Case Study

Ysgol Y Gogarth increases thermal mass with two coat plaster

Our Thistle® HardWall and Thistle® MultiFinish plasters were specified at Ysgol Y Gogarth as they met project needs such as durability, impact resistance and a superior thermal mass. 

This project focused on improving the performance of Ysgol y Gogarth’s inherent thermal mass in order to avoid overheating during the summer months. Ysgol y Gogarth is a day and residential Special Educational Needs School catering for approximately 195 pupils between the ages of 3 and 19, so it was also important to provide a durable finish for this demanding environment.

Project managers used a two-coat plaster system by specifying our Thistle® HardWall undercoat plaster and Thistle® MultiFinish finish coat plaster to internal blockwork walls. Solid plastering was shown to lead to a better thermal mass performance than drylining, which was critical to the building’s south west elevation.

Impact resistance and durability were also key requirements of the project, along with improved maintenance cycles. The robustness of two-coat plaster helps to meet this requirement by preventing the need for regular repair work.

Convenience and improved performance

Other benefits of using a two-coat bagged plaster are its convenience compared to moving sand and cement to an application area, and the fact that a finishing coat can be applied on set undercoat and before it is fully dry, saving time and maximising productivity on site. There is also no danger from cracks appearing days or weeks later due to the shrinkage of the plaster.

“Superior thermal mass was required on the South West facing classrooms to avoid them getting too hot during the summer months. Thermal modelling was undertaken and showed that the addition of a two-coat plaster system led to a better performance than what a standard solution would achieve, alleviating overheating in the warm weather. This, combined with the high quality and durability provided by the solution, made it perfect for the job.” Michael Bool, from Atkins Architects

David Ombler, Owner of Ombler Williams Ltd, added: “The British Gypsum two-coat plaster system was a joy to work with as it was so quick and easy to apply. As this was a large project, with many different rooms to plaster, it was important that we didn’t have a lot of unnecessary building materials and equipment on site. Thistle HardWall and Thistle MultiFinish were so easy to mix on site, and the speedy drying times really helped us keep within our timescales.”

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Project name
Ysgol Y Gogarth
Building type