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Chapter 4 of 9

Masonry and Building Construction

In the AAI Manager (Civil) syllabus under Construction Technology, Equipment, Planning & Management · 3 parts

📑 Contents (29 sections)

Part 1 of 3

Brick Masonry

Last reviewed 16 Sept 2026 · 11 min read

Terms in brickwork

Term Meaning
Stretcher Brick laid with its length along the face of the wall (the longer narrow face — the stretcher face — exposed)
Header Brick laid with its length across the wall (the end face exposed)
Bed Lower surface of the brick when laid; bed joint — horizontal mortar joint
Frog Depression on one bed face — laid upwards and filled with mortar
Lap Horizontal distance by which one brick projects beyond a vertical joint in the course below (commonly one-quarter brick in standard bonds)
Perpend Vertical joint on the face of a wall — perpends in alternate courses should line up vertically
Closer A piece of brick cut lengthwise to complete a course or to maintain bond: queen closer (half the width, cut along the length — full length, half width), king closer (one corner cut off diagonally, leaving half header and half stretcher faces), bevelled closer, mitred closer
Bat A piece of brick cut across its width — half bat, three-quarter bat, bevelled bat
Quoin External corner of a wall; quoin header/stretcher — brick at the corner
Racking back Stepping back each course at the end of a wall section being built, so that later work can be bonded in
Toothing Leaving alternate courses projecting at the end of a wall for future bonding
Squint quoin Corner that is not a right angle
Course One horizontal layer of bricks

Rules for bonding

Bond is the arrangement of bricks in successive courses so that vertical joints do not coincide, distributing loads and binding the wall together.

  1. Bricks should be of uniform size; length about twice the width plus one joint.
  2. Lap should be at least one-quarter brick along the length of the wall and half a brick across the thickness.
  3. No continuous vertical joints in the face or within the thickness.
  4. Stretchers are used mainly on the faces; the hearting should be filled with headers as far as possible.
  5. Minimum use of bats; closers are placed next to quoin headers to develop lap.
  6. Vertical joints in alternate courses should be in the same vertical line (perpends).
  7. Each alternate header should be centrally placed over the stretcher below (in appropriate bonds).

Types of bonds

Bond Arrangement Use / remarks
Stretcher (running) bond All bricks laid as stretchers, with half-brick lap in successive courses Half-brick thick walls — partitions, cavity wall leaves, facing; not for thicker load-bearing walls (no bonding across thickness)
Header bond All bricks laid as headers with half-width lap (three-quarter bats at quoins in alternate courses) One-brick thick walls, curved walls (small radius), footings (for load distribution); less attractive for long walls
English bond Alternate courses of headers and stretchers; a queen closer placed next to the quoin header in each header course; headers centred over stretchers Strongest bond — load-bearing walls, piers; no continuous vertical joints
Flemish bond Headers and stretchers alternate in the same course; each header centred over a stretcher of the course below; queen closers next to quoin headers in alternate courses Better appearance; double Flemish (Flemish on both faces) and single Flemish (Flemish on face, English backing)
English garden wall bond One course of headers to three to five courses of stretchers Garden and compound walls (economical, attractive)
Flemish garden wall bond In each course, one header after three to five stretchers Garden and boundary walls
Facing bond Header courses at intervals tying a facing of stretchers to backing When facing and backing bricks differ in thickness
Raking bond Bricks laid at an angle in the interior of thick walls — diagonal bond (45° in each direction in alternate courses) and herring-bone bond (V-pattern) Increases longitudinal strength of thick walls; herring-bone for paving and decorative work
Dutch bond Modified English bond with three-quarter bats at quoins and no queen closers Strong corners
Zig-zag bond Similar to herring-bone with zig-zag pattern Brick paving, ornamental work
Stack bond Bricks stacked with continuous vertical joints Non-load-bearing decorative work (needs reinforcement)

English bond versus Flemish bond

English bond Flemish bond
Headers and stretchers in alternate courses Headers and stretchers alternate in every course
Stronger (fewer bats, better bonding through thickness) — preferred for load-bearing walls thicker than one brick Somewhat weaker for walls thicker than 1½ bricks; uses more brickbats
Less attractive (plain appearance) Better appearance on the face
Easier to construct; less skilled labour Needs more skill and care
Economical Slightly less economical (more cut bricks), but bats can use broken bricks

