BS 8000-3:1989 pdf free download.Workmanship on building sites Part 3 : Code of practice for masonry.
1.1 Scope
This Part of BS 8000 gives recommendations on basic workmanship and covers those tasks which are frequently carried out in relation to masonry work involving brickwork and blockwork.
For design aspects of masonry reference should be made to BS 5628.
NOTE This code of practice includes supplementary elements in the form of commentaries to assist in its use and understanding. Compliance with the commentaries is not necessary in order to be able to claim conformity with the standard.
1.2 References
1.2.1 Normative references This Part of BS 8000 incorporates, by reference, provisions from specific editions of other publications. These normative references are cited at the appropriate points in the text and the publications are listed on page 20. Subsequent amendments to, or revisions of, any of these publications apply to this Part of BS 8000 only when incorporated in it by amendment or revision.
1.2.2 Informative references This Part of BS 8000 refers to other publications
that provide information or guidance. Editions of these publications current at the time of issue of this standard are listed on the inside back cover, but reference should be made to the latest editions.
1.3 Definitions
For the purpose of this Part of BS 8000. the
definitions given in BS 6100-1.3.1:1987 and
BS 6100-5.1:1985, BS 6100-5.2:1984 and
BS 6100-5.3:1984 apply.
2.1.3 Handling and site storage
2.1.3.1 Masonry units. Unload and handle masonry units with care to minimize soiling, chipping and breakage. Do not tip masonry units from the carrier without permission. Never tip facing units. Handle loads with wrapping and banding in place unless it is impractical to do so. Use mechanical handling equipment where possible.
Do not stack units directly on sulphate bearing clinker and ashes or directly on the ground. Store them in stable stacks on a prepared hardstanding area. Protect the stacks from rain and frost, and from soiling from ground and passing traffic. Protect the bottom of the stack from becoming wet from ground moisture.
Stack unwrapped masonry units so as to allow free circulation of air. In addition, follow the manufacturer’s recommendations for handling and storage.
COMMENTARY. If masonry units are too wet the finished work may develop efflorescence or leaching from the joints causing white stains. The risk of unacceptable shrinkage cracking, particularly with concrete blockwork and calcium silicate brickwork, is greater when units have been wetted unnecessarily because of lack of protection.
2.1.3.2 Ancillary components. Handle components, e.g. lintels, flue linings, tiles, cavity closers and edge trims with care to avoid cracking, damage to edges, damage to surfaces and coatings, distortion and soiling.
Stack lintels and copings of precast concrete and pressed metal the correct way up on an adequate number of level bearers clear of the ground. Cover the stacks to protect them from staining and splashing of mud, and in accordance with any additional requirements in the manufacturer’s instructions.
Store metal and plastics components, e.g. wall ties, straps etc., under cover and protect them from damage and distortion.
2.1.3.3 Bags of cement and hydrated lime. Where materials are to be stored for later use, unless there are small quantities only, store as follows.
a) Store in a dry, weatherproof, frost-free, enclosed shed or building with a dry floor. If the floor is concrete, store on a timber platform.
b) Keep different materials in separate stacks.
c) Stack bags away from walls, not more than eight bags high. Cover stacks with tarpaulin or polyethylene sheet.
d) Stack bags so that consignments can be used in the order of delivery.
3.1 General
3.1.1 Weather conditions
3.1.1.1 Cold weather. Do not build masonry when air temperature is at or below 3 °C and falling or below I °C and rising (see 2.2.3.8)
Do not lay mortar on frozen surfaces.
Do not use wet bricks or blocks when there is a danger of freezing.
3.1.1.2 Frost damage. If brickwork or blockwork is damaged by frost, take it down and rebuild. If frost damage is considered superficial and unlikely to affect the performance and appearance of the wall, seek guidance and instructions.
3.1.1.3 Protection. Protect the tops of newly built brickwork and blockwork from rain and also from frost if imminent, and at all times when work is not proceeding. If there is any danger of the work being frozen consider using insulation under the covers.
COMMENTARY. Unless the work is protected when not proceeding there is always the risk that sudden frosts or showers will cause damage. It is important not to forget to cover work at the end of the day. Covers should be kept handy for use. Wet covers may freeze in contact wjth the work and are therefore not to be used. It may he preferable to top the wall with a reasonably clean and dry wooden plank, wider than the wall and place polyethylene or similar sheeting over the plank, clear of the wall face so as to provide an insulating air gap. It is important to weight the covers to prevent the wind lifting them.
3.1.2 Accuracy
Build brickwork and blockwork within the permissible deviations given in Table 2, unless otherwise specified.
3.1.3 General laying
3.1.3.1 Masonry bond. If the masonry bond is not specified. obtain instructions. Unless stack bond or similar is specified, lay the units with the cross joints in any course not less than a quarter of a unit from those in the course below.
3.1.3.2 Laying bricks. Unless otherwise permitted, lay bricks on a full bed of mortar and fill all joints. Keep courses level and perpends vertically aligned. Plumb quoins and wall faces as the work proceeds.
COMMENTARY. It is not possible to align vertically every perpend, particularly with bricks having the maximum permissible deviation from the work sizes.
c) the boards are securely fixed back to one leaf by an approved method only as instructed and form ledges which may collect mortar or moisture;
d) the air space is not blocked or bridged either by mortar or off-cuts of insulation;
e) mortar joints are struck flush within the cavity;
f) no gaps are left in the insulation:
g) joints are left open as weepholes in the outer leaf as specified (see 3.4.1.4);
h) horizontal joints of insulation correspond with the horizontal rows of ties.
COMMENTARY. The risk of moisture penet ration is increased unless the workmanship requirements are carried out carefully; if moisture pellet ration does occur, the fault cannot be cured easily. Further detailed guidance is giuen in the publication cavity insulated walls — Practice Note 112].
3.4.5.2 Full cavity fill. Fill insulation batts carefully in accordance with the manufacturer’s instructions and ensure that:
a) the batts fill the cavity;
b) the batts are close butted at both horizontal and vertical joints and at closures, and installed with staggered vertical joints;
c) the joints between batts are kept clean and free from mortar droppings;
d) mortar joints are struck flush within the cavity;
e) no gaps are left in the insulation;
f) that any small off-cuts are not placed with the cut edge against the wall surface;
g) joints are left open as weepholes in the outer leaf as specified (see 3.4.1.4);
h) the hatts are built in and not pushed into the cavity;
i) horizontal joints of insulation correspond with the horizontal rows of ties
COMMENTARY. The risk of moisture penet ration is increased unless the workmanship requirements are carried out carefully and if moisture penetration does occur. the fault cannot be cured easily. Further detailed guidance is given in BS 6676-2.1 986 and in the publication cavity insulated walls — Practice Note 1 [2].