Enter your Deck Length, Width, Post Spacing, Dead Load, Live Load, Soil Bearing Capacity, and Attachment type to calculate Corner and Intermediate Footing Diameters, Total Posts Required, Number of Beams, and Max Load per Post — so your deck stays stable and code-compliant.
Corner Footing Diameter
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Intermediate Footing Diameter
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Total Posts Required
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Number of Beams
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Maximum Load per Post
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Total Deck Load
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The number of footings depends on your deck size, post spacing, and load requirements. Generally, you'll need corner footings plus intermediate footings based on your beam layout and post spacing.
Footing diameter depends on the load per post and soil bearing capacity. Corner posts typically carry more load and may require larger footings than intermediate posts.
Post spacing typically ranges from 4-8 feet, with 6-7 feet being most common. Closer spacing reduces beam size requirements but increases the number of footings needed.
Dead load is the weight of the deck structure itself (joists, beams, decking), typically 10 psf. Live load accounts for people, furniture, and temporary loads, typically 40 psf for residential decks.
Attached decks use a ledger board connected to the house, reducing the number of footings needed. Freestanding decks require additional support but don't affect the house structure.
Soil bearing capacity varies by soil type and should be determined by local building codes or a geotechnical engineer. Typical values range from 1,500-3,000 psf for most residential applications.
Pre-cast concrete blocks work for smaller, ground-level decks with lighter loads. For elevated decks or higher loads, poured concrete footings extending below the frost line are typically required.