When this multi-screen cinema on the outskirts of Doncaster needed a section of its asphalt flat roof refurbished as part of extension and maintenance works, the owners needed the building to stay open to the public throughout the installation. SIG Design & Technology explain how this was done.
The 750m2 roof, located in the centre of the cinema above a stair and lift core and projection rooms, was covered with a lot of mounted plant, equipment and trunking, making it too disruptive and noisy to take up and replace the existing asphalt. A liquid cold-applied waterproofing product was considered ideal to avoid the need for complex edge detailing associated with single ply or bitumen products around the plant.
With the cinema screens in operation a few feet away there was also potential for fumes to enter the building through air conditioning intakes on the roof. As these units could not be shut down, it was vital to both the client and project that a solvent and fume free solution was used in the course of the refurbishment.
An odour free waterproofing liquid
With these concerns in mind, specification manager Cameron MacAndrew, from SIG Design & Technology recommended Hydrostop AH-25, a wet-on-wet cold applied liquid waterproofing system that contains no solvents or isocyanates, and also has a very low VOC content.
‘Hydrostop AH-25 emits no fumes and no odour, which meant the cinema could continue business as usual for the week,’ said MacAndrew; ‘Installers like AH-25 because it goes down wet on wet in a single pass install.’
For the installation process, the roof was first cleaned; then a base coat of AH-25 was applied, into which a 110gsm layer of polyester reinforcing fleece was embedded. The second coat of liquid can be applied immediately, saturating the reinforcement and completing the waterproofing. AH-25 is totally impervious to standing water, and as a single component liquid, it does not require a catalyst to be mixed into the product before use. The product comes with a 25-year guarantee which can only be offered by SIG’s DATAC accredited installers
Re-Roofing and New Roofing: Quick to Install
The Hydrostop AH-25 liquid roofing system is now even quicker to install. The system can be applied directly to the face of the specified insulation board and only requires the application of a 100mm wide self-adhesive jointing tape to the joints of the insulation, rather than having to apply an entire bitumen carrier membrane over the insulation as some other liquid systems do.