Hidden Deck Fasteners - Continued

Deck Clip — DC50 series

The instructions for this clip tell you to "Fasten the first deck board onto the joists by toe-nailing up through the joist below into the deck board. Be sure no sharp points protrude above the deck surface." Well, I suppose that's one way to do it, but not the way I would. To attach subsequent deck boards, you nail DC50s onto the inside board edge, positioned 2 inches to one side of each joist. Move the deck board into position, sliding the DC50's lip under the previously laid deck board. There's no connection between clip and joist; you toe-nail the deck boards' outside, or leading, edge to the joist.

The DC50 is the only edge clip that doesn't provide a direct decking-to-joist connection. Instead, the clip's protruding metal lip slips below the preceding board's leading edge, off-set from the joist, preventing uplift at the inside edge of the next deck board.

The concept behind this clip is to make square-edge lumber behave like tongue-and-groove stock. By jamming the protruding metal lip under the preceding board's toe-nailed edge, the inside, or back, edge of the board is held down (see the illustration above). Perhaps more accurately put, the clipped edge resists uplift. A source at the company (see "Fastener Manufacturers," page 4 of article) informed me that most people go back and screw the deck down after five or six years of service. (He added that the DC50 has been around for about ten years.) It isn't that the deck boards are in any danger of coming up, but with lumber shrinkage comes a slight looseness and rattling underfoot.

Made for lumber that is a minimum 1 1/8 inch thick — which may rule out a lot of so-called 5/4 stock — the DC50 has a pair of raised dimples that provide uniform spacing between boards, but you can also ignore them and adjust the gap for irregular board widths.

Because there is no direct connection between the clip and joist, the decking rests directly on the framing. This makes it feasible to use a good, exterior-grade subfloor adhesive under the decking to compensate for the eventual "loose" effect. But you take that approach at your own risk.

The DC50 comes in boxes of 50 for $9.20 (about 18¢ each) making this the least expensive system available. You'll need 2.5 clips per square foot of decking.

Dec-Klip

The Dec-Klip measures 2x1x7/8 inch overall. The 7/8-inch height makes the clip unsuitable for decking thinner than 5/4, assuming minimum 1-inch-thick stock. To install the electroplated galvanized-steel Dec-Klip, you toe-nail a 10d galvanized box nail through the clip's upright neck into the edge of the decking board and the joist below. There's an elongated slot in the clip to accommodate the angled nail.

The approximately 3/32-inch-thick clip has a bi-directional tongue that rests on the joist underneath the deck board. This tongue elevates the decking board above the joist and encourages complete air-drying by eliminating direct contact with the joist. (You shim the first board level using a flat washer of equal thickness to the tongue.) The tongue fastens to the top of the joist with an 8d box nail. The manufacturer suggests using #6 drywall screws as an alternative to the 8d nail, but this is a suggestion I'd avoid. Brittle, rust-prone drywall screws are suited to one purpose only, and there are some good, durable deck screws available now.

The Dec-Klip has a bi-directional base that elevates the decking board and encourages complete air-drying by eliminating direct contact with the joist.

A 7/16-inch-long, sharp prong projects from the neck of the installed clip. The next deck board is forced onto the prong, either by driving the board with a heavy maul (remembering to protect the board's edge with a scrap of wood), or by using a specialized levering tool known as a BoWrench (Cepco Tool; 800/466-9626).

Whichever way you move the board into position, it's important to keep the weight of your body on the board to avoid misalignment. The prong is the only connection holding the far, or blind, edge of the decking down in place. The manufacturer admits that hard lumber species such as Ipe can be a real challenge, so you may want to consider using a different system when working with hardwoods.

The 3/32-inch-thick neck of the clip establishes the gap between boards. Such a narrow gap may not be adequate for lumber that swells when wetted. Perhaps a greater concern is shrinkage; when typically wet pressure-treated lumber dries out, the gap could become wide enough to release the 7/16-inch prong. For this reason, the manufacturer's literature warns that your decking lumber should be fairly dry before installation.

Butt joints. Because two clips can't share a single joist location, you should use the longest lumber available to reduce the incidence of butt joints. Where joints do occur, you'll need to sister a length of framing material onto the joist to support the clip for the continuing board. Randomly sistered joists may not look so good from the underside of an elevated deck.

The literature states that you'll need about 2.53 clips per square foot on a deck with 16-inch joist centers and 31/2-inch-wide decking. A box of 200 clips costs $50, or 25¢ each. The price drops to 20¢ per clip for purchases of six or more boxes. A 16x24, 384-square-foot deck would require five boxes of clips.

Deckmaster

This bottom-fastening 22-inch-long, T-section bracket attaches to alternating sides of each joist with the provided #8x1-inch screws. The top flange flares out to catch the decking before doubling back to rest on the joist's edge, creating a small gap between decking and joist.

The Deckmaster track is attached to alternating sides of each joist before fastening it to the decking. Deck boards are connected by reaching underneath and screwing upward through the perforated flange.

There are 23 joist and deck screws combined per track-length, which translates to 12.5 screws per linear foot of track installed. That's a lot of screwing and, when working with dense, hard decking material, possibly predrilling, too. The included screws do have self-drilling tips. The manufacturer suggests preparing the top of the track — which comes in galvanized- or stainless-steel — with black spray-paint to reduce its metallic glare between deck boards on sunny days.

To calculate the number of brackets needed, multiply the linear footage of the deck joists by 12 and divide by 22. On 16-inch joist spacing, you'll need 2.5 brackets per 25 square feet of deck surface. A case of 100 galvanized brackets and all necessary screws costs $251; that works out to about 25¢ per square foot. Stainless steel brackets cost $451 per 100. Because the track is fastened to the joists first, you'll want to plan the occurrence of butted decking seams ahead in order to provide fastening at both sides of the joint.