Construction practice and precautions

  1. Use good-quality bricks (well burnt, uniform); soak bricks in water before use (to prevent absorption of water from mortar) but lay them surface-dry.
  2. Lay bricks with frogs upward on a full bed of mortar; fill all vertical joints ("buttering").
  3. Keep mortar joints uniform — commonly about 10 mm.
  4. Build walls plumb and courses level using a mason's line, spirit level and plumb bob; check with a straight edge.
  5. Raise the wall uniformly along its length; limit the height built in a day (commonly about 1 m or less) to allow mortar to gain strength; use racking back rather than toothing at junctions where possible.
  6. Break joints according to the bond; use closers at quoins; avoid excessive use of bats.
  7. Cure brickwork by keeping it moist (commonly at least 7 days for cement mortar).
  8. Rake joints (about 10–12 mm deep) while mortar is green if the wall is to be plastered or pointed.
  9. Provide holdfasts for door and window frames, and bond walls at junctions.
  10. Protect fresh work from rain, hot sun and frost; do not load newly built walls prematurely.
  11. Leave scaffolding holes only as permitted and fill them afterwards.

Reinforced brick masonry and brick nogging

  • Reinforced brick masonry (RBM) — steel bars or hoop iron embedded in mortar joints or grouted cores to resist tension, shear and seismic forces — lintels, slabs (reinforced brick concrete), walls in earthquake zones.
  • Half-brick walls (partitions) are often strengthened with hoop iron or reinforcement in every third or fourth course.
  • Brick nogging — brickwork filling a framework of timber or concrete posts and rails (panel walls).
  • Earthquake-resistant masonry — horizontal RCC bands (plinth, lintel, roof bands) and vertical reinforcement at corners and junctions as per IS 4326.

Strength of brickwork

The strength of brick masonry depends on:

  • Compressive strength of bricks and mortar grade (masonry strength is less than brick strength).
  • Workmanship — filling of joints, joint thickness (thicker joints reduce strength), wetting of bricks, bond.
  • Slenderness ratio of walls and columns — effective height (or length) ÷ effective thickness; higher slenderness reduces permissible stress (stress reduction factor).
  • Eccentricity of loading.
  • Shape and size of units.

IS 1905 (Code of practice for structural use of unreinforced masonry) gives basic compressive stresses for masonry based on unit strength and mortar type, stress reduction factors for slenderness and eccentricity, area reduction factors, limits on slenderness ratio (commonly up to about 27 for walls in cement or cement–lime mortar), and minimum wall thicknesses.

FormulaSlenderness ratio

= effective height (depends on end restraints — e.g. about 0.75 × clear height when floors restrain the wall at top and bottom); = effective thickness.

Part 2 of 3

Stone Masonry

Last reviewed 16 Sept 2026 · 10 min read

Masonry

Masonry is construction with individual units (stones, bricks, blocks) laid and bound together with mortar. Stone masonry is used for foundations, walls, retaining walls, piers, abutments, dams and architectural facings where good stone is locally available.

Technical terms

Term Meaning
Course A horizontal layer of stones or bricks
Bed The surface of a stone perpendicular to the line of pressure (its top/bottom in a wall); bed joint — horizontal mortar joint
Joint (cross/vertical joint, perpend) Mortar joint perpendicular to the bed joints
Header A stone (or brick) laid with its length across the wall (perpendicular to the face)
Stretcher A stone laid with its length along the face of the wall
Through stone (bond stone) A stone extending through the full thickness of the wall — ties both faces together
Quoins Stones forming the external corners of walls, usually larger and dressed
Corbel A stone projecting from the wall face to support a beam, cornice or other load
Cornice A projecting ornamental course at the top of a wall (also sheds rainwater)
Coping Covering course on the top of a wall/parapet to protect it from rain; weathered (sloped) and throated
String course Horizontal course projecting from the wall face along its length (at floor or sill level) — appearance and weather protection
Plinth course The top course of the plinth
Jambs Vertical sides of a door or window opening
Reveal The exposed part of the jamb between the frame and the wall face
Sill Horizontal member at the bottom of a window opening (weathered to shed water)
Lintel Horizontal member spanning over an opening
Hearting The interior filling of a wall between the face and back stones
Spalls (pinnings) Small chips of stone used to fill interstices in rubble masonry
Weathering Sloping top surface of projecting courses to shed rainwater
Throating A groove on the underside of a projecting course or sill so that water drips off and does not run back to the wall
Blocking course Course placed above a cornice to weigh it down
Parapet Low wall at the edge of a roof, terrace or bridge
Template A stone/concrete block placed under a beam to distribute load on the wall
Arris The sharp edge where two surfaces of a stone meet

Classification of stone masonry

1. Rubble masonry

Stones of irregular sizes and shapes (as obtained from the quarry or roughly dressed) laid in mortar. Economical but lower strength than ashlar.

