Metal Roof Over Purlins No Vapor Barrier

That reduction of air and moisture infiltration can then help improve roof longevity.

Metal roof over purlins no vapor barrier.

They give added support to the roof and also provide a nailing surface for the end panels and drip edge. Metal roof purlins are installed horizontally under metal roofs. In this installation the vapor barrier is installed on the side of the insulation nearest the interior of the building. I ll never forget seeing wind blown snow a quarter to a half inch thick on the attic insulation after one storm.

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. Mcelroy metal has develop several methods to recover an existing metal roof using the symmetrical 238t standing seam roof system. Purlins vs decking for metal roof 12 10 2016 12 53. As long as the plywood under the shingle roof is in good condition this way can provide many benefits.

The problem with using. 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. 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. 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.

Traditionally we ve insulated the roof panel to try and keep the temperature on the panel from reaching the dew point. They are installed on top of the roof rafters with a felt underlayment or vapor barrier installed on top. We ll add a vapor barrier so the moist air does not flow up through the insulation and condense on the roof. There is no need to roll a vapor barrier over purlins and then seal with tape which can reduce labor hours and cost.

Purlins are 2 by 4 feet and are installed much like metal roofing. This is by far the most common way to install a metal roof. 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. In the old days we used to do 5 v metal roofs on 2x4 purlins with lead headed roofing nails and no sheathing.

But a preinstalled membrane may be even more effective at removing condensation. 238t recover systems provide a long term solution to existing exposed.