How Under-Decks Work

Decks are intentionally built with gaps between the floor planks, protecting them from water damage by allowing rain to drain through to the ground.  Unfortunately, this means the usability of the space below the deck is limited.  In under-deck systems, material is installed to create a watertight ceiling, which either surrounds a drainage system or is supported by gutters.  Runoff from the deck is caught by the structure, which is angled to drain water into the waiting gutters; rain exits through one or two downspouts.  To ensure drainage, the ceiling should be pitched properly and angled to divert water away from the house.  If water pools on the structure, it could encourage wood rot; and if water pools next to the foundation, waterproofing problems could occur.