Tank waterproofing. Two tanks in ACTFLEX 5000.
·1 min read·FORSPEC Technical Team
The short version
- Two concrete tanks were wrapped on the outside face in ACTFLEX 5000 self-adhesive sheet.
- The sheet runs from the top of the wall down over the footing, with every corner wrapped in the same sheet.
- ACTFLEX 5000 is a Class III membrane to AS 4654.1. It stretches 374% before it breaks.
A tank wall that will be buried gets one chance. Once the backfill is in, nobody sees that face again. On this job the outside of two concrete tanks was wrapped before the ground went back.
What was built
- ACTFLEX 5000 self-adhesive sheet on the outside face of both tanks.
- Sheets taken from the top of the wall down over the footing, so the wall and footing joint is covered.
- Corners wrapped in the same sheet.
- Left ready for backfill protection.
Why a self-adhesive sheet
A sheet goes on at a set thickness, and it can be backfilled without a cure time. It sticks to concrete primed with ACTFLEX EP250, and the laps are 75 mm at the sides and ends.
- Class
- Class III to AS 4654.1 (Report 373, 19 February 2025)
- Stretch at break
- 374%
- After 56 days in water
- Pass, 254% stretch
- Laps
- 75 mm, side and end
See every project or the below-ground system for the full build-up, with waterstops in the joints and drainage cell against the backfill.
Where this comes from
- ACTFLEX 5000 Technical Data Sheet, Revision 2, 9 November 2026
- XTec Gen Report 373-2, ACTFLEX 5000 to AS 4654.1 (summary)
- Job facts: the FORSPEC site photo folder for this job (what the photos show; no dates or quantities on file)
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