SECTION 07 54 23
THERMOPLASTIC POLYOLEFIN (TPO) ROOFING
A. Slopes: Do not use on slopes over 1: 12 (one inch per 12 inches). Provide 1: 50 (1/4 inch per 12 inches) minimum to drains without any "Gutters"
(no slopes between drains). NO EXCEPTION TO MINIMUM SLOPE. Slope crickets 1: 50 (1/4 inch per foot).
B. Coordinate with HVAC requirements for roof penetrations and locations.
C. Coordinate details and systems used to provide code required fire rated roofing system.
D. Adhered system is preferred over mechanically anchored system.
E. Do not use polystyrene, urethane, or wood fiberboard insulation under membrane.
F. Do not use over bituminous materials where direct contact occurs, including grease, oil, or other substances not compatible with TPO. Use a thin layer of insulation, slip sheet or separator sheet depending upon method of attachment.
G. Terminate base flashings minimum 200 mm (8 inches) above roof surface including curb for building expansion joints.
H. Do not put expansion joints at roof surface level.
I. Do not use "pitch pockets" or "sealant pockets" in lieu of base flashings and cap flashings. Coordinate special conditions with Project/Construction Manager.
K. Do not use pipe boots that provide less than 200 mm (8 inch) height above roof.
PART 1 - GENERAL
A. Section Includes:
1. Thermoplastic Polyolefin (TPO) sheet roofing // adhered // mechanically fastened // to roof deck.
1.2 RELATED WORK
A. Section 01 81 13, SUSTAINABLE CONSTRUCTION REQUIREMENTS:Non‑Flooring Adhesives and Sealants VOC Limits.
B. Section 07 01 50.19, PREPARATION FOR REROOFING: Preparation of Existing Membrane Roofs and Repair Areas.
C. Section 07 22 00, ROOF AND DECK INSULATION: Roof Insulation.
1.3 APPLICABLE PUBLICATIONS
A. Comply with references to extent specified in this section.
B. American National Standards Institute/Single‑Ply Roofing Institute (ANSI/SPRI):
FX‑1‑16................ Standard Field Test Procedure for Determining the Withdrawal Resistance of Roofing Fasteners.
C. American Society of Civil Engineers/Structural Engineering Institute (ASCE/SEI):
7‑16................... Minimum Design Loads for Buildings and Other Structures.
D. American Society of Heating, Refrigerating and Air‑Conditioning Engineers, Inc. (ASHRAE):
90.1‑13................ Energy Standard for Buildings Except Low‑Rise Residential Buildings.
E. ASTM International (ASTM):
C67‑20................. Sampling and Testing Brick and Structural Clay Tile.
C140/C140M‑20a......... Sampling and Testing Concrete Masonry Units and Related Units.
C1371‑15............... Determination of Emittance of Materials Near Room Temperature Using Portable Emissometers.
C1549‑16............... Determination of Solar Reflectance Near Ambient Temperature Using a Portable Solar Reflectometer.
D1876‑08(2015)e1....... Peel Resistance of Adhesives (T‑Peel Test).
D4263‑83(2018)......... Indicating Moisture in Concrete by the Plastic Sheet Method.
D4434/D4434M‑15........ Poly(Vinyl Chloride) Sheet Roofing.
D6878/D6878M‑13........ Thermoplastic Polyolefin Based Sheet Roofing.
E408‑13................ Total Normal Emittance of Surfaces Using Inspection‑Meter Techniques.
E1918‑16............... Measuring Solar Reflectance of Horizontal and Low‑Sloped Surfaces in the Field.
E1980‑11(2019)......... Calculating Solar Reflectance Index of Horizontal and Low‑Sloped Opaque Surfaces.
F. Cool Roof Rating Council (CRRC):
1‑20................... Product Rating Program.
G. National Roofing Contractors Association (NRCA):
The NRCA Roofing Manual: Membrane Roofing Systems.
H. U.S. Department of Agriculture (USDA):
BioPreferred® Program Catalog.
I. UL LLC (UL):
580‑06................. Tests for Uplift Resistance of Roof Assemblies.
