Waterproof backing board, as an important component of building waterproofing system, is widely used in damp environments such as basements, bathrooms, roofs, etc. However, in actual construction and use, various problems often arise due to material quality, construction techniques, or environmental factors. The following summarizes common problems and solutions for waterproof backing boards for reference.

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1、 Common Problems and Root Cause Analysis

1. Cracking or fracture

-Reason:

-The material itself has insufficient tensile strength and cannot withstand deformation of the base layer;

-Failure to reserve expansion joints during construction resulted in stress concentration due to temperature changes;

-The grassroots is uneven or has hollowing, and the backing board is subjected to uneven stress.

-Solution:

-Choose backing plate materials with high elasticity and tensile strength that meet the standard;

-During construction, reserve expansion joints according to specifications (recommended spacing ≤ 6m) and fill them with flexible sealant;

-Before construction, level the base layer and repair any hollow areas.

2. Leakage at the joint

-Reason:

-No specialized adhesive or sealing material is used for the seams;

-Insufficient overlap width (such as<10cm) or incorrect overlap direction (against the direction of water flow);

-During construction, the environmental humidity is too high and the adhesive is not fully cured.

-Solution:

-Use specialized adhesives or hot melt welding processes compatible with the backing plate;

-Ensure that the overlap width is ≥ 10cm and overlaps in the direction of water flow;

-The humidity in the construction environment should be controlled below 85%, and drying equipment should be used if necessary.

3. Bulging or bubbling

-Reason:

-The moisture content at the grassroots level is too high (such as>8%), causing hollowing after water evaporation;

-Uneven application of adhesive and incomplete adhesion in some areas;

-Insufficient exhaust after the backing board is laid.

-Solution:

-Before construction, check the moisture content of the base layer and only proceed with construction after it meets the standard;

-Apply adhesive evenly using a serrated scraper to ensure a bonding area of ≥ 90%;

-After laying, use a pressure roller to exhaust air from the center to the edges to remove any air.

4. Peel off from the waterproof layer

-Reason:

-Improper surface treatment of the backing plate (such as uncleaned oil and dust);

-Poor compatibility between waterproof materials and backing plates (such as solvent based coatings corroding backing plates);

-After construction, no protective layer was applied, resulting in peeling due to external damage.

-Solution:

-Clean the surface of the backing board with solvent before construction to ensure no contamination;

-Choose waterproof materials that match the backing board (such as water-based coatings or reactive adhesives);

-Cover the waterproof layer with a protective layer (such as cement mortar or PE film) in a timely manner after completion.

5. Performance degradation after long-term use

-Reason:

-Poor weather resistance of materials, aging caused by UV or chemical corrosion;

-Long term immersion in water with water absorption exceeding the standard (such as>3%);

-Microorganisms (molds, algae) breed and damage structures.

-Solution:

-Select UV resistant and corrosion-resistant backing plates (such as HDPE material with added antioxidants);

-Control water absorption rate ≤ 1%, or use foam materials with closed cell structure;

-Add antibacterial agents or regularly spray anti mold solutions.

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2、 Systematic preventive measures

1. Material selection

-Priority should be given to products certified by national standards (such as GB 18173.1);

-Select characteristics based on the usage environment: low temperature resistance (below -30 ℃) is required in high-altitude areas, and salt spray resistance is required in coastal areas.

2. Construction process control

-Grassroots treatment: Flatness deviation ≤ 3mm/2m, cracks need to be repaired with epoxy mortar;

-Node strengthening: Add additional layers (width ≥ 30cm) to the corners of yin and yang, the roots of pipelines, and other areas;

-Environmental requirements: Temperature between 5-35 ℃, humidity ≤ 85%, construction is prohibited on rainy days.

3. Acceptance and maintenance

-Conduct a 24-hour closed water test during acceptance, and a water level drop of ≤ 2mm is considered qualified;

-Regularly inspect the joints and edges, and promptly repair any aging found.

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3、 Special problem handling cases

Case 1: Brittle cracking of backing plate under low temperature environment

-Problem: During winter construction in the north, the backing board broke during transportation.

-Solution: Use low-temperature backing plates (glass transition temperature ≤ -40 ℃) and maintain an environment above 5 ℃ during transportation.

Case 2: Reaction between backing plate and coating

-Problem: After applying polyurethane waterproof coating, the surface of the backing board dissolves.

-Solution: First apply interface agent (such as epoxy primer) for isolation, and then apply waterproof layer.

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Conclusion

The quality issues of waterproof backing boards often involve multiple aspects such as materials, design, construction, and maintenance. By scientifically selecting materials, standardizing construction, and regular maintenance, the risk of leakage can be significantly reduced and the service life can be extended. It is recommended to establish a complete quality control system in the project to avoid potential hazards from the source.