Wraptite Tape has proven to be a real winner in combining the essential properties of airtightness and vapour permeability behind rainscreen cladding in the newly refurbished Chester le Street Primary School.
The key drivers in both regulation, and targets on energy efficiency in buildings, have brought the design of airtight buildings to the forefront of the agenda. Whilst airtightness is clearly central in the design of new buildings, it is also critical in the application of building refurbishment programmes. The school at Chester le Street is part of an on-going commitment by Durham County Council to upgrade its primary schools across the county.
Wraptite Tape was installed in conjunction with Kingspan Rainscreen Insulation Board behind the new rainscreen cladding. Typically an aluminium coated Butyl adhesive tape would be used to seal joints, openings and penetrations. Whilst providing a seal against air leakage, these tapes may not only prevent air, but also prevent the movement of moisture vapour, leading to potential problems and damage to the boards underneath over time. Due to the nature of the project being a refurbishment, breathable felt was not suitable for the Vapour Control Layer (VCL) as it would come into direct contact with the rear cladding surface, and conflict with specified continuous air fl ow ventilation methods. The introduction of the Wraptite Tape solved all issues with airflow, and necessary air clearances to ensure a continuous Vapour Control Layer to the existing Building.
Wraptite Tape was selected because it is not only an effective airtight barrier, but because its high vapour permeability allows damp sheathing to dry quickly, and moisture vapour to escape. Thus ensuring good indoor air quality and reducing the likelihood of mould, mildew, condensation, timber distortion and metal corrosion. The rainscreen cladding, insulation and Wraptite Tape was installed by contractors Midas Cladding as the second school in the refurbishment programme for Durham Direct Services, with more schools to follow bringing the buildings in the county to a higher standard of performance.
For any building to have an energy efficient, healthy, moisture free building envelope there is a clear need to manage the balance of Heat, Air and Moisture movement (HAMM) throughout the building’s life cycle from design, construction, completion and use.