What is a lintel? A lintel is a structural support over an opening, allowing loads to be transferred to the foundations without unnecessary stress placed upon frames such as windows or doors. A lintel should have sufficient strength and stiffness and be made of a material that is compatible with the masonry it supports. Commonly, lintels are made from the following materials: Galvanised or stainless steel Reinforced or prestressed concrete Reinforced or prestressed masonry stone.
Often the specifications on the building plans will also state additional reinforcing measures such as steel rod through bed joints in subsequent courses of masonry above openings. This is to ensure that the masonry above becomes a solid mass, and adequately transfers load either side of the opening.
Lintels are lifted into position whilst constructing brickwork, which may be done manually or by assistance of a crane. Usually a small gap is left above a window or door frame, to ensure that the lintel is supporting the load, as well as allowing for minor movements such as settlement of foundations or swelling of the frame itself.
This is particularly applicable if timber frames are installed, as timber tends to swell or contract depending upon environmental factors such as moisture content or temperature. Steel Lintels should have a minimum of masonry mm high between the flange and the application level of any form of loading. When the underside of a lintel is exposed, its appearance can be enhanced by the addition of lintel soffit cladding. Do not cut lintels to length or modify them in any way without consulting an IG engineer.
Ensure lintel is level along its length. Lintel position within a cavity wall In accordance with BS EN and NHBC requirements all external wall lintels MUST be installed with a flexible damp proof course with the exception of those adequately protected by an eaves overhang or similar form of protection. Lintel should be centred in the cavity and the distance between lintel up-stand within the cavity and masonry must not exceed 10mm Masonry should not overhang any flange by more than 25mm.
Concrete floor units or other heavy components which bear on lintels should be positioned carefully to avoid damage or shock load. Also see:. Lintels, and supporting beams, shall be installed correctly, safely support the applied loads and be of the type and dimensions appropriate to their position within the structure. Issues to be taken into account include: thermal insulation and condensation durability and resistance to water entering the home placing lintels.
Minimum bearing length mm Span m Simple lintel Lintel combined with cavity tray Up to 1. Builders' Book - An illustrated guide to building energy efficient homes.
Builders' Book - An introductory guide to thermal bridging in homes. Technical Extra 04 - Cast stone. Technical Extra 04 - Good construction practice versus requirements for accessible thresholds. Technical Extra 06 - Residual cavities. Technical Extra 11 - Low-strength factory-made mortar.
Technical Extra 14 - Fixing of copings. Technical Extra 15 - Movement joints in external walls. Technical Extra 17 - Design and use of autoclaved aerated concrete masonry units.
Technical Extra 17 - Provision of weep holes and weep vents in masonry walls.
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