AIM FOR QUALITY IN CONSTRUCTION

• TRAIN YOURSELF TO BE QUALITY CONSCIOUS!

• WHAT QUALITIES & ABILITIES MUST YOU CULTIVATE TO BE QUALITY CONSCIOUS?

• HOW CAN YOU ENSURE THE QUALITY OF BUILDINGS YOU SUPERVISE?

1. Be observant regarding:* Quality of materials* Quality of workmanship* Quality from foundation to finishes2. Be capable of convincing masons, carpenters, beneficiaries of reasons to maintain quality standards3. Be informed about:Quality construction standards & specific technical requirements for the project.4. Be concerned about: implementing quality standards in construction

FUNDAMENTALS OF STURDY, SUSTAINABLE CONSTRUCTION

• ALL COMPONENTS MUST BE WELL INTEGRATED TO WITHSTAND EXTERNAL FORCES

• ALL LOADS MUST BE TRANSFERRED DIRECTLY DOWNWARDS

• ALL CONSTRUCTION METHODS MUST CONFORM TO THE HIGHEST STANDARDS OF QUALITY

• DESIGN AND CONSTRUCTION MUST ENSURE THAT WATER/DAMPNESS DOES NOT ENTER THE BUILDING FROM ABOVE, SIDES, AND UNDER.

• ALL COMPONENTS MUST SATISFACTORILY WITHSTAND THE HARMFUL EFFECTS OF SUN, WIND, RAIN, AND FLOOD.

CHECK QUALITY OF BASIC MATERIALS

Foundation Stone – Size, hardness

Bricks and blocks – Size and strength

Sand – Free of excessive clay and impurities

Metal (aggregate) – Consistency of size

Timber – Quality and sizing

Roofing tiles/sheets – Quality consistency

CHECK FOUNDATION TO FINISHES

• Foundation

• Plinth beam & DPC

• Compacted earth fill & DPM

• Superstructure

• Roof

• Doors and windows

• Wall and floor renderings

• Wall finishes

REJECT POOR QUALITY BLOCKS/BRICKS

• To check use drop test, scratch surface for quality, tap bricks together for ringing sound.

ENSURE THST MASONRY BLOCKS/BRICKS ARE OF GOOD QUALITY

Good quality masonry blocks and bricks:•Have clean sharp edges•Have hard surfaces that do not crumble when scraped•Will not break when dropped from 3 ft. Height.•Have non-porous quality

Always soak blocks or bricks before placement.

REJECT SAND WITH & EXCESSIVE CLAY/IMPURITIES (left side of picture)

CHECK ON-SITE FOR SAND QUALITY

ENSURE THAT QUALITY CEMENT AND REIFORCEMENT STEEL ARE USED

• Cement must be of powdery texture. Reject cement that is gritty or contains hard lumps.

• Cement must be stored in a sheltered, dry location, and used without delay.

• Reinforcement steel must be relatively free of dirt & rust. Where rust is present, remove rust by brushing with a wire brush. Where oil is present, it must be wiped off or burned away thoroughly before using.

REJECT WARPED, SPLIT, DECAYED, TIMBER WITH EXCESSIVE KNOTS & PITH

REJECT POOR QUALITY TILES THAT ARE CRACKED, DEFORMED, OR CHIPPED

SITE CLEARING/PREPARING CHECK

• Uproot trees, remove vegetation at building footprint. Remove top soil when excavating foundation trenches and store safely for re-use.

• Ensure that water does not stagnate on site near building operations.

• Determine locations for material storage, concrete mixing, bar bending, work bench, etc.

CHECK SOIL TYPE TO KNOW IF PLINTH BEAM IS NEEDED. SOIL ON RIGHT SIDE

IS CLAYEY; NEEDING PLINTH BEAM

CHECK WATER TABLE LEVEL AT SITE

HOW CAN THE WATER TABLE BE CHECKED?

– Check the level of water in the well on-site, or check water level in the closest well.

– Find out from local residents the known high water level during past rainy seasons.

WHY CHECK WATER TABLE LEVEL (WTL)?

