The reasons for the leakage of waterproof membrane as following:

1. Stripping of coil and base layer

2. Stripping of coils

3. Leakage occurs due to improper handling of internal and external corners and embedded pipe fittings

The general problems are related to materials and construction methods. Next, we will explain the specific reasons one by one.

1. Stripping of the coil from the base layer, blistering and cracking of the coil

Reason analysis: The waterproof protective wall was not built on the cushion layer, resulting in uneven settlement and tearing of the coiled material pasted on it; The grassroots treatment is not in place, making it difficult for the rolls to be firmly adhered; Directly laying coiled materials on a damp base layer, the moisture in the base layer is heated and vaporized, causing water vapor to cause blistering and cracking of the coiled materials; The adhesive used is incompatible with the roll material, and the joints of the roll material are difficult to bond firmly.

Response measures:

1) Waterproof protective wall built on concrete cushion

2) Grassroots treatment

a. Plaster cement mortar

UEA and other expansion agents (10-12%) can be added to prevent cracking; Mixing inorganic aluminum salt waterproof agent (5-10%) to achieve quick drying; Apply a circular arc at the corners to prevent breakage. Modified asphalt waterproof membrane R ≥ 50mm (others ≥ 20mm);  

b. Smooth surface

After the pouring of the concrete outer wall is completed, the through-wall bolt holes should be sealed; Polish the uneven joints, and remove any remaining mortar hard blocks or protruding parts from the surface of the base layer.

c. Base maintenance and drying

Curing and crack prevention; Dry again until the moisture content is not more than 9% (test: dry laying for 1m × 1m roll, 3-4 hours in winter and 2-3 hours in summer, without watermarks), otherwise measures will be taken.  

d. Spraying base treatment agent

Compatible with rolls and adhesives to prevent corrosion or poor bonding with rolls. Spray and apply evenly without bottom leakage.

3) Adhesive usage

Supplied by the coil manufacturer as a complete set.

2. Stripping of rolls and rolls

Reason analysis:

The working conditions of the coiled material do not meet the requirements;

The operating temperature of the coil material may be high or low, which does not meet the requirements

The joint width of the waterproof membrane does not meet the requirements;

The waterproof layer was not covered and protected in a timely manner after construction.

Response measures:

1) Work environment

It is strictly prohibited to construct waterproof rolls in rainy, snowy, or strong winds of level 5 or above;

During the construction process, when it rains or snows, protective measures should be taken for the already laid roll materials.

Characteristics of the hot melt method – torch melting, laying exhaust, rolling and bonding, and joint extrusion liquid scraping tightly; (Construction temperature ≥ -10 ℃)

The characteristics of the cold adhesive method – reasonable selection of adhesive, uniform application of adhesive, exhaust compaction, and separate adhesion of joints; (Construction temperature ≥ 5 ℃)

The characteristics of cold self-adhesive method – uncoiling the paper while uncovering, overlapping according to the line, exhaust and compact, and heating at low temperatures. (Construction temperature ≥ 5 ℃)

2) Waterproof construction method

Internal sticking method

Construction sequence: cushion layer, protective wall → waterproof layer → bottom plate and structural wall

Features: Small slot width, saving template; The damage is imperceptible, the reliability is poor, and the inner template is not easy to fix.

Used in situations where the venue is small and external pasting cannot be used.

External pasting method

Construction sequence: Wall structure → Waterproofing → Protection features: The quality of the structure and waterproof layer is easy to check and has strong reliability; The fertilizer tank needs to be wide and the construction period is long.

This method is commonly used.

The waterproof layer of large-area coiled materials on the bottom plate should be laid in an empty space. When laying the coiled materials, the plane should be laid first, and then the facade should be laid. The joints should be crossed and overlapped. Empty paving method should be used for construction; The contact area between the coiled material and the temporary protective wall or enclosure structure template should be temporarily attached to the wall or template, and the top should be temporarily fixed.  

The overlapping length of the roll joint is 150mm for polymer modified asphalt roll materials; When using two layers of coil material, the coil material should have staggered joints, and the upper layer of coil material should cover the lower layer of coil material.

The hot melt temperature is too high or too low, unstable. If the temperature is too high, it can easily scorch the coil, leading to a decrease in its elongation, serious carbonization, and loss of waterproof performance; If the temperature is too low, the coil material will not melt properly, and the bonding will not be firm, becoming a hidden danger of water seepage.

3) Waterproof protection

a. Plane:

Pouring fine aggregate concrete with a thickness of ≥ 50

b. Facade:

Internal sticking method –

Spray glue and apply 20 thick 1:2.5 mortar (hard protection)

Paste 5-6 thick PVC foam plastic sheet (soft protection)

External pasting method –

Build brick walls, pour mortar or apply sheet materials (hard protection)

Stick polystyrene extruded board or foam board (soft protection)

3. Leakage occurs at internal and external corners and embedded pipe fittings

Reason analysis:

Improper handling at the grassroots level, difficulty in handling details, or inadequate construction, resulting in poor bonding, wrinkling, mouth opening, or edge warping.

Response measures:

1) Grassroots treatment

The internal and external corners of the base layer and the root of the embedded pipeline for laying the coiled material should be in a circular arc shape. The arc radius of the waterproof layer of polymer modified asphalt waterproofing membrane should be 50mm. Before laying the coiled material, the dirt and rust on the surface of the base layer must be removed. Depending on the specific situation, sandpaper, wire brush, or solvent can be used to remove it. If necessary, high-pressure air can be used to clean the root of the pipeline and the surrounding base layer for the last time.  

2) Strengthening layer paving

For areas with significant deformation, susceptibility to damage, or aging, such as deformation joints, corners, three sided corners, as well as around through-wall pipelines and underground entrances and exits, additional layers of coiled materials should be laid, not less than 500mm. During construction, standardized treatment methods should be adopted according to different special parts. During the operation, the coiled materials should be carefully cut according to the shape, the surrounding area should be flattened and tightly adhered, and the bonding should be firm. There should be no warping, wrinkling, or other phenomena. After completing the additional layer paving of these parts, careful inspection should be carried out to ensure good acceptance.