It's been many years since I built a deck, and never a two story one. Existing deck getting replaced, it's a two story, with the pitch of the house roof (1) extending a few inches past the face of the deck. Note I said a few inches.... What is the right way to mount a support column to a deck and to a header? won't work for me as it would put the deck past the drip line!

County will accept a rough-drawn sketch (sketchup) for a permit, when I called about this question, was informed they issue permits, if I need design, call an engineer! Any way, my question is about the rim joist to post connection. My knee-jerk reaction is the notch the post and use a single 2X6 (3). Or do I need a double header here (4), if so, doesn't notching a 6 by 6 post...3 inches...too much?

My second question is, what about when two rim-joists meet? I assume I meet them in the middle of the notch (5)?

Can't use existing deck as example, there's a reason why it needs replaced.

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1 Answer 1


I’ll try to help. There are several issues.

First, I don’t think the posts have to extend two stories. I think the posts could extend from a foundation support up to the deck structural system.

Second, posts could extend from the deck structural system up to the roof overhang if necessary for the guardrail support. (The posts could align with the first floor posts, if necessary.)

Third, the size of the deck support beam (you call it a “rim joist”) is dependent on how far the deck extends from the wall AND how far it spans from post to post. By Code, “decks” are required to support 40 lbs. per square foot (psf). See Table R301.5)

If the exterior balcony is more than 6’ deep (I’ll assume 6’ you tell me if I’m wrong) and posts are more than 6’ apart, a single 2 x 6 will not provide enough support. In fact, 2-2 x 6’s will not give enough support.

Fourth, notching a 6 x 6 about 3” is excessive and will not give adequate support for the deck and guardrail.

I would restructure the balcony so that an adequate sized beam is used (4 x 8) and so that it is placed on top of a post, rather than notched into a 6 x 6.

Please note that the code requires decks to be anchored to the house in at least two locations using straps like this tie:


I’d use a steel post cap (like Simpson Strong-Tie) to connect the beam to the post, but there isn’t enough info to size the connector.

  • Existing posts are 10 feet apart, there are 4 of them, each 1 a single post from ground to the header supporting the roof overhang. 1 (!) 2X10 support beam. I'm having trouble envisioning "posts could extend from the deck structural system up to the roof overhang if necessary for the guardrail support". So I basically build a 1 story deck (8 foot post at grade, typical deck on top),then put 8 foot posts on top of that to support the roof? How do I connect the "roof" posts the beam on top of the first story posts and meet the guardrail rules per Wood Deck Construction Guide - 2015 IRC Version
    – tpcolson
    Mar 3, 2021 at 16:18
  • joist span (depth of deck) is exactly 6 feet. It's more of a walkway/additional means of building entrance than a deck, really, but enough for my rocking chair and grill!
    – tpcolson
    Mar 3, 2021 at 16:42

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