For example nasa uses.
Roofing refridgerated storage without vapor seal.
Provide a heavy duty vapor barrier similar to a pond liner at a freezer slab.
It should be installed in layers with staggered joints at both the slab and the roof to prevent easy transmittance of temperature.
That s why single ply roofing is the go to choice for refrigerated buildings.
In this situation the water vapor on the outside of the building will by vapor pressure differential move into the cold storage building s interior.
Between the two air leakage moves far more moisture than vapor diffusion.
2 internal floating type cover.
Without a complete vapor seal vapor drive will result in condensation or ice formations at the building interior what follows are general details provided by metl span showing typical cold storage imp vapor barrier installation steps.
Spf polyurethane foam is a high tech insulation product.
Spf insulation and cold storage often processing plants and distribution centers require complete buildings to be insulated from floor to ceiling.
F any emergency roof drain shall be provided with a slotted membrane fabric cover or equivalent device that covers at least nine tenths 9 10 of the area of the opening.
Hence the need to reduce moisture flow into the attic and the need for a vapor barrier.
In addition to being water tight single ply roofs serve as excellent vapor barriers minimizing air leaks and the thermal loss and excess moisture that can accompany such leaks.
There s one other important qualification.
Part i general refrigerated facilities are any buildings or sections of a building that achieve controlled storage conditions using refrigeration.
Vapor moves in two ways by diffusion through materials and by air leakage through gaps and holes in building assemblies.
For coolers and freezers the roof exterior vapor barrier whether imp or membrane must tie into the imp wall at roof to wall connections.
The building location s annual outside temperatures plays a role in determining insulation thickness both for walls and roofs.
If the vapor barrier is not installed properly or does not have a complete seal moisture vapor will penetrate into the building and over time ice will begin forming and expanding.
In cold storage facilities moisture vapor flow is reversed from a traditional building in a northern climate including the roof.
Usually polyurethane sprayed foam is chosen due to its high r value vapor blocking thermal resistance flexibility and performance under extreme temperatures.
Continuous vapor seal is achieved and the specified warranty prerequisites have been met.
Residential and commercial roofing shingles slate roof ventilation roof underlayments asphaltic and tpo roof membranes.
Moisture flow and vapor retarders.
In the primary seal envelope surrounding the annular vapor space enclosed by the roof edge seal fabric and secondary seal.