Type Description Use
Uncoursed random rubble Stones of irregular shape and size laid without regular courses; interstices filled with spalls and mortar; larger stones at corners and jambs; through stones at intervals Walls of low-height buildings, compound walls, godowns, foundations
Coursed random rubble Stones of irregular shapes brought to level courses at intervals (e.g. every 30–45 cm) Residential buildings, public works — better than uncoursed
Uncoursed squared rubble Stones roughly squared (hammer dressed) laid without courses Ordinary buildings
Coursed squared rubble Squared stones in courses of varying height Better class walls
Regular coursed rubble Squared stones with uniform course heights Public buildings, residential buildings, piers and abutments of ordinary bridges
Polygonal rubble Stones hammer dressed to polygonal (irregular polygon) faces fitting together Decorative walls
Flint rubble Flints (nodules of silica) as facing, with lacing courses of brick or stone Regions where flint is available
Dry rubble masonry Rubble laid without mortar, carefully packed with spalls Retaining walls on hill roads, pitching, compound walls, revetments (allows drainage)

2. Ashlar masonry

Stones finely dressed to regular shapes and sizes, laid in courses with fine, thin joints (often about 3–6 mm). Strong, attractive, but costly.

Type Face finish
Ashlar fine Every stone finely dressed on all sides; very thin joints — superior facing, monuments, important buildings
Ashlar rough tooled Bed and side joints finely dressed; exposed face rough tooled (with a margin chisel-drafted)
Ashlar rock (quarry) faced Exposed face left rough as from the quarry, with chisel-drafted margins — rustic appearance, massive look
Ashlar chamfered Edges of the exposed face chamfered (bevelled) to form grooves at joints — used for plinths, quoins
Ashlar facing Ashlar stones used as facing with rubble or brick backing
Block-in-course Intermediate between rubble and ashlar — stones squared and dressed, courses of uniform height (often 20–30 cm), joints thicker than in ashlar — heavy works (bridges, docks, retaining walls)

3. Composite masonry

A combination of different masonry types or materials — e.g. stone facing with brick backing, stone and concrete — for economy and appearance while using cheaper backing.

General principles of construction

  1. Use hard, durable, well-seasoned stones free from defects; wet stones before laying to avoid absorbing water from mortar.
  2. Lay stones on their natural bed (bed perpendicular to the pressure); in arches the bed is radial; in cornices vertical.
  3. Provide through (bond) stones at regular intervals (commonly about 1.5–2 m apart in each course and at every course or alternate courses in height) or headers overlapping from both faces where full-length stones are not available.
  4. Break (stagger) vertical joints in successive courses — avoid continuous vertical joints.
  5. Face stones should tail well into the wall (length into the wall at least equal to height); hearting solidly filled with stones, spalls and mortar — no hollow spaces.
  6. Use the largest stones in the lower courses, at corners (quoins) and jambs.
  7. Use mortar of suitable proportion (commonly cement mortar 1 : 6 for rubble work); joints fully filled.
  8. Raise walls uniformly throughout their length — limit the height raised in a day; stagger (rack back) junctions for later work.
  9. Keep walls plumb and courses level; check with plumb bob and spirit level.
  10. Cure masonry by keeping it wet (commonly at least 7 days for cement mortar).
  11. Protect fresh work from rain, frost and hot sun.
  12. Provide weathering and throating on projecting courses; coping on parapets.

Part 3 of 3

Damp Proofing & Water Proofing

Last reviewed 16 Sept 2026 · 9 min read

Dampness in buildings

Dampness is the presence of unwanted moisture in walls, floors or roofs. Keeping buildings dry is essential for durability, health and comfort.

Causes and sources

Source Mechanism
Rising damp (ground moisture) Water from the ground rises by capillary action through porous foundations and walls where there is no or a defective damp-proof course
Rain penetration Driving rain through porous bricks, cracks, defective pointing and plaster; splashing of rain at the base of walls; poor sills and copings without throating
Roof leakage Defective roof coverings, inadequate slope, blocked rainwater outlets, cracks at parapet–roof junctions, poor flashing
Condensation Warm moist indoor air condensing on cold surfaces (cold walls, windows, uninsulated roofs) — kitchens, bathrooms, poorly ventilated rooms
Leaking services Water supply and drainage pipes, sanitary fittings, overflowing tanks
Construction moisture Water used in construction trapped in walls and floors (drying out takes time)
Groundwater pressure Basements below the water table
Faulty site conditions Buildings on low-lying, badly drained sites; high water table; improper orientation (walls facing prevailing rain)
Hygroscopic salts Salts in masonry absorb moisture from the air

Effects of dampness

  • Efflorescence, peeling and blistering of plaster and paint, stains and discolouration.
  • Decay of timber (dry rot, wet rot), warping of wooden floors and frames.
  • Corrosion of steel reinforcement and fixtures; deterioration of masonry and mortar.
  • Growth of mould, algae and termites — unhealthy living conditions (respiratory problems, allergies).
  • Damage to electrical installations, furnishings and floor coverings.
  • Reduced thermal insulation; unpleasant appearance and smell; reduced life of the building.

