Material wastage standard and value engineering

Material wastage standard

A wastage standard is the permitted percentage loss of a material during handling, storage, cutting and use, allowed for in estimates and rate analysis. Consumption above the standard is treated as excess wastage and must be investigated. Typical allowances: cement 2-3%, sand 5-10%, aggregate 5-10%, bricks 5%, steel bars 3-5% (cutting loss), tiles 5-10%, paint 5%, concrete 2-3%.

Uses: fixing the quantity to be purchased, comparing actual with standard consumption to judge site efficiency, and controlling cost.

Application of value engineering in material procurement

VE studies the function of each material and obtains the same function at the lowest total cost:

1. Rank materials by ABC analysis and apply VE to the high-value (A) items.
2. Define the function and required specification of each item; remove unnecessary requirements (over-specification).
3. Generate alternatives: local or substitute materials, different grades, standard sizes.
4. Evaluate the alternatives on cost, quality, durability, availability and life-cycle cost.
5. Use bulk or contract purchase, suppliers near the site, and reduced transport and handling.
6. Choose the best-value alternative, write it into the purchase order, and review the savings.

Example: using PPC for plain concrete work, or block masonry instead of brick masonry, where the function and strength are the same but the cost and wastage are lower.