Overview
What is cement concrete flooring/screeding?
In RCC building construction, what we do is do chipping work with the help of a chipping hammer over the floor and place concrete of a specified thickness and ratio to give a uniform finish to the floor. This process of placing concrete over a floor is called concrete flooring (screeding). In normal practice in Nepal, a concrete mix ratio of 1:2:4 (cement/sand/aggregate) is used where the thickness varies from 38 mm to 75 mm. Concrete flooring is done with main propose of providing a uniform surface to the floor and cover the conduits laid over the floor. As a concrete material, it's durable and resistant to fire and moisture too. You can place marble, tiles, parquet, or even carry out cement punning work over it. In some cases, you can replace cement concrete flooring with ips flooring.
Here we are dealing with a rate analysis of 38mm thick cement concrete flooring with a mix ratio of 1:2:4 (cement/sand/aggregate).
Calculations
As in our other blogs on rate analysis, we are taking references to rates and workers from the district rate of Kathmandu, 079/80, and DUDBC norms. You can find its details in our previous blog: https://www.ieccc.com.np/2024/06/cost-of-m20-grade-concrete-in-Nepal.html.
Also, the calculation steps follow similar steps.
- Estimate of materials and cost
- Workers rate
- Cost of hiring tools and equipment
- Contractor's overhead and profit
Let's consider concrete flooring with a thickness of 38 mm and a mix ratio of 1:2:4. We are taking a 10 sq m floor as the workers rate in the DUDBC code has been specified for 10 sq m. We will finally find the rate per square meter by dividing by the floor area.
Materials estimate
Volume of concrete = area of floor * thickness
= 10 * (38/1000)
Volume of concrete = 0.38 cu.m.
Concrete dry volume: 1.54 * wet volume
= 0.38 * 1.54
Dry volume of concrete = 0.58 cu.m.
Adding 10% extra for uneven surfaces,
Dry volume = 0.58 + 0.58 * 0.1 = 0.63 cu.m.
Volume of cement = dry volume of concrete * (cement ratio/sum of ratios)
= 0.63 * (1/7)
Volume of cement = 0.09 cu.m.
Cement in KG = volume * density
= 0.09 * 1440
Cement in KG = 129.6 kg
Number of bags of cement = 129.6/50 = 2.5 bags
Volume of sand = 2 * volume of cement (since mix ratio is 1:2:4)
= 2 * 0.09
Volume of sand = 0.18 cu.m.
(Alternately, you can find the volume of sand by: dry concrete volume * (sand ratio/total ratios))
Volume of aggregate = 4 * cement volume
= 4 * 0.09
Volume of aggregate = 0.36 cu.m.
Alternately, you can find the volume of aggregate by: dry concrete volume * (aggregate ratio/sum of ratios)
Volume of water from water to cement ratio
Water/cement = 0.6 (from IS 1489 code)
Volume of water = 0.6 * 2.5 * 50 = 75 ltr (2.5 bags of cement are used).
The cost of the material, as mentioned, is KTM district rate 079/80.
Cement: 2.5 bags at 700 = Rs. 1750.00
Sand: 0.18 cu.m at 3319.61 = RS.597.53
Aggregate: 0.36 cu.m. at 3390.21 = Rs. 1220.47
Water: 75 ltr. at 0.2 = Rs. 15.00
Total cost of materials: 1750.00 + 597.53 + 1220.47 + 15.00 = Rs. 3583.00
Rate analysis of workers as DUDBC and KTM district rates: 089/80
Skilled workers: 1.25 at 1185.00 = Rs. 1481.25
Unskilled workers: 2.5 at 870.00 = Rs. 2175.00
Total worker cost: 1481.25 + 2175.00 = Rs. 3656.25.
Cost of tools and equipment's used
The cost of tools and equipment's at 3% of unskilled workers = 3% of 2175.00 = Rs. 8.25.
Total cost: materials cost + workers cost + tools and equipment hire cost
= 3583.00 + 3656.25 + 8.25
Total cost = Rs. 7247.50
Including the contractor's overhead and profit
Contractor overhead: 15% of the total cost
= 15% of 7247.50
Contractor overhead = Rs. 1087.12
Total cost per 10 square meters Concrete flooring: 7247.50 + 1087.12 = Rs.8334.62
Total cost per square meter of concrete flooring: 8334.62/10 = Rs. 833.462
Summery
|
Screeding work in a 1:2:4 mix: all complete per 10 sq m of floor area. |
||||||
|
Description |
Type |
Unit |
Quantity |
Rate |
Amount |
Remarks |
|
Workers |
Skilled |
MDay |
1.25 |
1185.00 |
1481.25 |
|
|
Unskilled |
MDay |
2.50 |
870.00 |
2175.00 |
|
|
|
Materials |
Cement |
Bags |
2.50 |
700.00 |
1750.00 |
|
|
Sand |
Cu.m. |
0.18 |
3319.61 |
597.53 |
|
|
|
Aggregate(10mm) |
Cu.m |
0.36 |
3390.21 |
1220.47 |
|
|
|
Water |
Ltr. |
75.00 |
0.20 |
15.00 |
|
|
|
Tools and plants account for 3% of unskilled workers. |
8.25 |
|
||||
|
Sub-Total |
7247.50 |
|
||||
|
Contractor overhead and profit at 15% |
1087.12 |
|
||||
|
Total cost per 10 sq m of concrete flooring |
8334.62 |
|
||||
|
Total cost per unit square meter of concrete flooring |
833.46 |
|
||||
In words: Rs. eight hundred thirty-three and forty-six paisa only.
Others
Similarly, you can calculate rate analysis for other mix ratios and thicknesses too, following similar processes and codes.
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