Types of Openings in Walls, its Parts, and Types of Lintels

 Types of Openings in Walls, its Parts, and Types of Lintels

Types of openings in walls, its parts, and types of lintels and arches for openings about the stability and strength of the wall is discussed. The size of openings (windows and doors) in both solid walls and cavity walls are restricted by regulations for the sake of stability and strength of the wall.

Openings in Walls and its Parts

The different parts of the openings in walls such as opening head and jambs of openings and their limitations to preserve the stability and strength of the wall will be discussed and explained in the following sections.

Rebated jambs

Head of openings in solid walls

Jambs of Openings

In solid walls, windows, and doors opening jambs can be either rebated or plain.

The latter is employed for small section windows and door frame that is made from steel. It can be used for large sections where the entire external face of frames is to be exposed externally.

It is advised to paint windows and door frames that are created from softwood. This is to protect the wood from rain influences, and the wood would swell and decay when it is wet.

Furthermore, it is architecturally desirable to hide all or part of the window and door frames. Because not only does rebated openings jambs protect against the weather but also it is more aesthetically appealing.

illustrates typically rebated opening jambs, rebated jambs openings consist of different components such as inner reveal, outer reveal, and threshold.

Reveal is used to describe the thickness of brickwork which appears at jambs of openings and rebated jamb separate outer and inner reveal.

The thickness of the outer reveal is mostly half of the wall width to facilitate and provide good bonding whereas the thickness of the inner reveal is based on the inner reveal thickness wall width.

The depth of the rebated jamb opening can be either half or quarter of wall width. The former is employed to protect and mask box frames to vertically sliding wood windows while the latter is utilized to protect and mask solid wood frames.

Concerning bonding of bricks at rebated jambs, similar to angles and quoins in brickworks, bricks have to be cut specifically to complete 1/4B overlap caused by bonding. Therefore, at jambs brick with 1/4B width on the face need to be employed.

In case the outer reveal width is 1/2 and when is 1/4B deep, the bonding at one jamb is arranged in every other brick course a header face and then a closer face of 1/4 wide need to appear at the angle or jamb of the opening.

To avoid continuous vertical joint up the wall and producing 1/4 B deep rebate, two cut brick is required to employ. These cut bricks are beveled bat and king close and they are not specifically manufactured but cut from a brick.

Finally, there are two other bricks which are called beveled closer and are used behind stretcher brick to prevent vertical joint.

Head of Openings in Solid Walls

Lintels or arches should be used to support solid brickwork over the head of openings. The solid brickwork over either lintels or arches is an isosceles triangle with a 60o degree that is created by the bonding of bricks.

If the solid brickwork inside the triangle in a bonded wall is taken out the arching effect will take place which means the load of the wall above the triangle would be transferred to the bricks of each side of the opening.

A lintel is a term used for any single solid length of stone, timber, steel, or concrete and which is constructed above the opening to support the above brickwork.

Lintels are capable of transferring the load to the jambs if the lintel ends are built into the bricks properly. Moreover, the wall area on which the end of a lintel bears is called it's bearing at ends.

As the width of the opening is increases the load which is required to be transferred by lintels is increased and consequently, it is bearing at ends are needed to be must be larger. Furthermore, the depth of lintel is usually around 75 mm and its depth is commonly not smaller than 150 mm.

Types of Lintels and Arches for Openings in Walls

Timber Lintels

This type of lintel was employed to support loads over the opening of solid brickwork and was common up to the beginning of the twentieth century. The application of timber lintels was decreased because it has no proper resistance against fire.

Concrete Lintels for Openings in Walls

These are economical and practical lintel types and can be cast in different shapes and forms. Concrete is considerably strong in withstanding crushing and will not deteriorate unless it is exposed to the weather.

The most outstanding disadvantage of the concrete lintel is its low tensile strength for which steel bars are introduced to compensate for concrete disadvantage.

The diameter of reinforcing steel for lintels of 1.8 m span is 10mm or 12mm diameters and the end of the bars should be either bent up at ninety degrees or hooked.

Concrete lintel can be either precast or in-situ but the former is more advantages because the latter needs molds and after the concrete is placed and after it hardens then loading the lintel is possible, and this is not the case in precast lintels.

Prestressed Concrete Lintels for Openings in Walls

This type of lintel is employed mostly for internal openings. There are two types of prestressed lintels includes composite lintels and non-composite lintels.

The composite lintels are relatively thin precast lintels that are constructed over openings. If the width of the opening is higher than 1200 mm, the prestressed lintels have to be supported until the brickwork over is set to prevent excessive deflections.

The non-composite prestressed lintels are used when there are large loads and not adequate brickwork over to act compositely with the lintel.

Boot Lintels for Openings in Walls

These lintels are used to decrease the lintel depth which is exposed externally.

Prestressed Steel Lintels

It is possible to use this type of lintel instead of the concrete lintel to support both non-load bearing and load-bearing walls. Generally, a hollow box form is used for lintel over a door opening in an internal load-bearing wall.

Prestressed steel lintels with different lengths and sections are constructed to be used for standard openings, the thickness of walls, the height of the brickwork course, and sufficient bearing at ends.

The crushing resistance of hollow prestressed steel lintels must be improved by filling it with concrete when the width of the opening is large. Thin corrugated prestressed steel lintels are produced to suit thin, non-load bearing brickworks over narrow door openings in partition walls.

Brick Lintels

Brick lintels can be constructed as bricks on end, bricks on edge, and coursed bricks laid horizontally over openings.