The greatest threat to the longevity of your deck framing is moisture. Water has the ability to seep into the tightest joints and all unprotected areas to cause a nesting zone for rot and decay. Pressure treated lumber has the ability to withstand the attack of moisture and rot for a period of time. However, season after season, the inevitable will set in and you may find that your once new deck has begun it’s return to the dust from which it came.
Enter waterproofing membranes and advanced silicones.
If you have a second floor deck and would like it to act as a roof for the first floor, keeping it dry, a waterproof membrane is your best solution. Even a first floor deck, when you desire to increase it’s life or create a dry storage space underneath, a waterproof membrane will serve your goal.
With most installations, you can expect a cost increase of around 15% to create a dry solution under your decking.