Monday, September 26, 2011

SEVAI/Rural Technology Rattrap Bond Walling Is Eco-Friendly and Cost Effective-Dr.K.Govindaraju

Rattrap walling in SEVAI technology centre,Sirugamani
While laying bricks, the manner in which they overlap is called the bond. There are several types of bonds developed in different countries from time to time. They are called as stretcher bond, English bond, Flemish bond and rat-trap bond. The advantages are Strength is equal to standard 9" (229mm) brick wall, but consumes 20% less bricks, the air medium that is created by the bond helps maintaining a good thermal comfort inside the building. As the construction is appealing to the eye from both internally & externally, plastering is not necessary, The overall saving on cost of this wall compared to the traditional 9" wall is about 25%, An ideal mechanism for the congested low-income communities where land is scarce, but building a standard up-stair house is not a financially viable option, It is true that open wiring and plumbing is preferred. But, if you plan your services at an early stage of design, it can enrich your building. You can also save on plastering cost and materials, and on future costs of re-painting (it's maintenance-free). With this technique there is reduction in cost of the wall by 25% as with conventional English bond (9’’thk wall) 350 bricks are required per cu. m whereas in Rat-trap bond only 280 bricks are required and also the reduced number of joints reduces the mortar consumption. No plastering of the outside face is required and the wall usually is quite aesthetically pleasing and the air gaps created within the wall help make the house thermally comfortable. In summer the temperature inside the house is usually atleast 5 degrees lower that the outside ambient temperature and vice versa in winter. In the RTB bricks are placed on edge in 1:6 cement mortars. The air medium or cavity created in between the bricklayers helps in maintaining a good thermal comfort inside the building. This phenomenon is particularly helpful for tropical climate. As the construction is done by aligning the bricks from both sides with the plain surfaces facing outwards, plastering is not necessary except in a few places. The finished surface is appealing to the eye from both internally & externally, Buildings up to two stories can easily be constructed with this technique. In R.C.C. framed structures, the filler walls can be made of rat-trap bond. Due to lesser load on the base of the walls, the width of foundation is also decreased, resulting in a saving of about 8% on use of bricks, cement and sand in foundation and plinth. Govin
While laying bricks, the manner in which they overlap is called the bond. There are several types of bonds developed in different countries from time to time. They are called as stretcher bond, English bond, Flemish bond and rat-trap bond. The advantages are Strength is equal to standard 9" (229mm) brick wall, but consumes 20% less bricks, the air medium that is created by the bond helps maintaining a good thermal comfort inside the building. As the construction is appealing to the eye from both internally & externally, plastering is not necessary, The overall saving on cost of this wall compared to the traditional 9" wall is about 25%, An ideal mechanism for the congested low-income communities where land is scarce, but building a standard up-stair house is not a financially viable option, It is true that open wiring and plumbing is preferred. But, if you plan your services at an early stage of design, it can enrich your building. You can also save on plastering cost and materials, and on future costs of re-painting (it's maintenance-free). With this technique there is reduction in cost of the wall by 25% as with conventional English bond (9’’thk wall) 350 bricks are required per cu. m whereas in Rat-trap bond only 280 bricks are required and also the reduced number of joints reduces the mortar consumption. No plastering of the outside face is required and the wall usually is quite aesthetically pleasing and the air gaps created within the wall help make the house thermally comfortable. In summer the temperature inside the house is usually atleast 5 degrees lower that the outside ambient temperature and vice versa in winter. In the RTB bricks are placed on edge in 1:6 cement mortars. The air medium or cavity created in between the bricklayers helps in maintaining a good thermal comfort inside the building. This phenomenon is particularly helpful for tropical climate. As the construction is done by aligning the bricks from both sides with the plain surfaces facing outwards, plastering is not necessary except in a few places. The finished surface is appealing to the eye from both internally & externally, Buildings up to two stories can easily be constructed with this technique. In R.C.C. framed structures, the filler walls can be made of rat-trap bond. Due to lesser load on the base of the walls, the width of foundation is also decreased, resulting in a saving of about 8% on use of bricks, cement and sand in foundation and plinth. Govin

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