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INCA EWI Case Study: Tregenna Estate, Cornwall


Tregenna Estate

External Wall Insulation Case Study

Project Type: New Build

Building Type: Residential Low Rise

Architect: Mike Bradbury Designs

System Designer: Saint-Gobain Weber

Installer: DMF Plastering

System & Finish: weberend MT

Render system onto render board

140mm of PIR in the walls of timber frame construction

Nestled within the 72-acre Tregenna Estate, Castle Approach, is a new development offering stunning views over St Ives Bay and the peaceful grounds of the estate gardens.

The lodges are positioned in a crescent shape to provide residents with sea views. Each lodge is built using a timber frame system with a masonry ground floor structure. The buildings were insulated with 140mm polyisocyanurate board (PIR) within the frame to offer an efficient thermal barrier and completed with a render carrier board, the whole structure was then rendered. A further 175mm of PIR board was used in the floor and 150mm in the roof space.

“It was important that we used a render that would withstand the elements over time, particularly as we had chosen such a light-coloured render,” said Mike Bradbury, architect for the development. “Being by the coast and surrounded by trees, we wanted to prevent algae growth and discolouration on the render.”

Phillip Powell, regional applications manager at Weber, is part of the technical team that has been supporting Tregenna Estates during the construction of the lodges.

“We recommended that the applicator used weberend MT, a BBA approved system for use on render board systems. It incorporates weberend LAC, a lightweight base-coat render commonly used in our webertherm XM EWI system, meshcloth reinforcement and a decorative finish of webersil TF,” said Phillip. “This combination of products is particularly suitable for this project as the weberend LAC is polymer-modified which allows some flexibility, a necessity for timber frame systems. Using this with the webersil TF, a silicone based textured finish, makes it much more resistant to the type of weather experienced in these coastal areas.

“For each property, an initial 3mm pass of weberend LAC was applied, followed by meshcloth reinforcement and then a second 3mm pass. A coat of weber PR310, a render primer, was used before applying a final finish of webersil TF in Winter White.”

The technical team at Weber stayed in touch with team at Tregenna Estate throughout the construction of each lodge, also sourcing one of its local recommended installers DMF Plastering, to ensure the products were applied correctly using best practice methods.

Neal Peek, contracts manager at Tregenna Estate, said: “From the moment they stepped on site, the service provided by the Weber team has been brilliant. They are always on hand with technical advice and have visited the site regularly.”

It was important that we used a render that would withstand the elements over time, particularly as we had chosen such a light-coloured render.

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