How to Waterproof Deck Joists
Why worry about waterproofing?
To maximize the life of a deck, we want to protect it from water infiltration. Water can rot the joists and compromise the integrity of your deck. As water seeps into cracks in the wood, it expands. This can loosen the fastener connections. To avoid this, we’ll show you how to create a reliable water barrier with joist tape.Installing Joist Tape™
Make sure the area is clean and dry. It should also be free from oil and debris. We want to ensure that the tape is able to adhere to the surface completely. For best results, install on a day that is 40°F or warmer.
Start with the longest joists. Measure out enough tape to cover the length of the joist with ½” – ¾” extra on the ends. Center the tape, then peel the backing off a little at a time. Stick firmly to the board and be sure to smooth out any wrinkles or bubbles. Use a roller to get a smooth finish.
Once the top of the tape has been properly placed, work on folding down the sides. Make sure that the edges are secure. You may use staples for extra assurance.
For the inside corners, cut and fold the insides down.
Let the top edge extend out and overlap at the board intersection.
Let’s take a second to consider protection around the joist hangers. If you’re not using stainless steel hangers, the alternatives, including those made of galvanized steel or aluminum, react with the chemicals in pressure treated lumber. It’s a good idea to think about investing in protection to slow the corrosion that will develop over time. Joist tape™ will help reduce this by keeping the wood dry around the screws. Tape the area where the hanger will come in contact with the wood. Then install the hanger over the taped surface.
After all tape is in place, continue to install the deck boards as usual. The tape will seal in the fasteners. Be sure to cover the taped surfaces by deck boards in 90 days or less. This material is not designed to withstand direct sunlight.
Shielding your deck from water has been proven to prolong the life of your deck. When planning your decking project, keep in mind that the wood will settle and expand. Water will flow along the path of least resistance and infiltrate any cracks or holes in your boards. Having a solid, protected foundation will allow you and your family to safely enjoy your deck. Make sure to think long term in your planning to save money in the long run.
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