1897‑20................ Uplift Tests for Roof Covering Systems.
J. U.S. Department of Commerce National Institute of Standards and Technology (NIST):
DOC PS 1‑19............ Structural Plywood.
DOC PS 2‑18............ Performance Standard for Wood‑Based Structural‑Use Panels.
K. U.S. Environmental Protection Agency (EPA):
Energy Star............ ENERGY STAR Program Requirements for Roof Products Version 3.0.
1.4 PREINSTALLATION MEETINGS
A. Conduct pre-installation meeting at project site before beginning Work of this section.
1. Required Participants:
a. Oroject/Construction Manager.
f. Other installers responsible for adjacent and intersecting work,, particularly HVAC contractor and exhaust hood provider/contractor.
2. Meeting Agenda: Distribute agenda to participants minimum 3 days before meeting.
a. Installation schedule.
b. Installation sequence.
c. Preparatory work.
d. Protection before, during, and after installation.
g. Transitions and connections to other work.
h. Inspecting and testing.
i. Other items affecting successful completion.
j. Pullout test of fasteners, if applicable.
k. Material storage, including roof deck load limitations, if applicable.
3. Document and distribute meeting minutes to participants to record decisions affecting installation.
Contractor to provide submittals on materials and methods used
B. Submittal Drawings:
1. Roof membrane penetration details.
2. Base flashing and termination details.
C. Manufacturer's Literature and Data:
1. Description of each product.
2. Minimum fastener pullout resistance.
3. Installation instructions.
1. Roofing Membrane: 150 mm (6 inch) square.
2. Base Flashing: 150 mm (6 inch) square.
3. Fasteners: Each type.
4. Roofing Membrane Seam: 300 mm (12 inches) square.
E. Temporary protection plan. Include list of proposed temporary materials.
J. Operation and Maintenance Data:
1. Maintenance instructions.
1.6 QUALITY ASSURANCE
A. Installer Qualifications:
1. Approved by roofing system manufacturer as installer for roofing system with specified warranty.
2. Regularly installs specified products.
3. Installed specified products with satisfactory service on five similar installations for minimum five years.
a. Project Experience List: Provide contact names and addresses for completed projects.
4. Employs full‑time supervisors experienced installing specified system and able to communicate with Contracting Officer's Representative and installer's personnel.
A. Deliver products in manufacturer's original sealed packaging.
B. Mark packaging, legibly. Indicate manufacturer's name or brand, type, and manufacture date.
C. Before installation, return or dispose of products within distorted, damaged, or opened packaging.
1.8 STORAGE AND HANDLING
A. Comply with NRCA Manual storage and handling requirements.
B. Store products indoors in dry, weathertight facility.
C. Store adhesives according to manufacturer's instructions.
D. Protect products from damage during handling and construction operations.
E. Products stored on the roof deck must not cause permanent deck deflection.
1.9 FIELD CONDITIONS
1. Product Temperature: Minimum 4 degrees C (40 degrees F) for minimum 48 hours before installation.
2. Weather Limitations: Install roofing only during dry current and forecasted weather conditions.
A. Construction Warranty: FAR clause 52.246‑21, "Warranty of Construction."
1. Specify extended manufacturer's warranties for materials in contract
B. Manufacturer's Warranty: Warrant roofing system against material and manufacturing defects and agree to repair any leak caused by a defect in the roofing system materials or workmanship of the installer.
1. Warranty Period: minimum of 2 yrs
PART 2 - PRODUCTS
2.1 SYSTEM DESCRIPTION
A. Roofing System: Thermoplastic Polyolefin (TPO) sheet roofing // adhered // mechanically fastened // to roof deck.
2.2 SYSTEM PERFORMANCE
A. Design roofing system complying with specified performance:
1. Energy Performance:
a. EPA Energy Star Listed for low‑slope roof products.
2.3 PRODUCTS - GENERAL
A. Provide roof system components from one manufacturer.
2.4 TPO ROOFING MEMBRANE
1. Use sheets without fabric backing when adhering to rigid insulation board cover boards.
2. TPO Sheet: ASTM D6878/D6878M, internally fabric or scrim reinforced, 1.5 mm (60 mils) thick, // with no backing // with fabric backing //.
