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  1. #1
    Jon mackay's Avatar
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    Default Deck structure questions

    I often see 4x4 deck supports and almost always when they are tall supports, they are twisted. Is this acceptable or are 6x6 posts required?

    Also, I often see undersized joist hangers. The hangers should be the same size as the joist correct?

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    Default Re: Deck structure questions

    Quote Originally Posted by Jon mackay View Post
    I often see 4x4 deck supports and almost always when they are tall supports, they are twisted. Is this acceptable or are 6x6 posts required?
    Depends on the load.



    Quote Originally Posted by Jon mackay View Post
    Also, I often see undersized joist hangers. The hangers should be the same size as the joist correct?
    Not necessarily. You'll need to look at the application of that specific hanger to determine if the joist they support are applicable. I've seen what I thought to be 2X6 joist hangers that were also applicable for a 2X8 also.


  3. #3
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    Default Re: Deck structure questions

    Here is what the NC code says about height and bracing of 4x4 post.

    Attached Files Attached Files

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    Default Re: Deck structure questions

    NYS Code. Don't forget your SNOW loading, frost/freeze depth, support, flashing, structure support/lateral restraint, uplift, wind resistance, and all the other red-flags, due to size and helght and your location as well.

    With the apparent 45-gallon plastic garbage can in the left foreground of the second picture for a scale, I think its safe to say the 'deck" has some serious design issues. It is obviously more than 4-5 feet elevation and likely far in excess of seven, with grass at the base of the far-spaced posts (and elevation above personel door as shown in first photo).



    Last edited by H.G. Watson, Sr.; 07-28-2010 at 04:24 PM.

  5. #5
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    Default Re: Deck structure questions

    Those 4x4 posts look very thin and spindly for that installation.

    "It takes a big man to cry. It takes an even bigger man to laugh at that man". - Jack Handey

  6. #6
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    Default Re: Deck structure questions

    4x4's can be used to an extent, depending upon height, but they should have cross bracing for lateral support.

    The joist hangers usualy at times have a stamp on them stateing the size they are designed for, 2x6 and 2x8 at times are the same size as well 2x10 and 2x12 as well but at least 2/3 of the joist should be covered by hanger. Also should be secured with 10d nails at minimum.

    I did notice that there is no support beam at post under the deck, a single rim joist / band board some call it is not suited for the load / support of the joist and I am curious to the span of the 2x joist and size, in the pic it looks to be to far of a span but hard to tell just looking at pics. Ther is also a lack of lag bolts in the ledger for attachment to the house, and is there any flashing.

    If you already noticed all of this then just ignore my comments i guess :-)


  7. #7
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    Default Re: Deck structure questions

    All the holes should be used in the joist hangers. Probably should have used one size up. Why is one ledger bumped out and the one next to it flush against the house?

    If the posts are twisting, then that should be enough to call it out. They should not twist. Also, shouldn't the foundations be a little higher above grade to avoid soil contact. The posts should also be in a bracket instead of just resting on the foundation.


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    Default Re: Deck structure questions

    Quote Originally Posted by Jon mackay View Post
    I often see 4x4 deck supports and almost always when they are tall supports, they are twisted. Is this acceptable or are 6x6 posts required?

    Also, I often see undersized joist hangers. The hangers should be the same size as the joist correct?
    No, those posts are unacceptable in size and we doubt if they have adequate footings.

    Yes, those hangers are undersized.

    Bolts or lag screws should be used to attach the ledger boards to the house.

    That deck is dangerous, and you were right to question it.

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  9. #9
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    Default Re: Deck structure questions

    In NC 4x4 post can be up to 8' tall as long as they are braced properly...6x6 can be 20' tall. I would consider twisting a cosmetic problem....not structural.


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    Default Re: Deck structure questions

    Quote Originally Posted by James Duffin View Post
    In NC 4x4 post can be up to 8' tall as long as they are braced properly...6x6 can be 20' tall. I would consider twisting a cosmetic problem....not structural.
    And James would wire the lights to that deck by using the panel as a junction box too.

    Oh, wait, that's right ... James is from North Carolina - what am I thinking ... codes in NC? Wha fer?

