Polyiso Insulation Products for Commercial Roof Applications

October 20th, 2011

In the current commercial building environment there is increased attention on energy-efficiency which naturally leads to discussions about insulation. Polyiso is the insulation of choice in low slope roofing and is growing in presence for steep slope applications as well, with the development of nailable insulation products. Since polyiso provides more R-value per square inch than any other foam insulation it’s considered the top performer in sheet insulation. For specific roofing applications it’s fairly simple to spec the correct product with some basic familiarity.

Low Slope Polyiso

Flat sheets of closed-cell polyiso foam core are commonly used in almost every commercial flat roof application. It provides a semi-rigid energy efficient insulation component that can be used in all modified bitumen, BUR and single-ply membrane applications. In some cases a glass facer is added to create greater dimensional stability.

Polyiso sheets used on flat roofs are usually configured in layers according to required R-values  for a specification. When the layers are installed, their joints are staggered to prevent thermal bridging. Configuration of polyiso layer thicknesses and corresponding R-values based on ASHRAE requirements can be completed on the interactive LTTR Calculator at www.GreenZone.com. The calculator configures Atlas Roofing™ ACFoam® products for thickness and layers to achieve Long Term Thermal Resistance standards.

Tapered Polyiso

Flat roof applications that require positive drainage or slope for other purposes within the flat roof use a tapered polyiso solution to achieve high R-values while meeting design specifications. Tapered polyiso is custom designed to meet drainage specs according to roof dimensions. Tapered insulation sheets that enable the roof component of the building envelope to achieve required R-values and engineered drainage requirements require sophisticated calculations.

Atlas Roofing™ provides a tapered services group so contractors and specifiers can easily configure tapered polyiso products for design and bid projects. Using the Tapered Design Services Portal at www.AtlasRoofing.com, contractors, architects and other specifiers can work on all phases of tapered polyiso projects from shop drawings and bids to delivery of the tapered system.

Nailable Polyiso

Closed-cell polyiso board bonded to nailable OSB is frequently used in steep slope roof applications and under metal roofing where fastening directly to the roof deck is required. Nailable polyiso provides the insulating benefits of polyiso with the convenience of a pre-attached nailable surface.

ACFoam® CrossVent® also combines engineered ventilation for unventilated steep slope roof decks with a nailable OSB surface. Vent spacer strips enable air flow between the polyiso and the nailable surface which will ultimately increase the life and performance of the entire roof system.