2.5 MEMBRANE ACCESSORY MATERIALS
A. Sheet Flashing: Manufacturer's standard sheet flashing of same material, type, reinforcement, thickness, and color as TPO sheet membrane.
B. Factory Formed Flashings: Inside and outside corners, pipe boots, and other special flashing shapes to minimize field fabrication.
C. Bonding Adhesive: Manufacturer's standard, water based.
D. Metal Termination Bars: Manufacturer's standard, stainless‑steel or aluminum, 25 mm wide by 3 mm thick (1-inch wide by 1/8 inch thick) factory drilled for fasteners.
E. Battens: Manufacturer's standard, galvannealed or galvanized steel sheet, 25 mm wide by 1.3 mm thick (1-inch wide by 0.05 inch thick), factory punched for fasteners.
F. Fasteners: Manufacturer's standard coated steel with metal or plastic plates, to suit application.
G. Primers, Sealers, T‑Joint Covers, Lap Sealants, and Termination Reglets: As specified by roof membrane manufacturer.
H. Adhesive and sealant materials recommended by roofing system manufacturer for intended use, identical to materials utilized in approved listed roofing system, and compatible with roofing membrane.
2.6 WALKWAY PADS
A. Manufacturer's standard, slip‑resistant rolls, minimum 900 mm (3 feet) wide by 5 mm (3/16 inch) thick.
2.7 ROOF PAVERS
A. GENERAL GUIDELINES
1. Ensure pavers are detailed showing size and shape.
2. Do not exceed 600 mm square (24 inches square) for non‑interlocking units with approximate weight of 23 kg (50 pounds) each.
3. Pavers require 73 kg/square meter (15 pounds/square feet.) minimum for fire rating.
4. Interlocking pavers are preferred over non interlocking pavers.
5. Use interlocking type that has been tested in a wind tunnel for wind uplift meeting project requirements.
6. Do not use light weight aggregate pavers.
7. Extensive use of pavers is not appropriate for roof systems with solar reflective design requirements.
B. Roof Pavers: Precast, normal weight, // interlocking // non‑interlocking // concrete units // with ribbed bottom surface for drainage //.
1. Weight: Minimum 73 kg/square meter (15 pounds/square feet).
2. Compressive Strength: ASTM C140/C140M; minimum 55 MPa (8,000 psi).
3. Freeze Thaw: ASTM C67; maximum 1 percent mass loss.
4. Units of size, shape, and thickness as shown on drawings.
A. Temporary Protection Materials:
1. Expanded Polystyrene (EPS) Insulation: ASTM C578.
2. Plywood: NIST DOC PS 1, Grade CD Exposure 1.
3. Oriented Strand Board (OSB): NIST DOC PS 2, Exposure 1.
PART 3 - EXECUTION
A. Examine and verify substrate suitability with roofing Installer and roofing inspector present.
1. Verify roof penetrations are complete, secured against movement, // and firestopped //.
2. Verify roof deck is adequately secured to resist wind uplift.
3. Verify roof deck is clean, dry, and in‑plane ready to receive roofing system,
4. Firestopping verification for fire rated roof assembly required.
B. Correct unsatisfactory conditions before beginning roofing work.
A. Existing Membrane Roofs and Repair Areas:
1. Comply with requirements in Section 07 01 50.19 PREPARATION FOR REROOFING.//
3.3 TEMPORARY PROTECTION
A. Install temporary protection consisting of a temporary seal and water cut‑offs at the end of each day's work and when work is halted for an indefinite period or work is stopped when precipitation is imminent.
B. Install temporary cap flashing over top of base flashings where permanent flashings are not in place to protect against water intrusion into roofing system. Securely anchor in place to prevent blow off and damage by construction activities.
C. Temporarily seal exposed insulation surfaces within roofing membrane.
1. Apply temporary seal and water cut off by extending roofing membrane beyond insulation and securely embedding edge of the roofing membrane in 6 mm (1/4 inch) thick by 50 mm (2 inches) wide strip of temporary closure sealant. Weight roofing membrane edge with sandbags, to prevent displacement; space sandbags maximum 2400 mm (8 feet) on center.