•The WTL needs to be known to design suitable foundation•The high water table level must be known to determine the placement of the septic tank, and the height of the toilet floor.

SETTING OUT CHECK

• Centre lines of walls must correspond with dimensions in working drawings.

• Use 3-4-5 method to establish 90 degree corners, and verify with diagonal check.

• Check distances to all boundaries.• Technical officers must personally check &

approve all setting-out lines before foundation trenches are cut. Allow for working space in trenches.

CHECK CORNERS AND SQUARENESS OF ROOMS AND BUILDINGS

FOLLOW STEPS IN SETTING OUT ACCURATELY

CHECK FOUNDATION DEPTH with drawings & BLINDING SCREED (3” thick, 1: 3: 6 (1 ½”) mix)

@ FOUNDATIONS (min: w=18”, d=18”)

MORTAR & CONCRETE: FIRST - THOROUGH DRY MIX. NEXT - THOROUGH WET MIX,

WITHOUT EXCESSIVE WATER

USE SLUMP TEST WITH EVERY BATCH OF MIXED CONCRETE

DO NOT ALLOW FOUNDATION STONES TO BE PLACED DIRECTLY ON SOIL WITHOUT SCREED CONCRETE AT THE BASE

INSIST ON PROPER SCREED CONCRETE TAMPING METHOD WITH TAMPING DEVICE AS

SHOWN ON RIGHT

CONCRETE, SCREED & MORTAR MIXES

• Concrete for foundation and superstructure columns, beams, lintels, floors, staircases, and lintels – 1 : 2: 4 (3/4”) cement; sand; metal

• Blinding screed under foundation of walls and columns – 3” thick, 1: 3 : 6 cement : sand: metal (1 ½”)

MORTAR & RENDERING• Mortar in foundation random rubble to DPC – 1:6 cement

: sand• Mortar in s/s Conc. Block masonry – 1:5 cement : sand• Mortar in s/s 9” brick Brick masonry – 1:8 cement : sand• Floor cement rendering – 5/8” 1:3 cement : sand• Skirting & Plinth ct. rendering – ¾” 1:3 cement : sand

IN FOUNDATIONS, USE LARGER STONES MOSTLY (picture @ left); DO NOT USE MANY SMALL STONES WITH EXCESS MORTAR (picture @ right and sketch in next slide)

IN FOUNDATIONS USE THROUGH STONES, AND DOWEL STONES AT CORNERS & JUNCTIONS

FOUNDATION/SUPERSTRUCTURE FAULTS

• Faults in foundation can cause cracks in superstructure walls, rectification is difficult and expensive. Be sure foundations are built properly.

DO NOT PLACE MORTAR ON UNFINISHED MASONRY (as in this picture)

To ensure good bonding between lower and upper layers:

Remove all previously laid hardened mortar from top of foundation walls before placing upper layers.

Place vertical dowel stones at regular intervals to bond with upper layers.

REMOVE RESIDUE MORTAR BEFORE CASTING PLINTH BEAM, REJECT INCORRECTLY LINKED, CONNECTED & LAPPED REINFORECEMENTS

REINFORCEMENT LAPPING & CONCRETE COVER FOR REINFORCEMENTS

• Vertical reinforcement lap length 30 x bar diameter

• Horizontal reinforcement lap length 50 x bar diameter

Note: Follow engineer’s specifications if different to above standards.

Ensure the following minimum thickness of concrete cover to reinforcements•Foundations – 2” to 3”•Columns – 1 ½”•Beams – 1 1/2”•Slabs/stairs – 1 1/2”

Note: Cover thickness to be increased near coastal areas due to salt content

REINFORCEMENTS BASICS

ENSURE Damp Proof Course IS PROVIDED & Damp Proof Membrane PLACED PROPERLY

• DPC laid not less than 12” above ground level. Lay 1/½” 20mm) layer cement/sand (1: 3) concrete; 3 coats tar. Sprinkle with dry sand

• DPM (if used) to be placed on bed of sand on surface of dampened & compacted earth fill. Use 1000 gauge polythene film, lapped 6”@ joints & sealed by taping.

