Fasteners are fixed from above the deck into a suitable support structure. It is not possible to install fasteners from below the deck. This unfortunately does leave the drill point and end of the fastener visible from below.
Fasteners are fixed from above the deck into a suitable support structure. It is not possible to install fasteners from below the deck. This unfortunately does leave the drill point and end of the fastener visible from below. Any attempt to remove the protruding end could result in damage to the deck coating but more importantly could cause elongation of the hole, which then will seriously impair the stability and fastener performance.
Removal of the drill point protrusion is only permissible when the support structure steel flange is 6mm or thicker. Therefore it is not possible to remove the protruding end of stitching screws through the deck side lap. Stitching screws, or rivets, for the side lap could be installed from the underside of the deck. However this has access problems, leading to longer installation times, which will increase costs.
Where decks are installed above thin gauge purlins approximately 6mm threaded shank should protrude to ensure correct location. Fastener manufacturers can confirm minimum requirements to suit their product.
For correct specification of fasteners consult supplying manufacturer. To minimise the visual effect, colour coated caps, to match the deck colour, can be inserted over the protruding ends.
Should the visibility of fasteners be an issue, this should be determined at the initial design concept stage by designing supporting steelwork of square or rectangular hollow sections which will ensure fastener non visibility.