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OPERATING MANUAL CONSTRUCTION ACTIVITY SARVA SHIKSHA ABHIYAN SCHOOL EDUCATION DEPARTMENT GOVERNMENT OF WEST BENGAL. SIMPLE GUIDELINE AND SUGGESTIONS FOR PEOPLE CONSTRUCTING SCHOOL BUILDINGS. Dr. B.B. Niyogi Chief Engineering Advisor School Education Department Government of West Bengal.
Dr. B.B. Niyogi
Chief Engineering Advisor
School Education Department
Government of West Bengal
One should start construction with a budget for instance, you could a budget based on an area that you have available for construction say @ Rs. 500/- per sqft poor planning needs to major over run tropically to major expenses cost of land and cost of construction.
Selection of a Plot
The critical decision before starting construction is to decide the location and size of plot.
Size of the Plot
Size of the plot should be depending on size of the building and the length-breadth ration of the plot should not exceed 1:2.
8. Supplier of Building Materials
10. Guardian and VEC Member
Please make sure that choose a reputed Architect/Engineer from near by area where school is being constructed
The contractor is responsible for arranging and supervising the workmen for different activities of construction. Contractors are generally paid either on per square foot basis or in terms of labour employed. It goes without saying that the reliability of your contractor defines the quality and durability of the construction.
The carpenter handles any woodwork – the making of doors and windows, frames for grills and related fittings and furniture for the house.
After completing the construction process, the painter can correct any minor detects and paint the house to achieve the desired look. Information on painters is available at paint stores or you could get a recommendation from an acquaintance who has recently painted their building.
All of the electrical layout and wiring is designed and completed by the electrician. Please ensure that only licensed electricians are employed for this activity. Electricians can normally be contacted at electrical equipment shops in the area.
Laying concrete and bricks, maintaining proper even levels and surface layouts – implementation issues like these are the responsibility of the mason.
Water supply, sanitation and waste disposal are important elements for any house. The plumber will help you design the best location and layouts for these. He will also help you install sanitary ware and pipes. For references, ask at sanitary ware and hardware stores.
Purchasing all building materials from authorized dealers of reputed companies is one way of ensuring a durable, long-lasting home. It is advisable to check specifications prior to purchase. Looking for low-cost options may lead to substandard results in construction.
Some useful tips can be picked up from people who have recently completed constructing their own homes. These tips could help in avoiding pitfalls, and lead to major savings in time and cost.
· Maintain minimal stocks of construction materials at the site.
·Stock all the raw materials properly so that they are safe.
· Fixtures and fittings should be chosen for durability rather than just appearance.
·Electrical points need to be minimized.
· If air-conditioning is to be used, plan the location in advance.
Procedures for Identifying Good Quality Sand:
Sand should not contain water. Generally, if the sand contains about 5% of water, then use 25% additional quantity of sand for construction. Sometimes construction labourers add too much water which is detrimental to durable construction.
Bricks can be tested just by observation. Visually they should be in the correct shape with sharp corners. A uniform colour also ensures good quality. One test is to break a brick, it should not scatter into small pieces. Another process of testing is to strike two bricks against each other. Good quality bricks produce a ringing sound when struck with each other. Also, a good brick when dropped from a height of about a meter should not break. Another practical test is to soak a brick in water for about 24 hours. The weight of the brick before and after soaking should be checked. If the brick shows an additional weight of more than 15% after soaking, it should be rejected. For example, a dry brick weighing 2 kg should not weigh more than 2.3 kg after being soaked in water for 24 hours.
Concrete has good compressive strength. However, it does not withstand tensile or bending stresses. To overcome this, reinforcement bars (steel rods) are placed inside the concrete to provide the necessary strength. Hence, the term Reinforced Concrete Cement.
We suggest that only BIS certified steel bars should be used for RCC construction. It is essential to ensure when purchasing them that no rust is visible on the bars. The steel bars are normally fixed in pre-designed formats. So, be careful that all design requirements are strictly adhered to.
Use of cover blocks are highly recommended to ensure that adequate concrete covers the steel bars. Cover blocks are normally made using mortar and should be of a thickness of 2 inch for footing, 1.5 inch for columns and ½ to ¾ inch for slab and beam structures.
Coarse aggregates are normally small pieces of stone which give concrete its strength. The two most commonly used sizes are ¾ inch or 20 mm and ½ inch or 12 mm. At times both are used together in the ratio of 60:40 or even up to 70:30.
