Waterproofing and moistureproofing are critical components of any building’s structural integrity. As a professional building inspection company, we understand the importance of these elements in protecting your property from water damage and ensuring its longevity.

This article will provide an in-depth look at the various aspects of waterproofing and moistureproofing, based on the City of San Diego’s CWP Guidelines. These processes are governed by specific codes and standards, including the Uniform Building Code and ASTM specifications for materials such as asphalt primers, organic felts, and roofing asphalt.

Types of Waterproofing and Moistureproofing

Waterproofing Coating

Waterproofing coatings are typically applied to the water side of walls and bottoms of channels or tanks that are adjacent to occupied spaces. These coatings are usually coal tar epoxy resins, applied in multiple layers to achieve a minimum dry film thickness of 20 mils.

Moistureproofing Coating

Moistureproofing coatings are used on the exterior of below-grade concrete walls that are common with occupied spaces. These coatings are often coal tar solutions applied in multiple coats to achieve a dry film thickness of at least 15 mils.

Waterproofing Membrane

Waterproofing membranes are heavy-duty rubberized asphalt composites, typically 65 mils thick, with a puncture resistance of 200 pounds. These membranes are applied to surfaces that require additional protection against water infiltration.

Below-Grade Waterproofing

Below-grade waterproofing systems use cold fluid applied, single coat, high build, water-based polymer-modified asphalt emulsions. These systems often include protective layers such as expanded polystyrene boards or geotextiles.

Application Processes

Surface Preparation

Proper surface preparation is crucial for effective waterproofing and moistureproofing. This typically involves:

1. Allowing concrete to age for at least 28 days

2. Cleaning and drying surfaces thoroughly

3. Repairing voids and cracks

4. Sandblasting concrete surfaces when necessary

Application Techniques

Application methods vary depending on the type of product:

1. Coatings are typically applied in multiple layers, with specific drying times between coats

2. Membranes are applied according to manufacturer’s instructions, often requiring priming of surfaces

3. Below-grade waterproofing systems are spray-applied and require careful thickness monitoring

Special Considerations

Shower Pan Waterproofing

Shower pan waterproofing requires special attention:

1. The system should extend at least 6 inches up the walls above the finished shower floor

2. It must be properly lapped over the curb at the shower entrance

3. Testing is required by ponding water for two hours to ensure no leakage

Moistureproofing Underlay

Moistureproofing underlay is typically used under concrete slabs-on-grade:

1. Membranes should be lapped 6 inches at joints and sealed with pressure-sensitive tape

2. Special care must be taken where pipes and conduits pass through the membrane

Quality Control and Testing

Ensuring the quality of waterproofing and moistureproofing applications is crucial:

1. Below-grade waterproofing should be tested for thickness using a depth gauge

2. Areas found to be thinner than specified should be built up to the required thickness

3. Shower pan waterproofing systems should be tested by ponding water

US Commerical Building Inspections Conclusion

Proper waterproofing and moistureproofing are essential for maintaining the structural integrity and longevity of buildings. As building inspectors, we emphasize the importance of following industry standards and manufacturer’s recommendations for all waterproofing and moistureproofing applications.

Regular inspections and maintenance of these systems can prevent costly water damage and ensure the long-term health of your property.

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