Which plaster type is generally more breathable?

Which plaster type is generally more breathable?

• A. Cement plaster
• B. Lime plaster
• C. Gypsum plaster
• D. Resin plaster

Answer: (B)

Breathability in plaster means how easily water vapor can move through the plaster and the wall behind it. Lime plaster is generally more breathable because its lime-based binder forms a porous, micro-porous matrix that allows moisture to diffuse through rather than trap it. This helps moisture migrate in and out with changing conditions, reducing damp-related problems in walls. Cement plaster cures into a dense, cementitious matrix with low porosity, which acts like a barrier to vapor and can trap moisture inside the wall. Gypsum plaster also forms a relatively dense structure after setting, making vapor movement less easy than with lime. Resin plaster relies on synthetic binders that often create a tighter, less permeable surface, further reducing breathability. In moisture-sensitive wall assemblies, lime plaster is preferred for its vapor-permeable nature, aiding in moisture management.

Breathability in plaster means how easily water vapor can move through the plaster and the wall behind it. Lime plaster is generally more breathable because its lime-based binder forms a porous, micro-porous matrix that allows moisture to diffuse through rather than trap it. This helps moisture migrate in and out with changing conditions, reducing damp-related problems in walls.

Cement plaster cures into a dense, cementitious matrix with low porosity, which acts like a barrier to vapor and can trap moisture inside the wall. Gypsum plaster also forms a relatively dense structure after setting, making vapor movement less easy than with lime. Resin plaster relies on synthetic binders that often create a tighter, less permeable surface, further reducing breathability.

In moisture-sensitive wall assemblies, lime plaster is preferred for its vapor-permeable nature, aiding in moisture management.