SIG Design & Technology were specified for the restoration of the Grade II listed Plymouth Market, which is operated by Plymouth City Council.

Over the years, the roof had deteriorated, with leaks springing up and holes emerging in the gutters, as well as problems surfacing with heavy leaks from the market’s windows.

Deposits of seagull guano had also built up across the roof area, with its acidic content corroding the membrane.

An important criteria was finding a roofing solution which meant things could be “business as usual” and the small traders who are the backbone of the market would be able to continue selling their produce to customers there.

Initial thoughts involved stripping off the original roof membrane by mechanical means. However, closer investigations raised concerns that this would generate excessive stress and vibration that could damage the roof shell.

The AH-25 liquid waterproofing system was the ideal solution for this important heritage building.

Hydrostop AH-25 is a one component product which offers significant advantages over conventional PU and PMMA systems and has a warranty for up to 25 years. Very low in odour and fast-curing, it is fully reinforced with a polyester fabric. It can be applied under practically any conditions - even as low as 0oC such as during the winter months when the Plymouth Market refurbishment was underway.

AH-25 is ideal for small scale or large commercial projects, whether they are new or refurbishments.

The roofing team had to deal with difficult access due to the elevation of the building and steep slopes of the roofing shell waves – which were in complete contrast to typical flat roofing projects where they had previously applied the product.

AH-25 presents no COSHH or disposal issues and since the liquid is non-solvent based, it is very low in odour. Importantly, this meant no impact on the market’s business and trading operation including several cafés within the market remained uninterrupted.

Due to the building’s listed status, Historic England supervised and approved the refurbishment.
SIG asked the AH-25 manufacturers to create a colour – Weathered Silver – specifically for the market roof membrane repair, in keeping with Historic England’s requirements.