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Armatherm Fabric Reinforced Resin (FRR) thermal break pads deliver high performance thermal insulation between interior and exterior steelwork or concrete to prevent thermal bridging. Cutting out thermal bridging stops conduction heat loss and prevents surface condensation from forming inside the building that can be due to cold transfer meeting warm air. The product has been independently evaluated and approved by the Steel Construction Institute (SCI) and the National House Builders Council (NHBC).

Armatherm™ FRR structural thermal break material can be used directly behind the masonry shelf angle as a thermal break within the insulating layer. The Armatherm™ thermal break significantly reduces the linear transmittance (heat loss) of the shelf angle connection. Rigid, metal flashing used as waterproofing can also be replaced with a non-conductive, self-adhered membrane to reduce the effects of thermal bridging further.

Masonry veneer walls require tie-backs and shelf angles which form significant thermal bridges and can reduce a walls’ R value by as much as 50% making it difficult to meet energy codes. Shelf angles transfer the masonry load back to the buildings’ structural steel or concrete slab edge interrupting the continuous insulation of the wall assembly creating a linear thermal bridge.

Performance (scenarios):

- Continuous Steel Shelf Angle:

  • Exterior + cavity insulation 1D R-value: R-15 + R-12 (2.64 + 2.11 m²K/W).
  • Clear wall R-value: R-19.8 (3.48 m²K/W).
  • U-value: 0.101 (0.58 m²K/W).
  • R-value (effective) with shelf angle: R-9.9 (1.74 m²K/W).
  • U-value (effective): 0.101 (0.58 m²K/W).
  • Linear transmittance of shelf angle: 0.314 (0.544 m²K/W).
  • Reduction in heat loss: n/a.

- Steel Shelf Angle with 1" Armatherm FRR with washer, bushing and S.A.M.:

  • Exterior + cavity insulation 1D R-value: R-15 + R-12 (2.64 + 2.11 m²K/W).
  • Clear wall R-value: R-19.8 (3.48 m²K/W).
  • U-value: 0.072 (0.41 m²K/W).
  • R-value (effective) with shelf angle: R-13.8 (2.43 m²K/W).
  • U-value (effective): 0.072 (0.41 m²K/W).
  • Linear transmittance of shelf angle: 0.135 (0.234 m²K/W).
  • Reduction in heat loss: 57%.

General information
Specification data
Product Reference

Armatherm™ Grade FRR Masonry Shelf Angle


6 mm

10 mm

13 mm

15 mm

20 mm

25 mm

50 mm




Insert size; M12, M16, M20 and M24 available.


Insert size; M12, M16, M20 and M24 available.

Standard product features

Technical characteristics:

  • Ultimate loading pressure: 290 N/mm².
  • Strain at maximum pressure: 5%.
  • Compressive modulus: 4640 N/mm².
  • Shear strength: 110 N/mm².
  • Surface Burning Characteristics: ASTM E84.
  • Flame spread: 25 (class A).
  • Smoke-developed: 50 (class A).
  • Density: 1350 kg/m³.
  • Thermal conductivity: 0.30 W/m×K. (For comparison, the thermal conductivity of carbon steel is 56 W/m·K).
  • Operating temperature: -51°C to + 90°C.

Product Options


Custom thicknesses available on request.


- Bushing and washers:

  • With a bolt-through insulation pad, there is the possibility of a slight thermal transfer along the connecting bolt. This effect can be reduced with the addition of insulation washers and bushing. Thermal modelling has demonstrated an improvement of 5% in energy transfer by using bushing and washers.
  • In extreme applications (e.g. swimming pools), to prevent condensation on the bolt head, a polyurethane nut cap can be supplied to effectively screen this cold surface from the internal environment.
  • Thermal breaking, bushes and washers are installed on the warm face of the connection.

Third party certifications
  • SCI : (Steel Construction Institute)
  • NHBC : (National House Builders Association)
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