Chapter 6General Requirements

NBC 2016 (SP 7:2016) Volume 1

2016 · PDF page 719

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6.1 Methods of Construction

6.1.1 General

Construction of the following types of load bearing and non-load bearing masonry walls shall be carried out in accordance with good practice [6-4(4)]:

a) Brickwork,

b) Stone masonry,

c) Hollow concrete block masonry,

d) Gypsum partition blocks,

e) Autoclaved cellular concrete block masonry, and

f) Lightweight concrete block masonry.

6.1.2 Construction of Buildings in Seismic Zones

Special features of construction for earthquake resistant masonry buildings in Seismic Zones II, III, IV and V shall be applicable according to 8.

6.2 Minimum Thickness of Walls from Consideration other than Structural

Thickness of walls determined from consideration of strength and stability may not always be adequate in respect of other requirements, such as resistance to fire, thermal insulation, sound insulation and resistance to damp penetration for which reference may be made to the appropriate Parts/Sections of the Code, and thickness suitably increased, where found necessary.

6.3Workmanship

6.3.1 General

Workmanship has considerable effect on strength of

masonry and bad workmanship may reduce the strength of brick masonry to as low as half the intended strength. The basic compressive stress values for masonry as given in Table 9 holds good for commercially obtainable standards of workmanship with reasonable degree of supervision.

6.3.2 Bedding of Masonry Units

Masonry units shall be laid on a full bed of mortar with frog, if any, upward such that cross-joints and wall joints are completely filled with mortar. Masonry units which are moved after initial placement shall be re-laid in fresh mortar, discarding the disturbed mortar.

6.3.3 Bond

Cross-joints in any course of one brick thick masonry wall shall be not less than one-fourth of a masonry unit in horizontal direction from the cross-joints in the course below. In masonry walls more than one brick in thickness, bonding through the thickness of wall shall be provided by either header units or by other equivalent means in accordance with good practice [6-4(5)].

6.3.4 Verticality and Alignment

All masonry shall be built true and plumb within the tolerances prescribed below; care shall be taken to keep the perpends properly aligned:

a) Deviation from vertical within a storey shall not exceed 6 mm per 3 m height.

b) Deviation in verticality in total height of any wall of a building more than one storey in height shall not exceed 12.5 mm.

c) Deviation from position shown on plan of any brickwork shall not exceed 12.5 mm.

d) Relative displacement between load bearing walls in adjacent storeys intended to be in vertical alignment shall not exceed 6 mm.

e) Deviation of bed-joint from horizontal in a length of 12 m shall not exceed 6 mm subject to a maximum deviation of 12 mm.

f) Deviation from the specified thickness of bed joints, cross-joints and perends shall not exceed one-fifth of the specified thickness.

NOTE — These tolerances have been specified from the point of view of their effect on the strength of masonry. The permissible stress recommended in 5.3 may be considered applicable only, if these tolerances are adhered to.

6.4 Joints to Control Deformation and Cracking

Special provision shall be made to control or isolate thermal and other movements so that damage to the fabric of the building is avoided and its structural sufficiency preserved. Design and installation of joints shall be done according to the appropriate

recommendations in accordance with good practice [6-4(6)].