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be either nuclear, capacitance or infrared. All wet roofing materials must be removed prior to any recover.

Should the existing roof be used as a bonding substrate, the surface must be properly prepared for the application of the new roof or insulating layer. Loose and large gravel shall be removed; blisters and splits shall be repaired and existing flashings should be removed to create a clean bonding surface for new elements. Where the new roof is mechanically attached to the underlying substrate, withdrawal resistance testing should be carried out to confirm the attachment values for each fastening point. Testing should be carried out in compliance with ANSI/SPRI FX-1-2006 or TAS 105. Copies of the test protocols are available from CertainTeed Technical Services. Fastener values should meet or exceed 325 lbf or the fastener density should be increased. The test data shall be evaluated by the roof designer of record for the evaluation of the fastening pattern. CertainTeed Technical Services can provide test data for a wide variety of system to assist in the evaluation.

Areas of ponding shall be corrected prior to the installation of a recover roof. Fillers designed to fill low spots should be used to correct these conditions. For a list of available products, please contact CertainTeed Technical Services.

It is the responsibility of the designer of record, and/or building owner to determine whether an existing roof is structurally sound, firmly attached, dry and suitable for recover. CertainTeed Technical Services can provide additional warranty information for specific recover projects.

Preparation and Field Conditions

The following requirements shall be used in conjunction with good roofing practices to qualify a new assembly for the NDL Limited Warranty or the Limited Product Warranty Program:

  • 1.

    Deck shall be dry, structurally sound and suitable for the application of the roof assembly.

  • 2.

    Parapet walls, perimeter edges, equipment and load bearing supports, platforms, curbs, etc., shall be structurally sound and suitable for the application of the flashings and terminations.

  • 3.

    Existing roof assemblies should be evaluated to determine if additional expansion or control joints are needed. Visual observations of wall cracks, membrane splits and materials out of plane are indicators of such conditions.

  • 4.

    The designer of record should evaluate combined live and dead loads to insure the recover roof assembly meet current code criteria and sound engineering practice.


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