Hello dear forum members,
The FMW ceramic underfloor heating system has been on the market for 30 years, but it seems it has not gained acceptance and appears to have stalled... or has it? So far, I haven’t found anyone who has heard of the FMW ceramic underfloor heating system, let alone installed it or had it installed...
The principle of this underfloor heating system sounds very interesting, but I see an obvious contradiction in the description: “It does not heat the entire screed like traditional systems, and due to the bricks used, this floor retains heat longer than conventional screed.”
Furthermore, the construction using dry fill without impact sound insulation, as described, seems quite daring to me. Perlite and similar materials do not have good impact sound insulation properties...
Also, using a wood fiber board as a base for the dry fill, as described there, is rather unusual, isn’t it?
Unfortunately, there are many examples of the best products not necessarily winning out in the market, and many good developments have come from Franconia... Could it be due to the price, the installation effort, or perhaps the company simply lacks proper distribution?
Many, many thanks for your experience reports or for connecting me with people who have successfully installed this system or have it installed in their homes...
Best regards
Maddin
The FMW ceramic underfloor heating system has been on the market for 30 years, but it seems it has not gained acceptance and appears to have stalled... or has it? So far, I haven’t found anyone who has heard of the FMW ceramic underfloor heating system, let alone installed it or had it installed...
The principle of this underfloor heating system sounds very interesting, but I see an obvious contradiction in the description: “It does not heat the entire screed like traditional systems, and due to the bricks used, this floor retains heat longer than conventional screed.”
Furthermore, the construction using dry fill without impact sound insulation, as described, seems quite daring to me. Perlite and similar materials do not have good impact sound insulation properties...
Also, using a wood fiber board as a base for the dry fill, as described there, is rather unusual, isn’t it?
Unfortunately, there are many examples of the best products not necessarily winning out in the market, and many good developments have come from Franconia... Could it be due to the price, the installation effort, or perhaps the company simply lacks proper distribution?
Many, many thanks for your experience reports or for connecting me with people who have successfully installed this system or have it installed in their homes...
Best regards
Maddin
I believe it never became popular due to the relatively complex installation process. After all, the effort required to create a flat and durable surface is significantly higher.
Ceramic is definitely excellent for heat storage – that is beyond question.
How is the insulation here handled? There should be insulation beneath the tiles to prevent warming the basement ceiling or similar areas.
I wouldn’t use loose fill for this either, since the tiles are relatively small and therefore don’t form a truly stable, load-bearing composite.
The connecting pieces don’t look sturdy enough to withstand high shear forces, especially since the material is quite brittle.
Ceramic is definitely excellent for heat storage – that is beyond question.
How is the insulation here handled? There should be insulation beneath the tiles to prevent warming the basement ceiling or similar areas.
I wouldn’t use loose fill for this either, since the tiles are relatively small and therefore don’t form a truly stable, load-bearing composite.
The connecting pieces don’t look sturdy enough to withstand high shear forces, especially since the material is quite brittle.
Hello Joerg24,
thank you for your comments. Here is the manufacturer's information: The FMW system blocks actually create a load-bearing, tile-ready subfloor when combined with the grout. This has often been doubted, including by architects, but it works unquestionably, partly because the tiles and the gaps between the blocks are filled with and bonded by the grout. After grouting, the individual tiles no longer move; instead, the entire floor acts as a composite structure. Since the FMW system is normally operated as a low-energy system at temperatures below 30°C (86°F), thermal expansion is no greater than on warm summer days. (Of course, the system can also be operated at higher temperatures without any issues.) The FMW system has already been installed on insulation made of mineral wool or horsehair. The only challenge during installation is when pressing down the tiles or during the grout pouring phase. After grouting, the system forms a load-bearing slab that compresses the insulation evenly over the entire surface up to a certain level. In 30 years, we have not had a single floor crack in any way. Even on large surfaces, no expansion joints are required in the top layer. This is due to the special installation pattern (herringbone pattern) of the FMW blocks. No stress concentrations can develop that would cause cracks in the subfloor—and therefore in the top layer—since the longest continuous joints are only 45 cm (18 inches) long. Floors of 300 m² (3,230 sq ft) and 550 m² (5,920 sq ft) have already been installed on one surface without expansion joints.
This is what our floor structures are planned to look like, and I appreciate critical feedback...
