Thumb Rules for Civil Engineering
Percentage of Steel in Structural Members
Following are thumb rules for reinforcement in concrete members,
1) Slab – 1% of the total volume of concrete (Slab steel calculation thumb rule)
2) Beam – 2% of the total volume of concrete
3)column – 2.5% of total volume of concrete
4)Footings – 0.8% of the total volume of concrete
Example:
How to calculate the steel quantity of slab having the Length, width, and depth of the slab is 4m x 4m x 0.15m
Step 1: Calculate the Volume of Concrete:
The Total Volume of Concrete for the given Slab = 4 x 4 x 0.15
= 2.4m3
Step 2: Calculate The Steel Quantity Using the Formula:
As per the guidelines given in the BN Dutta reference book the steel quantity of the slab is 1% of the total volume of concrete utilized.
A thumb rule to estimate the steel quantity of the above slab is to use the following formula:
Steel Quantity = Volume of Concrete x Density of Steel x % of Steel of the Member
Steel weight required for above slab = 2.4 x 7850 x 0.01 = 188Kgs
Thumb Rules For Shuttering Work
Shuttering costs are taken as 15-18% of the total construction of the building. Shuttering work is done to bring the concrete into Shape. The Thumb rule to estimate the shuttering required is 6 times the quantity of concrete or 2.4 times the plinth area.
For example, if the concrete quantity is 0.5m3, then
Area of Shuttering is 0.5 x 10 = 5m2
Components of Shuttering
Shuttering Ply Quantity estimation
The Shuttering plate Ply, Battens, and Nails are components of Shuttering.
Suppose, The Shuttering Ply has a length, width & depth of 2.44 x 1.22 x 0.012
The No. of Shuttering Ply Sheets = 0.22 times of Shuttering
Suppose, the Shuttering Area = 5m
Then Ply required for shuttering = 0.22 x 5 = 1.1m2
Battens Quantity Calculation
Shuttering Batten usually has a length & width of 75mm x 40mm.
Batten Quantity = 19.82 x No. of Ply Sheets
If work requires 25 Ply sheets, the total quantity of Battens is 19.82 x 20 = 396 Battens
Nails & Binding Wire Quantity in Shuttering:
Approximately, 75 grams of Nails were used in the shuttering of the 1m2 area.
75gms of Binding wire is used for every 1m2 of Shuttering.
The thumb rule for Shuttering oil estimation :
Shuttering oil is applied on the shuttering plate surface used to de-frame or de-assemble from the concrete easily.
Total required Shuttering oil = 0.065 x Total Area of Shuttering
(or)
For every 15m2 of shuttering 1 liter of shuttering oil is consumed.
Example :
If, total area of shuttering is 15 m2, then Shuttering oil Consumption = 0.065 x 15 = 0.975.
Thumb Rules for Civil Engineering
Thumb rule for Cement, Sand, Coarse Aggregate Quantity in Different grades of Concrete :
M15(1:2:4) 6.34 Bags 15.5cft 31cft 158ltr
M20(1:1.5:3) 8 Bags 15cft 30cft 201ltr
M25(1:1:2) 11 Bags 13.5cft 27cft 275ltr
Thumb Rules for Civil Engineering
Thumb rules for civil
The number of bricks required for 1 cubic meter
NOS OF BRICKS = 500
CEMENT = 1.26Bags
SAND = 9.28cft
Standard size of bricks is 19cm X 9cm X 4cm.
Weight of first-class clay bricks should be 3.85 kg.
Crushing strength of bricks is 10.5 MN/m2.
Water absorption in bricks is 12% to 15%.
De-Shuttering Period of Different RCC Members
- The period for columns, walls, and vertical formworks – is 16-24 hrs.
