FORZAFLEX BASE 3MM Torch-on base ply
Torch-applied APP-modified bitumen membrane, base and intermediate layer
Class I torch-on base ply, fully fused to the substrate and to the cap sheet above it.
FORZAFLEX BASE 3MM sizes and key figures
Base or intermediate ply of a multi-layer torch-applied system for roofs, podiums, balconies, retaining walls, lift pits and below-ground structures. Always overlay it with a cap sheet, board, screed or finish.
- Roll size
- 10 m × 1 m10 m² gross, approx. 9.1 m² effective after laps · TDS p7
- Thickness
- 3.0 mmnominal, EN 1849-1 · TDS p4
- Class
- Class Ilow extensibility, AS 4654.1, Report 597-1 · TDS p2
- Laps
- 75 / 150 mmside / end lap, end laps staggered at least 1 m · TDS p4
- Apply at
- 5°C to 40°Ctypicalambient. No torching in rain, wet or high wind · TDS p4
- Substrate fall
- 1:100minimum, draining positively to outlets · TDS p4
- Upturn
- 150 mmminimum, unless specified otherwise · TDS p4
- Cooling
- Approx. 30 minbefore seam probing and foot traffic · TDS p7
- Flood test
- 50 mm, 24 hafter all plies and detailing, before any cover · TDS p8
From the FORSPEC data sheet, TDS-FORZABASE3 · Revision 1 · 25 August 2026. Times are at 25°C and 50% relative humidity unless the data sheet says otherwise. Typical = FORSPEC’s own typical value, not a laboratory-certified one.
Where FORZAFLEX BASE 3MM is used
Use it for
- Roof systems, as the base or intermediate layer beneath a cap sheet
- Podiums and plaza decks beneath protection layers
- Balconies and terraces beneath tiles, screeds or pavers
- Retaining walls, positive side, beneath protection and drainage
- Below-ground foundations, lift pits and wet basements
- Intermediate ply in engineered multi-layer torch-applied build-ups
Know before you start
- Not a finished surface: never leave it permanently exposed to UV
- Class I only: use a higher-class membrane where Class II or III is needed
- No torching direct to combustible substrates, or onto wet, damp or green surfaces
- Not in direct contact with polystyrene, PVC or plasticised sheet without separation
How to apply FORZAFLEX BASE 3MM
- 01
Prepare
Concrete cured 28 days minimum, Concrete Surface Profile 3–6, dry and free of laitance and contaminants. Falls at least 1:100 to outlets. Repair defects with FORBUILD 100 or FORCRETE 100.
- 02
Prime
Roller, brush or spray FORZAPRIME over all concrete, masonry and metal. Let it dry tack-free. Never torch onto wet or uncured primer.
- 03
Lay out
Start at the lowest point with sheets across the fall. Side laps 75 mm, end laps 150 mm, end laps staggered at least 1 m. Reinforce every corner with an extra torched piece.
- 04
Torch
Heat the underside film evenly until molten and roll steadily. Aim for about 6 to 12 mm of molten bitumen ahead of the roll and 3 to 6 mm bleed-out along every lap. Do not overheat.
- 05
Inspect
Let it cool about 30 minutes, then probe every lap with a blunt probe. Check for blisters, fish-mouths and hollow areas. Cut out and re-patch defects, lapped 150 mm.
- 06
Cap
Fit the cap sheet once the base ply is cool and inspected: MINERALE 4.5 for UV-exposed, RR for planted areas. Flood test at 50 mm for 24 hours before protection or screed.
A short guide from the data sheet. Read the full FORZAFLEX BASE 3MM TDS before you start.
Where it has been used
FORSPEC projects built with FORZAFLEX BASE 3MM.
FORZAFLEX BASE 3MM test reports and compliance
- AS 4654.1-2012
- Class I (low extensibility), all durability criteria passNATA Report 597-1
- AS 4654.1 Appendix B
- Pass, 50 cycles, no rupture, crazing or tearsNATA Report 597-1
- ASTM D6207
- No changes observed over two full cyclesReport 597-1
- ASTM E96
- 0.07 g/m²/24 h water vapour transmissionReport 597-1
- ASTM C794
- 22.63 N raw peel force, unprimed concreteReport 597-1
Download the reports
Results as stated in the data sheet, TDS-FORZABASE3 · Revision 1 · 25 August 2026. Warranty up to 25 years, depending on the system: ask FORSPEC which term applies to your system.
FORZAFLEX BASE 3MM questions
Can I leave FORZAFLEX BASE 3mm exposed?
No. It is a base and intermediate ply, not a finished surface. Overlay it with a cap sheet, protection board, screed or finishing system. Never leave it permanently exposed to UV.
How many rolls do I need for 100 m²?
About 11. Each 10 m × 1 m roll gives approx. 9.1 m² after laps. Allow at least 10% extra, and more on cut-up areas. Quantities double if the design needs two base plies.
Do I need a primer?
Yes. Apply FORZAPRIME to all concrete, masonry and metal, and let it dry tack-free before torching.
Can I torch it onto timber?
No. Torch application direct to a combustible substrate is prohibited. Install a suitable non-combustible overlay board first.
How do I know the weld is good?
Look for continuous bitumen bleed-out: about 6 to 12 mm ahead of the roll and 3 to 6 mm along every lap. A lap without bleed-out has not fused.
When can I flood test it?
After all plies, laps and detailing are complete and inspected, and before any protection, screed or overburden. Flood to at least 50 mm and hold for 24 hours.
Used with FORZAFLEX BASE 3MM
FORZAFLEX BASE 3MM TDS and SDS
Always work from the current data sheet. Every FORSPEC TDS and SDS →
Specify it. Or buy it.
Send the drawings or photos and FORSPEC comes back with the system, the details and the quantities. Or find a FORSPEC stockist for FORZAFLEX BASE 3MM.