What Is Lintel?
- The lintel is a horizontal flexural member that spans over the openings in the walls for doors, windows, ventilators, cupboards, etc.
- A load of masonry above the opening is transferred to the wall by flexural action of the lintel so that frames of doors, windows, etc. are not unduly loaded. The end bearings for the lintel should be at least 200 mm.
- The width of lintels is the same as that of the wall.
- Always provide adequate bearing at the ends of lintels. The manufacturer’s recommendations should be followed, but the usual hearing is 150mm (6″) each end.
- If you don’t give enough end bearing, the lintel will fail under load.
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Types of Lintel.
- Wood (Timber) Lintel
- Stone Lintel
- Brick Lintel
- R.C.C. Lintel
- Steel Lintel
- Reinforced Brick Lintel
- Precast Lintel
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Wood Lintel (Timber)
- Timber or wooden lintels are the oldest kinds of lintels and are commonly used in hilly terrain areas.
- These lintels are expensive, structurally weak, liable to decay, and vulnerable to fire. As per below fig. illustrates the application of a wooden lintel within the wall.
- Often wooden lintels are used along with mild steel plates at their top and bottom in order to strengthen the timber lintels.
- Good quality timber with some coating using suitable preservative is only used for lintel applications, and either end of these lintels are supported by mortar base on walls.
- It may be a single piece or may be assembled by joining 2 to 3 pieces.
- Sometimes the Tiber lintels are strengthened by steel plates at top and bottom. Such lintels are called as flitched beams
- These lintels are a type of stone slab with good length, width, and thickness.
- Stone lintels can also be used over openings within brick walls (as per below fig.).
- Generally, stone lintels are used in areas for construction, where the stone is easily available.
- As a stone is weak in tension they can be used only for small spans.
- Their depth is kept about 1/10 th span. Stones are cut to the width of the wall and dressed before using as lintels.
- Sometimes dressed stone lintels used in the buildings, which give a very good architectural appearance.
- Stone lintels are weak in tension and cracks easily when subjected to vibration loads. Thus the application of these lintels should be avoided in the seismically active areas.
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- Brick lintels are used to provide small openings with lighter loads.
- These lintels are not structurally very strong and consist of bricks placed on end or edges of piers or abutment or walls (as per below fig.).
- The depth of brick lintel depends on the span and is constructed over temporary wooden centering.
- The bricks along with frogs are suitable for lintel construction because the frogs when filled with mortar form joggles, increase the shear resistance of end joints.
- Brick lintels are built up with hard, well burnt, crack-free, sharp, and straight edges bricks.
- RCC has replaced practically all other materials for the lintel.
- RCC lintels are fire-proof, durable, strong, and easy to construct.
- The usual concrete mix used for lintel is 1:2:4. Plain concrete lintels can be used up to a span of 800 mm. The amount of reinforcement depends upon the span.
- RCC lintels can be cast-in-situ.RCC lintels are convenient for spans up to 2 m.
- Also, they increase the speed of construction and allow sufficient time for curing before fixing.
- The top of the lintel should be properly marked with tar or paint so that the lintel can be placed correctly.
- For cast-in-situ RCC lintels, centering is prepared, reinforcement is placed, and concreting is done.
- Sunshades can be easily projected from the lintels.
- Where appearance is not important, the surface of the RCC lintel is left exposed. As per below fig. shows a lintel over a wall.
Reinforced Cement Concrete Lintel
- Flexible DPC must be provided, and the toe of the lintel should be strong enough to bear the load of the wall above it.
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- One of the most common types of lintels in use today is the structural steel lintel or angle iron.
- The steel angle iron, which is shaped like the letter L, should have a thickness not less than 1/4″ and a width not less than 3W’ to support the standard 4″ masonry unit.
- Angle irons such as this one may be installed back to back when building an 8″ wall. Three angle irons are required to build a wall 12″ in thickness, as per below fig.
- There are some important items to remember when installing steel lintels over openings.
- The mason should consult the specifications on the job to determine the lintel bearing (the load which the lintel must bear).
- The lintel should bear a minimum of 4″ on each side of the opening on houses or small commercial buildings.
- Most angle irons have been cut from a larger piece of iron with a burning torch.
- This burning causes small beads of steel to form on the surface of the bottom and top portions of the angle iron.
- The beads should be removed from the irons with the brick hammer before installing them.
- The masonry units will not lay level over these rough welds.
- This is especially important if flashing is to be installed over the lintel, as the rough deads of steel may puncture the flashing.
- The lintel must be set plumb and level so that the unit which is laid on it is also in the proper position.
- It is also important that a steel lintel has rust protected paint.
- The steel lintel must be set back 3/8″ to1/2″ from the face of the wall so that a mortar joint may be formed in front of the steel without cracking, as per below fig. Never set the angle iron on the wall until the masonry unit under it has set sufficiently to avoid sinking.
Reinforced Brick Lintel
- When bricks lintel are required to be used over large spans, they are reinforced with steel bars.
- These lintels are constructed on the same principle as R.C.C lintels. the only difference being good quality bricks are used instead of concrete.
- The bricks are so arranged in parallel rows that at a 2 cm to 4 cm wide space is left lengthwise of inserting the reinforcement, i.e., steel bar or rods.
- These spaces with reinforcement are then filed or embedded with rich cement motor or cement concrete.
Reinforced Brick Lintel
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- Precast concrete lintels are affordable and supply strong support for structures like masonry over door and window openings.
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