Standard duty Thermally Broken Lintels
Within the Catnic Thermally Broken Lintel (TBL) range, the steel lintels offered for standard duty loading conditions are suitable for uniformly distributed loads imposed by masonry, timber floors and roofs.
Catnic TBLs are designed to give equivalent load-bearing performance to ‘conventional’ steel lintels for masonry cavity walls, while delivering improved thermal efficiency and lower psi values. Nevertheless, structural openings should always be assessed on an individual basis and loadings calculated accordingly in case heavy duty lintels or extra heavy duty lintels are required instead.
To aid lintel specification, manufacturers produce safe working load (SWL) tables, giving the maximum loads for given lintel lengths.
Safe working load tables for standard duty TBLs
| TS90/100 | |||
|---|---|---|---|
| 90-105 mm Cavity. 100-115 mm inner leaf. | |||
| Standard lengths (mm) | SWL 1:1/3:1 (kN) | Weight (kg/m) | Nominal height (mm) |
| 750 - 1500 | 15 | 7.9 | 153 |
| 1650 - 1800 | 18 | 11.8 | 202 |
| 1950 - 2100 | 20 | 11.8 | 202 |
| 2250 - 2400 | 22 | 15.7 | 233 |
| 2550 - 2700 | 26 | 15.7 | 233 |
| 2850 - 3600 | 26 | 16.7 | 229* |
| TS110/100 | |||
|---|---|---|---|
| 110-125 mm Cavity. 100-115 mm inner leaf. | |||
| Standard lengths (mm) | SWL 1:1/3:1 (kN) | Weight (kg/m) | Nominal height (mm) |
| 750 - 1500 | 15 | 8.0 | 153 |
| 1650 - 1800 | 18 | 11.9 | 202 |
| 1950 - 2100 | 20 | 11.9 | 202 |
| 2250 - 2400 | 22 | 15.8 | 233 |
| 2550 - 2700 | 26 | 15.8 | 233 |
| 2850 - 3600 | 26 | 16.9 | 229* |
| TS130/100 | |||
|---|---|---|---|
| 130-145 mm Cavity. 100-115 mm inner leaf. | |||
| Standard lengths (mm) | SWL 1:1/3:1 (kN) | Weight (kg/m) | Nominal height (mm) |
| 750 - 1500 | 15 | 8.1 | 153 |
| 1650 - 1800 | 18 | 12.0 | 202 |
| 1950 - 2100 | 20 | 12.0 | 202 |
| 2250 - 2400 | 22 | 16.0 | 233 |
| 2550 - 2700 | 26 | 16.0 | 233 |
| 2850 - 3600 | 26 | 17.0 | 229* |
| TS150/100 | |||
|---|---|---|---|
| 150-165 mm Cavity. 100-115 mm inner leaf. | |||
| Standard lengths (mm) | SWL 1:1/3:1 (kN) | Weight (kg/m) | Nominal height (mm) |
| 750 - 1500 | 15 | 8.2 | 153 |
| 1650 - 1800 | 18 | 12.2 | 202 |
| 1950 - 2100 | 20 | 12.2 | 202 |
| 2250 - 2400 | 22 | 16.1 | 233 |
| 2550 - 2700 | 26 | 16.1 | 233 |
| 2850 - 3600 | 26 | 17.1 | 229* |
* channel to inner leaf
What is the load ratio shown in the standard duty SWL tables?
The loads imposed on masonry cavity walls are, generally, distributed unequally between the inner leaf and the outer leaf. As a result, they are referred to as ‘asymmetric loads’ and steel lintels for masonry cavity walls must be capable of bearing them.
The load imposed on the inner masonry skin is usually higher, and the difference is expressed as a ratio of the inner leaf load to outer leaf load. As the tables above show, a standard duty Catnic TBL is capable of bearing inner to outer load ratio between 1:1 and 3:1.
The 1:1 ratio refers to where the Thermally Broken Lintel is supporting masonry alone. The ratio increases to 3:1 when the lintel is carrying additional load on the inner leaf (timber floor and/or roof load).
Further information and advice on specifying Catnic TBLs is available from Catnic technical support.