If you are renovating a period property or an older build, you are likely dealing with solid brick or stone walls. Unlike modern cavity walls, these structures manage moisture by absorbing it and letting it evaporate.

The Mistake: If you seal these walls with cheap plastic sheets or the wrong insulation, you trap moisture. This leads to damp, mold, and rotting joists.

The Solution: You need an "Intelligent" membrane. You need Passive Purple X.

For deep retrofits, we often recommend upgrading to Passive Purple X for internal use. Here is why it is the smart choice for the self-builder renovating an
older home:

1. It Lets Your Walls "Breathe"
Passive Purple X is an intelligent vapour control layer. It changes its molecular
structure based on humidity.

• In Winter: It closes up to stop warm, moist air from your home entering the cold wall structure (preventing condensation).
• In Summer: It opens up to allow any moisture trapped inside the wall to
  evaporate back into the room to be ventilated away.
• This "breathability" is vital for preserving the health of solid walls.

2. Superior Fire Safety (Class B)
When working with older timber structures, safety is paramount. Passive Purple X is Class B-s1, d0 fire rated. This offers a significant upgrade over standard Class C membranes, giving you extra peace of mind—especially in tight spaces or near restored timber features.

3. Seals the Impossible Places
Old houses are full of awkward gaps: crooked window reveals, old pipe penetrations, and uneven brickwork.

• Joist Ends: Sealing around timber joist ends embedded in brickwork is
  notoriously difficult with tape. Passive Purple X paints right over them, sealing the gap without rotting the wood.
• Surface Adhesion: It bonds aggressively to old brick, stone, concrete, and new timber stud work alike.

• Internal Solid Walls: Applied before insulated plasterboard or framing to manage vapour.
• Window & Door Reveals: Stops drafts in the trickiest part of the insulation envelope.
• Loft Conversions: Ideal for spraying
  hard-to-reach eaves and rafter lines.
• Swimming Pool Extensions: If your renovation includes a pool, Passive Purple is highly effective in high-humidity environments.

(Note: It must be applied at the specifically required thickness for pool areas—check our datasheet!).