Rat trap bond is a brick masonry method of wall construction, in which bricks are placed in a vertical position instead of conventional horizontal position and thus creating a cavity (hollow space) within the wall.
Method Of Construction
The rat trap bond construction is a modular type of masonry construction. In this type of brick, masonry bricks are placed on edges making visible the shinner and rowlock. Thus 110 mm face is exposed from front elevation (for the brick size of 230mmx110mmx75mm). This gives the wall an internal cavity which provides effective thermal insulation.
Advantages of Rat Trap Bond
1- The cavities in the masonry act as thermal insulators. Thus, the interiors remain cooler in summer and warmer in winter.
2- Rat Trap masonry uses fewer bricks and mortar reducing the cost of masonry up to 30% when compared with conventional brick masonry.
3- The number of bricks used in the construction of rat trap masonry is 470, whereas, in conventional masonry, it is 550.
4- Walls constructed using rat trap masonry can be used as load-bearing as well as a thick partition wall.
5- Rat-trap bond when kept exposed, creates aesthetically pleasing wall surface and the cost of plastering and painting may also be avoided.
6- As this type of masonry has 30% of cavities, the dead load of the structure is reduced which in turn reduces the structure supporting members such as column and footing.
7- In case of more structural safety, reinforcement bars can be inserted through the cavity until the foundation.
8- Many buildings that were constructed decades ago have proved that this type of walling technology is durable and the maintenance costs are low.
Disadvantages of Rat Trap Bond
1- Due to the formation of cavities in the masonry, the building does not provide good sound insulations.
2- Skilled labour is required to construct this type of masonry.
3- Frequent cleaning of external surface required if not plastered.
4- Special care and attention to be given while designing and constructing rat trap bond masonry.
