Hello, everyone.
This is Enta.
It’s been a while since we switched to a two-day weekend system, hasn’t it?
If you are the general contractor, there is a markup of about 5% in the cost estimate.
So, I’d like to consider what the markup rate would be for us as subcontractors.
Calculate the number of days based on the following conditions. Condition 1
The standard is two days off per week
Two-day weekend
Closed on Public Holidays
Obon Holiday
New Year's Holiday
The past 10 years
| 年 | Number of Workdays | Number of Vacation Days |
| 2024 | 246 | 119 |
| 2023 | 243 | 122 |
| 2022 | 240 | 125 |
| 2021 | 240 | 125 |
| 2020 | 239 | 126 |
| 2019 | 238 | 127 |
| 2018 | 243 | 122 |
| 2017 | 244 | 121 |
| 2016 | 243 | 122 |
| 2015 | 242 | 123 |
| 2014 | 242 | 123 |
Calculate the number of days based on the following conditions. Condition 2
One day off per week
Closed on Public Holidays
Obon Holiday
New Year's Holiday
| 年 | Number of Workdays | Number of Holidays |
| 2024 | 296 | 69 |
| 2023 | 290 | 75 |
| 2022 | 290 | 75 |
| 2021 | 289 | 76 |
| 2020 | 290 | 75 |
| 2019 | 288 | 77 |
| 2018 | 291 | 74 |
| 2017 | 292 | 73 |
| 2016 | 293 | 72 |
| 2015 | 291 | 74 |
| 2014 | 293 | 72 |
Calculate the number of days based on the following conditions. Condition 3
One day off per week
No days off on holidays
Obon Holiday
New Year's Holiday
| 年 | Number of Workdays | Number of Holidays |
| 2024 | 306 | 59 |
| 2023 | 306 | 59 |
| 2022 | 306 | 59 |
| 2021 | 306 | 59 |
| 2020 | 305 | 60 |
| 2019 | 305 | 60 |
| 2018 | 305 | 60 |
| 2017 | 306 | 59 |
| 2016 | 307 | 58 |
| 2015 | 304 | 61 |
| 2014 | 304 | 61 |
Let's compare the above.
| Two days off per week, holidays off, Obon and New Year's holidays Condition 1 | One day off per week; holidays off; Obon and New Year's holidays Condition 2 | One day off per week; no days off on public holidays; Obon and New Year's holidays Condition 3 | ||||||||
| 年 | Number of Workdays | Number of Holidays | 年 | Number of Workdays | Number of Holidays | 年 | Number of Workdays | Number of Holidays | ||
| 2024 | 246 | 119 | 2024 | 296 | 69 | 2024 | 306 | 59 | ||
| 2023 | 243 | 122 | 2023 | 290 | 75 | 2023 | 306 | 59 | ||
| 2022 | 240 | 125 | 2022 | 290 | 75 | 2022 | 306 | 59 | ||
| 2021 | 240 | 125 | 2021 | 289 | 76 | 2021 | 306 | 59 | ||
| 2020 | 239 | 126 | 2020 | 290 | 75 | 2020 | 305 | 60 | ||
| 2019 | 238 | 127 | 2019 | 288 | 77 | 2019 | 305 | 60 | ||
| 2018 | 243 | 122 | 2018 | 291 | 74 | 2018 | 305 | 60 | ||
| 2017 | 244 | 121 | 2017 | 292 | 73 | 2017 | 306 | 59 | ||
| 2016 | 243 | 122 | 2016 | 293 | 72 | 2016 | 307 | 58 | ||
| 2015 | 242 | 123 | 2015 | 291 | 74 | 2015 | 304 | 61 | ||
| 2014 | 242 | 123 | 2014 | 293 | 72 | 2014 | 304 | 61 | ||
What do you think at first glance?
Condition 1 is now.
Condition 3 is in the past.
The break is now half as long, isn't it?
1. Changes in the Number of Workdays (When Comparing a Two-Day Weekend to a One-Day Weekend)
- Two days off per week and holidays off → Approximately 238–244 days per year
- One day off per week and holidays off → Approximately 288–296 days per year
- An increase of about 50 working days per year(an increase of approximately 201 TP3T)
2. Changes in Working Hours per Person
- Assuming an 8-hour workday, this amounts to 400 hours (50 days × 8 hours) of additional work per year.
- This is equivalent to an increase of approximately 201 TP3T under a two-day-off-per-week system.
3. Reduced workability (construction time vs. construction efficiency)
- As the construction time increases,Accumulated fatigue among workersand a decrease in workability (output per hour)
- Long working hours lead to mistakes and reduced efficiency.(As noted in the Japanese Labor Statistics)
- According to general research (you can find the results online), when labor (construction) hours increase by 20%,Productivity has decreased by approximately 5 to 151 TP3TI often do that
4. Specific Impacts of Declining Productivity
- Accumulated Fatigue → An increase in construction errors and a slowdown in construction speed
- Loss of Motivation → When long working hours become the norm (overtime every day), my motivation for work drops (I get sick of watching *Sazae-san*, lol).