DRY EARTH FILL MUST BE FREE OF VEGETABLE MATTER, WELL COMPACTED IN

LAYERS AND DAMPENED (picture @ left)

Above picture shows failure to remove all vegetable matter in earth fill at plinth.

WALLS TO BE VERTICAL WITH VERTICAL JOINTS PROPERLY STAGGERED

MASONRY FOR SUPERSTRUCTURE

• For 6” (external load bearing) & 4” (internal non load bearing) concrete block walls, use solid blocks. Do not use hollow concrete blocks.

• Provide a continuous RCC lintel at 7’ height with vertical rfmts. at corners/junctions to above wall plate level. Reinforcement bars to wrap round wall plate.

• For 9” & 4 ½” thick brick walls, provide a continuous RCC lintel at 7’ height with vertical reinforcements at corners to wall plate level. Reinforcement bars to wrap round wall plate.

CLOSELY MONITOR QUALITY OF MASONRY WORK AND RECTIFY FAULTS

• Too much mortar has been used here, and improper sized bricks in this masonry work. Use uniform full, half, ¼ & ¾ size bricks

• Masonry mortar must be of uniform thickness not greater than 5/8”.

WALLS AT JOINTS AND CORNERS MUST BE PROPERLY KEYED FOR CONNECTIVITY

PLACE INERSECTING WALL TO ENUSRE THEY BOND WITH EACH OTHER

POSITION DOOR OPENINGS CORRECTLY

Above picture shows failure to provide masonry nib at the corner of the wall for placement of door.

ENSURE THAT ADJOINING WALLS ARE KEYED IN TO AVOID CRACKS DEVELOPING

• Failure to key-in adjoining walls can cause cracks at joints in superstructure walls

POSITION EXTERNAL DOOR & WINDOW OPENINGS SAFELY

CHECK SIZE AND PLACEMENT OF EXTERNAL DOOR AND WINDOW OPENINGS; RECTIFY

IMMEDIATELY WHERE NECESSARY

ENSURE PROPER CASTING OF CONTINUOUS RCC LINTEL (picture @ left). REJECT

INDIVIDUAL LINTEL CASTING (picture @ right).

ENSURE THAT CORNER REINFORCEMENTS ARE PLACED AT CONTINUOUS LINTELS

PROVIDE CENTRAL RCC STIFFENER AT GABLE WALLS FOR TILED ROOFS

• Load bearing gable walls of 4” and 6” thickness require a vertical RCC stiffener because of the increased height of the apex of tiled roofs.

• Failure to provide stiffeners can weaken flexural strength of walls.

BE ALERT TO NON PROVISION OF CORNER REINFORCEMENTS & FAILURE TO WRAP REINFORCEMENTS OVER WALL PLATE

REINFORCEMENT AT CORNERS VITAL

• Clearly explain to masons, carpenters & beneficiaries why vertical reinforcements must be used at key corners of the building

• Ensure that the bars are wrapped round wall plates

CHECK QUALITY OF DOOR & WINDOW FRAMES

PLACEMENT OF DOORS & WINDOWS: GOOD PRACTICE

USE ONLY PROPER HOLDFASTS (Not nails) FOR DOOR & WINDOW FRAMES

ENSURE THAT ADEQUATE NUMBER OF HOLDFASTS ARE USED

• Holdfasts for doors: 3 pairs

• Holdfasts for windows: 2 pairs

• Failure to fix holdfasts can result in plaster around frames being dislodged as shown in this picture

BE ALERT TO HEAD FRAME OF DOORS NOT PLACED AT LINTEL SOFFIT HEIGHT

ROOF SLOPES MUST MATCH ROOF TYPES

• Minimum pitch of 25 degees for tiled roof may be allowed in areas with no high winds.

• Surface rendering on RCC flat roofs to be sloped to allow ready run-off of rain water and prevent ponding of water on roof surface.

