Refurb or renew?

When flat roofs fail, the task of stripping, disposing of and replacing it is a costly and time-consuming process. This is particularly true for hospitals. Here, Rod Friel of Wolfin discusses a solution that can save on time, money and disruption.

Afailed flat roof allows moisture to enter the roofing layers, resulting in a loss of thermal performance and disturbance to building occupants. For hospitals, the integrity of the building is key. If this is lacking, important areas of the hospital, such as the wards, operating theatres and plant rooms could be compromised. A failing roof needs to be rectified promptly.

Clients often make the assumption that the entire roof will need replacing, causing even more disruption, while delaying the repair of any damage inside the building. For vulnerable patients needing around the clock care, the work could cause disruption from an air quality and noise perspective, having a negative impact on their wellbeing. Hospitals cannot afford the significant downtime or financial cost.

Time should be taken to undertake a roof condition survey to ascertain if the existing roof layers and structural components have become unstable. If so, a strip and recover should be the chosen method. If a vapour control layer is absent or damaged or if there is fungus, mould or mildew in the roofing layers, the roof must be stripped and disposed of.

However, if the structural components have not become unstable and there is no damage to the vapour control layer, a complete replacement may not be necessary. Instead, a refurbishment product, such as a vapour permeable membrane could be used, saving time and money while mitigating risk to patients.

The roof can be overlaid with the refurbishment membrane. Due to the unique formulation and the black colour of the membrane, the roof layers rapidly heat up under the influence of solar radiation. This causes a high vapour pressure that gradually dries out the trapped moisture by forcing it up and through the vapour permeable membrane. As the roof dries out the thermal properties of the existing insulation are restored.

Savings are made in relation to the reduction in labour time and materials required, as there is no need for stripping back the roof, which eliminates unnecessary waste disposal. In fact, according to an independent cost analysis carried out by Aecom this could reduce costs by as much as 28 per cent compared to solutions requiring the failed roof to be stripped. A solution such as this also makes it possible to upgrade the roof’s thermal performance, as additional insulation can be added prior to the overlay.

From a project management point of view, specifiers can see how the benefits of refurbishing a hospital’s roof with a sheet applied waterproofing solution outweighs that of a replacement roof. Not only will time on site be significantly shorter and labour costs be reduced, but the overall cost of the project will be less with a well-refurbished roof compared with a replacement. This helps to keep projects within deadline and budget, but importantly for healthcare buildings this also helps to maintain the care provided to patients.

Rod Friel is the business development manager at Wolfin