Face screwing – use stainless steel trim head screws for superior corrosion resistance and maximum holding power, driven with a slow speed drill into a pilot hole and countersink to prevent splitting. Use two fasteners to attach decking to each joist, approximately 3/4″ from the edge of each side of the board. It takes approximately 3.5 screws to cover 1 square foot if you are 16″ on center.
Many contractors use #7 x 2-1/4″ stainless steel “trim head” screws with a square or hex drive head.
Pre-drill to the diameter of the screw shank to avoid splitting. The screw tip will bite into the joist below to hold the board in place.
Trim head screws are recommend as wider heads may break off. The narrow head also produces a lower visible profile.
To determine screw length needed, multiply the wood thickness by 2.5.
Pre-drill to avoid splitting. Screws require a pilot hole, and if plugging you will need a countersink tool. Use of a countersink/drill bit combo is recommended. Judge the depth of the countersink based on the screw head size, typically the plugs used will be 3/8″. Trim heads require little to no countersink, while wider heads require a deeper countersink. Also consider the depth of the countersink if using plugs to hide the screw heads.
While coated or galvanized steel fasteners have been used, they stain the wood black and have a shorter service life, and are therefore not recommended.
In addition to screwing, use a bead of high quality exterior adhesive, similar to PL Premium or PL 500, between the deck boards and joists on all installations.
DO NOT USE NAILS. Hand nailing Garapa will cause the wood to split; pneumatic nail guns tend to curve the nail back out of the wood, and can be extremely dangerous due to the density of the wood.
Plugging will help conceal the fastener head. Plugging is an aesthetic that is sometimes preferred, however is labor intensive. Use species specific 3/8″ diameter plugs (Garapa Plugs for Grapa) and set the depth of your countersink using a stop collar to accommodate the plug, approximately 1/4″ deep. Using a dab of exterior adhesive, such as PL500 or TightBond2, tap the plug into place using a rubber mallet and allow the adhesive to set. Using an electric hand planer, plane the remaining material nearly flush with the deck board. Go over again with a belt sander, spot sanding where needed to ensure flush plug. Alternately, many contractors use a sharp chisel with the bevel face down parallel with the deck surface and chisel away excess material. While this method is quicker, it will lead to raised and indented areas on the plugs. Spot sanding can minimize this result.
Hidden fasteners, although labor intensive, can eliminate the screw head from showing on the deck surface if the plugging aesthetic is not desired.
Most hidden fasteners, such as the Eb-Ty, are installed from the top side of the deck onto kerf cuts made either by a biscuit joiner or by a three-winged router bit into the side of the deck board. Deck boards are also available “pre-grooved” along both sides of the board for receiving hidden fasteners. Fasteners screwed into the decking from the underside are not recommended because they do not directly anchor the deck boards properly to the joist potentially resulting in failure, nor are they readily accessible for repairs.
When installing hidden fasteners, angle the screw through the fastener, through the deck board, and into the joist. This will require pre-drilling a pilot hole.
A drawback to using a hidden fastener system is the difficulty in removing a board for repair. Face screwing requires removing the screws on each individual board that needs to be removed, and possibly removing plugs. Many boards may have to be removed to get to the damaged board that has been installed with hidden fasteners
Other hidden fastener systems, like CAMO Hidden Fastener System and the KREG Deck Jig, use a method to “pocket screw” the fastener on the shoulder, or eased edge, of the deck board, thereby hiding the screw head from the face. This sytem is typically less expensive than a clip system and more stable since you are putting two screws into each joist.