Living room (heated, secondary rooms):
Approx. 31 m² (334 sq ft), max. 7 cm (2.8 inches) available from raw floor level:
- 14 mm (0.55 inch) tile finish in thin-bed mortar
- 35 mm (1.4 inch) FMW ceramic underfloor heating system with 15x1 mm (0.6x0.04 inch) copper pipe
- 1 mm (0.04 inch) DELTA-REFLEX foil (aluminum facing upwards)
- 5 mm (0.2 inch) impact sound insulation (XPS heavy foam 35 kg/m³, 0.232 m²K/W)
- 20 mm (0.8 inch) ISOPERL/cement mix to level very uneven raw floor
- 12 cm (4.7 inch) reinforced concrete slab (existing on site)
Conservatory (5°C to 30°C, 41°F to 86°F, depending on outdoor temperature and sunlight, heated, bathroom, bedroom, office):
Approx. 28 m² (301 sq ft), max. 17 cm (6.7 inches) available from raw floor level...
- 14 mm (0.55 inch) tile finish in thin-bed mortar
- 35 mm (1.4 inch) FMW ceramic underfloor heating system with 15x1 mm (0.6x0.04 inch) copper pipe
- 1 mm (0.04 inch) DELTA-REFLEX foil (aluminum facing upwards)
- 100 mm (3.9 inch) polystyrene, PS 20 or PS 30 type
- 1 mm (0.04 inch) DELTA-REFLEX foil (aluminum facing downwards)
- 20 mm (0.8 inch) impact sound insulation
- 18 cm (7.1 inch) reinforced concrete slab (existing on site)
Are these floor constructions acceptable?
I welcome any suggestions or possible improvements!
thank you for your comments. Here is the manufacturer's information: The FMW system blocks actually create a load-bearing, tile-ready subfloor when combined with the grout. This has often been doubted, including by architects, but it works unquestionably, partly because the tiles and the gaps between the blocks are filled with and bonded by the grout. After grouting, the individual tiles no longer move; instead, the entire floor acts as a composite structure. Since the FMW system is normally operated as a low-energy system at temperatures below 30°C (86°F), thermal expansion is no greater than on warm summer days. (Of course, the system can also be operated at higher temperatures without any issues.) The FMW system has already been installed on insulation made of mineral wool or horsehair. The only challenge during installation is when pressing down the tiles or during the grout pouring phase. After grouting, the system forms a load-bearing slab that compresses the insulation evenly over the entire surface up to a certain level. In 30 years, we have not had a single floor crack in any way. Even on large surfaces, no expansion joints are required in the top layer. This is due to the special installation pattern (herringbone pattern) of the FMW blocks. No stress concentrations can develop that would cause cracks in the subfloor—and therefore in the top layer—since the longest continuous joints are only 45 cm (18 inches) long. Floors of 300 m² (3,230 sq ft) and 550 m² (5,920 sq ft) have already been installed on one surface without expansion joints.
This is what our floor structures are planned to look like, and I appreciate critical feedback...
Living room (heated, secondary rooms):
Approx. 31 m² (334 sq ft), max. 7 cm (2.8 inches) available from raw floor level:
- 14 mm (0.55 inch) tile finish in thin-bed mortar
- 35 mm (1.4 inch) FMW ceramic underfloor heating system with 15x1 mm (0.6x0.04 inch) copper pipe
- 1 mm (0.04 inch) DELTA-REFLEX foil (aluminum facing upwards)
- 5 mm (0.2 inch) impact sound insulation (XPS heavy foam 35 kg/m³, 0.232 m²K/W)
- 20 mm (0.8 inch) ISOPERL/cement mix to level very uneven raw floor
- 12 cm (4.7 inch) reinforced concrete slab (existing on site)
Conservatory (5°C to 30°C, 41°F to 86°F, depending on outdoor temperature and sunlight, heated, bathroom, bedroom, office):
Approx. 28 m² (301 sq ft), max. 17 cm (6.7 inches) available from raw floor level...
- 14 mm (0.55 inch) tile finish in thin-bed mortar
- 35 mm (1.4 inch) FMW ceramic underfloor heating system with 15x1 mm (0.6x0.04 inch) copper pipe
- 1 mm (0.04 inch) DELTA-REFLEX foil (aluminum facing upwards)
- 100 mm (3.9 inch) polystyrene, PS 20 or PS 30 type
- 1 mm (0.04 inch) DELTA-REFLEX foil (aluminum facing downwards)
- 20 mm (0.8 inch) impact sound insulation
- 18 cm (7.1 inch) reinforced concrete slab (existing on site)
Are these floor constructions acceptable?
I welcome any suggestions or possible improvements!
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