    When we were up in NC last week I found SEVERAL homes which would make Jeff Foxworthy jealous ... his 'You know you might be a red neck if ... you mowed the grass and found six cars abandoned in the yard.' was exceeded by the amount of (yes, 'the amount of') semi trucks we saw abandoned in yards with grass and vines growing up over them. Forget "six cars", if you have an abandoned semi truck in your yard you know you ARE a red neck.

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    Default Re: Deck structure questions

    Quote Originally Posted by Jerry Peck View Post
    And James would wire the lights to that deck by using the panel as a junction box too.

    Oh, wait, that's right ... James is from North Carolina - what am I thinking ... codes in NC? Wha fer?

    When we were up in NC last week I found SEVERAL homes which would make Jeff Foxworthy jealous ... his 'You know you might be a red neck if ... you mowed the grass and found six cars abandoned in the yard.' was exceeded by the amount of (yes, 'the amount of') semi trucks we saw abandoned in yards with grass and vines growing up over them. Forget "six cars", if you have an abandoned semi truck in your yard you know you ARE a red neck.
    Or you could build your home on a storm swept sandbar that is full of sink holes .

    The beatings will continue until morale has improved. mgt.

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    Default Re: Deck structure questions

    Quote Originally Posted by Vern Heiler View Post
    Or you could build your home on a storm swept sandbar that is full of sink holes .
    Attached is the real Florida map (well, one of them).

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    Default Re: Deck structure questions

    And another Florida map.

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    Default Re: Deck structure questions

    I was just upset you didn't stop in for a beer on your way through!

    The beatings will continue until morale has improved. mgt.

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    Default Re: Deck structure questions

    New York State requires min. 40 lb live load and min. L360 construction.

    NYS further requires minimum 6x6" posts or equiv. for any elevation exceeding five feet.North Carolina code adoptions have NOTHING TO DO with New York State (the OP's "location").

    New York State requires minimum 42" footings....some areas deeper.

    Yes there is no proper girder tying in the posts either, there is MUCH WRONG with this "deck" as I already indicated.

    Due to its flimsy under-engineered and faulty construction, I would also suspect lot sideyard setbacks were not respected. WAG someone attempted to "re-purpose" a prior "car port" without permits or inspection to "grandfather" around a sideyard setback limitation. The structure is as photographed DEFICIENT (and likely should be condemmed).

    I see NO POINT in detailing beyond what Jon MacKay asked, especially those using inapplicable and inadequate references.


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    Default Re: Deck structure questions

    Jerry, it depends on where you go in NC, pretty much the same story for all states too.

    I saw a code inspection sticker yesterday on a new condo in NC, it failed due to a closet light globe being too close to the wall the shelf was mounted on. It was about 22 inches.

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  17. #17
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    Default Re: Deck structure questions

    Thank you for the information, very helpful.

    The deck was originally a cantilever design I believe, that's why the ledger board is strange.

    I never like to see high 4x4 posts, just seems too small for those family reunions or college parties.. (ya just never know).


  18. #18
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    Default Re: Deck structure questions

    Other than the undersized support posts, the lack of proper beams, the over-spaced deck boards, the improper ledger attachment, the lack of lateral support, and the obvious disregard for load ratings, it looks fine to me.


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    Default Re: Deck structure questions

    Quote Originally Posted by Jon mackay View Post
    The deck was originally a cantilever design I believe, that's why the ledger board is strange.
    Just curious... Since old cantilevered joists remain partly in place, what type of fastening was used to support the new ledger in that location? Any other photos?


  20. #20
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    Default Re: Deck structure questions

    Quote Originally Posted by Fred Comb View Post
    Just curious... Since old cantilevered joists remain partly in place, what type of fastening was used to support the new ledger in that location? Any other photos?
    The photo in the original post is the only one I have. It is fastened by nails into the original joists.


