Metal Roof Over Purlins No Vapor Barrier

Hi just trying to put the finishing touches on the plans for a very small 12x16 cabin and am unsure about the best way to install the metal roof.

Metal roof over purlins no vapor barrier.

Hmm i am thinking that this will not be an issue due to having a sound vapor barrier on the warm side of the roof. Purlins vs decking for metal roof 12 10 2016 12 53. This is by far the most common way to install a metal roof. That reduction of air and moisture infiltration can then help improve roof longevity.

Purlins are 2 by 4 feet and are installed much like metal roofing. 3 install 1 4 purlins down over the shingles before installing the metal roof the third way to install a metal roof over shingles is by applying 1 4 purlins over the shingle roof. They are installed on top of the roof rafters with a felt underlayment or vapor barrier installed on top. 238t recover systems provide a long term solution to existing exposed.

Available systems include a patented frame less metal over metal recover option that provides a low cost retrofit solution over existing exposed fastened panels with ribs up to 1 5 tall. The rubber backer on the material helps protect the back side of the panel from corrosion although there is no protection at the panel s cut edges. As long as the plywood under the shingle roof is in good condition this way can provide many benefits. A roof design that includes an adhered roof membrane with multiple layers of insulation with board joints offset and staggered over a vapor retarder air barrier helps lower the risk that air and the moisture it carries will infiltrate the roof system.

Metal roof purlins are installed horizontally under metal roofs. I ll never forget seeing wind blown snow a quarter to a half inch thick on the attic insulation after one storm. Traditionally we ve insulated the roof panel to try and keep the temperature on the panel from reaching the dew point. Mcelroy metal has develop several methods to recover an existing metal roof using the symmetrical 238t standing seam roof system.

When using plywood nail it directly to the purlins and screw the metal roofing panels through the plywood into the purlins as instructed by the manufacturer. We ll add a vapor barrier so the moist air does not flow up through the insulation and condense on the roof. Some say the outside air. They give added support to the roof and also provide a nailing surface for the end panels and drip edge.

There is no need to roll a vapor barrier over purlins and then seal with tape which can reduce labor hours and cost. The problem with using.