From what i ve read online it seems wise to install a vapor barrier over the plywood to prevent condensation from getting absorbed into the plywood from the steel roof.
Metal roof deck vapor barrier.
Selecting applying metal roofing touch up paint.
Traditionally we ve insulated the roof panel to try and keep the temperature on the panel from reaching the dew point.
Selecting metal roofing trim.
In this example although roofs and walls both need similar water vapor barrier properties the roof barrier often needs to be either inflexible or air permeable to prevent being blown away in an updraft.
But a preinstalled membrane may be even more effective at removing condensation.
How to prepare for metal roof installation.
The roof is a large part of the building envelope and therefore has a significant impact on the flow of energy in and out of buildings.
Benefits of metal panels for agricultural buildings.
Tips for installing metal roofing accessories.
Exceptions to this idea include roofs over indoor swimming pools or other high humidity producing activities and over new concrete roof decks to prevent the moisture in the concrete from drying into the roof system.
In a low slope roof assembly the vapor retarder is normally installed under the primary roof insulation.
In order to add moisture barrier under metal roof you can spray the undersides of the roof by using a thick layer of polyurethane spray foam.
The problem with using.
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 wood panels that is installed directly over a metal deck.
Polyurethane spray foam metal roof insulation.
A roof vapor barrier needs to have different properties to a barrier in a wall or one used to prevent radon permeating through a floor.
Vapor control membranes play a very important role in this.
We ll add a vapor barrier so the moist air does not flow up through the insulation and condense on the roof.
It will help you to eliminate problems that may come when the house becomes extremely cold in the winter and terribly hot in the summer.
The firestone v gard vapor control membrane is designed to be used as vapor control layer in firestone roofing systems.