Deck Posts

[jchamp]

Any thoughts on the three deck posts for the top deck in this picture. It had 3-4" X 4" posts that were notched on the top and bottom. Any thoughts would be great.

[rwand1]

Those notched posts are prone to splitting if the upper deck should rack. Personally speaking I would call them out for repair or improvement. I also feel they should be 6x6, the 4x4 look to few to support that deck and loading.

[Brian A. MacNeish]

Would be my call, also.

[Jeffrey R. Jonas]

I would think that the load capacity of the 4x4's is max'd out just with the weight of the unloaded decking material. Also considering the method of attachment to the lower deck.

[Roy D. Cooke, Sr]

Originally Posted by jchamp

Any thoughts on the three deck posts for the top deck in this picture. It had 3-4" X 4" posts that were notched on the top and bottom. Any thoughts would be great.

Please write hard this deck is a disaster waiting to happen .
....... Cookie

[Bob Elliott]

Why is there no corner column?
Shouldn't the columns be spliced together also?
C:\Documents and Settings\bob elliot...heschicago.htm

[Roy D. Cooke, Sr]

I expanded the picture and made it lighter,there are hangers but can not see how it is fastened to building .
Only one hand rail on stairs large opening a kid can get through on back side of stairs. No cross braces to stop racking .
No cross braces on Up rites .
Do not like Half 4*4 supporting top deck.
Do not like doing inspections from Picture but this is bad.
How are the lower posts connected to the ground .
Concrete piers or into ground ?


........ Cookie

[Richard A. Hetzel]

It is strange but probably OK. The 4x4 columns are fine for one story of height, and the loads don't appear to be great, as the deck appears to be fairly small. The corner cantilever was, I hope, designed by a professional, and not just guessed at by the framer. My biggest concern is that the connections at the base of the columns may be insufficient to (a) carry the vertical load without shear failure, and (b) to connect the 4x4's to the 6x6's below to resist uplift. And is there sufficient bearing area of the girders on the tops of the 4x4's? The upper notch itself is not a concern otherwise. I also have a concern about the girder sizes and their ability to carry that double cantilever at the corner.

If there are design documents existing for the deck, these concerns can be easily checked by a design professional, either a good architect or a structural engineer. If not, on-site evaluation of the as-built deck is also not complicated.

There is, however, some over-reacting by some of the previous posters here. It is one thing to raise a concern. It is quite another to condemn the design on no specific structural basis.

[Stephen W. Stanczyk]

A Death Deck in the waiting. I might trust 1 person, just not me, with a cup of coffee on that deck.

How were the posts attached at the lower level? Lag bolts probably instead of through bolts.
And that rim joist is really acting as a beam, which means it should be doubled. And if that is considered a beam, that exterior corner might be past the allowable cantilever of 2 or 3 feet (cant remember which and too tired to get up and look).

And the lag bolts holding the ledger board to the house, are there enough and in the correct postions?

I think the height of the posts is also beyond the allowable for the number and size of deck.

Defer Defer Defer. Make them understand that it is unsafe.

[Roy D. Cooke, Sr]

Originally Posted by Richard A. Hetzel

There is, however, some over-reacting by some of the previous posters here. It is one thing to raise a concern. It is quite another to condemn the design on no specific structural basis.

I think you are just a little out of step here .
In proper Decks are wrong and should not be taken lightly.
Please do a little more research and see what happens every Month in North America.
A good start is here.
http://www.nachi.org/forum/showthrea...ighlight=Decks

Thanks . Cookie

[Joe Funderburk, CMI]

Stephen, help me to understand when a rim joist should be doubled. I see single rim joists fairly often.

[Kenton H. Shepard, CMI]

Lack of knee (diagonal) braces, 4x4 post connection to lower deck and stair opening mentioned by Roy is what I'd call.

To test decks like this I get up on the top deck and with my back to the home, grab the railing, spread my feet way out and try to rock the deck back and forth. If I can move it, think what fifteen people up there dancing to a heavy beat could do.

The result: I almost always call out knee braces for decks like this because the decks without them (like this one), unless they have diagonal planking always move quite a bit. Realtors don't like it.

I've never seen failure from notching posts and have trouble imagining it happening unless the post were over-notched and/or the deck was experiencing excessive lateral movement due to lack of knee bracing or the notch had decayed wood.

Like Richard, I don't like the connection of the bottoms of the long 4x4 bosts at their bases, especially the one on the corner. I guess the post's base was notched to bear on the corner of the lower deck floor framing, but corners are weak areas in which to try to install a crucial (shear) bolt because the bolt hole is so close to the end of the rim joists that the joists can split more easily than when a bolt is installed back from the end even a few inches. The handrail post above is installed on the corner too. One more reason to make sure that neither the deck or the handrail moves.

Rim joists should be doubled when supporting two or more joists. This would include the rim joists on the upper and lower decks which run parallel to the home and which have hangers nailed to them which support floor joists. On longer spans, when to triple the rim joist or switch to larger size rim joist or to engineered lumber such as microlam or paralam is an engineering call. The rim joists on this deck are doubled, I believe.

The cantelever rule is 2/3 back and 1/3 out, so if the deck cantelevers 4' out, the section extending back toward the home should be 8' long minimum. This looks OK to me. I'd bounce on it and mention it if it felt too bouncy.
Actual failure from overextended cantelevers? Realistically, you can practically reverse the 2/3 rule and as long as the fasteners hold, it's just a real bouncy deck unless joists are also overspanned. Always call it if they break the 2/3 rule.

Bolt schedule attaching the ledger to the home is typically one 1/2" bolt every 2', staggered up and down and two bolts at the ends of each ledger board.

[Larry D. Kage]

Originally Posted by kshepard

Bolt schedule attaching the ledger to the home is typically one 1/2" bolt every 2', staggered up and down and two bolts at the ends of each ledger board.

See page 9... http://www.fairfaxcounty.gov/dpwes/p...ks/details.pdf

[Richard A. Hetzel]

The cantelever rule is 2/3 back and 1/3 out

That's the general cantilever rule for joists, but it certainly does not apply to girders. Both "rim joists" on the pictured deck are not rim joists at all, but are cantilevered girders, which must be designed individually for the exact condition which will exist. There is no rule of thumb applicable here.

The girder coming in from the left appears to cantilever and carriy the load of several joists. Actually though, this may not be a cantilever at all, because the end of this girder may be carried by the cantilevered girder coming in from the right. That would make the connection between the two girders critical, and something like a top-hung joist hanger would be necessary at that corner. We can't see if there is one, so we cannot comment on it, except to raise the concern. The two girders, however, might have been designed each as cantilevers, in which case, no connection at all is required at the corner. We don't know, because we don't have any information upon which to base a judgement.

There is no limit on the length of a cantilever if it is engineered. There is no need to double a rim joist unless the rim joist is also acting as a grider, and then, it must be calculated and designed. Maybe a double will be enough; maybe it won't be enough. In the case of the pictured deck, we don't know the sizes of the girders, nor the species and grade of wood, so we do not have enough knowledge to do anything but raise a concern.

To those who continue to condemn this design without the benefit of any structural information or calculations, I suggest they make some assumptions about the size of the deck and do some calculations. They may surprise themselves, and may also fall off their high horses.

[klott]

The family reunion will quickly turn into the family funeral, that deck is going to come down. It is not a matter of if but when. Save a life, call it out!