- Decline in Efficiency in Work Requiring Creativity → The more mentally demanding the work, the more important rest is. Take work schedules within legal frameworks, for example (a two-day weekend system is more efficient).
5. Estimated Decline in Overall Productivity
- When comparing a two-day weekend to a one-day weekend, the number of working days isEven if there is an increase of approximately 201 TP3T, construction will proceedGender is5–151 TP3T decline; if this continues, it could decline further
- Even if the number of construction days is increased, it is not certain that the construction volume will increase by 20%.
- With one day off per week, the actual increase in productivity may be limited to around 5 to 101 TP3T.
- This could have a particularly negative impact in the case of long-term field assignments
With that in mind, let’s consider what the actual rate of increase in estimates is for a two-day weekend.
1. Assumptions for the Calculation
- A Craftsman's Daily Wage：30,000 yen(Hypothetical, Routine, By Expense Category)
- Number of Working Days Under a Two-Day-Off-Per-Week System(Closed on holidays)
- Number of Working Days Under a One-Day-Off-Per-Week System(Closed on holidays)
2. Calculation Method
(1) Number of working days per month under each system
Calculate the number of working days for each year, andCalculate the number of working days per month by dividing by 12。
Example (for 2024):
- Number of Working Days Under a Two-Day-Off-Per-Week System：246 days
- Number of working days per month = 246 ÷ 12 = May 20.5
- Number of Working Days Under a One-Day-Off-Per-Week System：296 days
- Number of working days per month = 296 ÷ 12 = July 24–7
(2) Calculation of Monthly Salary Under Each System
-
Two-day weekend system
- Monthly Salary = Number of Working Days in the Month × Daily Wage
- For 2024 → 20.5 days × 30,000 yen = 615,000 yen
-
One-day-off-per-week system
- Monthly Salary = Number of Working Days in the Month × Daily Wage
- For 2024 → 24.7 days × 15,000 yen = 741,000 yen
3) Calculating the Increase Rate
Increase Rate = ((Monthly Salary Under the One-Day-Off-Per-Week System – Monthly Salary Under the Two-Day-Off-Per-Week System) / Monthly Salary Under the Two-Day-Off-Per-Week System) × 100
- For 2024:
(741,000 − 615,000) / 615,000 × 100 = 20.331 TP3T
- If we calculate the other years in the same way,The increase ranges from approximately 19 to 211 TP3T.
Also, since this is a quote, the machinery is included in this amount, so we’ll need to add a surcharge for the machinery as well.
That's what I think, but in reality, the number of construction days has decreased, and the condition of the machinery has actually improved.
Since construction time is reduced by about 20%, you might think the cost would be 20% lower, but in reality, due to rising prices, lease and purchase costs have increased, and
Given the rising prices of fuel and other supplies, I expect costs to remain flat or increase by 5% or less.
In light of the above,
Production increased by about 20 percent
Machinery costs are expected to rise by about 1 to 5 percent
Aside from the ingredients,
The rate of increase in estimates is 20–25%!
I think that's about right.
Everyone, please make sure to add 20% to your future quotes lol
Then, when we fed this data into an AI model to compare the construction progress rates for a two-day weekend versus a one-day weekend,
| Construction Progress Rate (based on 100) | |
| Two days off per week | 100 |
| One day off per week | 102.6 |
It only improves by 2.61 TP3T!!!!
Whaaaaaaaaaaaat?!
Are you serious!!??
So that's how it is...
So, I decided to consider what would happen if I worked about 1.5 hours of overtime every day, assuming a standard two-day weekend.
I entered the following conditions into the AI.
- Normal Daily Working Hours = 8 hours
- Average Overtime Hours = 1.5 hours
- Productivity During Overtime = 75% for Regular Work(Taking into account the decline in efficiency due to overwork)
- Two days off per week (standard) = 100%
- One day off per week (increased number of workdays + decreased productivity + machinery risks) = 102.6%
2. How to Calculate Construction Progress
(1) Rate of increase in daily workload
Compared to the standard workday (8 hours),Add 1.5 hours of overtimeHowever, the productivity during overtime is set at 751 TP3T.
3. Comparison with a One-Day-Off Week
-
One day off per week (Construction Progress: 102.6)
→ Although increasing the number of working days improves progress, the effects are limited to approximately +2.61 TP3T due to reduced productivity and machinery risks. -
Two days off per week + 1.5 hours of overtime (Construction progress: 114.1)
→ By increasing the daily workload, we can proceed with construction more efficiently, and+14.11 TP3T Progress Improvement...can be expected.
4. Conclusion 1
- Construction progress improves more with a two-day weekend plus 1.5 hours of overtime than with a one-day weekend (+14% vs. +2.6%).
- Increasing the number of working hours per day allows work to proceed more efficiently with less waste.
- However, it is necessary to take into account fatigue resulting from long working hours and the increased cost of overtime pay.
Final Conclusion!
1. The quoted price is 20% higher.
2. On projects with tight deadlines, we work about an hour of overtime every day! (Construction efficiency up 14%)
3. If overtime is worked, the amount of work completed will increase, but so will construction costs, so profits may decrease. (However, the project will be completed sooner.)
Just for your reference ^^
See you later.
