Sealing Joints in Wet Areas with a Flexible Acrylic Sealant
A waterproof wall is only as good as its joints. Corners, wall-to-floor junctions and changes of plane are where wet-area waterproofing most often fails — so they need a flexible seal that moves without cracking.
Why joints are the weak point
Rigid fillers crack at moving joints, letting water track behind tiles and finishes. BS 5385-4 is explicit that all junctions — wall-to-floor, internal corners and around penetrations — must be sealed as part of a watertight enclosure before tiling. Miss the joints and the best tanking on the open areas still leaks.
The solution: a flexible acrylic sealant
Copagro Acry-DSP is a flexible acrylic sealant for finishing connection joints. Water-resistant and paintable, it works alongside Poseidon to form a continuous watertight tanking system — sealing the moving junctions while the membrane covers the faces. It applies with a standard mastic gun.
How it is applied
- Clean and prepare the joint
- Gun the sealant into corners, junctions and around penetrations
- Tool to a neat profile
- Overcoat with Poseidon and tile once cured
Benefits
- Flexible, water- and weather-resistant
- Paintable and easy to tool
- Pairs with Poseidon for full tanking
Frequently asked questions
Can I tile straight over it? Seal the joints, apply the membrane over the area, then tile per BS 5385-4.
Is sealant alone enough to waterproof a wet area? No — it seals the joints; the faces still need a tanking membrane.
See the full method in How to Waterproof a Wetroom Before Tiling.