Building A Deck
Footings & Posts
Footings transfer loads from the deck framing to the ground and should be securely anchored to resist uplift. Posts support the beams and transfer deck loads to the footings. See the Prescriptive Residential Wood Deck Construction Guide for footing requirements, typical footing options, footing sizes and post requirements. Deck posts are generally solid-sawn timbers, but may also be glued-laminated timber or structural composite lumber. The International Residential Code (section R407.3) specifies a minimum 4x4 (nominal) wood column size. The Prescriptive Residential Wood Deck Construction Guide, however, requires a 6x6 (nominal) post size for residential decks. A 6x6 post is conservative for most deck applications, allows a deck height up to 14’ and provides adequate bearing for beams. Diagonal bracing is required for decks greater than two feet above ground.
Support posts can be notched within limits to accommodate bearing for the beam. However, notching may expose untreated wood to decay. Notching also reduces the post cross section, thus reducing strength. To avoid notching, use a post cap connector to attach the beam directly on top of
the post. If high lateral loads are anticipated (wind or seismic), notching is prohibited.