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Tapered Climate Boards taper from 30mm to 8mm
Calsitherm tapered board to reduce thermal bridging at junction between solid internal wall and external wall

Calsitherm Tapered Climate Board

500mm x 1.25m x 30mm to 8mm

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  • Product Overview
  • Technical Details
  • Installation guide

Main purpose

Eliminating cold corners (thermal bridges) on internal walls and ceilings where the external wall is insulated with Calsitherm Climate Boards. Also minimises the visual impact of Calsitherm Climate Board insulation on walls with ceiling cornices.

Use it on

Level internal walls or ceilings that adjoin an external wall insulated with Calsitherm Climate Boards. Can also be used on solid external walls directly under a ceiling cornice.


Calsitherm Tapered Climate Board has two main uses. One is to eliminate thermal bridges in corners where uninsulated internal walls and ceilings adjoin with an insulated external wall. The other is to ensure beautiful ceiling cornices on walls, insulated with 30mm Calsitherm Climate Boards, look their best by tapering the insulation up to the cornice rather than using full thickness boards right up to the edge.

Where to use it

Calsitherm Tapered Climate Boards can be used on level walls or ceilings. Any gypsum plaster should be removed from the wall before installing. Uneven walls should be made level with a breathable lime-based plaster like Diathonite (for additional thermal insulation) or any other lime plaster prior to installation.  

When used to protect the visual appearance of cornices on walls insulated with 30mm Climate Boards, it should be installed with the 8mm thick edge touching the cornice and the 30mm thick edge touching the Calsitherm Climate Boards.

What it does

Tapered Climate Boards are designed specifically for use with Calsitherm Climate Boards as part of the Calsitherm Solid Wall Insulation System. Other than the size and thickness, they are identical to Calsitherm Climate Boards with the same capillary active moisture managing insulation properties.    

When an external wall is insulated with Calsitherm Climate Boards, any uninsulated adjoining internal wall or ceiling is a potential thermal bridge. A tapered board provides additional insulation in these corners, so the insulation is extended into the room thereby reducing cold spots that cause condensation, mould and structural damage.  

Thermal bridges should be controlled to achieve the best performance and greatest benefit of the Calsitherm system.

If the external wall being insulated with 30mm Calsitherm Climate Boards has a ceiling cornice, a Tapered Climate Board can be used to minimise the visual impact of the insulation. The insulation thickness can taper off towards the cornice so there is no unsightly ridge or step at the cornice edge.

The board is supplied as a 500mm x 1250mm board. One of the long edges is 30mm thick and the other long edge is 8mm thick. 

Why we love it

The Calsitherm Solid Wall Insulation System provides thermal insulation, moisture control and humidity regulation for a much-improved level of comfort and indoor climate for the building’s occupants. 

By having a Tapered Climate Board, the Calsitherm system is more versatile and adaptable in buildings where a balance between insulation and preserving the beauty of original features is often very necessary.


  • Tapered profile
  • Insulates thermal bridges
  • Capillary active
  • Helps eliminate mould growth


  • Blends-in to the wall from corners and at cornices to minimise the visual impact of the edge of thick insulation boards.
  • Insulates thermal bridges effectively without compromising the aesthetic appearance of interior walls.
  • Allows moisture in the wall to rapidly evaporate minimising the risk of condensation.
  • Its high PH reduces mould growth, improving indoor air quality.


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Technical Details

Key Technical Data

Technical Datasheet

Material Safety Datasheet (MSDS)

Environmental Product Declaration (EPD)

Declaration of Performance (DOP)

System Brochure

Installation Guide

How to Install

Calsitherm Tapered Climate Boards should be installed on to a level surface where all gypsum plaster has been removed. Any firmly attached cement or lime-based plaster may remain in place. All non-breathable paint and wallpaper must be removed prior to application. If the wall is uneven, use a lime-based plaster or Diathonite (for additional insulation) to level it before installing Calsitherm. Any mould on the stone/brick should be cleaned off before applying the levelling coat.

Apply Calsitherm Adhesive Mortar to the corner and on to the internal wall with a 10mm (or wider) notched trowel. The thick edge of the tapered board should be in the corner and the thin edge should extend into the room. Ensure there is no gap between the Calsitherm on the external wall and the edge of the tapered board. This may require the edge of the tapered board to be cut or contoured to match the angle of the wall. Apply the board pressing it tightly into the corner. For optimum performance, the board must be completely bonded to the wall or ceiling with no air pockets behind.  

The wider edge of the Tapered Board fitted to the corner junction while the narrow edge tapers outwards
The wider edge of the Tapered Board fitted to the corner junction while the narrow edge tapers outwards
Tapered Calsitherm Board at the junction of a ceiling and concrete floor
Tapered Calsitherm Board at the junction of a ceiling and concrete floor

Calsitherm Tapered Climate Boards should be finished with a layer of Calsitherm Finishing Plaster (KP Kalkglatte), then Reinforcing Mesh to overlap the adjacent wall, then a second coat of Finishing Plaster. In order to optimise the performance of the Calsitherm System, the final top layer should be a breathable paint such as Auro natural paint. If you wish to use ceramic tiles on the wall, at least one third of the area insulated with Calsitherm Boards must be left un-tiled so the system can continue to work effectively. Wallpaper is not suitable for use over Calsitherm Climate Boards.

Hints and Tips

Where the timber studs of an internal wall meet external walls, we recommend removing the studs (and part of the wall) so a continuous run of Climate Boards, with no gaps, can be installed on the external wall. Once that is done, the internal wall can be reinstated. The internal wall and studs will then be in contact with Calsitherm Climate Board (rather than cold masonry) so the potential for a thermal bridge can be avoided.

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