BASIC THUMB RULES FOR VALUERS & CIVIL ENGINEERS
Thumb Rules For Civil Engineering is essential for any civil engineer, Site engineer, or civil supervisor. They play a crucial role while taking quick decisions on site. The Thumb Rule of Civil Engineering or the thumb rule for construction helps you in finding out the solution using a simple mathematical formula and make smart decisions whenever needed.
But, while using these thumb rules, you must remember that the thumb rule never gives the exact or accurate results, you just have used them for approximate results.
There is a number of Thumb Rule For Civil Engineers that we used in construction work. So, the following are some most frequently used Thumb rules on the Construction site.
The Thumb rule method is an approximate & comparing method. In thumb rules and the units are not the same when we compare to get the results. So, ignore units while performing the thumb rule.
Thumb Rule for estimating the Concrete Volume with respect to the area:
The volume of concrete required = 0.038 m3/square feet area
Example:-If Plan Area = 40 x 20 = 800 Sq. m.
So, for the plan area of 800 Sq. m. the area the total volume of concrete required
= 800 x 0.038m3 = 30.4m3
Thumb Rule for Steel quantity required for Slab, Beams, Footing & columns:
Steel required in residential buildings = 4.5 Kgs – 4.75 Kgs / sq. Ft.
Steel required For Commercial buildings = 5.0 Kgs-5.50 Kgs/Sq. Ft.
Thumb rule for Civil Engineers to estimate the shuttering area:
Shuttering costs are taken as 15-18% of the total construction of the building. Shuttering work is done to bring the concrete in Shape. The Thumb rule to estimate the shuttering required is 6 times the quantity of concrete or 2.4 times of the Plinth area.
The following recommendation Thumb Rules for Civil Engineers are gven in B N Dutta for the steel quantity used in different members of the building Percentage of steel in structural Members
- Slab- 1 % of the total volume of concrete
- Beam- 2% of the total volume of concrete
- Column- 2.5% of the total volume of concrete
- Footing- 0.8% of the total volume of concrete
Thumb Rules For Civil Engineers for Brickwork
Following are Thumb Rules for civil engineering for brickwork and cement quantity calculations.
| Brickwork for 1m3 | Cement Qty in m3 | Cement Qty in Bags |
| 230 mm Brickwork | 0.876m3 | 25.4 Bags |
| 115 mm Brickwork | 0.218m3 | 6.32 Bags |
Thumb Rules For Cement Masonry Quantity
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Thumb Rules Plastering Quantity
| Type of Plastering | Cement Qty in Bags | Cement Qty in Kgs |
| Rough Plastering | 0.09 Bags/m2 | 4. 5Kgs/m2 |
| Internal Wall Plastering | 0.09 Bags/m2 | 4.5 Kgs/m2 |
| Duct Plastering | 0.09 Bags/m2 | 4.5 Kgs/m2 |
| External Wall plastering | 0.175 Bags/m2 | 8.75 Kgs/m2 |
| Stucco Plastering | 0.175 Bags/m2 | 8.75 Kgs/m2 |
| Lathen Plastering | 0.55 Bags/m2 | 27.5 Kgs/m2 |
THUMB RULES USED IN THE CONSTRUCTION INDUSTRY
Thumb rules for construction are general guidelines that are commonly used in the construction industry to estimate quantities, time, and cost. I do not have personal experience or beliefs, but I can provide some common thumb rules that civil engineers often use: some thumb rules that are commonly used by civil engineers.
However, it is important to note that these thumb rules are not absolute and may vary depending on specific situations and circumstances. These rules are not precise, but they are useful for quick estimates and rough calculations. Here are some common thumb rules for construction:
These are just some of the thumb rules that civil engineers use in their day-to-day work, but it’s important to note that these are not definitive and may vary depending on specific project requirements, site conditions, and other factors.
Rule of thumb for the slope of a drainage pipe: The slope of a drainage pipe should be at least 1% (1/8 inch per foot) to ensure proper drainage.
Rule of thumb for concrete strength: The concrete mix should have a compressive strength of at least 20 MPa (mega pascal) for regular structures and 30 MPa for structures that are exposed to high loads or harsh environmental conditions.
Concrete mix proportion: The standard ratio of cement, sand, and aggregate in the concrete mix is 1:2:4.
Rule of thumb for the spacing of expansion joints in concrete: The spacing of expansion joints in concrete should be approximately 24 to 36 times the thickness of the concrete.
Rule of thumb for the bearing capacity of soil: The bearing capacity of soil should be at least three times the maximum expected load.
Safe bearing capacity of soil: The safe bearing capacity of soil varies between 2.5 to 4.5 tons per square meter depending on the type of soil.
The slope of the land for drainage: The slope of the land for drainage purposes should be at least 1:100 or 1% for efficient water flow.
Approximate quantity of material required:
Water requirement for construction: Approximately 100 liters of water per cubic meter of concrete is required for normal construction purposes.
Rule of thumb for the depth of foundation: The depth of the foundation should be equal to or greater than the depth of the zone of moisture variation, which is typically around 1.5 to 2 meters.
Depth of footings: The depth of footings should be at least equal to or greater than the depth of the adjacent soil that has not been disturbed by excavation.
Steel requirement for construction: Approximately 1% of the total volume of concrete is used for steel reinforcement.
Reinforcement for columns: For columns, approximately 2% to 5% of steel reinforcement is used for the cross-sectional area of the column.
Lintel depth: The depth of the lintel should be at least equal to the thickness of the wall on which it is placed.
These thumb rules are not intended to replace engineering design or calculations but rather to provide a quick reference guide for a common man by the civil engineers. It is important to always follow the relevant codes and standards for construction and engineering practices.
Rule of thumb for steel reinforcement: The steel reinforcement should be 1% to 2% of the cross-sectional area of the concrete member.
Concrete: To estimate the quantity of concrete required for a particular project, you can use the following rule: for every cubic meter of concrete, you will need 7 bags of cement, 0.42 cubic meters of sand, and 0.83 cubic meters of aggregate.
Brickwork: To estimate the number of bricks required for a particular project, you can use the following rule: for every square meter of brickwork, you will need approximately 500 bricks.
Bricks requirement: Approximately 5000 bricks are required to construct a single room of size 10 ft x 10 ft with a height of 10 ft.
Plastering: To estimate the quantity of plaster required for a particular project, you can use the following rule: for every square meter of plastering, you will need approximately 0.02 cubic meters of mortar.
Steel: To estimate the quantity of steel required for a particular project, you can use the following rule: for every cubic meter of concrete, you will need approximately 100 kg of steel reinforcement.
Excavation: To estimate the quantity of excavation required for a particular project, you can use the following rule: for every cubic meter of excavation, you will need approximately 1.5 to 2.0 cubic meters of loose soil.
It is important to note that these thumb rules are not general guidelines and should not be relied upon completely for accurate estimates. Actual quantities may vary depending on the specific project requirements, site conditions, and other factors. It is always recommended to consult with a qualified engineer or contractor for more accurate estimates.