• Steel lintels for use in internal and external cavity wall construction to support walls, floors and roofs above window and door openings.
• Cavity widths greater than 50 mm or solid wall.
• Lintels should be installed with a minimum end bearing of 150 mm, bedded on mortar and levelled along its length and across its width.
• The masonry above the lintel should be built in accordance with BS EN 1996-2.
• Raise the inner and outer leaves simultaneously to avoid excessive eccentricity of loading, with a maximum height difference of 225 mm (masonry should be laid on a mortar bed and all perpendicular joints should be filled).
• Allow the mortar to cure before applying floor or roof loads (temporary propping beneath a steel lintel is practiced to facilitate speed of construction).
• NHBC & LABC recommend a damp proof course (DPC) or cavity tray should be installed over all openings in external cavity walls.
• When installing concrete floor units or other heavy components above a lintel, care should be taken to avoid shock loading and floor units should not be dragged into position. Masonry immediately above the lintel should be allowed to cure.
• Point loads should not be applied directly onto lintel flanges. Lintels should have a minimum of 150mm masonry between the flange and the application level of any form of loading. Consult Keystone’s Technical Department if applying a point load above a lintel.
• The external lintel flange must project beyond the window/door frame and it is recommended that a flexible sealing compound is used between the underside of the lintel flange and the frame.
• Do not cut lintels to length or modify them in any way without consulting a Keystone engineer. 
• Lintel should be centred in the cavity and the distance between lintel up-stand and masonry must not exceed 10 mm.
• Masonry should not overhang any flange by more than 25 mm. 
• The practice of propping a lintel is sometimes used to facilitate speed of construction. It should only be introduced after initial masonry load has been applied to the lintel. 
• Stop ends are required at each end of a lintel to prevent moisture cascading over the ends into the cavity and onto the inside wall.
• At least two weep vents are required per opening and positioned not more than 450 mm apart. 

All Keystone standard lintels satisfy the thermal performance requirements of Approved Document L of the Building Regulations (E & W), Northern Ireland’s Technical Booklet F and Scotland’s Technical Handbook, section 6. The Keystone patented Thermal Break Plate reduces thermal bridging while adding extra rigidity. Keystone lintels are insulated with expanded CFC-free profiled polystyrene insulation conforming to BS EN 13163. Provide a damp proof course / cavity tray over all lintels.

For more detailed information applicable to a particular wall construction, contact Keystone Lintels Technical Department. Refer to manufacturers literature for details regarding lintel ranges, height, thickness and Uniformly Distributed Load (UDL) figures.

Performance:

Fire:

• Keystone lintels have been subjected to a fire test (WARRES No. 101263) in accordance with BS 476-20 and (Report No. 508704/R) in accordance with BS EN 1363-1 at Exova Warrington Fire and achieved a one hour fire performance.

Corrosion:

• Keystone’s standard range of lintels are manufactured from high quality grade pre-galvanized mild steel to BS EN 10346 DX51D with a zinc coating of 600 g/m² (including both sides) conforming to BS EN 845-2. 
• The use of austenitic stainless steel is ideal when the life expectancy and maintenance programme of a building are key considerations. 
• Material / coating specification in buildings exceeding three storeys in a non-aggressive environment should be limited to austenitic stainless steel (chrome nickel alloys). 
• Material / coating specification for buildings in an aggressive environment (e.g. coastal sites) should be limited to austenitic stainless steel (molybdenum chrome nickel alloys). 

Structural:

• The Keystone lintel range has safe working loads as detailed in each applicable loading table in the Keystone Steel Lintel Manual.
• The structural performance figures within each table have been ascertained by testing in accordance with the requirements of standards BS EN 5977-2, BS EN 846-9 and BS EN 845-2.

Certification:

• BBA Agrement certificate 98/3493 including regular assessment of production.
• UKCA Assessment of performance, System 3.
• CE Assessment of performance, System 3.
• EN 1090-2 Execution Class 2, Declaration method 1,2,3a & 3b, Certificate 14/F106 & 14/F107.
• ISO 9001 Quality Management Systems, Certificate 18/Q059.
• ISO 14001 Environmental Management Systems, Certificate 18/E019.

Special lintels:

Keystone lintels can be supplied to suit a wide range of wall types, loading scenarios and bespoke custom made specials:

• Arch lintels,
• Bay lintels (square or splayed),
• Corner lintels,
• Bow lintels,
• Sunlounge lintels.

Contact Keystone Lintels Technical Department for further information.

Stainless steel:

• All Keystone’s range of lintels can be manufactured from austenitic stainless steel, grade 304 2b BS EN 10088-Part 2 Astm 240 (European Grade 1.4307). Upon request, other grades of stainless steel lintels are available conforming to BS EN 845-2.

Additional features:

• Free scheduling and specification service.
• Keystone Steel lintels have a service life commensurate with that of the building in which they are installed.
• Keying options to suit required plastering applications.
• Eaves lintel.
• Feature plate.
• Cant brick.
• Stepped.
• Powder coating.
• Soffit cladding.
• Brick slip cladding.
• Universal arch.
• Roller shutter.
• Weep holes.
• Stop ends.
• Bespoke.

Contact Keystone Lintels Technical Department for further information.