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Re: Deck over patioFrom: info@builderswebsource.com
Category: Decks
Remote Name: 63.198.181.43
Date: 06 Sep 2002
Time: 02:51 AM
CommentsWe don't like either of your plans. Supporting a 2nd story deck with only two piers spaced 30 feet apart in a snow load area is trouble waiting to happen. Running some quick checks, the snow load in Ohio (Dayton area) is about 20 psf. It may be more (or less) in your area. Assuming the deck is 12' x 30', you would need a massive glulam or steel I-beam to span 30 feet and carry the deck load, assuming a 40 psf live load from people, a 10 psf dead load from misc. furniture and other items plus the snow load. To provide good stiffness with under 0.3" of deflection, you'd need a beam on the order of 8-3/4"x30". You could get by with something smaller from a structural standpoint, but it would be bouncy under full load. The joists would need to be (2) 2x10 or similar on 16" centers. On the other hand, by adding two intermediate piers (to cut your spans down to 10 feet), you could get by with a much smaller beam. We prefer reinforced concrete piers for 2nd story decks, drilled sufficiently deep into the soil to withstand the load from the deck. You'd need to know the skin friction of the soil and the load on each pier. Due to the safety considerations of a 2nd-story deck, coupled with your aesthetic concerns, we urge you to consult with a licensed structural engineer who can formulate a plan based on actual local snow loads (accounting for nonlinear snow drifts that can accumulate on decks). The above estimates are based on limited information and are for illustrative purposes only. Do not use these figures to build your deck as your assumptions may be materially different than our assumptions. Whatever you do, build a sturdy deck and ask your engineer to make sure that the deflection is less than L/480 and that the total deflection is less than approximately 0.3", whichever is most stringent. Builders Websource.
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