Roundtower SuperTherm Finishing Plaster

Roundtower SuperTherm Finishing Plaster is a breathable lime-based finishing coat specifically designed for use over Roundtower SuperTherm insulating plaster systems. Applied as a thin reinforced finish layer, it stabilises the underlying insulating plaster, improves crack resistance, and creates a durable, vapour-open surface ready for breathable decorative finishes such as limewash, silicate paint, or mineral paint systems.

The finishing plaster forms part of the complete Roundtower SuperTherm internal insulation system and is designed to maintain vapour permeability throughout the wall build-up while providing a stronger, more uniform final surface.

Technical Data

Key Benefits

Designed Specifically for SuperTherm

Formulated as a compatible finishing layer over Roundtower SuperTherm insulating plaster systems to maintain consistent vapour permeability and adhesion throughout the build-up.

Vapour Open & Moisture Safe

The lime-based composition remains breathable and supports the hygrothermal performance of solid masonry walls by allowing moisture vapour to diffuse and evaporate safely.

Reinforced for Durability

Designed to receive embedded fibreglass mesh reinforcement, improving:

• tensile strength,
• surface stability,
• and crack resistance

within the finished plaster layer.

Creates a Uniform Finish

Provides a smooth, consistent surface suitable for breathable decorative finishes including:

• limewash,
• silicate paint,
• mineral paint,
• and other vapour-open coatings.

Protects the Insulating Layer

Acts as an “armoured” protective surface over the lightweight insulating plaster beneath while still maintaining breathability.

Suitable for Heritage & Breathable Retrofit

Fully compatible with:

• solid masonry buildings,
• lime-based construction,
• heritage retrofit projects,
• and moisture-sensitive structures.

Why Use SuperTherm Finishing Plaster?

Lightweight insulating plasters require a durable reinforced finish layer that remains compatible with the vapour-open behaviour of the insulation system beneath.

Conventional gypsum skim coats and impermeable finishes can restrict vapour diffusion and compromise the moisture performance of breathable wall systems.

SuperTherm Finishing Plaster differs because it remains:

• breathable,
• lime-based,
• and fully compatible with moisture-regulating masonry systems.

When combined with embedded mesh reinforcement, the system creates a highly stable and durable finish layer while still allowing the wall assembly to continue drying naturally.

Installation Overview

1. Background Preparation

Ensure the underlying Roundtower SuperTherm plaster is sufficiently cured, stable, and appropriately prepared before application.

2. Mesh Reinforcement

An R52 internal fibreglass reinforcing mesh is embedded within the finishing plaster layer to improve crack resistance and tensile stability.

3. Plaster Application

The finishing plaster is generally applied at approximately 5 mm thickness across the insulated surface.

4. Surface Finishing

The plaster can be finished to provide:

• a smooth mineral surface,
• or a lightly textured breathable finish

depending on the desired aesthetic.

5. Decorative Finish

Suitable breathable finishes include:

• limewash,
• silicate paint,
• mineral paint,
• and vapour-open decorative coatings.