Update 24 February 2023
RECOMMENDATION FOR ALL AJ GRANT CONTRACTORS INSTALLING DEKTITES ON METAL AND TILED ROOFS
In recent months AJ Grant has had an influx of rectification jobs directly associated and caused by the poor and non-compliant installation of rubber Dektites. This has prompted this guideline to all contractors carrying out repairs for AJ Grant.
All Dektites must be installed as per the relevant Australian standard HB39 and manufacturers specifications.
INSTALLATION OF DEKTITES TO METAL ROOFS
When installing Dektites to metal roofs, it is a requirement as per the manufacturer’s specifications, to secure all Dektites with self-tapping and self-drilling screws or selected pop rivets. Fastening of Dektites with sealant alone has no longevity and is non-compliant.
It is recommended that anywhere the roof has been penetrated/Dektite has been installed, if it interferes with the pan or bottom of the corrugation of the roof sheet, that a pan flashing must be installed to prevent any potential water ingress. This will ensure a weather tight seal. Further to this, all Dektites should be installed on a diagonal axis to the profile of the roof sheet.
Cut penetrations through the rib of the sheet require silicone to seal the penetration to the roof sheet. This will eliminate the risk of any condensation between the dry pan flashing and the penetration running down inside the roof cavity. When measuring a dry pan flashing also allowing 1x full rib and pan either side of the penetration to eliminate any chance of the roof sheet filling up and flowing back under the tray during heavy rain.
INSTALLATION OF DEKTITES TO TILED ROOFS
When installing Dektites to tiled roofs it is a requirement as per the manufacturer’s specifications, to install all Dektites with the associated aluminium flashing to achieve a weather tight seal and compliance.
The top side of the aluminium flashing should go beneath the tile directly above and be turned up/weathered to avoid any water ingress. Again, sealing Dektites to roof tiles using sealants is non-compliant and will lead to water ingress.
INSTALLATION OF DEKTITES TO SINGLE PENETRATIONS WITH MULTIPLE LEADS/PIPES
It is now a requirement for any contractors installing Dektites with multiple cables/pipes exiting a singular Dektite, to install a goose neck to ensure a proper weather tight seal is achieved. Once cables/pipes are installed through the goose neck, it is to be sealed off with sealant to ensure it is vermin proof.
