New Build Passivhaus Scheme, Somerset

Project Overview

Background

Permarock has a long-established relationship with the architectural practice Mikhail Riches, and the two organisations have worked together on a number of Passivhaus schemes.

This particular project featured a residential new-build in Nailsea in North Somerset. Led by Stonewood Homes, it began in 2023 and envisaged the creation of 52 sustainable homes; a mix of two, three, and four-bedroom layouts. Known as ‘Elm Grove’, it is due for completion in 2025.

This £19 million project, which launched in 2023, formed part of that effort, focusing on decarbonisation retrofit measures to more than 650 solid-walled homes.

Brief

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 minimise the transmission of heat.

There was no requirement for external wall insulation on this scheme, so Permarock’s role was to design and supply systems that would enable the creation of the airtight facades while also producing an attractive, durable finish.

Design and Specification:

Part of the specification called for Permarock Exterior Render to be applied onto Euroform Versarend carrier board, followed by SiliconeUltra K-Finish in a number of colours. This would form part of a back-ventilated render rainscreen system for many of the houses. The work was 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 required special detailing to highlight the windows. This was achieved by applying the SiliconeUltra K-Finish in different grain sizes: 2mm in bands around the windows, and 1.5mm elsewhere.

Result:

The scheme has produced Passivhaus homes that are attractive and highly energy efficient. Such has been its success that it has been made the subject of numerous media articles. (Examples below.)

The development 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.”

Stonewood Homes estimates that, as a result of the exceptionally high standards of energy efficiency at Elm Grove, residents could save up to 75% on their energy bills when compared against a typical UK household.

Lee Zeffiretti, Stonewood Homes’ Contracts Manager, added: “Collaborating with Permarock 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.”

More details about the project can be found here:

Note:

This scheme is one of several notable projects involving collaboration between Permarock and Mikhail Riches. Other projects have included Park Hill Flats (Phases 2 and 4) in Sheffield, Goldsmith Street in Norwich, and another new-build Passivhaus scheme at Burnholme Green, also for City of York Council.

Project
New Build / Residential
Client
Stonewood Homes
Specifier
Mickhail Riches / APG Architecture
Substrate
Timber Frame & Carrier Board
Finish 1
Permarock Exterior Render
Finish 2
Permarock SiliconeUltra K Finish