Damp-proof course (DPC)

A DPC is a layer of impervious material built into walls and floors to prevent the passage of moisture.

Requirements of a good DPC material

Impervious to water; durable (as long as the building); strong to carry loads without being squeezed out; flexible enough to accommodate small movements without cracking; resistant to decay and chemicals; not easily damaged during construction; dimensionally stable; economical; free from harmful deleterious materials.

Materials

Category Material Remarks
Flexible Hot bitumen, bituminous felts (hessian- or fibre-based), plastic sheets (LDPE, PVC), metal sheets (lead, copper, aluminium) Accommodate movements; lead and copper are durable but costly; aluminium needs protection from alkaline mortar; bitumen felts should be lapped (commonly about 100 mm)
Semi-rigid Mastic asphalt Impervious, durable, laid hot in layers; may squeeze out under heavy loads in hot climates
Rigid Dense cement concrete (commonly 1 : 1.5 : 3, about 40–50 mm thick) with waterproofing compound, often painted with hot bitumen; cement mortar (1 : 3) with waterproofing compound; stones (slate, dense granite) laid in mortar; engineering/dense bricks in cement mortar Common in India (cement concrete DPC); rigid — cracks if the building settles
Coatings Bitumen and polymer-based coatings Used with other treatments

Position and principles of laying DPC

  1. The horizontal DPC in walls is laid at plinth level, generally at least about 150 mm above the finished ground level to be above splashing, and below the lowest timber (floor joists) and above the highest ground.
  2. The DPC must cover the full thickness of the wall (excluding the cavity in cavity walls).
  3. It should be laid on a level, smooth mortar bed; joints in sheet materials lapped and sealed.
  4. It should be continuous — carried across door openings and connected to the floor damp-proof membrane; where levels change, vertical DPC links horizontal DPCs.
  5. It must not be pierced by fixings, pipes or plaster bridging (plaster should not bridge over the DPC externally).
  6. In cavity walls, DPCs and cavity trays direct water outward above openings and at the base (with weep holes).
  7. Provide DPC below sills, copings and parapets, and at junctions of roofs and walls.

Methods of damp prevention

Method Description
Membrane damp proofing Layers of impervious DPC materials in walls and floors (horizontal and vertical)
Integral damp proofing Waterproofing admixtures added to concrete/mortar: pore fillers (chalk, talc, fuller's earth), water repellents (soaps, stearates, oils), crystalline admixtures; plus dense, low w/c concrete
Surface treatment Water-repellent coatings on external surfaces — silicones, silanes/siloxanes, sodium silicate, bitumen coatings, cement-based paints; keep surfaces breathable where possible
Cavity walls Two leaves separated by a cavity (commonly about 50–75 mm); moisture cannot cross the cavity; wall ties, cavity trays and weep holes
Guniting (shotcreting) Pneumatic application of rich cement mortar on exposed surfaces — dense impervious layer
Pressure grouting Injection of cement grout into cracks, voids and joints of masonry and foundations
Site drainage Grading ground away from the building, plinth protection/apron, surface and subsoil drains (French drains) around foundations, lowering water table
Chemical DPC injection For existing walls — silicone or siliconate solutions/creams injected into drilled holes to form a water-repellent barrier
Electro-osmotic DPC Electrical system to reverse capillary rise (limited use)
Good design details Adequate roof overhangs, drip moulds and throating on sills, copings and chajjas, weathered projections, proper flashing, rainwater pipes

Damp proofing of floors and basements

Ground floors

  • Damp-proof membrane (DPM) — e.g. polythene sheet or bitumen layer below the floor bed (over a blinding layer), turned up and connected to the wall DPC.
  • Sub-base of compacted coarse sand, gravel or brick ballast (capillary break) under the floor concrete; floor raised above ground.

Basements — tanking

Tanking is the continuous waterproofing of basement walls and floors against groundwater.

Method Description
External tanking Waterproofing membrane (mastic asphalt, bitumen sheets, polymer membranes, bentonite) applied on the outside of walls and below the floor slab, protected by a brick/block protection wall — preferred, since water pressure presses the membrane against the structure
Internal tanking Membrane on the inside face, held in place by a loading coat (internal wall and heavy floor screed) designed to resist water pressure — used when outside access is not possible
Integral waterproof (watertight) concrete Dense concrete with low permeability, waterproofing admixtures, water bars (waterstops) at joints and crack control
Drained cavity systems Internal cavity membranes collect water that penetrates and lead it to sumps for pumping
Crystalline and injection treatments For repairs and joints

Hydrostatic uplift on basement floors is resisted by the weight of the slab (and structure) or by tension piles/anchors.

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