Calderstones Park – The Reader

Set in Liverpool’s Calderstones Park, the Calderstones Mansion is a three-floor Grade II listed Georgian building, constructed in 1824, with a separate stable yard and coach house. In 1875, the house and estate were purchased by the McIver family, owners of the Cunard Line.

The family bequeathed the grounds to the city of Liverpool as a public park in 1902 and in the 1940s the mansion house itself became council offices, falling gradually into disrepair. In 2013, The Reader, a national charity dedicated to improving literacy, was given a 125-year lease to use the house and associated buildings for events and activities, winning Heritage Lottery funding for a complete renovation and re-development.

For this high-profile project, which began in 2017, Complete Roofing Systems was hired by the main contractor John Turner Construction Group to completely strip and re-slate the mansion house, waterproof the existing gutters and install new downpipes. Other works included the installation of a green roof and a felt system to other buildings.

Client

The Reader

Project Location

Liverpool – Calderstones Park

Building Type

Grade II listed civic building

Finish

  • Second-hand welsh slates – Tun Slates for the main house with sized slates to the link block and internal slopes.
  • Tor Coatings to gutters and Land valleys
  • Eco Green Roof plus Armourplan with metal perimeter flashings
  • Cast Aluminium Rainwater goods were supplied by Alumasc
  • The Felt system to the rear theatre was 4mm Charcoal felt from Lancastria

Workmanship

The stripping and re-instatement of the Welsh Blue Grey random slates in diminishing courses, required meticulous approach from the team. The entire existing roof covering had to be stripped to allow for a full timber inspection with almost 50% lowered to ground level to avoid undue loading of the scaffold, all had to be` cleaned, sorted and graded. With only around 50% of the original slates salvageable, it was essential that matching replacements were found. The client wanted a uniform colour to the front elevation and the team successfully managed to source closely matching second-hand slates from a reclamation yard.

The roof was re-covered, according to BS 5534:2014+A2:2018 ‘Slating and tiling for pitched roofs and vertical cladding. Code of practice’.

Since heritage works are exempt from the requirement for mechanical fixings, the slates bedded using lime mortar in accordance to NFRC Technical Bulletin ‘TB42 Lime Mortar for Roofwork’.

Project Safety

As with all its projects, the team made safety a priority and the team were given a comprehensive toolbox talk at the start of the project. A dedicated Safety Officer also visited the site to carry out safety audits.

Project Complexity

The project involved the replacement of all elements of the existing 985m2 of roof coverings, including battens, underlay and flashings. In total almost 100 tonnes of slates were stripped, cleaned, stored with 450m2 of reclaimed slates being used which had to be loaded to roof level and distributed over the various roofs.

In the valleys to main roof, all valley boards and lead linings had to be removed and replaced with extended, pressure-treated timber valley boards and lead lining.

The mansion house had two Georgian wire-glazed lantern rooflights which also had to carefully removed for modern replacements, in keeping with the building’s aesthetics.

The team also waterproofed all the existing gutters with TOR liquid coatings and installed cast aluminium downpipes.

To the rear of the building the theatre had a new torch on felt system applied.

A purpose-built circular structure was erected to house, which was a boarded roof with Armourplan membrane and green sedum roof and curved fascia to the perimeter.

Project Challenges

Complete Roofing Systems was already working within a tight construction programme, made more challenging due to the poor state of the roof structure, which meant the site team was tasked with completely stripping all elements of the roof within two weeks to enable detailed structural survey and repairs over a two-month period.

The team then had to reinstate the entire roof covering, alongside other trades. This required careful project management and a collaborative approach with the main contractor to ensure the roofing project was completed on time and to budget, while ensuring it met the client’s expectations for a beautiful heritage roof.

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