4HAND is an authorized dealer and expert in the installation of Marbet’s Polish Warm Mounting Beam System (CBM).


Warm mounting beam – airtight installation for energy-efficient construction

Since 2021, the requirements for thermal insulation of partitions in residential buildings have increased significantly.

Marbet’s Warm Mounting Beam (CBM) is the best way to tightly install windows, meeting the highest requirements of investors.

Installation in the thermal insulation layer of the building (woodwork installed outside the face of the wall) is a method of installation that originated in passive construction and allows maximum reduction in the value of linear thermal bridges.

Proper quality of warm installation easily allows you to reduce heat loss and achieve significant savings in building maintenance costs!

Comprehensive solution

CBM is a thermo-insulating support frame – a new, extended jamb, which permanently connects the frame of the fenestration joinery with the existing wall.

In addition, in the case of a two-tier wall, it meets the requirements of NRO (non fire-spreading from the outside).

CBM maintains the excellent performance of the woodwork and guarantees a tight and warm installation for years.

Safe system

CBM is a system of steel bearing brackets and elastic complementary materials. It allows the highest classes of parameters to be achieved in terms of strength, airtightness and thermal activity of the constructed connections.

The system significantly reduces the risk of moisture and fungus within the window and eliminates the phenomenon of freezing. This has a significant impact on the comfort of use and the health of residents.

Easy to mount

CBM is an assembler-friendly system that allows contractors to offset the unevenness of walls and even out wall curvatures. It contains a number of improvements that facilitate the assembly – just like “building with bricks”.

Thanks to the CBM system, we can install any type of joinery – uPVC, aluminum, wood – from windows, doors, balcony windows to the largest HST sliding doors, in the insulation layer.

Economic and durable for years

CBM ensures a warm and airtight installation. Thus, it allows heat loss to be reduced and significant savings in the building’s maintenance costs to be gained – solutions confirmed by ageing tests.

It is the only system on the market with two National Technical Assessments from ITB and a certificate from the Passive House Institute in Darmstadt (Passive Building Institute), which guarantee the safety of use and the achievement of the parameters required for passive construction.


Characteristics of the CBM system

  • Possibility of architectural extension of the woodwork up to 20 cm from the face of the load-bearing wall (design, more efficient use of solar energy and better illumination of the object)
  • Design load capacity as high as 600 kgf/mb (installation in load-bearing masonry or foundation, total load capacity of 4 CBM beams with a length of 25 cm each with a unit load capacity of more than 150 kgf/piece).
  • Thermal conductivity coefficient λ ≤ 0.032 [W/mK] (most favorable course of isotherms at the frame-wall interface)
  • Temperature index fRsi with a range of achieved design results from ITB evaluations in the range of
    • 0.86 ≤ fRsi ≤ 0.93 appropriate for outdoor air temperature – 20°C
  • Air infiltration coefficient 0.03 < a < 0.05 [m3/(mhdaPa2/3)]
    (air infiltration results confirmed by ITB after aging; thermal and fatigue cycles)

    • with standard requirements according to PN-EN12114:2003 at a < 0.3 [m3/(mhdaPa2/3)]
    • with passive house requirements of a < 0.1 [m3/(mhdaPa2/3)]
  • Mechanical resistance to vertical force (racking) – CLASS 4 (800N) [that is, about ~80 kgf]
  • Mechanical resistance to static torsion – CLASS 4 (350N) [~35 kgf]
  • Wind load resistance – “safety” pressure P3 – resistance to wind speed pressure of 3000 Pa [300 gkf/m2] (equivalent to the passage of a devastating hurricane, blowing at speeds above 250 km/h)
  • Watertightness (resistance to the effects of rainwater) – CLASS 9A (600 Pa) [~60kgf/m2]
  • Fire safety – Class E – reaction to fire
  • NRO Fire classification (non fire-spreading system from the outside – a requirement in public buildings

Detailed information about the CBM system to download