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Case Study

New Life for a National Treasure: Roofing the Library of Wales with Permavent APEX.

National Library of Wales, Aberystwyth

The National Library of Wales in Aberystwyth, a Grade II listed building set within a historic park and garden, is the largest library in Wales and home to over 6.5 million books and priceless national collections. Today, the library has reached a major milestone with the completion of a full roof refurbishment—the first in 98 years. This work formed part of the Library’s wider Decarbonisation Project, supporting the Welsh Government’s ambition to achieve net zero emissions in the public sector by 2030. The project not only aimed to preserve the historic structure but also to enhance its sustainability, including the integration of a 3500m² solar panel system capable of generating approximately 700kW of energy—enough to power around 116,000 LED light bulbs.

View products used in project

Location

National Library of Wales, Aberystwyth, Wales

Requirements

The re-roofing of Bookstacks 1 and 2 was essential, as the original slate coverings had reached the end of their service life after more than 80 years. The project required a solution that could meet the demands of a Grade II listed building, ensuring minimal disruption to the structure while protecting the invaluable collections housed within.

To maintain uninterrupted protection during the winter months, a 2500m² temporary roof was constructed over the entire area. This allowed work to proceed safely and efficiently, safeguarding the library’s contents from weather exposure.

Why Permavent was chosen

Permavent APEX was specified for the project due to its exceptional breathability and durability—key qualities for a heritage building requiring long-term protection without compromising its historic fabric.

APEX was selected for its outstanding breathability, robustness, and compatibility with heritage roofing materials. The performance characteristics made it ideal for ability to manage moisture while supporting the longevity of natural slate made it the ideal underlay for this sensitive conservation project. APEX also aligns with the project’s sustainability goals, contributing to the long-term energy efficiency of the building.

 

How Permavent was installed

Permavent APEX was installed beneath new Welsh slates sourced from Blaenau Ffestiniog, ensuring a low carbon footprint and supporting local industry. The installation was carried out by a Welsh-based team of contractors and architects, with careful coordination to meet the strict conservation requirements of the site.

Permavent APEX was installed in a standard manner over the timber rafters, with its integrated double tape system allowing for quick and efficient installation—even during the windy, wet autumn months—while also helping to minimise waste. Its vapour and air permeability meant that no additional ventilation was required, a crucial factor in preserving the original aesthetics of the historic roof.

 

 

APEX was installed according to Permavent’s fitting instructions, good roofing practice and compliance with BS 5534:2014+A2:2018 Code of practice for slating and tiling for pitched roofs and BS 5250:20121 Management of moisture in buildings – code of practice.

The roofing contract was awarded to LEB Construction, who undertook the installation of over 2000m² of Cwt-y-Bugail Welsh Slate, nearly 40,000 individual slates, along with 14,000 metres of roofing batten, 115,000 nails, and associated leadwork. All slates were sourced from Blaenau Ffestiniog, ensuring a low carbon footprint and supporting local industry.

Working closely with conservation experts, the library’s estates team, and consultants, LEB Construction ensured that every aspect of the installation met the highest standards of heritage preservation.

On 8 May, where the last slates were laid and the photovoltaic system was activated, signalling the successful completion of a roof designed to last another century.

Client:

National Museums Wales

Contractor:

LEB Construction,

Unit 8B,

Glanyrafon Industrial Estate,

Llanbadarn Fawr,

Aberystwyth,

SY23 3JQ

Design And Build Company, Commercial Builder

 

Architect:

DB3 Group,

30 Heol Y Wig,

Aberystwyth,

Ceredigion,

SY23 2LN

Award-Winning Architectural Services in the UK | DB3

 

 

Products Used

Permavent APEX

Air open and vapour permeable underlay

  • Suitable for use with all types of solar panels
  • BBA certified 23/6867
  • Integrated double tape system
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