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Old 04-06-2013, 05:51 PM   #1
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weight bearing limits of wood 4x4


Anyone know the following:

Weight bearing load of a vertical 4x4 piece of wood, compared to a 6x6

And weight bearing load capability of horizontal 4x4x8, at its center.

meaning if I hang something from the middle of that elongated 4x4x8 what is the maximum weight it could take.

Thanks anyone everyone for thoughtful answers

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Old 04-06-2013, 06:03 PM   #2
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weight bearing limits of wood 4x4


what grade and species of wood, treated or untreated? strictly vertically loaded? 8' column height?

I ask these questions because each grade and species of wood have different physical properties, i.e., #2 grade douglas fir is typically stronger than #2 spruce. treated wood typically has less strength than untreated wood. of course untreated wood does not last as long when exposed to the weather unless a naturally durable species.

length of the column determines its load capacity. Have a unrestrained column of too great a height and it can buckle from the load, not enough height and it could fail in compression.

not trying to be difficult, trying to get you to provide the information needed to answer your question.

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Old 04-06-2013, 06:04 PM   #3
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weight bearing limits of wood 4x4


again, if you tell us what it is you are attempting to do you may find you'll get some positive replies .... real world questions get more attention than home work problems
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Old 04-06-2013, 11:01 PM   #4
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weight bearing limits of wood 4x4


like gb stated the post can buckle under excessive load or if its an exterior post it can snap from deflecting do to wind load.. too many decks have had this happen in the last 10-15 years all over so current codes will not allow 4x4 posts to be used for supporting a deck their only rated to be used for hand rail posts
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Old 04-07-2013, 12:39 AM   #5
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weight bearing limits of wood 4x4


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Originally Posted by woodworkbykirk View Post
like gb stated the post can buckle under excessive load or if its an exterior post it can snap from deflecting do to wind load.. too many decks have had this happen in the last 10-15 years all over so current codes will not allow 4x4 posts to be used for supporting a deck their only rated to be used for hand rail posts
Snap from deflecting due to wind load ???? A 4 x 4 ????

Thats a new one on me. You must have some powerful winds where you live.
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Old 04-07-2013, 07:27 AM   #6
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weight bearing limits of wood 4x4


the whole deck can start to wobble under heavy wind loads. and im right on the coast. for the last 10 years weve been seeing more and more class 3 and 4 hurricanes. thats when they changed the code.

is also the same reason that we have to frame tall walls with 2x8 lvl studs or 2x8 timberstrand studs no spruce allowed except for cripple studs and lentils under headers
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Old 04-07-2013, 11:39 AM   #7
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weight bearing limits of wood 4x4


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the whole deck can start to wobble under heavy wind loads. and im right on the coast. for the last 10 years weve been seeing more and more class 3 and 4 hurricanes. thats when they changed the code.

is also the same reason that we have to frame tall walls with 2x8 lvl studs or 2x8 timberstrand studs no spruce allowed except for cripple studs and lentils under headers
So instead of installing wind bracing, such as installing a 2 x 8 at a 45 degree angle about three feet down anchored to the posts and the band joist, they went to a thicker post? Since "Wobble" is due to lateral forces, why did they increase the compression requirement of the post?

You must have the same type of engineers up there that we have in our town. They run electric model trains, and wear those striped hats.
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Old 04-07-2013, 04:08 PM   #8
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weight bearing limits of wood 4x4


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So instead of installing wind bracing, such as installing a 2 x 8 at a 45 degree angle about three feet down anchored to the posts and the band joist, they went to a thicker post? Since "Wobble" is due to lateral forces, why did they increase the compression requirement of the post?

You must have the same type of engineers up there that we have in our town. They run electric model trains, and wear those striped hats.

think about what you just stated. their not increasing the compression requirement, howver a deck must have a a beam thats no less than 4-1/2" thick or a 3ply 2x10 and the beam must fully bear on the post. your increasing the thickness of the post which reduces the deflection rating, its the same as a floor joist's live load or dead load.. and as for our codes. by upping the size of the post you can also eliminate the need for a angled lateral brace which just looks hideos 99% of the time.. i see that on low end builder grade decks on cookie cutter homes... those decks are built to the bare minimum of code and done as fast and cheap as possilbe. Canadian building standards are higher than most of the u.s.a. i know several high end contractors in the u.s.a and they are familiar with our standards and have adopted them. its something called over building.. i hate to say it but based on quite a few of your posts your not exaclty a top notch builder, several of your recommendations on how to do things would never fly in several regions

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Old 04-07-2013, 05:08 PM   #9
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weight bearing limits of wood 4x4


I have 4x4 pressure treated and lathe cuts in them to round them off at certain heights to make them look fancy,

Smallest dia must be 3" where lathe cuts grove out.
They are holding up a Porch on a 12x 30 foot deck. They are spaced about 6 FT apart. The roof is 24 FT LG 2x6 with 1/2" ply sheating with torch down. Main header is 2 pcs 2x10 for roof . Deck is 2x12 double header.

15 years now no problem, not 1 nail pop. Used 3" spiral nails countersunk. Would have used deck screw but at the time the nails seemed to be the thing to use. I have built since then and screw everything now.

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