While selecting the coarse aggregate, the following points should be kept in mind:
Water should be free of all contamination when used in construction. Salty water or sea water should never be used for making RCC. It is advisable to use potable/drinkable water, as far as possible.
Addition of excess water is detrimental to concrete. A low water to cement ratio makes the construction strong and durable.
It is always useful to have containers of five or ten liters of water handy while carrying out construction. One bag of cement normally requires 25 liters of water.
As a general rule, after mixing the water with cement and other ingredients, a ball of concrete mix should be made. If this ball is thrown up in the air to a height of a meter, it should not break or crumble as this is an indication of excess water content. It would then be advisable to reduce water content in the mix immediately.
It is advisable to purchase only well known brands of cement from reliable sources. A few rupees extra is money well spent as an inferior quality cement could lead to significantly higher cost later. Remember that cement once used cannot be replaced or improved in the same way as you can do with tiles and other such work. Besides, the cost of cement is only a small percentage compared to the total cost of construction. As a rule, cement should constitute only 10%-14% of the total construction cost. For example, if the total expenditure is about Rs.5 lakh, the cost of cement is likely to be 10 to 14 percent, which is around 500 bags. At a premium of five rupees per bag for good quality cement, the cost of cement will increase by about Rs.2500/-, which is quite insignificant when compared to the total budget of Rs.5 lakh.
·Some people believe that the colour of cement determines its quality. This is totally untrue. The colour of the cement is determined by the quantity of the raw materials used in its manufacture.
This is the temporary formwork meant to support your construction while the concrete work is in progress. It comprises of wood props, plywood and steel plates. A good formwork should be strong, solid and without any gaps so that water leakage through through the joint or any gap is almost minimum. 24 gauge micron polythene sheet should be used to prevent any water leakage. Apply a layer of releasing agent (like diesel or grease mix) to the formwork where the concrete is to be poured. This enables it to be removed with ease and ensures a smooth finish.
For RCC work, the ingredients of concrete should be in the ratio of 1:1.5:3 (cement one part, sand 1.5 parts and coarse aggregates 3 parts). All of these items are measured by volume and are best measured using a container of wood or steel. Traditionally, the size of this container would be 350x250x400 mm, which holds 35 litres. While preparing the mixture, 25 litres of water must be added per bag of cement. If the mix is prepared in a machine, it should be mixed for at least 2 minutes so that the mixture blends well with the water. If you are mixing by hand, then it is advisable to prepare a dry mix of cement and sand in a tray. After blending, when the colour appears uniform, the coarse aggregate may be added and then finally add the water.
for a 4 inch wall (divider walls in the middle of the house)
cement:sand = 1:4
for a 9 inch wall (outer walls)
It is best not to lay bricks higher than 5 feet at a time, as the mortar should given adequate time to set. The task of joining should begin from 2 corners (3-4 layers). The parts in between should be filled within the leftover frames. The line level and plumb need to be continuously checked.
Curing must be done for at least 10 days.
In this context, please read the section on the quality of bricks carefully.
Plaster is the skin of your house. Just as our skin gives shape and texture to our body, and protects your house from damage caused by salts, acid and rain. It also makes your house look beautiful. Therefore, it is important to pay close attention to it.
·Ensure that the wall is slightly wet before starting the plastering. Dry walls adsorb water from the plaster and this will cause the plaster, in time, to fall off.
·Check that the mason has not prepared the mix for the whole day. The mix must be prepared only in small quantities; as much as will be used in an hour. Your mason can, however, keep a large quantity of dry mix ready.
1:5 to 1:6 for internal plaster
1:4 to 1:5 for external plaster
1:3 to 1:4 for the ceiling
However, if the sand particles are very fine, 1:4 ratio mix is suitable for all three areas.
· Use wooden float for finishing as steel floats can sometimes cause small cracks.
· Curing should be done for 10–14 days.
The process of maintaining moisture in the concrete is called curing. Concrete begins to dry after casting. So, the parts exposed to the environment should be cured to ensure that the concrete surface is never dry. This needs to be done continuously, till the mandated period of curing. Usually, 10-14 days of curing is considered optimal. It is best to make small curing ponds or bunds on flat or horizontal surfaces. For vertical surfaces, you may wrap jute or hessian cloth on the surface and then pour water onto it. This helps keep the surface wet for longer periods.
