1. Scope of Work

This method statement describes the installation procedure for industrial roofing waterproofing using TPO (Thermoplastic Polyolefin) or PVC (Polyvinyl Chloride) single-ply membrane systems, including surface preparation, membrane installation, detailing, and quality control.

2. Materials

• TPO / PVC roofing membrane (1.2mm / 1.5mm or as specified)
• Compatible primer (if required)
• Insulation boards (PIR / EPS / XPS, if applicable)
• Vapor barrier (if required)
• Mechanical fasteners and plates
• Adhesives (for fully adhered system)
• Hot-air welding equipment
• Sealant and prefabricated accessories (corners, outlets, flashing)

All materials shall comply with approved project specifications and manufacturer requirements.

3. Surface Preparation

• Ensure substrate (concrete deck or metal deck) is structurally sound, dry, clean, and free from dust, oil, sharp edges, and debris.
• Check roof slope to ensure proper drainage (minimum 1–2% recommended).
• Repair cracks, voids, or uneven surfaces before membrane installation.
• Install vapor barrier and insulation (if specified) according to design.

4. Installation Method

4.1 Layout

• Unroll membranes and allow relaxation for at least 20–30 minutes before fixing.
• Position sheets according to wind direction and drainage layout.
• Overlap edges minimum 80–100 mm (as per manufacturer specification).

4.2 Fixing Methods

Depending on the project specification:

A. Mechanically Fastened System

• Secure membrane using approved fasteners and plates along the overlap line.
• Spacing as per wind load calculation and manufacturer guidelines.

B. Fully Adhered System

• Apply adhesive evenly on substrate.
• Roll membrane into adhesive and press firmly to remove air pockets.

4.3 Hot-Air Welding

• Weld membrane overlaps using automatic or manual hot-air welding machine.
• Welding temperature: 350–600°C (adjusted according to weather conditions and membrane type).
• Seam width: minimum 30–40 mm.
• Conduct seam probe test after cooling to ensure proper bonding.

5. Detail Treatment

• Install prefabricated internal/external corners.
• Reinforce around roof penetrations (pipes, vents, equipment supports).
• Properly seal parapet walls, flashing edges, roof drains, and terminations.
• Apply termination bars and sealant where required.

6. Inspection and Quality Control

• Check all seams using seam probe testing.
• Conduct random peel tests if required.
• Ensure no wrinkles, fish mouths, or unbonded areas.
• Perform water ponding test (24–48 hours) if specified.

7. Safety Requirements

• Workers must wear PPE (helmet, gloves, safety shoes).
• Ensure fire safety measures when using hot-air welding equipment.
• Follow site safety regulations at all times.

8. Completion and Warranty

• Clean the site after installation.
• Submit inspection report and warranty documentation.
• Provide manufacturer warranty (typically 10–20 years depending on system).