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    Default Re: Deck structure questions

    Quote Originally Posted by Elliot Franson View Post
    Other than the undersized support posts, the lack of proper beams, the over-spaced deck boards, the improper ledger attachment, the lack of lateral support, and the obvious disregard for load ratings, it looks fine to me.
    Hey Jon, I think what everyone is trying to tell you is your deck is a little unsafe buddy


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    Default Re: Deck structure questions

    Quote Originally Posted by David Garton View Post
    Hey Jon, I think what everyone is trying to tell you is your deck is a little unsafe buddy
    is that like being a little pregnant? tear the train wreck down,get a permit and start over before someone gets hurt.


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    Default Re: Deck structure questions

    information provided and the commentary at the end of this doc may be of use to some
    http://www.awc.org/Publications/DCA/DCA6/DCA6-09.pdf

    badair http://www.adairinspection.com Garland, TX 75042 TREC # 4563
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  24. #24
    Ted Glover's Avatar
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    Smile Re: Deck structure questions

    From the picture of the posts, I'd say these 4x4s appear to be bowed, which is a structural issue. Twisting means you bought them at (unnamed lumberyard) and is a cosmetic issue. You know, when the one plane starts at the bottom facing north and ends up facing northeast at the top.


  25. #25
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    Default Re: Deck structure questions

    If you can install the required bracing when you install the post it will cut down on the amount of twisitng and bowing a post will do.


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    Default Re: Deck structure questions

    Reminds me of the 4x4 post I put in for a satellite dish, one of the sats lost signal and I found the post had twisted so I readjusted the dish. Then the other sat lost signal when the post dried out some more and twisted back the other way.

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  27. #27
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    Default Re: Deck structure questions

    Sam was an old carpenter that could build you a deck or porch. He would never use 4x4s because they twist. He always used 2x4s nailed together. I have never seen his posts twist.


  28. #28
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    Default Re: Deck structure questions

    Quote Originally Posted by Philip View Post
    Sam was an old carpenter that could build you a deck or porch. He would never use 4x4s because they twist. He always used 2x4s nailed together. I have never seen his posts twist.

    Yea, treated 2x4's never twist.....or bow .

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  29. #29
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    Default Re: Deck structure questions

    Quote Originally Posted by chris mcintyre View Post
    Yea, treated 2x4's never twist.....or bow .
    Imagine they were nailed together against the bow. He also said when lumber was not good for anything else they treated it. I went with him to the lumber yard once, and we were told to leave because he was sorting through and flinging boards and cussing the lousy lumber. He did know his trade.


  30. #30
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    Default Re: Deck structure questions

    Quote Originally Posted by C.Johnson View Post
    4x4's can be used to an extent, depending upon height, but they should have cross bracing for lateral support.

    The joist hangers usualy at times have a stamp on them stateing the size they are designed for, 2x6 and 2x8 at times are the same size as well 2x10 and 2x12 as well but at least 2/3 of the joist should be covered by hanger. Also should be secured with 10d nails at minimum.

    I did notice that there is no support beam at post under the deck, a single rim joist / band board some call it is not suited for the load / support of the joist and I am curious to the span of the 2x joist and size, in the pic it looks to be to far of a span but hard to tell just looking at pics. Ther is also a lack of lag bolts in the ledger for attachment to the house, and is there any flashing.

    If you already noticed all of this then just ignore my comments i guess :-)
    To me, the key issue here is the lack of a continuous load path. From what I see in the photo, the outer rim is fastened to the sides of the posts. (bolts or nails?) A good prescriptive deck construction guide is available from the American Wood Council at http://www.awc.org/Publications/DCA/DCA6/DCA6-09.pdf


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    Default Re: Deck structure questions

    Great document. Thanks Roger.

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    Default Re: Deck structure questions

    Echo!

    Roger H, Barry A already recommended the same document and source of information (with link) only seven posts and two days prior.


  33. #33
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    Default Re: Deck structure questions

    This document seems to not apply in-whole in NC so if you are inspecting in NC be sure to see the NC amendments for decks.


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    Default Re: Deck structure questions

    Why would the Original Poster, Inspecting in NEW YORK STATE care about North Carolina Codes?!? How could your citations be even remotely HELPFUL to a NYS home inspector?

    In NYS elevations equal to or exceeding FIVE FEET require 6x6" posts or equivellent.Its not a matter of "don't like to see" it (4x4" or 4x6" posts) are not allowed for higher elevation decks, etc.

