Project Inputs
Example Data Table
| Scenario | Mode | Key inputs | Layers | Overlap | Waste | Typical outcome |
|---|---|---|---|---|---|---|
| Concrete slab protection | Floor | Length 40, Width 25 | 1 | 10% | 8% | Order ~1,080 sq unit adjusted |
| Room containment wrap | Walls | Perimeter 72, Height 10, Openings 40 | 2 | 12% | 10% | Higher rolls due to double layer |
| Multiple equipment covers | Rectangles | Count 8, Size 6 × 4 | 1 | 5% | 5% | Small total, easy roll planning |
Formula Used
- Floor / slab: Net Area = Length × Width
- Walls: Net Area = (Perimeter × Height) − Openings Area
- Multiple rectangles: Net Area = Count × (Length × Width)
- Custom: Net Area = Entered Area
- Adjusted area: Adjusted = Net Area × Layers × (1 + Overlap%) × (1 + Waste%)
- Roll coverage: Area per Roll = Roll Width × Roll Length
- Rolls needed: Rolls = Ceiling(Adjusted ÷ Area per Roll)
How to Use This Calculator
- Select units and a calculation mode for your layout.
- Enter dimensions, then set layers, overlap, and waste.
- Input roll width and roll length for roll planning.
- Click Calculate to view results above this form.
- Use CSV or PDF buttons to share the estimate.
Planning the coverage scope
Poly sheeting is commonly used for dust control, curing protection, moisture barriers, temporary enclosures, and surface isolation. Coverage planning should start with a clear scope: floor protection, wall wrapping, equipment masking, or full-room containment. Confirm boundaries, access routes, and tie-in points before measuring.
Choosing allowances for overlaps and waste
Seams, folds, corner turns, and taping paths create unavoidable overlap. A practical overlap allowance is often 5–15%, depending on seam spacing and crew method. Waste accounts for trimming, damaged sections, and rework; 5–12% is typical on active sites. Higher allowances reduce stoppages when roll changes or repairs occur.
Layering and protection performance
Layer count drives durability and containment. Single-layer installs fit short-term protection, while two layers improve puncture resistance, reduce tear propagation, and support high-traffic paths. For negative-air containment, extra layers at entry points and corners help maintain integrity. The calculator multiplies net area by layers, overlap, and waste to estimate ordering volume.
Roll strategy and layout efficiency
Roll width and length affect seams and labor time. Wider rolls reduce seam count on floors and long walls, but can be harder to handle in tight spaces. Use roll area to estimate how many rolls to stage per zone. If layout requires frequent cuts, consider shorter rolls to reduce handling and scrap. Always verify that dimensions match your selected unit system.
Worked example using typical site numbers
Example: A slab is 40 by 25 with one layer. Set overlap to 10% and waste to 8%. Net area equals 1,000 square units. Adjusted area becomes 1,000 × 1 × 1.10 × 1.08 = 1,188 square units. With a 12 by 100 roll, roll area is 1,200 square units, so rolls needed round up to 1. If you switch to two layers, rolls typically increase to 2 for the same slab.
FAQs
1) Should I measure gross or net area?
Measure net area for the surface you must cover, then use overlap and waste to reach an orderable quantity. For walls, subtract openings when practical.
2) What overlap percentage is a safe default?
A common starting point is 10%. Increase it for many seams, complex corners, or heavy taping. Reduce it for long, uninterrupted runs with wide rolls.
3) How do I account for doors and windows on wall wraps?
Estimate the total openings area and enter it under openings. If openings will still be partially sealed, subtract only the portion you truly will not cover.
4) When should I use two layers or more?
Use multiple layers for high-traffic protection, abrasion risk, negative-air containment, or when thicker coverage is specified. Layers scale material needs linearly.
5) Why do roll estimates sometimes feel low?
Roll math assumes you can use most of each roll area. Tight spaces, frequent cuts, and odd shapes increase scrap. Raise waste allowance to match site conditions.
6) Can I mix unit systems across inputs?
Avoid mixing units. Select feet or meters first, then enter all dimensions in that system. Mixed units can understate or overstate area significantly.
7) How should I validate results before ordering?
Run one scenario with conservative allowances, then compare against a quick field check. Confirm roll sizes with your supplier, and stage one extra roll for critical zones.