Each job must be approved by American WeatherStar before the project begins to be eligible for a warranty.

PART 3 – INSTALLATION

3.01  SUBSTRATE CRITERIA

The building owner or owner's representative is responsible for providing and determining that the substrate is suitable to receive the WeatherStar TPO roofing system. The WeatherStar authorized contractor should not proceed until all defects have been corrected. If possible, begin roof installation at the high point of the roof, and work toward the lowest point.

3.02  SUBSTRATE PREPARATION

A.   Typically, metal recover substrates are less than 22 gauge steel and require fastener pullout testing to be performed prior to submittal. The proper fastener assembly pattern is based on the pullout values achieved.

B.   A positive slope is recommended to provide adequate drainage.  Per NRCA guidelines, there should be no ponding water on the roofing system 48 hours after it has stopped raining.

C.   Any existing sprayed-in-place urethane foam roofs must be removed prior to the installation of this roofing system.

D.   Sweep the area of roof being covered to remove any loose dirt and debris.

E.   Cut the filler nailer boards to fit snugly between the metal roof ribs, and build up using multiple layers to equal the metal roof rib height. Install one continuous nailer board over the installed layers of filler nailer boards. Secure the nailers through the metal roof panels and into the building framework, e.g. purlin, to achieve a minimum of 200 lb of pullout resistance per linear foot of nailer assembly.

3.03  INSULATION APPLICATION

A.   Fill the metal roof area between the high ribs with a filler insulation board either supplied or field cut to span from rib to rib equal in thickness to the rib height. The rib top must be beneath the surface level of the fill insulation.

B.   Overlay the fill insulation with an AWS approved cover board. Apply the cover board perpendicular to the metal roof panels. The cover board must be of sufficient thickness to span any gaps remaining between fill panels.

C.   Stagger all insulation joints the maximum amount possible, and lay out with all joints tightly butted. Any gaps greater than 1/4"  wide must be filled with matching insulation material.

D.   When installing insulation thicker than 2 1/2", use multiple layers to maximize insulation thermal efficiency.

E.   When using multiple layers of insulation on a project, install each subsequent layer with the long axis running perpendicular to the layer below it with all joints staggered and tightly butted.

F.   Fit insulation tightly to roof penetrations, wood nailers, transitional walls, and parapets with any gaps greater than 1/4" filled with like material prior to membrane application.

3.04 INSULATION SECUREMENT

Insulation attachment defined below is based on 300 lbs. pullout resistance or greater, for pullout values less than 300 lbs. per fastener, refer to the following table titled"Supplemental Securement Table".

NOTE:  In the event the insulation is installed over an air barrier, the insulation securement must be in accordance with FM I-90 criteria for WeatherStar Fully Adhered Roof Systems.

All insulation must be mechanically attached to the approved structural deck using fasteners of appropriate type and length and insulation plates installed at the rate of one fastener and plate per 2 square feet  (16 fastener assemblies per 4' x 8' board) for 22 gauge steel decks and structural concrete (other decks require pull testing and may require additional securement).  When installing insulation greater than 1.5" in thickness a reduced fastening pattern may be applicable – refer to the table, Insulation Attachment Rates for Fully Adhered Systems, in the American WeatherStar standard details or contact American WeatherStar.

3 - Supplemental Securement Table for use on Projects with Fastener Pullout Values - Less Than 300 lbs. Pullout Resistance

Minimum Average Pullout Value per Fastener	Fastener & Plate Spacing
300 lbs. or greater	1 every 2 ft2 (16 per bd.)*
250-299 lbs.	1 every 1.75 ft2 (18 per bd.)
225-249 lbs.	1 every 1.50 ft2 (21 per bd.)
175-224 lbs.	1 every 1.25 ft2 (26 per bd.)
150-175 lbs.	1 every 1.0 ft2 (32 per bd.)
*           This value may be reduced by 50% when the top layer of insulation is a min. 2" or greater thickness single layer of ISO. (Not to exceed 2.5" in a single layer.) This table is NOT appropriate for Extended Wind Speed Warranties. Submit actual pullout test results to WeatherStar for evaluation. Provide a roof top drawing indicating the location and value of each test result. The number of pullout tests required are as follows:             A.         Less than 10,000 ft2 (929m2) - 6 pullout tests             B.         10,000 ft2 (929m2) to 50,000 ft2 (4645m2) - 10 pullout tests             C.         50,000 ft2 (4645m2) to 100,000 ft2 (9290m2) - 20 pullout tests             D.         100,000 ft2 (9290m2) and over - 1 pullout test per 5,000 ft2 (464.5m2) Pullout tests are required on any steel metal deck under 22 ga. thickness.

