Insulation Joints and Overlays

Jump to: navigation, search

Insulation Joints and Overlays

Revision as of 18:54, 22 August 2016 by James Klassen (talk | contribs) (General)

1 General

Insulation overlays are used to separate the roof membrane from the primary insulation, usually for one of two reasons:

  • to prevent the insulation from affecting the performance of the roof membrane
  • to prevent the roof membrane and / or the method of application from affecting the insulation

The insulation can affect the performance of the roof membrane in the following ways:

  • the insulation may be incompatible with the membrane, resulting in a loss of physical properties
  • different coefficients of thermal expansion may result in membrane splits / cracks.

The roof membrane and / or the method of application can affect the insulation in the following ways:

  • the insulation may not be capable of withstanding asphalt application temperatures and may “burn-out”
  • some insulation materials will not accommodate direct torch-applied membranes
  • insulation materials that are too “soft” may result in delamination or damage to the membrane or insulation when exposed to heavy loads or traffic
  • the solvents and adhesives used for flexible membranes may adversely affect the insulation.


NOTE: All hot asphalt-adhered asphaltic membranes (built-up roofing, modified bitumen, etc.) require an insulation overlay over heat sensitive insulations and heat insensitive foamed insulation. RoofStar Guarantee Standards for heat sensitive insulation materials require a two-layer overlay board for a five (5) or ten (10) year Guarantee. The RoofStar Guarantee Program requires the use of a two-layer overlay board over heat sensitive insulation in all cases, and also requires a single-layer overlay board application over heat insensitive insulation for all hot asphalt-adhered membranes. For single-ply, non-asphaltic membrane roofing systems, the membrane manufacturer should be consulted for proprietary options.

2 Insulation Joint Tape

Where the RoofStar Guarantee Standards or the roof system specifications call for taping fibreboard or insulation joints, consult the list of Accepted Materials: Insulation Joint Tape section of this Manual.

3 Asphalt and Paraffin-Impregnated / Coated Fibreboard Roof Insulation and Insulation Overlay Board

Under construction

4 Proprietary Overlay Boards

Under construction


5 Materials

To view materials accepted for use in the RoofStar Guarantee Program, see Accepted Materials: Insulation Overlay Board.




Back to Essential Elements

Fasteners and Fastening Requirements

Home