Lintels

Steel Lintels - Keystone

Keystone Lintels Limited, the leading manufacturer of steel lintels was founded in 1989.  The short history of Keystone has been one of relentless expansion and continuous innovation whist redefining the meaning of service in the lintel industry.

Material
Keystone Lintels are manufactured from Z1 grade galvanised steel to BS 2989: 1982 (BS EN 10327: 2004) with a zinc coating type G600 (H3) giving a minimum zinc coating of 600g/m2 (including both sides). In accordance with BS5977: part 2, 1983 (BS EN 845-2: 2003) all cut edges are treated with a corrosion resistant paint.

Insulation

The Keystone Lintel core is entirely filled with ‘CFC free’ insulation, which completely fills all voids in the lintel, particularly at the apex ensuring continuity with wall insulation and reducing cold bridge effect in this area. This ensures that the Keystone Lintel range is one of the most thermally efficient lintels available with a thermal conductivity of 0.033 W/mk.

Quality

Keystone Lintels are manufactured to the highest quality and are continually assessed by the BSI to ensure our quality assurance systems comply with BS EN ISO 9002: 1994. The ‘Keystone People’ are also a highly trained and motivated workforce. Our manufacturing premises have been approved as a N.V.Q. Training Centre and the company has also received the Investors In People Accreditation.

Structual Performance

The Keystone Lintel range have safe working loads shown in each applicable loading table, taking into account the differential loading arrangements which are common to traditional cavity wall construction.

Differential Load 3:1 ratio, 75% load on inner leaf.
Differential Load 19:1 ratio, 95% load on inner leaf.

Lintel Types HD/K, S/K-50 (215WIL), S/K-70 (215WIL), SK-90 (215WIL), S/K-110, S/K-130, S/K-150, SB/K, T/K, SL/K, RB/K, TJ/K, TW/K, INT/K, SW/K, IB/K, EL/K-50, EL/K-90, CFS/K, X/K have been tested as a composite unit with surrounding masonry, built in accordance with BS5628. These composite units have been tested in accordance with the requirements of BS5977: part 2 1983.

Testing

BBA – Extensive testing has been carried out on the Keystone range of lintels. The lintel testing procedure and Agrément Board assessment is carried out under the direct supervision of Dr. David O’Connor BSc, C.Eng, MIStrut E, MICE, Lecturer, Dept of C. Eng, University of Ulster.

Fire Test – The Keystone S/K lintel range has been subjected to fire tests at the Warrington Fire Research Station and has achieved a one hour fire certificate by successfully supporting their imposed load for 48 hours after the tests.

Durability – The service life of lintels shall be the same as that anticipated for the building within which they are used, when used in conjunction with a flexible D.P.C. and where the normal humidity and condensation levels of a habitable building exist. The Keystone Lintel range complies with the technical requirements of the Housing Association Property Mutual (HAPM) with appropriate adjustment factors.

Installation

Lintels should be installed with a minimum end bearing of 150mm bedded in mortar,
levelled along its length and across its width. With cavity walls, both leaves should be raised together to avoid excessive eccentricity of loading and be allowed to cure before applying floor or roof loads. Blockwork is permitted to overhang the lintel flange by a maximum of 25mm. Point loads and concrete floor units should not be applied without prior consultation with our Technical Department or a Structural Engineer.

Care should also be exercised in the selection of lintels for each application with regard
to wall construction, cavity width and loads applied.

COSHH – All components and materials in our products are considered as non-hazardous to health under normal conditions of use as determined by COSHH Regulations 1994.

Due care should be taken when lifting and handling lintels with regard to weights. A table of weights for individual lintel types is available on request. For further information contact our Technical Department.

A cavity tray should be installed over all openings in external cavity walls.

Please refer to pages 16 & 17 of our Lintels & Brickwork Accessories Product Catalogue & Price Guide or contact your local branch for further information.

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