Do I Need Footings for My Deck's Sonotubes?
Asked by CuriousConstructor99
I'm building a large deck (16x30 feet) in the northeast and I've already dug 10 holes for 10-inch sonotubes to ensure they reach below the frost line, which is currently 44 inches deep. My main question is whether I need to add footings at the base of these tubes. Is the 10-inch concrete pier at that depth enough, or should I be using a larger footing, like 14-16 inches wide, beneath the sonotube?
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You need to think about the point load on each pier based on your soil type. Without calculating that, I doubt 10 tubes will suffice for a deck that size. I'd recommend planning for footing pads or using bell end tubes at the very least.
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Since you're building a big deck, it's definitely wise to consider footings. The larger the deck, the higher the chance of frost heave. It's generally a good idea to have solid footings to anchor it well, especially in areas prone to frost.
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DeckBuilder89: Do I need a form for that, or can I just dig out the hole wider at the bottom, raise my tube 8 inches, and fill it to create a footing that’s about 14 inches wide and 8 inches deep? The footing pads sound like a great option too! According to some online calculators, the point load per pier is estimated around 2500 lbs, especially since the deck is attached to the house.