Retro EcoWall: Internally Insulating Traditional Buildings
Monday 12th December 2022
Retrofitting traditional buildings requires a sensitive approach to internally insulating solid stone or brick walls. Aside from providing thermal comfort, it is essential that the insulation promotes breathability in the walls and manages moisture. In response to these requirements, Ecological Building Systems has launched the Retro EcoWall system.




Retro EcoWall was officially launched at the RIAI Architecture & Building Expo in October 2022, where it was highly commended in the ‘Best Interior Product’ category of the Architect’s Choice Awards. The system combines the breathable, insulating and sustainability benefits of Diasen Thermactive cork lime thermal plaster, Gutex Thermoroom high performance woodfibre insulation boards, Gutex Thermoroom Reinforcing Mesh embedded within Lime Green Solo finishing plaster and Auro breathable natural paint.
On hard-to-treat traditional walls, it is important to ensure the thermal solution is compatible with the existing wall, not only thermally, but from a moisture management perspective also. Traditional walls are often uneven and require significant preparation to level prior to being internally insulated. This can lead to extended lead times and increased costs, along with the loss of precious internal space. Retro EcoWall provides a comprehensive solution to this by combining capillary active cork lime thermal plaster with moisture open woodfibre boards. Remaining true to the ethos of achieving ‘better building’ by adopting a ‘fabric first’ approach to design, breathable lime plaster and natural paint are then applied to complete the system.

Annotated image: Click the numbers for more detail

500mm solid stone wall
Diasen Thermactive.037
Lime and cork based insulating levelling plaster
Gutex Thermoroom Adhesive
Adhesive mortar for bonding Thermoroom insulation boards
Gutex Thermoroom
Natural wood fibre internal wall insulation boards
Lime Green Solo
One coat smooth lime finishing plaster
Reinforcing Mesh
Embedded within Lime Green Solo
Auro Natural Paint
Breathable Natural Paint
Annotated image: Click the numbers for more detail

220mm solid brick wall
Diasen Thermactive.037
Lime and cork based insulating levelling plaster
Gutex Thermoroom Adhesive
Adhesive mortar for bonding Thermoroom insulation boards
Gutex Thermoroom
Natural wood fibre internal wall insulation boards
Lime Green Solo
One coat smooth lime finishing plaster
Reinforcing Mesh
Embedded within Lime Green Solo
Auro Natural Paint
Breathable Natural Paint
A key benefit of combining insulating plaster with woodfibre is that lower U-values can be attained with smaller thicknesses. For example, combining just 30mm of Diasen Thermactive cork lime insulating plaster with 60mm Gutex Thermoroom woodfibre boards improves the U-value of a traditional stone wall from 2.38 W/m²K to just 0.35 W/m²K. Likewise, using the same products on a traditional brick wall, only this time with 20mm of Diasen Thermactive, would see the U-value improve from 2.19 W/m²K to 0.39 W/m²K. The complete Retro EcoWall build-up has also been verified using WUFI hygrothermal modelling on numerous projects by independent consultants and by the Ecological Building Systems technical team.
Key benefits:
- A complete specification solution: combining the unique properties of insulating cork and lime with wood fibre insulation
- Retains the breathability of traditional walls and protects against condensation, mould and building deterioration
- Uses natural insulating materials with EPDs
- Achieves low U-values with the optimum use of space
- Quick installation time

As embodied carbon emissions come more into focus, low carbon thermal solutions such as Retro EcoWall will be essential in the drive to bring traditional buildings back to life. If you are retrofitting a traditional building and would like to learn more about Retro EcoWall, or need advice on any of the products mentioned, get in touch to speak to one of our highly-trained technical team.
Blog author

Niall Crosson
Technical Director (BTech, MEngSc, MIEI, CEPHC)
Niall is the Technical Director for Ecological Building Systems and was also the company’s first employee. Niall holds a first class honours degree as a Bachelor of Technology and a Masters in Eng.Sc. Niall is a certified Passivhaus Consultant and has provided technical guidance on many award winning low energy projects in Ireland and the UK, and has authored or co-authored several chapters in both the Passivhaus Handbook and the Passivhaus Designers Manual. Niall is also on the board of directors of the Irish Green Building Council and provides guidance on several national standards committees. Along with this, Niall has contributed to several construction publications including The Journal of the RIAI.