Kier Group is a leading property, residential, construction and services group, which invests in, builds, maintains and renews buildings operating across many sectors, including housing, defence, education, power, transport and utilities. Kier has a long-standing relationship with the Cambridgeshire area, having worked on 23 projects with the University of Cambridge, so it was no surprise when they decided to build their brand new three-storey headquarters in the Cambridge Research Park. Although delivering the project themselves, Kier decided that with a flat roof forming part of the design, they required a roofing material that would provide exceptional acoustic management, good thermal insulation and a high quality finish that needed minimal maintenance.

Kier handled both the design and delivery process and worked directly with Cottenham-based roofing contractor, Voland Roofing, on this project.


The Challenge

The primary challenge faced during this project was Kier’s stipulation that the new roof deliver high levels of acoustic performance. Kier wanted the roof to not only insulate against airborne sound, but also to reduce noise from the impact of raindrops on the roof.  This meant that Voland Roofing had to achieve Rw 41 dB airborne sound reduction and Rw 52dB LiA rain impact noise.  Alongside this, it was important that the roof provides long term thermal performance to keep the building warm and reduce heating costs.


The ROCKWOOL Solution

Voland Roofing was responsible for installing ROCKWOOL HARDROCK® Multi-Fix (DD) and HARDROCK® Multi-Fix (DD) Underlay, with the ROCKWOOL Acoustic Membrane to cover the flat roof.  Having worked with these products previously, Voland Roofing was familiar with the installation process. The systems are quick and easy to install, which allowed the project to be completed in good time.

HARDROCK® Multi-Fix (DD) was installed within a mechanically fixed, single ply system. With only one fixing required per m2 of the total insulation thickness, this significantly reduced the complexity of the installation, cutting time and costs. The vast roof space on Kier’s new building is on two different levels. The ROCKWOOL solution had to be flexible enough to accommodate the change in level, and be installed smoothly and tightly around all the corners and edges. Thanks to the ease of installation of these products, this didn’t cause a problem for Voland Roofing. 

The ROCKWOOL HARDROCK® Multi-Fix products are renowned for their acoustic management properties, and when used in tandem with the ROCKWOOL Acoustic Membrane, offer a complete sound prevention system. Another added benefit is that this solution can be used with a variety of roof systems, so is very flexible. Approximately 1100m² of the 60mm HARDROCK® Multi-Fix (DD) and 1100m² of the 150mm HARDROCK® Multi-Fix Underlay were laid across the roof, with 1100m² of 5kgm² ROCKWOOL Acoustic Membrane laid directly beneath the insulation.

In addition to the acoustic properties, ROCKWOOL HARDROCK® Multi-Fix products provided 0.039W/mK thermal conductivity, and offered a Euroclass A1 Fire Classification, the highest class for non-combustible products that do not contribute to a fire.

ROCKWOOL’s products have provided the new Kier Construction offices with a complete roofing solution that more than satisfies the brief which Voland Roofing was set. They significantly reduce the airborne and impact noise and effectively insulate the building, which also helps to lower costs for Kier. 



For its new office, Kier required a roofing solution that reduced noise, insulated the building efficiently, and have a long lifespan. ROCKWOOL provided a fully tested acoustic system that has not only met all the key requirements, but its non-combustible properties meet the highest European fire classification performance, achieving an A1 rating.  The ROCKWOOL boards also provide a long term and stable thermal performance.  

Project Location

Kier Construction HQ

Kier Group, Head Office
Tempsford Hall
Sandy, Bedfordshire
SG19 2BD
United Kingdom

Kier Construction HQ
Kier Construction HQ
Kier Construction HQ
Kier Construction HQ

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