- Period for Soffit formwork to slabs – 3 days (props to be refixed after removal)
- The period for Soffit to beams props – is 7 days (props to be refixed after removal)
- Beams spanning up to 4.5m – 7 days
- Beams spanning over 4.5m – 14 days
- Arches spanning up to 6m – 14 days
- Arches spanning over 6m – 21 days
Labour productivity in construction site
1. BRICK WORK 9″ = 1.25CUM
1 MASON , 1 MALE HELPER, 1 FEMAIL HELPER
2 . INTERNAL WALL PLASTERING = 10 SQM
1 MASON , 1 MALE HELPER, 1 FEMAIL HELPER
3. EXTERNAL AND CELING PLASTERING = 8 SQM
1 MASON , 1 MALE HELPER, 1 FEMAIL HELPER
4. SHUTTRING WORK = 4.5 SQM
1 MASON , 1 MALE HELPER
5. STEEL CUTTING, BENDING AND FIXING = 200KG
1 FITER , 1 MALE HELPER
6. Labour productivity in construction siteTILING WORK = 10SQM
1 MASON , 1 MALE HELPER
7. SKITING WORK = 150 RFT
1 MASON , 1 MALE HELPER
8. BATHROOM AND WALL TILING = 12SQM
1 MASON , 1 MALE HELPER
9. O.B.D =600SFT
PRIMER = 800SFT
PUTTI = 600SFT
1 MASON , 2 MALE HELPER
10. WATER FROOFING =4SQM
1 MASON , 2 MALE HELPER
Standard Wastage Consideration for Building Materials
1. Bricks Materials:
During the loading, transportation, and placement of brick materials, it is common for a significant amount of breakage and cutting to occur.
Bricks wastage normally 5% will be considered
2. Cement Materials:
During the loading, transportation, mixing, shifting, and placement of cement materials, a considerable amount of wastage can occur.
In general, a wastage rate of 1.5% to 2% is typically considered for cement materials.
3. Fine Aggregate Materials:
During the loading, transportation, and placement of fine aggregate materials, a significant amount of wastage can occur.
Typically, a wastage rate of 10% is considered for fine aggregate materials.
4. Coarse Aggregate Materials:
During the loading, transportation, and placement of coarse aggregate materials, there is a possibility of significant wastage occurring.
Coarse aggregate materials wastage normally 5% will be considered.
5. Steel Materials:
The allowable wastage for steel works is typically set at 3%.( i.e. cutting/bending wastage).
For reconciliation purpose, + or -2% allowable for rolling margin in this accounts.
For steel rods with a diameter above 25mm, it is recommended to consider a wastage rate of 5%.
6.Concrete Materials:
During the process of concrete pouring or placement, as well as during loading and transportation, a certain amount of concrete wastage is expected. Typically, a wastage rate of 3% is considered for concrete.
7. Tiles Materials:
During the loading, transportation, and placement of tiles, it is common for a significant amount of breakage and cutting to occur.
Tiles wastage normally 5% Considered.
8. Paint Materials:
During the application of paints, it is possible for some paint to accidentally fall on the ground, resulting in wastage.
Paints wastage normally 2% Considered.
9. Structural Steel Materials:
During the fabrication of structural steel materials, a considerable amount of cutting and wastage can occur.
Typically, a wastage rate of 5% to 10% is considered for structural steel materials.
10. Electrical wires and cables
The standard wastage rate for electrical wires and cables is typically considered to be 3% to 5%. This accounts for any loss of wires and cables during cutting, stripping, handling, and also takes into account the skill level of the workers.
11. Plumbing pipes and fittings
The standard wastage of plumbing pipes and fittings is usually considered as 2% to 3%. This includes the loss of pipes and fittings during cutting, joining, and fixing in position. However, this may vary depending on the complexity of the plumbing installation, the method of handling, and the skill of the workers.
12. Plywood
The standard wastage rate for plywood is typically considered to be 5% to 10%. . This includes the loss of plywood during cutting, shaping, and fixing in position. However, this may vary depending on the quality of plywood, the method of handling, and the skill of the workers.
Thumb Rules for Civil Engineering