3.05 MEMBRANE APPLICATION

Membrane

1.   Position the TPO membrane over the approved substrate without stretching.

2.   Allow the membrane to relax a minimum of one-half (1/2) hour prior to any seaming or flashing.

3. Position all adjoining sheets in a manner that all sheets overlap a minimum of 2 1/2" (6.3 cm).

3.06  MEMBRANE ATTACHMENT

Adhering Membrane

1.   The fully adhered TPO system may be installed on roofs up to (50') in height. For heights exceeding (50') contact American WeatherStar. This design can be used for roofs requiring the Zone 1 and Zone 2 wind uplift criteria as contained in Loss Prevention Data 1-28 as published by the Factory Mutual Research Corporation.*

*   This does not mean these systems are approved by the Factory Mutual Research Corporation. Contact American WeatherStar or consult Factory Mutual Approval Guide for approved assemblies.

2.   Fold sheet back so one-half (1/2) of the underside of the sheet is exposed.  Ensure the sheet fold is smooth with no wrinkles or buckles.

3.   Stir the Bonding Adhesive in case settling occurred. DO NOT THIN WITH SOLVENTS.

4.   Apply Bonding Adhesive to the substrate and the membrane with a 9" medium nap roller, approved spray equipment (back rolling of adhesive is required) or power roller equipment. 100% adhesive coverage on both the membrane and substrate is required. Do not apply bonding adhesive to the splice area. Avoid globs or puddles of adhesive. One gallon (3.8 liter) of solvent based Bonding Adhesive correctly applied will cover approximately 60 square feet of finished surface. 

5.   Allow adhesive to dry to the point that it feels tacky to the touch but does not transfer to a clean dry finger when you conduct a push / tack test. Do not allow to over dry. If the surface dries to the point that it no longer feels tacky re-apply bonding adhesive to both surfaces at the prescribed application rate and allow to flash off again to the proper drying condition.

NOTE:  Do not allow adhesive to come into contact with areas that will be hot air welded. If contamination occurs remove any contaminates prior to hot air welding seams.

6.   Roll the adhesive coated membrane onto the adhesive coated substrate avoiding wrinkles.

7.   Using a push broom and positive downward pressure, brush down the bonded half of the membrane sheet to achieve maximum contact.

8.   Fold back the unbonded half of the sheet and repeat bonding procedure.

9.   Apply adjoining sheets in same manner, lapping edges a minimum of 2 1/2" (6.3 cm).

10. Any wrinkles found in the splice area or that impedes the flow of water drainage, must be cut out, laid flat and repaired using TPO membrane and standard hot air seam welding procedures.

3.07  SEAMING

Important:  Ensure both mating surfaces are free of debris and no moisture is present on the splicing surfaces.

1.   Unroll the membrane and allow to relax as long as possible.
(Minimum 1/2 - 1 hour)

2.   Position the top membrane to overlap the bottom membrane by 4 1/2" (11.4 cm).

3.   Using a clean rag saturated with cleaner, thoroughly clean an area on both sheets at least 4" (10.2 cm) wide if seam area has become contaminated with dirt, debris, etc. Change rags frequently to avoid depositing previously removed materials.

4.   Fold back the top sheet and position the seam plate on the appropriate dots that have been applied at 6" (15.2 cm) intervals to the seam area of the bottom sheet. Fasten with fasteners. Follow appropriate fastener spacing or contact American WeatherStar.

5.   Using an approved automatic heat welding machine or hand held heat gun and steel roller, continuously weld a minimum 1 1/2" (3.8cm) wide seam.  WeatherStar recommends that only approved Automatic Walker Welders be used to weld all field seams.  Special attention must be paid to areas where multiple layers of TPO field membrane (3 or more) come together (T-joints). 

a.   On .045" Membrane: If probing these areas reveals the presence of voids or cold welds, apply a TPO T-Joint Cover or a 4" round field cut unsupported flashing to the formed T-joint.

b.   On .060" or greater Membrane: A TPO T-Joint Cover or a 4" round field cut unsupported flashing is required at each T-joint.

6.   All welded seams must be manually checked for voids or seal deficiencies by probing the entire seam area with a dull cotter key extractor after the seam has cooled.  In addition, there must be destructive testing performed at the beginning of every workday and every time there is an interruption in the welding process (i.e. Power failure, welder shut down, job site conditions change and after lunch). All deficiencies must be repaired.

