Flat Roof Vapor Retarder

The vapor barrier protects the roof insulation from the vapor included in the interior air.

Flat roof vapor retarder.

Vapour retarders frequently are used in flat roof construction to prevent moist air from the inside of the building condensing onto the roof assembly and potentially causing damage to materials. The products are installed prior to the roof insulation. Astm d2178 astm e96. The problem with using.

Nrca these products are an important way to preserve the thermal efficiency of roof insulation and so make up a crucial part of protecting. Iko s roofing vapour barriers are designed to be used over various types of roof decks such as steel concrete and wood. We ll add a vapor barrier so the moist air does not flow up through the insulation and condense on the roof. Therefore one will often see it installed directly on a roof deck such as a concrete or wood deck or on a continuous substrate such as gypsum board or.

But a preinstalled membrane may be even more effective at removing condensation. Class i vapor retarders i e. A vapor retarder is a material or system that is designed as part of the roof system to substantially reduce the movement of water vapor into the roof system where it can condense. To learn more on vapour barriers visit our introduction to vapour barriers article.

In a low slope roof assembly the vapor retarder is normally installed under the primary roof insulation. A vapor retarder is commonly installed on the warm interior side of a roof or wall. However if a class i vapor retarder is used there is concern that any moisture e g construction moisture due to installation methods bulk water from weather etc that enters a roof system won t be able to dry out. Traditionally we ve insulated the roof panel to try and keep the temperature on the panel from reaching the dew point.

Even in these however he thought that the vents are unnecessary and may do more harm than good since they penetrate the roof surface making potential. Cold adhered asphalt adhered. Sopravap r is composed of a. Everyone knows that water in roof systems is never a positive.

Roofing vapor retarder air barrier. Typically a vapor retarder has to have a perm rating of 1 0 or less to be successful. Most roofing membranes as well as a single layer self adhered bituminous sheets are class i vapor retarders. Count on iko for the best in roofing vapour barriers.

A class iii vapor retarder is acceptable in climate zone 5. Vapor barriers can be installed in vented roof assemblies in climate zone 6 and climate zone 7 but should be avoided in climate zone 5 as top side condensation may occur in the summer months during air conditioning periods. This vapor if left unchecked can wet the insulation and over time will reduce the r value of the insulation and lead to mold. In roofs with vapor retarders tobiasson conceded that the two way vents may have a role to play in avoiding the creation of a vapor trap between the roofing membrane and the vapor retarder.