Inspection Insights: Ensuring Roof Performance

Part 1: How to Inspect Built-Up Roofing Systems

Part 2: Inspecting Roof-Deck Substrates Ensures Successful Installations

Part 3: What Role Does Insulation Play in Roof Installations?

Part 4: Inspectors Must Check Bitumen Temperatures During BUR Installation

Part 5: Roof Retrofits: Strategies for Membrane, Base Flashing Installation

What Role Does Insulation Play in Roof Installations?

By Tom R. Kaiser
November 2009

Roofing installations often include at least two layers of insulation boards, with offsetting and staggered joints to minimize the transfer of warm air through the roof system. The inspector should check insulation joints and ask the roofing contractor to fill in gaps wider than inch with insulation.

Failing to close these gaps can allow warm inside air to migrate through the system and meet cold outside air at the membrane level, resulting in constriction and contraction of the BUR membrane, causing it to split.

Inspectors should review insulation boards installed over steel decks according to the manufacturer's product data sheets for thickness requirements at spans over deck flutes. Also, if the specification calls for mechanical fasteners, the inspector must review these requirements to determine the number of fasteners required at outside building corners, perimeters, and the interior field of the roof area. Inspectors also should review specified fasteners and stress plates before installation.