Let’s Talk Fireproofing! How to plan for temporary heat in cold weather…
Nearly all spray-applied fireproofing materials are either mixed with water, contain water, or are applied with a spray of water. Due to the potential of freezing, a heated environment significantly above freezing is crucial to a successful application.
The established rule governing this condition is that the area must be heated to 40°F twenty four hours prior to the application, during the application, and twenty four hours after the application—including nights. Heating prior to is needed to assure that the inner mass of the structural member is temperature sufficient. Heat during the application should be obvious, as freezing could become a concern. Maintaining post application temperatures are necessary to allow the product’s chemical reactions time to bond and cure.
There are two common ways to provide the necessary heat. A pressurized system is the preferred method, utilizing (outside the building) combustion that forces hot air into the structure. This system builds a slightly positive pressure inside the building forcing excess gases and moisture to the outside.
The other method, although quite common, is the non-pressurized system, typically consisting of fire pots with 100 lb. gas cylinders spread throughout the structure. This method is not recommended because the combustion process not only creates excess gases and additional moisture, but both tend to stay within the confines of the structure due to the now slightly negative pressure. Less oxygen, more gases and additional moisture equate to a risky work environment and a slower drying and curing process.
Despite the initial cost, maintenance costs and technical reasons the pressurized method is not only preferred but may be less expensive in the end.