b'TECHNICAL & RESEARCHverysoftandsquishywhenwalk-ing across it, fasteners and plates pro-trudingupward,orinsulationtent-ingupwardandpossiblyprotruding through the roof membrane. Althoughwarpedinsulationboardscan bereplacedaftertheroofiscompleted,the repair costs are high and large patches must beinstalledtoaccommodatethesizeofthe repair or replacement. The best practice is to not install the damaged insulation in the first place, as stipulated in the roofing manufactur-ers specifications.INSULATION INSTALLATIONFigure 1. Insulation stored on the ground and not properly protected. In recent years, a popular insulation and coverboardinstallationprocedurehasbeen If the insulation becomes wet or con- It is easy to overlook signs that dam- to adhere both the insulation and cover board taminated by oils, fuels, or chemicals,aged products have been incorporatedwith low-rise expanding foam adhesive. This that could render the insulation unus- into the assembly. Signs of moisture inadhesive can be applied directly to a concrete able(seeFig.1).Acommon,incor- the insulation may include curled cor- deckinsomecases;alternatively,itcanbe rect practice is to install wet insulationners or edges of the boards or arched/ applied over a vapor barrier or substrate board, board so that visible damage is on thecupped boards, with the middle of theoroverametalorwooddeck.Therearea underside of the roof assembly, againstboards warped. Moisture in boards andnumber of other ways in which low-rise foam thesubstrate.Whethertheinsulationfacers can also cause delamination ofadhesive can be incorporated into the assem-is water damaged on one side or boththe insulation facers and, consequent- bly, such as adhering subsequent layers of flat sides, this is not an acceptable solution.ly, the delamination of adhered mem- or tapered insulation adhered over base layers Iftheinsulationisdamaged,wet,orbranes. In severe cases, the insulationofinsulationandcoverboards,andcrickets warped by moisture, it should not bemay cup and pull up over the fastenersadhered over previously installed layers of insu-installed in the roof assembly. and insulation plates on assemblies inlation (see Fig. 2).Because most roof observation site vis- whichtheinsulationismechanicallyThebeadsizeandspacingrequirements its are periodic in nature, the observerattached.can be based on a variety of design criteria, the may not be on site when all the materi- Saturatedpolyisocyanurate(polyiso)geographic location, and wind-speed require-als are being installed. insulation can compress from foot traf- ments. Bead size and spacing requirements vary fic,theweightby manufacturer, project-specified wind rating, ofheavyrains,and other design criteria. Roof manufacturers orsnowloads.specify minimum size and spacing criteria for Signsofthisconstruction,whichdonotrequirespecific conditionmaywind ratings (see Fig. 3).includeinsula- Roofsystemmanufacturershavevarying tionthatfeelsspecificationcriteriaforinstallation.Many Figure 2. Typical foam insulation beads.Figure 3. Typical example of sprayed foam size and spacing criteria from a roof manufacturer. Note: 1 = 1 in. = 25.4 mm36www.mrca.orgMidwest Roofer 7'