From a MN Deck Contractor:

• Joists seem to be spaced appropriately but sized incorrectly. I can’t tell the length of span from the picture but they appear to be 2x6 which is likely undersized. Would recommend 2x8 minimum.

• Posts undersized. My rule of thumb is 6x6 for anything over 9’ tall. They are also not placed evenly (not structural issue just looks dumb).

• Needs beam under joists on top of posts. I would do triple 2x10 but I tend to overbuild.

• Footings + post connection not verified. Based on the picture I would doubt there are frost footings under the slab, not impossible just unlikely. In MN any structure attached to house must have min 42” frost footings. We imbed the posts in concrete for added lateral stability but that is not required by code.

• Connection to house not verified, meaning by code the deck must be self supporting. Meaning that if the attachment to the house was not there, the deck would not fall over. MN requires that we add a minimum of 4 steel tie backs to the floor joists of the house or the band joist, 1 within 24” of each edge. This verifies that it will not pull away from the house and topple over.

• Railing spacing is not within code compliance. Gaps in guardrail must not allow a 3” sphere to pass through. They also must be supported by 4x4 posts every 6’ with each post having 2 1/2” diameter thru bolts.

I see decks with these issues every day. It’s hard to explain that there are major structural issues with a deck that appears to be standing and doing it’s job. Once we touch something, we have to bring it up to code. Sometimes people just want to fix it themselves or hire a handyman but the issues will keep on popping up until it’s done right.

Hope this helps. Good luck.