COMPATIBILITY AND ADHESION OF WET SEALS AND SILL TAPES IN WINDOW INSTALLATIONS
In recent months there have been questions raised about both the compatibility and adhesion of wet seals and sill tapes in window installations across the industry. Masterspec Product Partner pro clima responded to the issue and have been working with Sika, Tremco and Bostik on the matter conducting a series of tests.
Seemingly there have been significant issues in regards to the plasticizer migration with bitumen based tapes (compatibility issue), and sealants not bonding to substrates (adhesion issue). pro clima found that, while there was no compatibility issue with their sill tape as it is free of bitumen, there was an adhesion issue with the very top layer - a thin polyethylene foil that acts like a bond breaker. This meant that there was no sign off from any sealant supplier in the New Zealand market.
Feedback from these suppliers suggested that there were issues with bonding to standard wall underlays due to the water repellent coatings.
While international best practice is not to use wet sealants but to tape the window/door frames to the openings, currently this will not comply with the requirements of the New Zealand Building Code.
As an intermediate solution (before the industry changes to taping the windows and door into the openings), pro clima will offer a 30mm wide pro clima foil tape – available within the next few weeks.
pro clima will be able to sign off on the adhesion of their new foil tape to any substrate within the window and door opening. The sealant providers will then sign off on the adhesion of their wet sealants to the surface of the foil tape. This will provide a system with guarantees for the window and door installers.
Download the Tremco Pty Ltd Sealant Adhesion Test report
Download the Bostik MS Safe Seal with pro clima Adhiso WS Aluminium tape report
Download the Sika (NZ) Ltd Data Sheet