System Overview
Single-ply membrane roofing systems dominate the commercial flat roof market, accounting for over 60% of new installations. These systems consist of factory-manufactured sheets of waterproof material that are mechanically attached, adhered, or ballasted to create a seamless protective layer.
Understanding the differences between TPO, PVC, and EPDM - plus the various attachment methods and their cost implications - is critical for competitive and profitable commercial roofing estimates.
Pro Tip: Single-ply systems are often specified by the architect/engineer. Always verify the specified membrane type, thickness, and attachment method in Division 07 specifications before estimating.
Membrane Types
TPO (Thermoplastic Polyolefin)
The most popular single-ply membrane today, TPO combines the benefits of EPDM and PVC at a lower cost. White reflective surface reduces cooling costs and qualifies for Energy Star and cool roof programs.
45 mil, 60 mil, 80 mil (60 mil most common)
10 ft, 12 ft wide × 50-100 ft long
$0.60-1.20/SF (45-80 mil)
Hot-air welding (heat gun)
- • Lower cost than PVC
- • Energy efficient (white reflective)
- • Heat-welded seams (strongest)
- • Good puncture resistance
- • Wide acceptance and availability
PVC (Polyvinyl Chloride)
Premium single-ply membrane with excellent chemical resistance and fire performance. Preferred for restaurants, chemical facilities, and buildings requiring superior fire ratings.
45 mil, 50 mil, 60 mil, 80 mil
10 ft, 12 ft wide × 50-100 ft long
$0.80-1.60/SF (higher than TPO)
Hot-air or chemical welding
- • Buildings with grease/chemical exposure
- • High fire-rating requirements
- • Long-term performance critical
- • Premium warranty requirements
EPDM (Ethylene Propylene Diene Monomer)
The original single-ply membrane, EPDM (rubber roofing) has been used since the 1960s. Black membrane absorbs heat but remains popular for its proven durability and lower cost.
45 mil, 60 mil (60 mil standard)
10 ft, 20 ft, 25 ft wide × 50-100 ft
$0.50-0.90/SF (lowest cost)
Tape or liquid adhesive
- • Black color absorbs heat (higher cooling costs)
- • Tape seams less reliable than welded
- • Proven 30+ year track record
- • Lowest material cost
- • White EPDM available but less common
Attachment Methods
The attachment method dramatically impacts material costs, labor hours, and warranty terms. Specifications will typically dictate the required method.
1. Fully Adhered
Membrane bonded to substrate with adhesive or self-adhered backing. Highest wind uplift resistance and warranty coverage.
- • Solvent-based (fast cure, strong)
- • Water-based (low VOC, slower cure)
- • Two-part urethane (premium)
- • Adhesive: $0.30-0.60/SF
- • Labor: 2.5-3.5 hours/square
- • Most expensive method
2. Mechanically Attached
Membrane fastened to deck with screws and plates at seams or throughout the field. Most common method for new construction.
- • Seam only (12 inch on-center)
- • 6-inch pattern (high wind)
- • 4-inch pattern (hurricane zones)
- • Fasteners/plates: $0.15-0.40/SF
- • Labor: 2.0-3.0 hours/square
- • Mid-range cost
3. Ballasted
Membrane laid loose and held down with river rock, pavers, or concrete blocks. Requires structural capacity for ballast weight (10-15 psf).
- • River rock (1.5-2 inch, 10-12 psf)
- • Concrete pavers (easier to maintain)
- • Protection mat required under ballast
- • Ballast: $0.40-0.80/SF delivered
- • Labor: 1.5-2.5 hours/square
- • Crane/material handling costs
4. Hybrid Systems
Combination of methods - such as adhered at perimeter/penetrations with mechanically attached field, or ballasted field with adhered perimeter.
Common approach: Mechanically attach field of roof, fully adhere 10-15 ft perimeter zone for enhanced wind uplift resistance.
System Components
Insulation
Most single-ply systems include rigid insulation for energy efficiency and to create positive drainage (tapered systems).
R-6 per inch, $1.50-2.50/SF
R-5 per inch, $2.00-3.00/SF
Cover Board
Protective layer between insulation and membrane. Required for some warranties and high-traffic areas.
Options: 1/2 inch DensDeck, 1/4 inch Securock, 1/2 inch fiberboard ($0.60-1.20/SF)
Flashing Materials
Membrane flashing, metal termination bars, drip edges, and coping caps for transitions and penetrations.
Drainage Components
Roof drains, scuppers, overflow drains, and sump pans. Critical for proper water management.
HVAC Curbs & Penetrations
Pre-fabricated or field-built curbs for HVAC units, skylights, and other roof-mounted equipment.
Estimation Considerations
Deck Type Impact
Steel, concrete, and wood decks require different fastener types, insulation attachment methods, and labor approaches.
Warranty Requirements
NDL (No Dollar Limit) warranties require specific attachment methods, cover board, and manufacturer-approved details.
Roof Complexity
Penetrations, multiple roof levels, curved parapets, and limited access significantly increase labor hours.
Access & Staging
High-rise buildings, occupied facilities, and limited crane access drive up material handling and labor costs.
Material Takeoff Details
Step-by-Step Takeoff Process
Measure total roof area. Flat roofs use actual area (no pitch multiplier needed).
Account for seam overlaps (typically 6-12 inches), cuts around penetrations, and damaged material.
Determine roll size (typically 10 ft or 12 ft wide × 100 ft long) and calculate coverage.
Perimeter walls, curbs, expansion joints - all require membrane flashing.
Calculate based on specified fastener pattern and seam spacing.
Calculate layers of insulation (match roof area + 3% waste). Tapered systems require detailed layouts.
Labor Estimation Guidance
Single-ply labor rates vary significantly based on attachment method, roof height, and complexity. Use these baseline rates and adjust for site conditions.
Baseline Productivity Rates
| Task | Hours/Square | Crew Size | Notes |
|---|---|---|---|
| Tearoff existing roof | 1.5-2.5 | 4-5 | Varies by system type |
| Insulation install | 0.8-1.2 | 3-4 | Mechanical or adhered |
| Membrane - Fully Adhered | 2.5-3.5 | 3-4 | Most labor intensive |
| Membrane - Mechanically Attached | 2.0-3.0 | 3-4 | Standard method |
| Membrane - Ballasted | 1.5-2.0 | 3-4 | Plus ballast placement |
| Wall/curb flashing | Variable | 2-3 | $8-15 per LF installed |
| HVAC curb (each) | - | 2 | 2-4 hours per unit |
Example Labor Calculation
Key Takeaways
- ✓TPO is the most common - white, heat-welded, cost-effective
- ✓Attachment method drives cost - fully adhered most expensive, ballasted cheapest
- ✓Always verify specifications for membrane type, thickness, and attachment requirements
- ✓Flashing and detail work is where quality matters - dont cut corners on labor hours
- ✓Insulation and cover board add significant cost but are usually required for warranty
Get the Complete Single-Ply Estimating Template
Excel template with attachment method calculators, fastener pattern worksheets, insulation layouts, flashing takeoff tools, and labor estimators for TPO, PVC, and EPDM systems.
Template Includes:
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