Problems With Hidden Deck Fasteners
Hidden deck fasteners solve several common complaints in deck construction; they force even board spacing, keep unsightly nail or screw holes off the face of deck boards and remove the need for driving fasteners in a perfectly straight line. They do have drawbacks, however, the most significant being the time and effort required for installation.
Screw-In Hidden Fasteners
One variety of hidden fasteners requires screwing into the deck board from the underside. This makes for a strong attachment to both the deck board and the joist, and it keeps the fastener out of sight. Additionally, they allow the installer to drill pilot holes to prevent splitting exotic hardwoods used in some high-end decks. However, their underside attachment makes for an awkward installation process. This process is made somewhat easier if the installer can get under the deck during installation, but it is not always possible. Additionally, it is far more difficult to pull the deck boards completely to the joists when using these fasteners, due in large part to the difficult angle of access to the fastener.
Another hidden fastener option is the prong fastener. These fasteners drive sharp prongs into the sides of deck boards and then attach with nails or screws to the deck joists. They install fairly quickly and are easy to access during the installation. However, they are not completely hidden. They are partially visible between the deck boards, but this does not present a problem in most installations. Most significantly, the prongs can be difficult to drive into hardwoods, and if larger prongs are used they become easier to drive in but more likely to split the boards.
Although each variation of hidden fastener has its own pros and cons, the general drawbacks remain the same. With traditional fasteners the installation process is fast and straightforward. Only on wood that splits extremely easily would a pilot hole be made for the deck screws, and even then a skilled installer with a deck screwdriver may not have to use pilot holes. Deck screws are also relatively inexpensive and are readily available at home improvement and hardware stores. Hidden fasteners on the other hand are relatively expensive and may be special order items at hardware stores. They require more effort on the installer's part, regardless of which variety is used. This translates into a greater cost for overall deck installation.
Hidden Fasteners Have a Place
There are certain installations where hidden fasteners are critical, and for more than just aesthetic purposes. On certain types of exotic hardwoods, the wood's surface is extremely strong and water resistant, but if the surface is punctured, water will penetrate and subsequent freezing will cause the boards to lift. This is not an acceptable approach, particularly on a high-end deck, so hidden fasteners must be used in this case.