Technical Support

Thermal Performance

Building regulations require that lintels should be assessed for their effect on the thermal performance of a building. A lintels thermal performance is expressed in terms of Psi Values (ψ) i.e. linear thermal transmittance.

Therm Performance

Standard IG Lintel

All IG standard steel lintels satisfy the Thermal Performance requirements of England and Wales’s Part L of the building regulations, Northern Ireland’s Part F and Scotland’s Technical Handbook, section 6.
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Our standard L1 range has Psi values ranging from 0.2 to 0.3 W/m.k. The exact figure of your Psi value depends upon the wall construction the lintel is built in to. For more detailed information on Psi values applicable to your wall construction or for more information on accredited construction details please contact IG’s technical team.

Hi-Therm Lintel

IG’s Hi-Therm Lintel is a combination of Glass Reinforced Plastic (GRP) and Glavanised Steel. When combined these two materials form the ultimate in lintel design – Psi 0.05 W/m.K

Hi-Therm Lintel Technical Information

Outstanding Advantages

  • Outperforms all other cavity wall lintels for Thermal Performance. GRP has very low thermal conductivity
    which practically eliminates cold bridging.
  • Outperforms Stainless steel and Galvanised steel for corrosion resistance. The GRP outer flange, quite simply, will never corrode.
  • Outperforms stainless steel in price. GRP is more competitively priced than stainless steel.
  • DPC is not required* The GRP outer flange does not require the installation of a Damp Proof Course/ Cavity Tray. – ( * up to severe exposure )

Building regulations require that lintels should be assessed for their effect on the thermal performance of a building. A lintels thermal performance is expressed in terms of Psi Values (ψ) i.e. linear thermal transmittance.

Psi Comparison Chart

To help understand the immense thermal benefits of the Hi-Therm Lintel it must be compared to other lintel types.

Psi Comparison Chart

Testing of IG’s Hi-Therm Lintel was carried out by the BRE (Building Research Establishment) using Physibel’s thermal analysis software TRISCO which complies with BS EN ISO 10211-1. The modeling follows the requirements of the BRE conventions document BR497.

Hi Therm Lintel Technical Information

Structural Performance

The IG lintel range has safe working loads as detailed in each applicable loading table, please see section “Standard Lintels”. The structural performance figures within each table have been ascertained by testing in accordance with the requirements of BS 5977 Part 2 1983 and BS EN 845-2:2003.

The figures take into account the different loading arrangements that are common to traditional cavity wall construction.

Differential Load Ratio 3:1
Up to 75% loading on the inner leaf.
Differential Load Ratio 19:1
Up to 95% loading on the inner leaf.

How to interpret load tables and select the correct lintel

For detailed information on how to interpret our load tables and select a lintel, please see “How to Select a Lintel”.

Lintel Load Tables

For full details of load tables specific to your lintel type please see section “Standard Lintels”.

British Board or Agrement (BBA)Lintel types: L1/S 50, L1/S 75, L1/S 100, L1/HD 50, L1/HD 75, L1/HD 100, L1/S 50 WIL 215, L1/S 75 WIL 215, L1/S 100 WIL 215, L1/S 110, L1/S 130, L1/S 150, L10, L7, L11, L8/RB, L1/TJ, INT 100, L9, IBEAM, L1/E 50, L1/E 100, L5, L6 have been tested as a composite unit with surrounding masonry, built in accordance with BS EN 1996-2:2006.

Stainless Steel Close Up

Fire Testing

Fire Testing

Exova WarringtonfireAn IG lintel has been subjected to a fire test (ref: WARRES No. 101263) in accordance with BS 476:Part20: 1987, at Exova Warringtonfire and achieved a one hour fire performance.

If longer fire rating figures are required they can be achieved by applying a proprietary fire board to the soffit of the inner flange of the steel lintel. Please contact our technical team if further fire rating provisions are required.

Corrosion Resistance

IG lintels are manufactured from high quality grade pre-galvanised mild steel with a zinc coating of 600 g/m² (including both sides).

The “hot dipped, pre-galvanising” process is carried out at the mill to ensure a more consistent quality of zinc coating. This guarantees a more effective anti-corrosive system. Furthermore pre-galvanised lintels are much more “environmentally friendly” than post galvanised lintels.

Lintel Life Span

The IG lintel range complies with the technical requirements of the BLP (Building Life Plans) regarding the durability data of mild steel, cold formed lintels.

Building Defects Insurance The service life of IG lintels, when installed with a flexible DPC, will be the same as that anticipated for the building.

Lintels supplied by IG, almost 60 years ago, continue to perform without maintenance. A tested and proven track record.