Select electrical goods for your house carefully (these must be ISI marked).
·Make provisions for switch boards at the beginning of construction, or it will clash with the décor of your house later on.
·Make proper arrangements for earthing in your house and have it checked regularly.
·Do not make several temporary connections from one point.
Avoid using too many joints in the electrical wiring. Use good quality wires and insulation material.
·To protect your electric equipment, use a fuse on every power board.
·Do not use extension boards for permanent connections.
·Keep the power supply cord safe from water, heat and oil.
·Keep electrical materials away from children.
Note: Use electricity with restraint. Have your connections, wiring etc. checked regularly. Get your electric work done only from a registered or license-holding electrical contractor.
·Use good quality ISI marked GI pipes and fittings for the water supply.
·PVC pipes for sewage discharge are both durable and convenient.
The joints of pipes and fittings must be leak-proof. They should be double checked before laying the tiles.
Painting provides protection to the walls of your house as well as so much more. It is said that the colours of your house reflect your personality. The painting work is broken up into three parts:
Painting your Interiors step by step:
· Clean the surface thoroughly with sand-paper.
· Then apply a coat of good quality primer. If required, apply a second coat.
·Once the primer has dried, apply one or two coats of acrylic-based putty.
·Apply a further coat, or two or three coats. Thinner should be used as per requirement.
·If there is any dampness or cracks or other damages on your walls, have these repaired first.
·Select in advance the shades and colour schemes you wish to have on your walls. You can get help choosing the colours from catalogues, displays and show-rooms of well-known companies.
·Find out the entire product range of the company so you can select the colour that suits your needs.
·Choose light colours for outer walls. This will keep interior temperatures low.
·Also use light colours on internal walls where a lot of natural light is reflected.
Sample (100 sqft roof area)
Cement – 7 bags – Rs.1,750/-
Stonechips – 33 cft – Rs.1,320/-
Sand – Rs.300/-
Reinforcement – Rs.5,000/-
Labour – Rs.3,500/-
Total = Rs.11,870/-
Sample (1000 sqft plinth area)
a) Brick – 4000 upto plinth
8000 plinth to roof
Total = 12000 Nos. @ Rs.6.00/piece
b) Mortar 54 bag cement – Rs.13,000/-
400 cft sand – Rs.6,000/-
c) Labour – Rs.9,000/-
Total = Rs.(72,000/- + Rs.13,000/-
+ 6,000/- + 9,000/-)
= Rs.1,00,000/- (approx)
3. Calculation for Plastering:Sample (1000 sqft plinth area)a) Inside – 100 bags b) Outside – 60 bagRs.40,000/-c) Sand – Rs.18,000/-d) Labour – Rs.17,000/-Total = 75,000/-4. Calculation for Chaja & Lintel:a) Reinforcement – 200 nos. – Rs.10,000/-b) Cement – 20 bag – Rs.5,000/- c) Stonechips – 100 cft – Rs.4,000/- d) Sand – 70 cft – Rs.1,000/-Total = Rs.20,000/-
5. Calculation for Door & Window:a) Door – Rs.4,000/-b) Window – Rs.3,000/- Total = 7,000/-6. Calculation for Pipeline & Bathroom:a) Pipeline – Rs.20,000/-b) Bathroom – Rs.20,000/- Total = Rs.40,000/-7. Calculation for White Wash & Colour Wash:a) White Wash – Rs.10,000/-b) Colour Wash – Rs.30,000/- Hence, Rs.10/- & Rs.30/- per sqft respectively.
5. Calculation for Flooring:a) Mozaic (Gray colour) – Rs.45/- per sqft b) Mozaic (with white cement) – Rs.60/- per sqft c) Marble (2’-0” x 2’-0”) Slab – Rs.(70/- + 20/-) = Rs.90/- per sqftd) Marble Large Slab (Dugri) – Rs.(120/- + 30/-) = Rs.150/- Rs.(150/- + 30/-) = Rs.180/- Rs.(180/- + 30/-) = Rs.210/-
N.B. The drawing and estimate should be treated as reference. The area may vary as per site condition (like land availability, local material cost, labour charge, transportation cost etc.), but the unit cost of construction should be kept within Rs.2.00 lakh. The changed/modified plan and estimate must be prepared and checked by District Engineering Cell and vetted properly by the concerned district authority before implementation.