2. Direct water away from work. Provide drainage, preventing water accumulation.
3. Check daily to ensure temporary seal remains watertight. Reseal open areas and weight down.
D. Before the work resumes, cut off and discard portions of roof membrane in contact with temporary seal.
1. Cut minimum 150 mm (6 inches) back from sealed edges and surfaces.
E. Remove sandbags and store for reuse.
F. Use pull out tests for decks other than wood and wood blocking.
3.4 INSTALLATION - GENERAL
A. Install products according to manufacturer's instructions and approved submittal drawings.
1. When manufacturer's instructions deviate from specifications, submit proposed resolution for Contracting Officer's Representative consideration.
B. Comply with NRCA Manual installation requirements.
C. Comply with // UL 580 // UL 1897 // for uplift resistance.
3.5 ROOFING INSTALLATION
A. Install the membrane so the sheets run perpendicular to the long dimensionof the insulation boards.
B. Begin installation at the low point of the roof and work towards the high point. Lap membrane shingled in water flow direction.
C. Position the membrane free of buckles and wrinkles.
D. Roll membrane out; inspect for defects as membrane is unrolled. Remove defective areas:
1. Lap edges and ends of sheets 50 mm (2 inches) or more as recommended by the manufacturer.
2. Heat weld laps. Apply pressure as required. Seam strength of laps as required by ASTM D4434/D4434M.
3. Check seams to ensure continuous adhesion and correct defects.
4. Finish seam edges with beveled bead of lap sealant.
5. Finish seams same day as membrane is installed.
6. Anchor membrane perimeter to roof deck or parapet wall as indicated on drawings.
7. Repair areas of welded seams where samples have been taken or marginal welds, bond voids, or skips occurs.
8. Repair fishmouths and wrinkles by cutting to lay flat and installing patch over cut area extending 100 mm (4 inches) beyond cut.
E. Membrane Perimeter Anchorage:
1. Install batten at perimeter of each roof area, curb flashing, expansion joints and similar penetrations on top of roof membrane as indicated on drawings.
2. Mechanically Fastening:
a. Space fasteners maximum 300 mm (12 inches) on center, starting 25 mm (1 inch) from ends.
b. When battens are cut, round edges and corners before installing.
c. After mechanically fastening strip cover and seal strip with a 150 mm (6 inch) wide roof membrane strip; heat weld to roof membrane and seal edges.
d. At // gravel stops // fascia‑cants // turn roofing membrane down over front edge of the blocking, cant, or nailer. Secure roofing membrane to vertical portion of nailer; or, if required by the membrane manufacturer, with fasteners spaced maximum 150 mm (6 inches) on centers.
e. At parapet walls intersecting building walls and curbs, secure roofing membrane to structural deck with fasteners 150 mm (6 inches) on centers or as shown in NRCA manual.
F. Adhered System:
1. Apply bonding adhesive in quantities required by roof membrane manufacturer.
2. Fold sheet back on itself, clean and coat the bottom side of the membrane and the top of substrate with adhesive. Do not coat the lap joint area.
3. After adhesive has set according to adhesive manufacturer's instruction, roll roofing membrane into adhesive minimizing voids and wrinkles.
4. Repeat for other half of sheet.
G. Mechanically Fastened System Installation:
1. Secure roofing membrane to structural deck with fasteners through battens to achieve specified wind uplift performance.
a. Drill pilot holes for fasteners installed into cast‑in‑place concrete. Drill hole minimum 10 mm (3/8 inch) deeper than fastener penetration.
2. When fasteners are installed within membrane laps, locate battens minimum 13 mm (1/2 inch) from the edge of sheets.
3. Apply lap sealant under battens and anchor to deck while lap sealant is still fluid. Cover fastener head with fastener sealer.
4. Where fasteners are installed over roofing membrane after seams are welded, cover fasteners with minimum 200 mm (8 inch) diameter TPO membrane cap centered over fasteners. Where battens are used cover battens with minimum 200 mm (8 inch) wide TPO strip cap centered over batten. Splice caps to roofing membrane and finish edges with lap sealant.