PAINT PRESERVATIVE ON ALL ROOF TIMBERS BEFORE PLACEMENT

PLACE WALL PLATES FLAT, NOT ON EDGE,CENTRALLY ON WALLS (Supported at cantilever)

NOTE UNPAINTED ROOF MEMBERS AFTER PLACEMENT & CUTTING, AND ENSURE THEY

ARE PAINTED

IMPROPERLY PLACED ROOF TRUSSES ARE LIABILITIES WHEN PLACED ABOVE

OPENINGS IN WALLS

ALWAYS PROVIDE CONCRETE OR TIMBER BASE PAD AT WALLS TO SUPPORT LOAD-

BEARING ROOF TIMBERS TO SPREAD LOAD

FAULTY ROOF SUPPORT TIMBER FRAMING

THESE WALL PLATES FAIL TO SIT EVENLY ALONG FULL LENGTH OF SUPPORTING WALLS. ENSURE PROPER PLACEMENT.

SINGLE END-BATTEN ON EDGE UNSTABLE & IMPROPER; ALWAYS FIX DOUBLE BATTENS

EXTENSIONS TO RAFTERS MUST BE OF THE SAME SIZE AS RAFTERS (LHS picture); NOT

SMALLER IN SIZE (RHS picture)

BE ALERT TO IMPROPER PLACEMENT OF ROOF TILES AND RECTIFY

• EACH SUCCESSIVE ROW MUST BE STAGGERED. TOP PICTURE SHOWS FAILURE TO DO SO.

• CHECK TILES FROM INSIDE BUILDING TO IDENTIFY FAULTS IN TILE PLACEMENT OR QUALITY (Picture below).

INSUFFICIENT CONCRETE BANDS @ ROOF

EXPOSED BATTEN ENDS WILL DECAY, IF NOT COVERED BY BARGE BOARD

CORRUGATED ROOFING SHEET FIXING & PURLIN/RAFTER FIXING IN HIGH WIND AREAS

• “j” bolts may be used in areas with no high winds

FRAMING FOR CORRUGATED ROOFING IN HIGH WIND AREAS

• Provide diagonal bracing at underside of rafters at gable ends of roof

• Ensure that all rafters are firmly linked to wall plates, and rafters to purlins (see anchor points in figure)

ROOF EAVES IN HIGH WIND AREAS

• Eaves overhang not more than 2’- 0”

• To deflect wind, flat eaves soffit is better than soffit at rake

FLOORING: ENSURE RENDERING MIX IS PROPERLY TAMPED. CHECK FOR CRACKS.

PROPERLY SLOPE ALL FLOORS TO PERMIT EFFECTIVE DRAINING OF WASH WATER

• Ensure that toilet floors are properly sloped to allow surface water to be readily drained into outlet drain. Instruct masons accordinlgy.

CEMENT PLASTER RENDERING ON WALLS

• External: 5/8” (20mm) thick rough plaster in 1:1:4 cement : sand : lime.

• Internal: 5/8” (15mm) thick smooth plaster in 1:1:5 cement : sand : lime.

GIVE ATTENTION TO PROPER PAINTING STANDARDS

• Ensure plaster surfaces are smooth (rectify with filler), clean & dry, then apply paint undercoat and overcoats as per specifications

of manufacturer.

PAINT FINISHES

• For blistering, flaking, peeling and cracking; identify & eliminate source/s of dampness. Remove loose paint, ensure surface is free of grease, and allow to dry. Apply primer coat and repaint following manufacturer’s instructions.

IN KITCHEN/PANTRY KEEP WINDOW SILL HEIGHT ABOUT 6” ABOVE WORKTOP

Above picture shows raised sill height to reduce damaging effect of water form worktop on window frame.

CHECK HINGE FIXING OF DOORS & WINDOWS

• Make sure that adequate number of hinges are used for windows & doors

• Make sure that all screws are provided in all hinges

• Test if doors & windows open & close smoothly

RECTIFY IDENTIFIED BUILDING DEFECTS

• SPECIFY CORRECTIVE ACTION TO RECTIFY DEFECTS THAT ARE NOTED

• STRESS IMPORTANCE OF USING QUALITY MATERIALS AND WORKMANSHIP

• STRESS IMPORTANCE OF SAFETY AND SUSTAINABILITY OF BUILDING & ALL ITS COMPONENTS

• RE-CHECK AFTER RECTIFICATION