BLOCK MASONRY
Generally we are using in both residential and commercial buildings Hollow and Solid Block masonry as per site requirement.
Specification And General Guidelines For Block Masonry
1) Before starting any block work, prepare masonry layout on Typical Floor Plan (Architecture Plan/ Chaapkam drg.). Thickness of each wall to be marked on plan in different colours (Legend Type) and to be approved by the Project Incharge.Drawing is prepared before starting of first slab to put Electrical Conduits.
2. For H/B Ratio for less than or greater than 4 meter long masonry wall, the specs are given in below Para’s.
3. At the time of deciding the thickness of block for that particular wall, note that H/B ratio should not be greater than 20 for all walls less than 4 meter in length & for wall which is greater than 4 meter in length, H/B ratio should not be greater than 18. Where H = Height of block masonry and B = breadth of block masonry including plaster on both faces of block masonry.
NOTE: Please note that the above condition will not be applicable for wall having opening e.g. Door, Window, RCC Grill, etc. touching beam bottom and the space between two openings does not exceed more than 4 meter.
FOR EXAMPLE
CASE – 1 If wall is less than 4 meter, H/B ratio should not be greater than 20.
Example (A).
Height of block masonry (H) = 2400
Wall Thickness (4)” = 90
Thickness of both side Plaster of Wall (15+15) = 30
Breadth of block masonry including both side plaster (B) (90+30) = 120
H/B = 2400 ÷ 120 = 20.
But required H/B should not be greater than 20.
Therefore OK. Use 90mm (4”) Block
Example (B).
Height of block masonry (H) = 2700
Wall Thickness (4)” = 90
Thickness of both side Plaster of Wall (15+15) = 30
Breadth of block masonry including both side plaster (B) (90+30) = 120
H/B = 2700 ÷ 120 = 22.5
But required H/B should not be greater than 20.
Therefore not OK. Use 125mm (5”) Block and again check H/B ratio as explained above.
FOR EXAMPLE
CASE – 2 If wall is Greater than 4 meter, H/B ratio should not be Greater than 18.
Example (A).
Height of block masonry (H) = 2400
Wall Thickness (4)” = 90
Thickness of both side Plaster of Wall (15+15) = 30
Breadth of block masonry including both side plaster (B) (90+30) = 120
H/B = 2400 ÷ 120 = 20.
But required H/B should not be greater than 18.
Therefore not OK. Use 125mm (5”) Block and again check H/B ratio as explained above.
Example (B).
Height of block masonry (H) = 2400
Wall Thickness (5)” = 125
Thickness of both side Plaster of Wall (15+15) = 30
Breadth of block masonry including both side plaster (B) (125+30) = 155
H/B = 2400 ÷ 155 = 15.48
But required H/B should not be greater than 18.
Therefore OK. Use 125mm (5”) Block.
4) 5” Hollow block masonry compulsorily to be used at window sill (external wall), D.B. Board wall and Toilet down-take line wall.
5) Before starting the blockwork for the first time Chhapkam (masonry layout) to be done for complete floor and to be approved by Project Incharge, before going on blockwork. Below picture shows first layer of Block Masonry.