3.6 FLASHING INSTALLATION
A. Install flashings same day as roofing membrane is installed. When flashing cannot be completely installed in one day, complete installation until flashing is watertight and provide temporary covers or seals.
1. See NRCA manual for base flashing details.
2. Use with metal cap flashing.
3. Do not use "pitch pocket" or "sealant pocket" construction detail.
4. Coordinate with sheet metal work to provide metal cap flashing for base flashing on curbs and walls and penetrations.
5. Do not terminate base flashing or membrane edge exposed on top of parapet walls or in reglets on horizontal or sloped wash surface.
6. Terminate only under cap flashings or coping covers except for draw bands on pipe boots and gravel stops.
8. Use 200 mm (8 inch) minimum height for base flashing.
B. Installing Base Flashing and Pipe Flashing:
1. Install flashing sheet to pipes, wall or curbs to minimum200 mm (8 inches) above roof surfaces and extending roofing manufacturer's standard lap dimension onto roofing membranes.
a. Adhere flashing with bonding adhesive.
b. Form inside and outside corners of flashing sheet according to NRCA manual. Form pipe flashing according to NRCA manual.
c. Lap ends roofing manufacturer's standard dimension.
d. Heat weld flashing membranes together and flashing membranes to roofing membranes. Finish exposed edges with lap sealant.
e. Install flashing membranes according to NRCA manual.
2. Anchor top of flashing to walls and curbs with fasteners spaced maximum150 mm (6 inches) on center. Use surface mounted fastening strip with sealant on ducts. Use pipe clamps on pipes or other round penetrations.
3. Apply sealant to top edge of flashing.
C. Installing Building Expansion Joints:
1. Do not put expansion joints at roof membrane level.
2. Design joints to be installed on curbs minimum 200 mm (8 inches) high.
3. Detail expansion joint.
D. Other Flashing Details
1. Install base flashing on curbs as specified.
2. Coordinate installation with // metal expansion joint cover // roof expansion joint system //.
3. Install flexible tubing 1‑1/2 times the width of joint centered over joint. Cover tubing with flashing sheet adhered to base flashing and lapping base flashing roofing manufacturer's standard dimension. Finish edges of laps with sealant.
E. Repairs to Membrane and Flashings:
1. Remove sections of roofing membrane or flashing that are creased, wrinkled, or fishmouthed.
2. Cover removed areas, cuts and damaged areas with a patch extending 100 mm (4 inches) beyond damaged, cut, or removed area. Heat weld to roofing membrane or flashing sheet. Finish edge of lap with lap sealant.
3.7 WALKWAY PAD INSTALLATION
A. Heat weld walkway sheet to roofing membrane at edges. Weld area 50 mm (2 inches) wide by the entire length of the walkway sheet.
B. Finish edges of laps with lap sealant.
3.9 ROOF INSPECTION AND REPAIR
1. Inspect roof for any damages or wear to membrane and seams.
2. Repair areas where where marginal bond, voids, and skips occur.
3. Repair fishmouths and wrinkles by cutting to lay flat. Install patch over cut area extending 100 mm (4 inches) beyond cut.
A. Remove excess adhesive before adhesive sets.
B. Clean exposed roofing surfaces.Remove contaminants and stains // to comply with specified solar reflectance performance //.
A. Protect roofing system from traffic and construction operations.
1. Protect roofing system when used for subsequent work platform, materials storage, or staging.
B. Loose lay temporary insulation board overlaid with plywood or OSB.
1. Weight boards to secure against wind uplift.
C. Remove protective materials immediately before acceptance.
D. Repair damage
END OF SECTION
Radha Krishna Temple Construction
ROOF WORK GUIDELINES FOR PENETRATIONS AND TPO MEMBRANE SEAMING
SCOPE OF WORK
(1) Flash and patch roof membrane for new roof penetration for exhaust fan/grease duct to roof near North West Corner - location indicated on Roof Plan showing the work required in coordination with exhaust fan installer and Project/Construction Manager.
