Proctor Air provides peace of mind for residents during re-roofing works

Proctor Air has been used as part of a project to reroof an apartment building in Northumberland, thanks to its water holdout, vapour and air permeability benefits.

A significant challenge when working on the roof of any existing, occupied building is protecting the people inside the building without the full roof system in place. That challenge is multiplied when the building in question is large and work has to be carried out in sections over a longer period of time.

At Hatchmeadow apartments in Northumberland, a key performance characteristic of Proctor Air that helped to address these challenges was its water holdout. That, combined with its vapour and air permeability, offered long-term peace of mind for the building owners, as well as apartment residents.

Located close to the town of Ashington in Northumberland, Hatchmeadow apartments and bungalows is an age-exclusive development operated by the housing association, Bernicia. The T-shaped apartment building features a 2,500m2 pitched roof, including several gables and valleys. Unfortunately, problems with the existing roof specification were causing some residents to experience leaks during periods of poor weather.

To address the issues, Bernicia tasked Wensley Roofing – part of the Northern Bear family of companies – with stripping back the existing roof and installing a new system. The roof included an area of solar PV panels, so the new roofing system had to be capable of providing weathertightness and condensation control in several different circumstances across the single building – all while residents remained in occupancy during the work.

A ‘belt and braces’ solution

James Roy, Senior Quantity Surveyor at Wensley Roofing, describes the replacement roof system as a ‘belt and braces’ approach, saying: “The specification used Proctor Air over the rafters, followed by counter battens, tile battens, and a new pantile finish. We even used butyl tape over the nail holes to provide a complete seal against rainwater.”

At the time of writing, Wensley Roofing is about halfway through the reroofing work. “Some of the residents were having to use buckets to catch leaking water,” James continues. “Since installing this new system the leaks have now stopped, and there has been some bad weather.”

The attention to detail required to deliver the thorough specification, coupled with the size of the Hatchmeadow apartments roof, has naturally restricted the pace at which the work can be delivered. As a premium roofing membrane, Proctor Air has helped to alleviate any concerns about leaving the underlay exposed for short periods of time.

“The belt and braces approach has made labour a challenge on this project,” James adds. “But with the Proctor Air membrane in place, we’ve been comfortable leaving it exposed for a couple of days if necessary, knowing that residents in the apartments below are still protected.”

This reassurance is possible because Proctor Air is rated W1 under EN 13859-1, with over 1m Head of Water, and has hydrophobic additive in all three of its layers. Its water resistance meets the guidance of NFRC’s Technical Bulletin 6. Additionally, the membrane can be left exposed to UV for up to three months.

Proctor Air allows the underlay to be used on roofs featuring solar PV, provided a ventilated batten space is provided. This is in addition to tightly jointed slates, tiles and metal sheet, all of which would also normally be considered vapour impermeable. Because the Hatchmeadow apartments specification featured a counterbatten layer, Proctor Air could be used with confidence across the entire roof, including under the existing area of PV panels.

As a roofing underlay, Proctor Air’s key function is as a low-resistance (LR), vapour-permeable membrane. With an Sd value of 0.02m and a vapour resistance of 0.1MNs/g, Proctor Air is one of the highest performing vapour-permeable membranes on the market. Proctor Air also provides air permeability, which means no ventilation measures are required in cold roof spaces, since the membrane permits the passage of both air and moisture vapour through the roof construction.

www.proctorgroup.com