Targeting Keywords: Timber frame
settlement, flexible vapour barrier, airtightness for timber.

Every timber frame builder knows the
reality: Wood shrinks, settles, and moves. Whether it’s the natural drying process of the timber or the weight of the roof settling onto the frame, your building will move slightly in the first few years.

The Failure of Tape: Traditional paper membranes and airtightness tapes are static. When the building moves, the tape is put under tension. Eventually, it lifts, peels, or snaps. When the tape fails, your airtightness fails.

For the critical joints between your boards, we have a specific tool: Passive Purple Brush.

This is the fibre-reinforced version of our liquid membrane, designed specifically for bridging gaps and joints without the need for sticky tape.

Perfect for OSB & Cement Particle Board

Whether you are sealing standard OSB sheeting on a timber frame, or Cement Particle Board (CPB) on a steel frame, the joints are the weak points.

• Don't Tape It: Tapes struggle to adhere to the rough texture of OSB or dusty Cement Particle Board.
• Brush It: Simply paint Passive Purple Brush over the panel joints.
• The Result: It soaks into the texture of the board, creating a permanent, flexible bridge that seals the gap and accommodates movement.

Beyond flexibility, it’s simply faster.

• No Staples: Thousands of staples in a paper membrane are thousands of potential leaks. Passive Purple requires zero mechanical fixings.
• Spray Application: Once the joints are brushed, you can spray the main areas. A single operator can seal the walls and ceilings of a standard timber frame house in just one day.
• Vapour Control: It sits on the warm side of the insulation, acting as your primary Vapour Control Layer (AVCL) to stop moisture rot