(2) Relocate roof penetration for dryer vent in utility closet. Utility closet will be reduced in size to accommodate grease duct going to the roof to connect with Exhaust Fan. Work in coordination with HVAC contractor.
(3) Flash and patch roof for new penetration for rooftop condenser units for the new walk in coolers. This work to be coordinated with kitchen equipment installers.
 Install proper flashing per TPO manufacturer specifications, and follow general specifications below.
 Coordinate work with installation contractors and Project/Construction Manager. Phone and site meeting with all parties may be requested to coordinate the work.
 Complete full inspection of roof membrane. Patch and repair where/if necessary. Check seams and seals at Term bar and all other places for potential leaks. Caulk or patch where required. Check around base of steeples, boots, vent pipes, and drains, gas pipe penetrations, and other devices on roof.
ROOFING - WORK SCOPE, GUIDELINES & SPECIFICATIONS
Membrane Seaming Methods For Roof Penetrations
Visually inspect all hot air welders, both hand-held and robotic, for damage, loose parts or screws, and cleanliness. Check drive wheel and drive belt,
pressure wheel, rear guide wheel, and all other mechanical parts. Motion testing of the robotic welder to ensure it is tracking straight should also be
done before welder is used for membrane seaming.
Ensure you have a clean consistent power source for your hot air welders.
Generators should not be used to power other tools when hot air welders are in use. The surging created by other power tools cycling on and off can
cause inconsistencies in the final welded product.
It is recommended that extension cord length does not exceed 100’, which means generators may be required on some job sites.
Cut pieces of membrane to create test welds to ensure the settings of the robotic and hand-held welders are correctly configured to the current
membrane and environmental conditions.
Perform a 4’ or 5’ (1.22 m or 1.52 m) test weld before beginning each day’s application and any time the hot air welder has been turned
off for any length of time, to check peel strength, consistency, weld width, etc.
Adjust the welder accordingly.
Make sure the membrane is clean and dry on both sides of the membrane to be welded. If dirt and/or contaminants are not removed by wiping
membrane with a clean dry cotton cloth, Single Ply Membrane Cleaner may be used. If cleaner is used, give an appropriate amount for time for the
solvents to completely flash off, approximately 5 minutes.
Hand-Held Hot Air Welding
After verifying the areas to be welded are clean and dry, seams are aligned with the minimum required overlap, and the welding equipment is set to
the calibrated temperature setting; welding of the seam or flashing may begin.
1. Lift the top layer of membrane to insert the nozzle of the hand-held welder underneath with the end of the nozzle at a 45° angle to the seam.
2. Apply pressure with the 2” rubber/silicone roller, moving back and forth, parallel to the end of the nozzle, extending ½” past the nozzle in each
3. Follow the hand-held hot air welder approximately ¼” – ½” behind the nozzle end as you continue down the weld in a smooth and consistent
If you must stop in the middle of a weld for any reason make sure to pull on the last section of weld to release any cold or false welds. Then insert
the nozzle back into the weld and continue as described above.
Robotic Hot Air Welding
Robotic hot air welders provide many performance advantages over hand-held hot air welders but their larger size and directionality do not make
them applicable in all situations.
Several advantages are consistent speed of weld, constant pressure on welded area, higher powered heating element, built-in air damn, and
repeatability. Field seams must be completed by a robotic hot air welder.
After verifying the areas to be welded are clean and dry, seams are aligned with the minimum required overlap, and the welding equipment is set to
the calibrated temperature setting; welding of the seam or flashing may begin.
To begin the welding process, align the drive wheel of the welder onto the edge of the top layer of membrane, move the rear guide wheel onto the
same edge of the top layer of membrane, and insert the 2” nozzle into the lap to be welded. Fully seating the nozzle in the lap should activate the
automatic movement function of the robotic hot air welder.
NOTE: Use caution as the robotic hot air welder’s direction of movement usually is in the backward walking direction for the operator. The
assistance of a spotter and cord person is recommended.