7.   All TPO membrane cut edges with exposed reinforcement scrim require an application of TPO Edge Sealant by the end of the workday in which the membrane with the raw edge is installed in the roofing system. Failure to seal the raw membrane edge before moisture wicks into the scrim may result in an inferior hot air weld if not already welded, and or a leak source depending on the location of the cut edge in relation to fasteners penetrating the membrane. Issues relating to unsealed edges will be corrected by the installing contractor, at the contractor's expense, as either a punch list item or under their two-year obligation if identified by WeatherStar within twenty-four months of final inspection. 

3.08  PERIMETER AND BASE MEMBRANE SECUREMENT

A.   Regardless of the method used to secure the field of the roofing membrane, some points on every roof require additional membrane securement. These areas include roof perimeters (parapets, transitional walls and edges), deck angle changes in excess of 2"/12" (including drain sump areas), at all curb type roofing penetrations, at pipe type penetrations greater than 12" in diameter, on both sides of expansion joints and other areas where the membrane must be anchored to prevent movement, stress or damage to the roofing membrane. Refer to the TPO standard details in this manual for securement requirements.

     Perimeter Attachment

1.   American WeatherStar offers several different types of attachment methods. Consult the appropriate WeatherStar standard detail.

2.   Base attachment is required at each roof level, curb skylight, expansion joint and roof penetration over 12" in diameter or any angle change in slope or combined slopes that exceed 2" in 12" horizontal will require attachment.

B.   Wood nailers provide a termination point for roofing insulation as well as a securement point for base flashing securement. Wood nailers are not covered by the WeatherStar warranty because they are a product by others and considered part of the building structure.

3.09  FLASHINGS

A.   Perimeter flashing and flashing around vents, skylights and miscellaneous roof projections must be done with Pre-molded TPO Flashings to the greatest extent possible. Field fabricated detail flashings using unreinforced TPO flashing is acceptable only when a Pre-Molded Flashing is unfeasible; e.g. pipes without top access, etc. AWS offers numerous options for flashing. (See our standard details.)

1.   Complete seams between flashing and field sheet in accordance with Seam Tape Seaming procedures. Seam width must extend at least 3" beyond the fastener assemblies that attach the membrane to the horizontal surface.

a.    Apply Bonding Adhesive to both the flashing material and surface to which it is being bonded to at a coverage rate of approximately 60 ft²/g of adhesive.

NOTE:  DO NOT allow material to bridge where there is a change of direction.

b.   Terminate top edge of flashing per American WeatherStar standard TPO details.

2.   Flashing penetrations passing through the roofing membrane.

Flash all pipes with WeatherStar pre-molded pipe boots to the greatest extent possible. Field fabricate pipe flashings with TPO unreinforced flashing per standard American WeatherStar details when a pre-molded flashing is not feasible.

NOTE:  All existing flashings must be removed before applying a new flashing.

B.   Expansion Joints and Building Control Joints.

Consult American WeatherStar standard details for various application methods.

C.   Pitch Pans

Fill pitch pans in accordance with American WeatherStar's standard details.

D.   Roof Drains

1.   Consult American WeatherStar's standard details.

2.   Prepare substrate around each roof drain to prevent membrane bridging or distortion and to provide a smooth transition from the roof surface to the drain clamping ring.

3.   The surface between the clamping ring and the drain must be clean and smooth. Remove all existing flashing, cement or lead on retrofit projects down to bare clean metal.

4.   Apply one (1) complete tube of Waterstop between drain bowl compression flange and the underside of the new membrane before compressing the new membrane to drain bowl assembly with the compression ring mounted on the top surface of the new membrane. The detail is only complete when the Waterstop is fully compressed between the new membrane and the flange of the drain bowl forming a solid seal between the two. Be careful to evenly compress the assembly to avoid cracking or breaking the drain compression ring. Cracked or broken drain compression rings may result in a reinspection of the finished roof system to ensure corrective measures have been made before WeatherStar will accept the roof system for warranty coverage.

5.   All bolts and/or clamps must be in place in order to provide constant, even compression. Missing drain bolts may result in a reinspection of the finished roof system to ensure corrective measures have been made before American WeatherStar will accept the roof system for warranty coverage.

6.   Do not run seams through roof drains or sumps. If a seam is run through a drain sump cut the membrane with the assembled seam outside of the drain compression ring area and install a target patch of new membrane extending a minimum of 3" outside of the sump area and seamed into the field membrane using standard seam tape seaming procedures. Apply T-joint patches as required at the target patch to seam intersections in accordance with WeatherStar standard T-joint application procedures.

