Bubbles and Hollows
Controlling the uniformity of manually applied base adhesive can be challenging. Variations in coating thickness cause uneven solvent evaporation in the adhesive film after drying. This often leads to bubbles and hollow areas forming once the waterproofing membrane is applied. Additionally, repeatedly applying adhesive at roll seams can trap air bubbles. High temperatures exacerbate these issues, causing bubbles to expand and sometimes merge into larger areas.
Prevention and Control Measures
- Ensure even viscosity and uniform manual application of adhesive when laying waterproof rolls. Allow the base and lap adhesives to dry fully before membrane installation.
- After laminating the membrane, expel trapped air and use a roller or similar tool to smooth and compact the surface.
- Apply adhesive at seams in timed intervals. Avoid bonding joints too early to prevent bubble formation.
Damage to Waterproof Layer
Constructing equipment foundations after applying the waterproof layer can crush the membrane under their weight. If the waterproof layer is damaged during drilling or other operations and not repaired promptly, it compromises waterproofing integrity.
Prevention and Control Measures
- Always build equipment foundations before applying roof waterproofing. Wrap waterproof membrane material around the foundation’s upper part and add an extra protective layer. Seal and compact the waterproof edges tightly with sealant at the base.
- For lightweight equipment placed on waterproof layers, add a reinforcing membrane layer on top. If necessary, pour fine aggregate concrete at a minimum thickness of 50mm to protect the waterproofing.
- For post-excavation foundations, assess waterproof damage carefully and repair the roof waterproof layer promptly according to the damage extent.
Leakage at the Joints
Incorrect laying direction or insufficient overlap width between membranes often causes leaks at the joints of roof waterproofing membranes.
Prevention and Control Measures
- Use proper overlapping methods when laying rolls. For overlaps parallel to the ridge, align them in the water flow direction. For overlaps perpendicular to the ridge, align according to the prevailing wind direction.
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Adjust roll laying direction based on roof slope:
- For slopes under 3%, lay rolls parallel to the ridge.
- For slopes between 3% and 15%, rolls can be laid parallel or perpendicular.
- For slopes over 15% or areas subject to vibration, lay asphalt waterproof membranes perpendicular to the ridge.
- High polymer modified asphalt and synthetic polymer membranes may be laid in either direction.
- Stagger lap joints between lower layers and adjacent rolls by one-third to one-half of the roll width. Short edges should be staggered by at least 500mm, and lap widths must meet specified standards.
Wrinkles and Curled Edges
Forcefully stretching the membrane, improper handling, or missed adhesive application at joints can cause wrinkles and curling after installation.
Prevention and Control Measures
- Clean joint areas thoroughly before applying adhesive. Remove any contaminants with a suitable solvent.
- Apply adhesive evenly to joints, ensuring no missed spots. After bonding, roll the membrane evenly to eliminate dry edges. Repair any dry areas promptly with adhesive.
- Avoid stretching the membrane during installation. Apply adhesive evenly to prevent wrinkles and folds at the edges.
- Use short edge joints during installation to ensure even cutting and proper fitting, minimizing wrinkles and edge curling.
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