Surface irregularities can cause the pressure wheel to move slightly away from the seam. If this happens, apply light pressure on the machine’s
upper handle to maintain travel in a straight line and keep even pressure of the drive wheel on the welded seam
As the hot air nozzle moves along the weld area, the wide drive wheel behind the nozzle (relative to the direction of movement) applies immediate
and uniform pressure to the heated seam area.
Check all robotic hot air welded seams for voids and repair with a hand-held hot air welder before the end of each working day.
Voids may occur along the edge of the middle layer of membrane between the upper and lower layers of membrane. After the lower and middle layer of membrane have been welded:
In the case of hand welding:
1. To seal the void, gently lift the upper membrane sheet and apply sufficient hot air to heat both membrane surfaces.
2. Then, using the edge of a silicone rubber roller, roll and fuse the upper membrane surface into the lower membrane. A crease developed along
the intersection of the two surfaces indicates a proper weld.
In the case of robotic welding:
1. To seal the void, when the robotic welder passes over the T-joint and the pressure wheel clears, use the edge of a silicone rubber roller to roll and
fuse the upper membrane surface into the lower membrane. A crease developed along the intersection of the two surfaces indicates a proper
Applying heat to the top side of the upper membrane sheet will not effectively fuse the two membranes together and will only damage the upper
Patch all t-joints — including base flashing — using a 4.5” (11.43 cm) rounded piece of detail membrane or TPO T-Joint Patch.
Repairing Scorched Membranes
If a section of the membrane surface is overheated, the burned or discolored membrane must be patched, as a good weld cannot be achieved.
1. To repair a scorched section, cut a patch in a square or rectangular shape with rounded corners. Patches should be cut to extend at least 3” (7.62
cm) beyond all damaged area. Allowing for a minimum 1.5” (3.81cm) weld width on all sides.
2. Center the patch over the cut area and weld to the membrane, using normal hand-held hot air welder procedures.
Reinforced membrane is to be used for patches on field membrane; non-reinforced membrane is to be utilized at areas requiring a tight contour or
change in direction.
Test all welded seams for integrity and continuity before the end of each work day.
Hot air welded seams may be tested as soon as the seams cool, testing prior to the cooling of the seam will cause damage to the membrane and the
After the weld has cooled, carefully test every seam, t-joint, and patch along its entire length.
Do this by running a blunted scratch awl, cotter key extractor or other round-tipped, blunted tool along the seam edge while applying firm, steady
It is imperative to avoid scoring the membrane that has just been welded. Any penetration of the probe into the seam indicates a void in the weld,
which must be repaired.
Continuous seam probing will tend to sharpen the tip of the probe, so it is important to blunt the tip of the probe regularly.
In addition to probing, take seam samples to verify seam quality as necessary.
Cut the samples across the seam 6” (15.24 cm) on each side of the seam and 2” (5.08 cm) wide.
Peel these samples by hand to test seam strength.
Good seams will be virtually impossible to peel, and should delaminate the TPO film from the reinforcing scrim.
Cut and test a minimum of three seam samples each day — in the morning, at mid-day, and at day’s end.
Take additional test cuts when weather conditions change or after work interruptions when the automatic hot air welder has been shut off.
Sealing Tested Seams
Seal all cut seam edges with TPO Edge Sealant after testing and repairing. This prevents water from entering the welded area through wicking or capillary action.
Weld and seal seams at all cut edges on the same day.
Clean and dry any edges that stand overnight to ensure good sealant adhesion.
Apply sealant with a squeeze bottle.
Draw the tip smoothly along the cut edge of the membrane to produce a uniform 1⁄8” (3.18 mm) bead.
Flashings and Penetrations
There are several methods for flashing drains with TPO roofing membrane. The most common method is to taper insulation to the drain bowl
creating a sump. If you are using this method, ensure that a proper sump is created by using tapered panels, not shaving the edge of the
insulation board around the drain.
1. Apply one tube of single ply sealing mastic around the drain bowl. Cut TPO Flashing Membrane to overlay drain area, and cut out hole in center
area at least the same diameter as the drain leader. Cut holes one-half the size of bolt diameter at drain bolt penetrations. Make sure there are no
seams or fasteners through the drain clamping ring. Ideally, there should be no seams or fasteners in the drain sump. Add target patch if necessary.
