Lots of readers ask how long it takes to build with earthbags. Well, that’s difficult to answer because the strength of workers varies and every job is different. But it’s good to have an approximate figure to work with for planning purposes. The following calculations show how long it took to build the first 5’ of walls on the training center in Nepal. They had a mix of strong and average workers which helps make this example more realistic.
Wall height will vary so the calculations are for square feet of wall surface. Interior and exterior walls are included in this example. Wall length was determined by measuring the length of outside walls and the length of the interior wall. We’ll assume 8 hour days, and assume students work half as hard as strong workers, so use 5.5 students instead of 11. For ease of calculations, do not deduce for windows and doors.
Calculations for hours per square foot of earthbag wall surface:
1. Number of days for gravel bags: 2 days for 6 strong people = 12 worker days
2. Number of days for earthbags: 6 days for 20 people (9 strong and 11 students or 5.5 = 87 worker days)
3. Total labor: 12 + 87 = 99 worker days x 8 hrs = 792 hours
4. Wall height at this point: 5’
5. Wall length: 195’
6. Square feet of wall surface: 195’x 5’ = 975 sq. ft.
7. Solution: .81hour per square foot of exterior wall surface (check: .81 x 975 sq. ft. = 790 = OK)