PermaRock systems are regularly used on new-build projects across the UK and, recently, those have included a growing number of residential schemes built to the Passivhaus standard.
PermaRock Mineral Fibre External Wall Insulation systems are currently being used to enhance the thermal performance of two new Passivhaus housing projects in Yorkshire, and these follow new-build and retrofit schemes in Sunderland, Derbyshire, Hereford, Norfolk, Essex and London.
The latest Passivhaus scheme to feature PermaRock products is another residential new-build project, which is now being delivered in Nailsea in North Somerset. The project, led by Stonewood Homes, began in 2023 and will ultimately see the creation of 52 sustainable homes; a mix of two, three, and four-bedroom layouts. It will be marketed as ‘Elm Grove’, and it is due for completion in 2025.
The development features timber-framed designs with substantial insulation, energy-efficient triple glazing, solar photovoltaic arrays and mechanical ventilation heat recovery units. Importantly, each home will also have an almost completely airtight membrane, which will help to control water vapour permeability and minimise the transmission of heat.
Part of the specification calls for PermaRock Exterior Render to be applied onto Euroform Versarend carrier board, followed by SiliconeUltra K-Finish in a number of colours. This will form part of a back-ventilated render rainscreen system for many of the houses. The work is being carried out by Harbour Façade Systems, a PermaRock Registered Installer.
PermaRend is an impact-resistant, polymer-modified render that resists cracking and is suitable for use on brickwork, blockwork and concrete substrates. Easily applied in multiple coats, it is light but robust, and very flexible.
SiliconeUltra K-Finish is lightweight and water repellent, and it exhibits excellent water vapour permeability. It also sheds dirt very effectively and incorporates a preservative that deters the growth of algae and fungus. As a result, it retains a clean, bright appearance for much longer than conventional render systems.
A notable feature of the architect’s design is that it requires special detailing to highlight the windows. This is being achieved by applying the SiliconeUltra K-Finish in different grain sizes: 2mm in bands around the windows, and 1.5mm elsewhere.
The scheme has been the subject of numerous media articles. (Example: Builders Merchant News.) It is set on land owned by North Somerset Council, which recently stated that the project is part of its “ambitions to tackle the climate emergency and reach net zero carbon emissions by 2030.”
Lee Zeffiretti, Stonewood Homes’ Contracts Manager, added: "Collaborating with PermaRock systems on our Elm Grove development in Nailsea has been a remarkable experience. Their professionalism and top-quality materials have played a crucial role in the project's success, helping us achieve the highest standards and deliver exceptional results."