2. Carefully press membrane drain flashing over drain bowl area and work into the mastic to form seal. Place metal clamping ring over membrane
flashing so that bolt holes line up, and then tighten the bolts Do not run fleece back membrane into the drain bowl.
The drain flashing membrane shall not be installed under tension or showing signs of ridging or deformation.
There are two primary methods for installing vent pipes in TPO roofing systems:
Method A. Installing Prefabricated Vent Pipe Boots:
Use the appropriate size Pipe Boot(s) to accommodate the (various) diameter(s) for installation over pipes. Either peel-and-stick adhesive heat-
weldable style is acceptable
Bring the TPO field sheet up to the base of the pipe and fasten or secure with a minimum of four fasteners around the vent stack. If using the peel-
and-stick pipe boot, first prime the field area, then place the boot over the pipe and remove the peel-andstick tape then roll with a silicone roller to
make sufficient contact.
If using the prefabricated pipe boot, place the boot over the pipe and weld continuously around the bottom lip of the boot.
Ensure that pipe boot extends past outside edge of all fasteners by a minimum 1½” (3.81 cm).
Apply Single Ply Sealing Mastic behind the top of the pipe boot membrane before pulling draw band tight around the vent pipe.
Apply Single Ply Caulk to the top of the draw band to seal against water intrusion.
Method B, Sealing Pipe Base with TPO Flashing:
Prepare a square TPO Detail Membrane target patch to overlap the securement plate edges by at least 4” (10.16 cm), to accommodate sheet
movement and a 1½” (3.81 cm) weld width. Round off all corners.
Cut a hole in the center of the membrane that is about two-thirds of the diameter of the pipe.
Center hole over the pipe; heat area around the hole with a heat welder, and stretch fit membrane over the pipe to create a 1” (2.54 cm) turn-up,
with the collar seated flush on the deck.
Weld the membrane collar continuously to the field sheet and/or the metal collar.
Field wrap TPO detail membrane around the pipe stand and adhere to the vent pipe, while flanging the bottom of the field wrap. Extend field wrap
flange at least 1” (2.54 cm) onto the membrane stretch collar and weld continuously to the collar.
If the pipe has asphalt or other contaminants on it, it must be cleaned and wrapped completely with aluminum tape before installing the flashing.
Penetration pockets may be used to seal around irregular shaped penetrations through the roofing system that do not allow for previously
mentioned flashing methods.
Field-fabricated penetration pockets are also available, typically fabricated.
Leave an open, overlapped seam at the center of one side so the penetration pocket may be spread around penetrations before final riveting.
Minimum Field Fabricated TPO Clad penetration pocket height is 4” (10.16 cm).
Fasten penetration pocket flanges at the outside to the deck or nailer. The overlap or opening must be covered with aluminum tape and detail
membrane prior to stripping flange.
With strips of TPO detail membrane, strip in penetration pocket around all four sides, and weld continuously to TPO-Coated Metal as you would a
field sheet. Seal all cut edges with TPO Edge Sealant. TPO Primer must be applied to the inside surfaces of the penetration pocket or fabricated
Using TPO Pourable Sealer, fill until mounded above penetration pocket and slope from pipe to penetration pocket edges to shed water (no ponding
water should be present in penetration pocket).
Fasten penetration pockets greater than 18” x 18” (45.72 cm x 45.72 cm) to nailers securely anchored to the deck.
TPO-Coated Metal Flashing
Preformed TPO-Coated Metal Flashing is fastened around the roof perimeter edge. Welding the membrane to TPO-Coated Metal Flashings at
these points provides a watertight seal.
Leave a 3⁄8” to ½” (9.53 mm to 1.27 cm) maximum gap between each length to allow for thermal expansion. Aluminum tape should be applied over
all joints in TPO-Coated Metal prior to heat welding the joint covers and membrane in place.
Install all membrane flashings at the same time as the roof membrane. Do not use temporary flashings.
If water penetrates the flashings, immediately replace all affected materials.
Use only TPO adhered, mechanically attached, or prefabricated flashings.