Wet Areas

Only 4 linings and finishes are listed as suitable for wet areas in Acceptable Solution E3/AS1:

• integrally waterproof sheet material (such as PVC) with sealed joints
• ceramic or stone tiles with 6% maximum water absorption and waterproof grouted joints
• sheet linings finished with a semi-gloss or gloss coating or a hard-wearing low-sheen latex paint containing mould inhibitors
• water resistant sheet linings finished with decorative high pressure laminate or factory applied polyurethane or resin, installed with impervious joints.

E3/AS1 makes the comment that other wall linings and finishes finishes may also satisfy performance requirements, but they are outside the scope of the Acceptable Solution. This means that they must be consented as an Alternative Solution.

Characteristics and performance of wet area wall finishes.

Cement plaster

• Not damaged by water.
• May support bacterial and fungal growth as roughness of surface may make the wall difficult to clean.
• May absorb water if not sealed.
• Suitable for areas not normally wet.
• Suitable for splash areas if coated.
• Suitable for shower if it has an impervious coating system.

Concrete

• Not damaged by water.
• Doesn’t allow water to percolate.
• Suitable for areas not normally wet.
• Suitable for splash areas if it has a steel-trowelled dense finish.
• Suitable for shower if it has a steel-trowelled dense finish.
• A robust finish.

Concrete masonry

• Not damaged by water.
• May support bacterial and fungal growth as roughness of surface may be difficult to clean.
• Allows water to percolate.
• Suitable for areas not normally wet if suitably coated.
• Suitable for splash areas if suitably coated.
• Suitable for shower if suitably coated.

Decorative panels with proprietary jointing

• Not damaged by water, but material performs better when substrate sheet kept dry.
• Doesn’t support bacterial and fungal growth.
• Moisture may enter at sheet joints.
• Doesn’t allow water to percolate but must have proprietary jointers or expressed sealant joints.
• Suitable for areas not normally wet with correct coating.
• Suitable for splash areas.
• Suitable for showers.
• Seal sheets into jointer.
• Maintain clearance at bottom of sheets.

Fibre-cement sheet

• Not damaged by water, but material performs better when kept dry.
• Supports bacterial and fungal growth if wetted.
• Can absorb moisture if unprotected
• Suitable for areas not normally wet with correct coating.
• Suitable for splash areas with correct coating.
• Not suitable for showers.
• Can be suitable substrate for tiling or impervious coating in showers - tiles must be installed over suitable waterproofing membrane.

Particleboard

• Damaged by water if inadequately treated and coated – should be treated to H3.1 in wet areas.
• Supports bacterial and fungal growth if wetted.
• Can absorb moisture if unprotected, and moisture may enter at sheet joints.
• Suitable for areas not normally wet with correct coating.
• Not suitable for splash areas.
• Not suitable for showers.

Plasterboard – standard grade

• Damaged by water if unprotected.
• Supports bacterial and fungal growth if becomes wet.
• Can absorb moisture if unprotected.
• Suitable for areas not normally wet if painted or as tile substrate.
• Suitable for splash areas as a tile substrate with waterproof membrane.
• Not suitable for showers.

Plasterboard – water-resistant

• Supports bacterial and fungal growth if becomes wet.
• Can absorb moisture if unprotected.
• Suitable for areas not normally wet if painted or as tile substrate.
• Suitable for splash areas as a tile substrate – a waterproof membrane is recommended.
• Suitable for showers as a tile substrate with waterproof membrane.
• Cannot be used as bracing when installed in a shower.

Plywood

• Not damaged by water, but material performs better when kept dry.
• Supports bacterial and fungal growth if wetted.
• Moisture may enter at sheet joints.
• Suitable for areas not normally wet with correct coating.
• Not suitable for splash areas.
• Not suitable for showers.
• Can be suitable substrate for tiling in showers – tiles must be installed over suitable waterproofing membrane.

PVC (vinyl)

• Not damaged by water.
• Doesn’t support bacterial and fungal growth.
• Doesn’t allow water to percolate with welded joints.
• Suitable for areas not normally wet.
• Suitable for splash areas.
• Suitable for showers with welded joints.
• Can be homogeneous with PVC floor
• Welding normally HD quality.

Terrazzo

• Not damaged by water.
• Doesn’t support bacterial and fungal growth.
• Doesn’t allow water to percolate.
• Suitable for areas not normally wet.
• Suitable for splash areas.
• Suitable for showers.
• A robust finish when applied to concrete walls.

Tiles – ceramic

• Not damaged by water.
• Doesn’t support bacterial and fungal growth.
• Doesn’t allow water to percolate if tiles 6% or less moisture absorption, but does through grouted joints.
• Suitable for areas not normally wet.
• Suitable for splash areas – waterproof membrane recommended.
• Suitable for showers with waterproof membrane and durable substrate.
• Must include control joints.
• Must be on a rigid substrate.

Tiles – stone

• Not damaged by water.
• Doesn’t support bacterial and fungal growth.
• Allows water to percolate through grouted joints.
• Suitable for areas not normally wet.
• Suitable for splash areas – waterproof membrane recommended.
• Suitable for showers with waterproof membrane.
• Must include control joints.
• Must be on a rigid substrate.
• Stone must be of a non-porous type.

Timber boarding

• Damaged by water if inadequately coated.
• Supports bacterial and fungal growth if wetted.
• Moisture may enter through board joints.
• Suitable for areas not normally wet if suitably coated.
• Not recommended for splash areas.
• Not suitable for showers.
• Opening of joints due to movement may allow moisture entry.

Vinyl-coated wallpaper on plasterboard

• Not damaged by water if correctly applied.
• Supports bacterial and fungal growth if becomes wet.
• Doesn’t allow water to percolate.
• Suitable for areas not normally wet.
• Not suitable for splash areas.
• Not suitable for showers.
• Edges of wallpaper are at risk of water penetration.

Updated : 24 November 2021