but for a water-based underfloor heating system, you either need an extremely low-profile system (studded or velcro panels of about 20–25 mm (0.8–1.0 inches) plus 20–25 mm (0.8–1.0 inches) of screed) or a dry construction system, which works more easily with limited height. Calcium sulfate or cement-based flowing screeds are basically ruled out at your height. A dry screed system with integrated underfloor heating would probably be the most practical combination, even though it may initially be more expensive.
@ "Holzpaar":
I fully agree with the suggestion from "Nauer." Given the existing construction height, I would also avoid installing a wet screed.
However, I would skip the impact sound insulation. Why install it if the building is owner-occupied?
What would make much more sense, especially if there is no heated room beneath the vault and/or only a compacted clay floor exists as the base, is a sheet-type waterproofing layer above the loose fill.
If thermal insulation is necessary (which I suspect), it should be installed best beneath the vault ceiling of the floor below (the cold side)!
For the further construction above the waterproofing layer:
There are floor system panels where the heating elements are clipped in; afterwards, the whole system is covered with a high-strength thin screed (all system-compliant), approximately 3mm (about 1/8 inch) above the highest points of the studs. With the available 60mm (about 2 3/8 inches) construction height, you should definitely be fine, leaving enough "space" for the flooring build-up.
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Best of luck: KlaRa
I fully agree with the suggestion from "Nauer." Given the existing construction height, I would also avoid installing a wet screed.
However, I would skip the impact sound insulation. Why install it if the building is owner-occupied?
What would make much more sense, especially if there is no heated room beneath the vault and/or only a compacted clay floor exists as the base, is a sheet-type waterproofing layer above the loose fill.
If thermal insulation is necessary (which I suspect), it should be installed best beneath the vault ceiling of the floor below (the cold side)!
For the further construction above the waterproofing layer:
There are floor system panels where the heating elements are clipped in; afterwards, the whole system is covered with a high-strength thin screed (all system-compliant), approximately 3mm (about 1/8 inch) above the highest points of the studs. With the available 60mm (about 2 3/8 inches) construction height, you should definitely be fine, leaving enough "space" for the flooring build-up.
----------------------------
Best of luck: KlaRa
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