    OBVIOUSLY this deck is more than five feet above grade (already established via the two photos submitted, one showing over personel door, other with scale in photo clearly showing 45 gal waste basket). The Original Poster's LOCATION appears with each and every one of his posts (see Location info at upper right of every post).

    Enough crap already about what James Duffin thinks what dinky supports and structure requirements may or may not be permitted in freaking North Carolina. I seriously doubt even 4x4" posts at that elevation would be permitted at that spacing. All MOOT anyway since remaining structure is so totally wrong, as is its tie-in to the building. There are no 1/2" bolts - and the depth/length of the deck requires doubles not a single staggered spacing.

    OP's theory on prior cantillever is baseless.

    The "guide" is a general one not intended to be specifically locationally ammended code rule complaint but to the unammended 2009 IRC and contains additional "best practices" not proscribed by the unammended IRC, but you'd know that if you read it, and understood what information is contained within.

    Last edited by H.G. Watson, Sr.; 08-03-2010 at 10:00 AM.

  35. #35
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    Default Re: Deck structure questions

    balcony/deck failure Austin, TX
    many updates and vids with more to come on this one
    everyone play safe!

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  36. #36
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    Default Re: Deck structure questions

    Those posts need to be 6x6,sitting on footers with metal pads to avoid earth to wood or concrete to wood contact.
    They also require diagonal bracing from posts to beam.


  37. #37
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    Default Re: Deck structure questions

    In NC the post can be 4x4 if they are not over 8' tall plus they can be buried in the ground to eliminate the need for bracing. Not saying it is a good idea...just saying it is not a repair item in the areas I work in.


  38. #38
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    Default Re: Deck structure questions

    Quote Originally Posted by James Duffin View Post
    In NC the post can be 4x4 if they are not over 8' tall plus they can be buried in the ground to eliminate the need for bracing. Not saying it is a good idea...just saying it is not a repair item in the areas I work in.
    You keep saying such things, you're just going to have to prove it.

    Footings are required. Tributary area limitations. Notching requires 6x6. This is a wide, deep and tall deck.

    Even in NC, when attached to structure, decks greater than 4' high require lateral stability bracing. You're going to have to "show us the money", IOW, "where's the beef" that says you can use embedment for lateral stability bracing for a deck attached to structure that is 8'0" high and 4x4 posts!


    Now, in Durham, N.C., WHEN NOT attached to structure (i.e. free-standing decks), without knee-braces or diagonal braciing lateral stability may be provided by embedding the 4x4 posts (in concrete) to a maximum 4'0" post height, Max. Tributary area max 48SF, in concrete diameter of 1 Foot, with embedment depth of 2'6". Doing the same with 6x6 posts gets you up to a 6'0" max post height, 120 SF tributary area max, concrete diameter 1'8" and embedment depth of 3'6".

    So James Duffin, what's the citations that say you are permitted anywhere in NC to provide lateral stability to a deck attached to strucutre, solely by embedment (in EARTH?!? - not even in concrete?!?) of a 4x4 deck post height at 8'0" from grade without knee braces or diagonal bracing for lateral stability? And where does it say you can do so with even a free-standing deck?


  39. #39
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    Default Re: Deck structure questions

    The joist hangers are not correct in size and if like most decks in fastening as well. While attending a Simpson Strong Tie seminar I recall the Simpson rep saying a joist hanger needs to be at least 2/3 as high as the lumber it supports to accommodate adequate fastening and prevent rolling of the lumber.

    You can ask them yourself at Ask Simpson or call them on their (800) 999-5099 number.

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    Default Re: Deck structure questions

    Quote Originally Posted by Jon mackay View Post
    I often see 4x4 deck supports and almost always when they are tall supports, they are twisted. Is this acceptable or are 6x6 posts required?

    Also, I often see undersized joist hangers. The hangers should be the same size as the joist correct?
    True

    added
    Wet 4x4 and all others can twist while drying.. I dry mine before installing.same I don't think those supports are sufficient at all. Heck with the inspection. Make them make it safer. There are no X braces to prevent fall over.


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