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Waterproofing & Dampproofing

The Chicago Roofing Contractors Association has many members who install Waterproofing and Dampproofing in various forms.

Waterproofing is typically an “underground” application. Waterproofing can also have an above grade, but below the sidewalk, or paver location. Dampproofing is typically installed on below grade walls and under floor slabs that are grade.

Listed below are definitions, some of the categories of waterproofing and dampproofing, and how do choose a professional contractor for this scope of work:

Waterproofing Definition – Waterproofing is defined as the resistance of the passage of water under hydrostatic head pressure. Hydrostatic head pressure means water is present from underground water buildup (walls, or under the concrete basement floor) or from above the horizontal assembly that protects a basement space. The horizontal assembly could be a city sidewalk where the basement extends to the street from the building. It can also be an underground building’s roof, with vegetative, paver or other topping.

This hydrostatic pressure is greater in soils that don’t allow much water to flow away from a building’s vertical or horizontal assemblies. The soils that don’t flow well include clay and solid rock.

Waterproofing Materials are available to suit the varied building site conditions and surfaces such as:

Below Grade Walls – Walls of a building’s basement levels are sometimes protected against water seepage as the space may be used as storage, parking, or other occupancy use allowed by the building code.

 Above Grade, Buried Horizontal Plaza Areas – In many cases, horizontal plaza waterproofing is located above occupied spaces. The waterproofing then is buried under pavers, soil, grass and other plantings. These applications are referred to as waterproofing projects in most cases, and may have different assembly configuration and detailing methods than a conventional roofing assembly. However, they function as a roof, and need a professional roofing contractor’s attention.

Above Grade, Surfaced Waterproofing Systems – Many types of coatings are applied to horizontal assemblies for auto and pedestrian traffic, sports surfaces, and other applications. These coating systems are applied by CRCA Member Roofing and Waterproofing Contractors as well.

Underground Buildings – The roofs of underground buildings are considered roofing and waterproofing applications because they are usually buried under insulation, drainage systems and soil or other topping.  As such, waterproofing materials, systems and details are used instead of typical roofing details. This is due to the unknown direction of water travel. Once a structure is underground, water may seep from above or be driven by water pressure upward towards the ground surface. Special Flashings and other procedures are necessary to produce a successful waterproofing project – again needing professional workforce experience with this type of assembly for success.

Dampproofing
Dampproofing is defined as the resistance of water in the absence of hydrostatic head pressure. Dampproofing materials typically will not bridge cracks in concrete that may occur during the life of a building – meaning it might leak.

Dampproofing Applications
Dampproofing can be used on either Residential or Commercial / Industrial / Institutional Applications. Most Dampproofing products are spray applied very quickly and applied at thinner than most waterproofing membranes. Therefore, Dampproofing may be significantly less costly than waterproofing – and not provide waterproof protection. Dampproofing is also applied by CRCA Members.