Deck Frame Coating. Stop rot where it starts.

Yes. Water sitting on the tops of joists and around screw holes is what rots a deck frame from the inside out, usually long before the deck boards wear out. Sealing the framing — with coating, joist tape, or both — protects the structure and extends the life of the whole deck. It matters even more under composite decking, which is built to outlast the wood frame beneath it.

Both protect the framing; they suit different jobs. Coating is a liquid, so it reaches end cuts, notches, ledger boards and tight corners where tape is hard to apply, and it leaves almost no jobsite waste. Joist tape like G-Tape goes on fast along long, straight joist runs. Many builders tape the joist tops and coat everything else. Ask either store which fits your frame.

Add up the linear feet of framing you plan to coat and divide by 450 — that's roughly how many gallons you need. For example, a 12 x 16 ft deck with joists at 16 in. on centre has about 13 joists x 12 ft, plus rim joists and a ledger, which comes to roughly 210 linear feet — one gallon. Add stringers, beams and posts if you're coating those too.

Decking can generally go down after about 20 minutes of drying time. Full cure takes about 24 hours at 21°C and 50% humidity, and high heat or humidity can lengthen set time. The coating stays slightly tacky after it cures — that's normal.

Apply it when the temperature is above 4°C. Once cured, the coating is freeze/thaw resistant. Keep the pail from freezing in storage — if it does freeze, let it thaw for 12 hours before use.

It's free of VOCs and solvents and is non-flammable, and it cleans up with soap and warm water (mineral or baby oil also work on skin). Wear gloves and eye protection, and keep it away from children and pets. Check your decking manufacturer's warranty before using any cleaners on the boards.