When people shop for a new deck, they focus on the boards: the color, the texture, the brand. That makes sense, because it’s what you see. But the part that decides how long a deck lasts is underneath. Composite and PVC boards are built to resist rot for decades. The wood framing they sit on is not. That’s why we protect wood frames with G-Tape joist tape, and why we often recommend steel framing instead.
Where rot starts
Pressure-treated lumber resists rot, but it isn’t immune to it, especially where water sits for long periods. On a deck, that spot is the top of the joists and beams.
Every deck board is fastened into the joist below it. Each fastener makes a hole in the top of the joist, and water that drains through the gaps between boards runs right into those holes. It can’t evaporate quickly because the deck board is sitting on top of it. Over years, the joist rots from the top down, the fasteners lose their grip, and the boards start to loosen and bounce.
You won’t see it happening. By the time a soft spot shows up underfoot, the damage in the frame is usually well along.
Why it’s worse in Utah
Utah’s climate speeds this up. In winter, snow sits on the deck and melts a little every sunny afternoon, sending water down into the joists, then freezes again at night. Water that freezes in a fastener hole expands and opens the hole a little more. Spring and fall bring the same cycle almost daily. The result is more water getting into the wood, more often.
What G-Tape does
G-Tape is a butyl-based tape made for deck framing. We apply it to the tops of joists and beams, and over the ledger area, before the deck boards go on. It does two jobs:
- It sheds water off the top edge of the framing, so water doesn’t sit on the wood.
- It seals around fasteners. When a screw goes through the tape into the joist, the butyl closes around the shank, which helps keep water out of the hole.
It adds a little time to the build and almost nothing to the overall project, and it protects the part of the deck that’s hardest and most expensive to fix later. It’s a standard step on our wood-framed decks.
Joist tape and composite warranties
Composite and PVC decking warranties cover the boards, not the wood framing they sit on. A board that’s warrantied for decades doesn’t help much if the joist under it gives out sooner. Joist tape helps the framing keep up with the decking. Check the manufacturer’s warranty for your boards, and keep in mind that framing is your responsibility unless your builder covers it. Our 7-year workmanship warranty covers our work on the build.
The other option: steel framing
For homeowners who want a frame that won’t rot at all, we install Fortress Evolution steel framing. Steel joists and beams don’t rot, warp, twist or shrink, and they don’t get eaten by insects. They’re also straight and consistent, which gives a flatter deck surface, especially with long runs of composite boards that show every high and low spot.
Steel framing makes the most sense for:
- Tall second-story decks, where replacing rotted framing later would be a big job.
- Decks with a lot of water exposure, like hot tub decks or decks under roof drip lines.
- Homeowners who plan to stay and want the frame to last as long as the boards.
We’re also on the Owens Corning OC Pro Build Team, so we can build with Glas-Powered OC Lumber, a composite building material that is wood-free, rust-free and rot-proof. It’s another way to take rot out of the picture on parts of the build where wood would normally go.
Wood framing with G-Tape is still a solid, cost-effective choice for many decks, particularly low decks where the framing is easy to inspect. We’ll walk you through both.
A complete system
Joist tape is one part of how we build decks for Utah weather. The rest of the system includes:
- American Ground Screw footings that hold up in clay soils and frost.
- TimberTech decking, often the Advanced PVC lines, which don’t absorb water.
- Cortex plug fasteners or hidden fasteners for a clean surface.
- Trex RainEscape drainage under second-story decks when you want a dry space below.
Read more in our built-to-last guide.
G-Tape on a deck rebuild
When we do a full tear-out and rebuild, the old deck comes out completely and the new frame gets G-Tape (or steel framing) from day one.
See our composite deck options, or contact us for a free estimate over the phone.