Rat trap bond stands for a most recognized brick masonry method of wall construction. Under this system, the bricks are arranged in a vertical position rather than the traditional horizontal position. In this way, a cavity (hollow space) is formed inside the wall.

Detail Construction Process

The rat trap bond construction mainly refers to a modular type of masonry construction in which the masonry bricks are provided on edges so that the shiner and rowlock become detectable. As a result, 110 mm face is uncovered from front elevation (for the brick size of 230mmx110mmx75mm). It provides an internal cavity to the wall that leads to efficient thermal insulation.

Benefits of Rat Trap Bond

• The cavities function as good thermal insulators in the masonry wall. As a result, the temperature inside turns out to be cooler in summer and hotter in winter.
• Rat Trap masonry uses fewer bricks and mortar reducing the cost of masonry is curtailed up to 30% in relation to traditional brick masonry because less bricks and mortar are required for rat trap masonry.

• The number of bricks utilized in building the rat trap masonry is 470 but in traditional masonry, it should be 550.
• Walls built-up with rat trap masonry can be applied as load-bearing and a thick partition wall.
• When Rat-trap bond is uncovered, an aesthetically pleasing wall surface is formed and the plastering cost and painting are excluded.

• Since this type of masonry contains 30% of cavities, the dead load of the structure is minimized and consequently the numbers of the structure supporting members like column and footing are curtailed.
• For the structural safety of mortar, reinforcement bars are provided through the cavity until the foundation.
• This type of walling technology is long-lasting and the maintenance costs are less for the buildings which are built up long ago.

Drawbacks of Rat Trap Bond

• As the cavities are created in the masonry, the building does not have good quality sound insulations.
• Without the help of skilled labor, this type of masonry construction is not possible.

• If the exterior surface is not plastered, it should be cleaned on a regular basis.
• Special care and attention should be taken at the time of designing and constructing rat trap bond masonry.