Insulating A Low Slope Roof

Common low slope roofing assembly.

Insulating a low slope roof.

By martin holladay issue 250 april may 2015. Insulfoam single ply sp fire rated single ply roof insulation with factory laminated glass facer. He plans on replacing the low slope built up roof with an epdm membrane and the question is how to insulate it correctly. Eric dymond lives in a 1920s baltimore row house that needs a new roof.

The insulation used in low slope roof assemblies typically falls into one of the four categories. Box out light fixtures. Such roofs are generally considered to have a slope of less than 2 12. Currently the built up asphalt roof is installed over homasote or something similar and a roof deck made of wood planks.

Lightweight insulating concrete lwic. It creates a breeding ground for mold and mildew and ruins the air trapping pockets that block heat flow. Rigid board insulation rigid board insulation is the most common type of insulation used in low slope commercial roofing. Insulating a cool self drying vented low slope roof i own a mid century modern home in the seattle area with a 1 12 pitch roof over vaulted ceilings separated by 2x6 joists with r13 batt insulation venting at the soffit and ridge and a condensation issue that started after the modified bitumen roof was replaced last june with a white tpo.

The analysis was done for an assembly consisting of a steel deck two layers of polyisocyanurate foam insulation polyiso and tpo single ply membrane. Insulfoam sp is an engineered insulation consisting of a superior closed cell lightweight and resilient expanded polystyrene eps with a durable and stable factory laminated coated glass facer. Ideal for low slope roofing. It is made from.

Dual purpose structural deck and insulating planks. Water is insulation s enemy. Unvented roof assemblies should be insulated either with air impermeable insulation rigid foam or spray polyurethane foam or with a combination of foam and air permeable insulation. Or sprayed polyurethane foam spf.

Look for water stains on the roof sheathing or damp or moldy spots on attic joists and existing insulation as a clue to where leaks might be.