Historic and heritage buildings require a holistic approach when thermally refurbishing to avoid degradation and damage and to balance energy efficiency with breathability and damp protection. Most important is maintaining the characteristics of the building and preserving the facade. In the case of a regency building in Dun Laoghaire Rathdown, a balance was needed between the preservation and protection of the existing structure, while at the same time the client wished to substantially upgrade its thermal performance.

Constructed in the 1850s, the building is of architectural significance and externally insulating the walls of this elegant construction was not possible. When considering the internal thermal refurbishment of the external walls, the client carried out extensive research with architect Fionnuala O’Connor to evaluate which insulation was both the highest performing from a thermal and moisture control viewpoint and also to satisfy the heritage officers in the area that the planned work would be sympathetic to the original structure. For these reasons Calsitherm Climate Board, a calcium silicate insulating board, was selected to refurbish the external walls of his house. A 50mm board was used in this project. Once the existing surface is prepared, the board is adhered directly to the inside of the walls with Calsitherm adhesive plaster. Calcium silicate is a micro porous mineral building material with effective insulating properties. Its high capillary action ensures humidity regulation and the nature of the material means that mould cannot form on its surface, a key consideration in this project.

An extensive condensation risk analysis was carried by Ecological Building Systems’ technical engineer Niall Crosson, using the advanced calculation programme WUFI. This program was developed by the renowned Fraunhofer Institute in Germany to advance our understanding of building physics and to provide more accurate guidance to designers in the area of moisture control. This program calculates the coupled heat and moisture transfer though building components and is particularly useful in identifying the optimum materials that will alleviate any long-term risk of condensation in building elements.

The team leader on the project supervised the installation of the Calsitherm boards, which were installed by an experienced lime plasterer. The boards were finished with Calsitherm’s proprietary smooth lime plaster to a very high standard and to the requirements of the heritage officer. THERMO HEMP natural insulation was installed in the roof, which was dry-lined internally with GUTEX wood fibre soft board and plastered at a later stage. The roof was air-tightly sealed with the pro clima Intelligent airtight system to limit heat loss and maximise the overall breathability of the roof, again, in sympathy with the existing structure.

This project has been very well received and is now perceived as a benchmark for the sustainable refurbishment of such listed buildings in the future. Further information from Niall Crosson, Technical Engineer, Ecological Building Systems Ltd., Email: niallcrosson@ecologicalbuildingsystems.com, T 046 9432104, www.ecologicalbuildingsystems.com

Planning a Restoration Project with CPI
CPI have a solid track record in the supply of hydraulic lime products ideally suited to restoration and conservation projects. Products are available in 25kg bags or in bulk silos with all the advantages of the EuroMix silo system: Mortar is mixed only as it is needed; High efficiency mixing ensures excellent dispersion; Constant supply of mortar on site; Consistent high quality materials are used and consistent mix proportions; Better quality of mortar. In the EuroMix range you can choose from a range of  hydraulic lime mortar and render mix designs to suit client specifications. CPI also supply in Ireland the Baumit Range – an extensive range of modern lime and limecement products from one of Europe’s leading manufacturers.  info@cpi.ie, www.cpi.ie

Lagan Building Solutions
Penrhyn Bangor Blue® roofing slates from North Wales have been used to cover roofs in Ireland since the 15th century. Slates from this famous quarry are the traditional slate in Ireland and their heather blue colour is famous across the Irish landscape. They are the only roofing slate to have a proven lifespan and longevity in the harsh Irish climate. Penrhyn® slates can last hundreds of years and the lively market for second-hand Penrhyn® slates pay tribute to their quality. Although most commonly available in size 500x300mm, Penrhyn® slates can still be made to any size as explained by Peter Lagan, a director with Welsh Slate: “We work closely with most of the heritage and conservation architects in Ireland on re-roofing projects where, in many cases, the architect wants to replicate the exact slate that was on the original building. That is not a problem for us and we commonly make slates from as a small as 11 inches up to 50 inches, and everything in between. We have recently supplied over 2,000 35 x 24” Penrhyn slates for the re-roofing of Castletown House in Cellbridge, County Kildare to exactly replicate the original slates put up in the early 1700s”.

Lagan Building Solutions,
T 057 8680225,
www.LBSproducts.com.

Article as seen in Architecture Ireland issue 253