Fix a Bouncy Deck - Extreme How To
A: A “bouncy” deck is usually caused by long joists between beams. Assuming you can access the support framing, you can strengthen the deck by installing rows of blocking cut to fit tightly between the joists, spaced every 3 to 4 feet along the span. The blocking should be the same size as the joists (usually made of 2-by-8 or 2-by-10).