Metal Roof Wood Purlin Insulation

Traditionally we ve insulated the roof panel to try and keep the temperature on the panel from reaching the dew point.

Metal roof wood purlin insulation.

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. I m concerned about possible condensation on the underside of the steel roofing and i would like to know the best way to insulate this ceiling from the underside. This creates a thermal break which is very similar to a vertically seamed metal roof installed on battens. For heavier material such as gage steel the metal roof purlins spacing length could go up to 4 feet.

This type of assembly is designed to dry to the interior so the assembly should never include an interior polyethylene vapor barrier. Purlins are non pressure treated 1 x 4 x 12 lumber that is installed on to the roof in a specific layout pattern and screw pattern. We ll add a vapor barrier so the moist air does not flow up through the insulation and condense on the roof. The house has steel roofing installed over 1x3 purlins.

To calculate the amount needed multiply your metal roof square footage x 40. Can i insulate with foam board. For the lighter material such as lightweight aluminum the common spacing length is 4 inches of clear gap. But a preinstalled membrane may be even more effective at removing condensation.

Steel bands typically 1 wide are screwed to the underside of the metal purlin or wood truss in a pole barn 30 apart creating a grid system. Purlins are usually supported by rafter building walls or the weight of the roof deck itself. There is no plywood roof sheathing. Energy efficiency one contractor said that purlins help by adding an air gap that provides insulation.

Do all roofing projects require purlins. Commonly used in double layer high r value metal roof insulation systems and in retro fit insulation applications. Install a layer of closed cell spray foam against the underside of the steel roofing or roof sheathing and fill the rest of the purlin cavity with an air permeable insulation. The other says that gap provides more space for condensation to accumulate on the underside of the roof and cause inside out rusting.

The problem with using. As a great option to the expense and bother of battens there are concealed fastener metal shingles shakes and tiles available. The purpose of the purlins is to provide a solid foundation for the metal roofing panels and trim to be screwed to. I need to insulate a cathedral ceiling that will be finished with tongue and groove pine paneling.

In this installation the vapor barrier is installed on the side of the insulation nearest the interior of the building. It is a horizontal bar that used to support building at the roof structurally.