Considerations for Selecting a Below-Grade Waterproofing System

When selecting a below-grade waterproofing system, conservatism is the watchword. Remember, you only have the opportunity to do this once! Proper research and due diligence is required to ensure that all below-grade waterproofing issues are properly addressed. Site-specific issues and building requirements also necessitate proper consideration. There are several considerations that an architect or waterproofing designer must examine prior to the selection of a below-grade waterproofing system. Some of the considerations are:

• Occupancy.
• The water table.
• Soil characteristics.
• Substrate stability.
• The construction sequence.
• The track record of the products to be used.
• Risk vs. cost.
• Ease of application.

Occupancy

Important design factors to consider include leak risk tolerance and sensitivity to humidity of an occupied space. Leaks are an obvious detriment in most occupied spaces, but they are intolerable in occupancies with book storage, art storage, computer equipment, electrical switchgear and medical facilities. These types of facilities also require tight humidity control. Intrusion of air can be as detrimental as water in sensitive facilities. Medical facilities, research facilities and testing laboratories fall within this classification.

Proper membrane design for the aforementioned facilities would require positive side waterproofing with a low vapor permeable membrane.