Which underfloor heating boards to choose?
20, 25 or 30 mm?
Choosing the right thickness of an underfloor heating system board affects not only thermal insulation but also the overall floor build-up height. BEFIRO offers XPS boards in 20, 25 and 30 mm thicknesses, allowing you to select a solution that suits your project. All boards are made from durable XPS material and are designed for 16 mm heating pipes.
20 mm Boards – When Floor Height Matters
20 mm boards are particularly suitable for renovation and modernisation projects where every centimetre of floor height matters. They are a good choice when replacing an existing heating system or installing underfloor heating in rooms with limited available height. Their slim profile can help minimise the need to raise thresholds or modify doors.
Technical Specifications – 20 mm Boards
| Property | Specification |
| Dimensions | 1250 x 600 mm |
| Area per board | 0,75m² |
| Thickness | 20 mm |
| Pipe groove spacing | 10cm or 15cm |
| Compatible pipes | 16mm diameter |
| Material | Extruded polystyrene (XPS250) |
| Compressive strength CS(10) | ≥ 250 kPa |
| Declared thermal conductivity λD | 0,033 W/m·K |
| Thermal resistance Rd | 0,9 m²·K/W |
| Reaction to fire | Class E |
| Edge connection | Straight edge |
| Versions | With or without an aluminum foil layer |
25 mm Boards – A Versatile Choice for Most Projects
25 mm boards offer a balance between floor build-up height and thermal insulation. They are a suitable option for detached houses and apartments where good heating system efficiency is important without unnecessarily increasing the overall floor thickness. In many projects, this thickness provides a practical compromise between insulation performance and available installation space.
Technical Specifications – 25 mm Boards
| Property | Specification |
| Dimensions | 1250 x 600 mm |
| Area per board | 0,75m² |
| Thickness | 25 mm |
| Pipe groove spacing | 10cm or 15cm |
| Compatible pipes | 16mm diameter |
| Material | Extruded polystyrene (XPS250) |
| Compressive strength CS(10) | ≥ 250 kPa |
| Declared thermal conductivity λD | 0,033 W/m·K |
| Thermal resistance Rd | 0,9 m²·K/W |
| Reaction to fire | Class E |
| Edge connection | Straight edge |
| Versions | With or without an aluminum foil layer |
30 mm Boards – Enhanced Insulation and Thermal Comfort
30 mm boards provide the greatest insulation thickness among these three standard options available from BEFIRO. They are particularly suitable for ground-floor installations, floors above unheated spaces and other applications where reducing heat loss into the underlying structure is a priority. The increased insulation thickness can help direct more of the heating system’s energy towards the room rather than the substrate below.
Technical Specifications – 30 mm Boards
| Property | Specification |
| Dimensions | 1250 x 600 mm |
| Area per board | 0,75m² |
| Thickness | 30 mm |
| Pipe groove spacing | 10cm or 15cm |
| Compatible pipes | 16mm diameter |
| Material | Extruded polystyrene (XPS300) |
| Compressive strength CS(10) | ≥ 300 kPa |
| Declared thermal conductivity λD | 0,033 W/m·K |
| Thermal resistance Rd | 0,9 m²·K/W |
| Reaction to fire | Class E |
| Edge connection | Interlocking milled edge |
| Versions | With or without an aluminum foil layer |
When Should You Choose the Aluminium-Coated Version?
BEFIRO boards are also available in an aluminium-faced version with a 0.1 mm aluminium foil layer. The aluminium facing can help distribute heat across the board surface and is commonly used in dry underfloor heating systems. For projects where straightforward installation and effective heat distribution are priorities, this version is worth considering.
Summary
If keeping the floor build-up as low as possible is your main priority, consider 20 mm boards.
For many standard projects, 25 mm boards offer a practical balance between insulation and installation height.
For new buildings and applications where reducing heat loss is particularly important, 30 mm boards may be the preferred option.
The final choice should take into account the floor construction, available installation height and required thermal performance. Always ensure that the selected board thickness meets the project’s design and insulation requirements.