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EPDM Roofing

EPDM Membrane with Pre-Applied Seam Tape - Technical Data Bulletin

EPDM Membrane with Pre-Applied Seam Tape

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DuoPly Polyester Fleece Reinforced membranes are manufactured using a patented hot melt adhesive technology to bond a polyester fleece backing to the EPDM sheet membrane.

Once the EPDM membrane is reinforced and enhanced with fleece the total thickness is 2.54mm, creating an extremely tough, durable and versatile sheet that is ideal for re-roofing, overlayment and new build projects.

Manufactured with 75mm Pre-Applied Seam Tape (PST) to ensure consistent seam strength & quality with the added benefit of increased installation speed.

Features & Benefits

  • Rolls 1.52m wide by 12.20m long, thick 2.54mm membrane
  • 75mm PST provides consistent seam quality and enhanced on site productivity
  • 34% fewer seams than Modified Bitumen
  • Fleece reinforcement adds toughness, durability and enhanced puncture resistance
  • Labour and cost savings in field applications


Adhered Roofing System - Apply appropriate DuoPly Decking Adhesive to the suitable substrate. For DuoPly WBA decking adhesive lay membrane into adhesive when still wet, for PU Deck Adhesive allow adhesive to foam (adhesive will lighten in colour), using a rubber bladed squeegee press/smooth the membrane into the adhesive to ensure full embedment. Splices are sealed with DuoPly Pre-Applied Seam Tape (PST), end laps are sealed with DuoPly EPDM Cover Strip.


1. The entire surface where the membrane splice will be applied must be clean and dry. The adhesive on the PST will not adhere to wet and/or dirty surfaces. Any residual contamination will be detrimental to the bond strength of the adhesive.

2. Remove any dirt or excess dust from the splice by wiping with a clean rag. If needed, clean the splice area thoroughly with Weathered Membrane Cleaner. This is essential for membrane that has been exposed for a number of weeks.

3. Application of DuoPly EPDM Primer: Brush or roller(short pile roller) apply the primer to the splice area of the bottom DuoPly membrane. The properly primed area will be free of streaks, globules or puddles. Allow the DuoPly EPDM Primer to dry until it does not transfer to a dry finger.

4. Allow the taped edge of the top sheet to fall freely onto the primed sheet below.

5. Pull the poly backing from the PST beneath the top sheet and allow the sheet to fall freely onto the exposed primed surface.

6. Press top sheet on to the bottom sheet using firm, even hand pressure across the splice towards the edge of the seam.

7. Immediately roll the DuoPly seam with a 50mm wide roller using positive pressure rolling across the seam not along it.

8. For cold weather splicing when job site temperatures fall below 5°C, these steps must be followed:

a) Heat the primed area of the membrane with a hot air gun as the top sheet with PST is applied and pressed into place.

b) Prior to rolling the splice area with a 50mm hand roller, apply heat to the top side of the membrane with a hot air gun. The heated surface should be hot to touch, be careful not to burn or blister the membrane.

9. Install 225mm PS Uncured Elastoform Flashing over all field splice intersections.

Consult a DuoPly EPDM distributor for full installation detail.


1. Use proper stacking and storage procedures to ensure safe and suitable storage of materials.

2. Exercise caution when walking on wet membrane, EPDM membranes can become slippery when wet.

3. DuoPly rolls must be protected from water prior to installation. If the fleece gets wet ensure the fleece has dried before installation.

4. In warm sunny weather, shade the taped end of the rolls until ready to use.

5. Do not allow waste products (petroleum, grease, oils, solvents, vegetable or mineral oil, animal fats, etc.) to come into contact with the DuoPly EPDM Membrane.

Physical Property Test Method SPEC.(Pass) DuoPly
Tolerance on Nominal
Thickness, 0%
ASTM D751 =/-10 =/-10
Thickness over Fleece,
min 2.54mm
ASTM D4637
0.762mm 2.54mm
Weight, kg/m² 2.54mm




Breaking Strength, min N
Grab Method
400 890
Elongation, Ultimate min.% ASTM D412 300** 480**
Tearing Strength, min, N ASTM D751
B Tongue Tear
45 200
Puncture Resistance, Joules
ASTM D5635   15
Puncture Resistance, lbs
FTM 101C
Method 2031
Puncture Resistance, lbs
ASTM D120   18
Hail Resistance

Over Iso

Class 4 Rating Pass
Brittleness point, max, ° ASTM D2137 -45 -55
Resitance to Heat Aging* 
Properties after 4 weeks
at 116°C for DuoPly
ASTM D573    
Breaking Strength, min, N ASTM D751 355 890
Elongation, Ultimate, min % ASTM D412 200** 225*
Linear Dimensional change, max, % ASTM D1024 +/- 1.0 -0.7

Ozone Resistance

Condition after exposure to 100pphm
Ozone in air for 168 hours @ 40°C
Specimen wrapped around 7.5cm mandrel

ASTM D1149 No Cracks No Cracks
Resistance to Water Absorption*
After 7 days immersion @ 70°C
Change in mass, max, %
ASTM D471 +8, -2** +2.0**
Resistance to Outdoor Cracks
(Ultraviolet) Weathering* 
Xenon-Arc 17.640 kJ/m² (Black) and
total radiant exposure at 0.70 W/m²
irradiance, 80°C

ASTM D4637

No cracks
No cracks
No cracks
No cracks

*Not a quality control test due to the time required for the test or the complexity of the test. However all tests are run on a statistical basis to ensure overall long term performance of the sheeting.

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Registered in England and Wales, Company Number: 03984573

Registered Office: Flex-R Ltd, Sandswood House, Hillbottom Road, Sands Industrial Estate, High Wycombe, Buckinghamshire, HP12 4HJ

Telephone: 0800 037 1240   Email: enq@duoply.co.uk