BUILDING CONSTRUCTION AND DRAWING

LECTURE NO. 1 BY ENGR RAHAT ULLAH

 BRICK MASONRY

PART 2

DAMP PROOF COURSE

•  A damp proof course (dpc) is a layer of impermeable material built into the wall to prevent upward migration of ground water.
• Once in position, the brick laying continues as normal, covering the dpc with a bed of mortar and then laying the first course of bricks above dpc.
•  it costs very little and guarantees a longer life for the wall, as damp cannot rise above the dpc to saturate the facing brickwork.
• Rich plain or reinforced concrete with surface sprayed with bitumen is most commonly used for dpc.
• The use of polythene sheet should be avoided since it does not make adequate bond and act as a separation between upper and lower portion of masonry.

QUALITIES OF GOOD BRICKS:

• Bricks should be table moulded, well burnt in kilns, copper coloured, free from cracks and with sharp and square edges.
• Bricks should be uniform shape and should be of standard Size.
• Bricks should give clear ringing sound when struck each other.
• Bricks when broken should show a bright homogeneous and compact structure free from voids.
• Bricks should not absorb water more than 20 percent by weight for first class bricks and 22 percent by weight for second class bricks, when soaked in cold water for a period of 24 hours.
• Bricks should be sufficiently hard no impression, should be left on brick surface, when it is scratched with finger nail.
• Bricks should be low thermal conductivity and they should be sound proof.
• Bricks should not break when dropped flat on hard ground from a height of about one meter.
• Bricks, when soaked in water for 24hours, should not show deposits of white salts when allowed to dry in shade.
• No brick should have crushing strength below 55kg/cm2.

BOND IN BRICK MASONRY

The arrangement of bricks or stones  in each layer in such a way to break the continuity of vertical joints in the successive courses both on the face as well as inside of a masonry structure is called a bond.

This is done by overlapping bricks or stones in successive courses longitudinally as well as transversely.

Necessity of providing bond:

• To break the continuity of vertical joints.
• To ensure the longitudinal and lateral strength.
• To distribute the load over larger resisting area.
• To provide pleasing appearance by laying bricks symmetrically.

TYPES OF BOND IN BRICK MASONRY

1. English bond
2. Flemish bond
3. Header bond
4. Stretcher bond
5. Garden wall bond
6. Raking bond
7. English cross bond
8. Hoop iron bond
9. Facing bond
10. Dutch bond
11. Monk bond
12. Zig Zag bond
13. Brick-on-Edge bond
14. Silver lock’s bond

1.ENGLISH BOND

  This bond consists of alternate course of headers and stretchers. In this arrangement, vertical joints in the header courses come over each other and the vertical joints in the stretcher course are also in the same line in alternate courses.

Salient features of English bond:

• Header and stretcher are laid in alternate courses.
• A queen closer is placed after every quion heading course when the thickness of wall is 20 cm or above.
• The same course will show headers on the face and stretchers on the back and vice versa, if the thickness of wall is an odd multiple of half brick.

• The length of queen closer is usually kept equal to the thickness of wall.
• The same course will show headers or stretchers on face and back if the thickness of wall is an even multiple of half brick.  
• Each alternate header in the heading course lies centrally over every stretcher of the underlying stretching course.
• The inner filling is done in headers in the wall having thickness 40 cm or above.

Suitability:

      English bond is commonly adopted for brickwork of building where strength is of prime importance. 

2.FLEMISH BOND

The bond having headers and stretchers laid alternately in the same course is called Flemish bond. In this bond a queen closer is provided after every quion header in the alternate courses to break the continuity of vertical joints. Brick bats are to be used for forming this bond when the thickness of wall is equal to an odd multiple of half brick.

Salient features of Flemish bond

• Headers and stretchers are laid in the same  course.
• Queen closer is placed after every quoin header brick in the heading course when the thickness of wall is 20 cm or above. The length of queen closer is not kept equal to the thickness of wall and is usually intercepted by ¾ bats.
• Brick bats are to be used in wall having thickness equal to an odd multiple of half brick.
• Every header in each course lies centrally over every stretcher of the underlying course.

TYPES OF FLEMISH BOND

Flemish bond has following two types:

1.Double Flemish bond

The bond having headers and stretchers laid alternately in each course both in the face and back of the structure is called double Flemish bond.

• This type of bond provides good appearance but is weaker in strength than English bond for wall having thickness more than 20 cm.
• Double Flemish bond is considered as an economical bond as it facilitates the use of brick bates and closers.
• In this bond, it is easier to obtain a fair and more uniform face on both sides of 20 cm thick wall than in case of English bond.
• This bond is commonly known as Flemish bond.
• The salient features of double Flemish bond are the same as that of Flemish bond in addition to the following features.
• Each course will show different elevation on face and back if the thickness of wall is an odd multiple of half brick i.e. if header is seen in the front elevation then stretcher will be seen in line with that header in back elevation in the same course and vice versa.

    Suitability:

Double Flemish bond is used for brick work of building where appearance is of prime importance. 

• FOR MORE VISIT PART 3

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