E.   Metal Work

1.   No roof system is complete until all the edges are terminated in such a way as to prevent water infiltration into the roofed structure. This typically involves the use of manufactured or shop fabricated metal detailing such as coping caps, gravel stops, roof edging, flashing and counter-flashing components. All metalwork should be fabricated and installed according to SMACNA and National Roofing Contractors Association (NRCA) guidelines. Unless specifically agreed to in writing prior to installation, metalwork manufactured by others is not included in the WeatherStar warranty coverage.

a.    Factory formed metal work, when used in a warranted roof assembly, is fully covered by the WeatherStar Full System Warranty when installed to WeatherStar specification.

b.   Manufactured metalwork must be installed in accordance with the metalwork installation instructions available from the metalwork manufacturer.

c.    Metalwork by roofing contractors must be fabricated and installed in accordance with SMACNA and NRCA recommendations. All flange-mounted metalwork must be flashed according to the appropriate WeatherStar detail. 

d.   TPO projects with gravel stop configuration metal work (formed dam capable of holding water) with an TPO Cover Tape flange strip in of metalwork must have edge caulk applied on the dam side of the cover tape to aid in sealing the seam against trapped water.

2.   Any request for metal work by others inclusion into warranty coverage must accompany the Pre-Project Inspection Report via "Deviation Request" and include shop drawings of the metalwork that the request is based upon as well as a roof plan showing the installed location and linear dimension for each profile. To be considered for warranty coverage, the minimum requirements must be met: metalwork material is 24 gauge G-90 Kynar Pre-finished Steel or .040" Aluminum (mill finished, pre-finished or anodized); the proposed fabrication as shown on the submitted shop drawings complies with SMACNA and NRCA recommendations for the specific configuration submitted; installation securement is clearly defined on the shop drawings, e.g. fastener type and spacing, cleat type, etc. Keep in mind that approval of metalwork for inclusion into warranty coverage is conditional and subject to the "terms, conditions and limitations" of the requested warranty if approved and may involve an additional fee (warranty up-charge per square foot).

F.   Night Seal

1.   Consult American WeatherStar's standard detail.

2.   At the completion of each day's work, a watertight seal must be established at any loose edge of membrane with an appropriate sealant. Care must be used to guarantee that no water flows beneath any completed sections of roof. Consult American WeatherStar's standard detail for method of attachment. Membrane contaminated with the sealant used as a night seal must be cut out and discarded prior to resumption of work.

3.10  WALKWAYS

A.   Consult American WeatherStar's standard details.

B.   Walkways are required at all access points to the roof system and recommended anywhere routine (routine is defined as once a month or more) traffic on the membrane surface is anticipated. Walk pads are used to protect the weatherproofing membrane from damage or excessive wear and tear. Traffic related roof damage is not covered by the WeatherStar warranty. In areas of extreme traffic contact WeatherStar for options to enhance the roof system in order to prevent or mitigate insulation damage related to traffic. Walkway maintenance is the responsibility of the building owner as walk pads are not part of the warranted waterproofing assembly.

C.   Should access to the roofing membrane be required in order to perform warranty service to the roof system, only WeatherStar approved walk pads will be moved and replaced as necessary to perform service at WeatherStar's expense. Pavers, walkway systems, patio surface components and other products neither manufactured nor supplied by American WeatherStar that impede roof system service must be removed and replaced at the building owner's expense. Should the obstacle removal and replacement be performed by the WeatherStar contractor servicing the leak call under building owner authorization and or purchase order, WeatherStar assumes no responsibility or liability for the performance of the contractor in performing that service.

3.11 FINISHED ROOF PROTECTION

When it becomes necessary for other trades to work over a completed area of new roof, the roofing membrane and flashing must be protected from physical damage. Proper and adequate protection includes installing a slip-sheet in the work area overlaid with plywood or OSB Board in order to dissipate the effects of traffic on the finished roof surface and to prevent impact damage to the system caused by dropped tools and or equipment. If damage does occur to the roof system it must be immediately repaired in order to preserve the integrity of the roof insulation. If membrane is damaged in more than 6 locations within a 100 square foot area (10' x 10') new membrane extending 6" beyond the border of the damaged areas must be installed over existing membrane in accordance with WeatherStar specifications. For fully adhered and mechanically attached applications, the membrane must be fully bonded with the existing underlying membrane with a WeatherStar approved adhesive.