Calculating the quantity of shuttering (or formwork) involves determining the surface area that will come into contact with the concrete. Here’s a general process on how to do it:
Identify the Shuttering Areas: Identify all the areas where you’ll be using the shuttering. This typically includes surfaces like slabs, beams, columns, and footings.
Measure the Surface Areas: Measure the length, width, and height (where applicable) of each of these areas. Use these measurements to calculate the surface area for each type of structural element. The formulae are as follows:
- For a rectangular slab: Area = length x width
- For a beam: Area = 2 x (length + width) x depth
- For a rectangular column: Area = 2 x (length + width) x height
- For a circular column: Area = 2πrh + 2πr² (where r is radius and h is height)
Sum Up: Add up all the calculated surface areas. This gives you the total shuttering area.
Waste Factor: It’s a good practice to include a waste factor to account for cutting losses, damage, etc. Typically, a waste factor of about 5% is added1.
Final Calculation: Multiply the total shuttering area by the waste factor to get the final quantity of shuttering needed.
Please note that this is a simplified explanation. The actual calculation can be more complex depending on the specifics of the project, including the shape and size of the structural elements, the type of shuttering material used, and other factors.
Consult with a qualified engineer or construction professional to ensure accurate calculations.