Converting a Wholesale Roofing Felt Area Requirement into Roll Quantities
Convert an area requirement into rolls using the actual roll dimensions. Keep nominal roll area separate from the project’s net coverage and purchasing allowance.
By Merily Waterproofing · Bulk supply for importers, distributors and building-material wholesalers
Calculate nominal area first
Nominal area per roll = width × length. A 1 m × 7 m roll contains 7 nominal m²; a 1 m × 20 m roll contains 20 nominal m².
This calculation says nothing about the roll’s tested performance or suitability for the intended assembly.
Use the buyer’s purchasing area
Ask whether the given figure is net finished area or the amount of material to purchase. Any allowance for overlaps, cuts, waste or multiple layers must come from the project’s actual design and purchasing plan.
Do not insert a universal percentage and describe it as correct for every roof.
Round to complete saleable rolls
Once the purchasing area is confirmed, divide by nominal area per roll and round up to whole rolls. Then check MOQ, packing and shipment practicality.
Illustration: a confirmed purchase requirement of 1,000 nominal m² needs 125 rolls at 8 m² each, or 50 rolls at 20 m² each. This is an arithmetic comparison, not a project take-off.
Put it in your buying record
| Roll format | Nominal area | Rolls for 1,000 nominal m² |
|---|---|---|
| 1 m × 7 m | 7 m² | 143 rolls, rounded up |
| 1 m × 8 m | 8 m² | 125 rolls |
| 1 m × 9 m | 9 m² | 112 rolls, rounded up |
| 1 m × 20 m | 20 m² | 50 rolls |
Questions buyers ask
Does this include overlap allowance?
No. The example starts from a confirmed nominal purchasing area.
Why round up?
A whole-roll purchase needs enough nominal material to cover the stated purchasing amount.
Can the calculation select the right material?
No. Confirm product suitability first, then use the chosen roll dimensions.