The installation of TPO-backed waterproofing membranes (especially self-adhesive types) requires strict adherence to process and detailed requirements to ensure the waterproofing layer's tightness and durability. The following is a summary by Tianda Waterproofing.
Construction steps and key points:
1. Pre-construction Preparation
Substrate Preparation
Flatness Requirements: The substrate must be solid, flat, and free of sand and sharp protrusions. Use cement mortar to level uneven surfaces, and pre-seal cracks.
Cleaning and Drying: Thoroughly remove dust, grit, oil, and other debris, and ensure the substrate is dry (moisture content ≤ 9%).
Special Area Treatment: Joints such as corners, pipe roots, and skylights should be rounded (radius ≥ 50mm) and reinforced with precast TPO sheets or non-reinforced flashing membrane.
Environmental Conditions
The application temperature should be between 5°C and 40°C. Avoid rain, snow, or strong winds.
Application is prohibited if the substrate is damp or contaminated.
Materials and Tools
Membranes: Self-adhesive TPO-backed membranes.
Tools: Hot air welder, roller, cutter, line spring, butyl tape (for joint sealing), etc.
2. Construction Process
Traditional Full-Stick Method (Non-Self-Adhesive)
Apply Base Adhesive
Apply a specialized adhesive (such as neoprene) evenly and allow to dry for 5-10 minutes until it is touch-resistant.
Laying the Membrane
Lay along the spring-drawn reference lines, compacting with a roller after removing any air.
Overlap Welding
Overlap ≥ 120mm on the long side, ≥ 75mm on the short side. Hot air welding (double welds require air testing for tightness).
Applying Self-Adhesive Membrane with a Backing
Release Film: Remove the release film from the bottom of the membrane to expose the butyl adhesive layer.
Direct Laying:
Lay the membrane in the direction of drainage, compacting and degassing immediately. No adhesive application is required (dry laying).
Overlap Treatment:
After cleaning the overlap area, seal it with a hot air welder (overlap width ≥ 80mm).
Key Advantage: Self-adhesive adhesive eliminates the need for gluing, increasing construction efficiency by over 50%. The butyl adhesive also penetrates the polyester fabric, creating a mechanical interlock and preventing bulging.
3. Detailed Joint Treatment (Critical!)
Joints (Parapets, Eaves): The facade ends are mechanically secured with metal strips and the gaps are filled with sealant. For parapets > 800mm high, press the ends of the sheet into the pre-recorded grooves to secure them.
Pipe Roots/Through-Wall Pipes: Cut annular reinforcement sheets and hot air weld them to the main sheet. Secure the pipe walls with metal hoops and sealant.
Expansion Joints: Add an additional layer of TPO sheet (width ≥ 300mm) and weld the edges to seal.
4. Construction Precautions
Overlap Specifications: Adjacent sheet sheets should overlap by 120-150mm on the long sides, with a ≥500mm stagger on the short sides.
Welding quality control: The welding temperature is controlled at 400℃~500℃, the speed is uniform, and after welding, check for cold joints and leaking welds.
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