Deck Question

[nishanf]

Hello - I'd appreciate some advice on my one year old deck. The far right hand side is sagging/tilting slightly, and I'm concerned that the deck is inappropriately cantilevered. The left hand portion spans about 13 feet (2x8 with 16" o.c.) with just over 2 feet cantilevered. In the right side, however, the cantilevered portion is about 50% of the total span. I know that it is only a small portion of the whole deck, but I'm concerned that it is the cause of the sagging. Am I right to be concerned, and any possible fixes? thanks in advance, Nishan

[Shawn Rowe]

Nishan,
Just at a quick glance you have justified concerns. The right cantilevered end is JUST WRONG and needs repair immediately! No keg parties for you!

[Paul W. Abernathy]

Where I am the Maxium Canti. is 2' MAX.

One of the rules used is the amount of Cantilever should be no more than one fourth of the joist's span.....But in our area for example no more than 2' regardless.

[ckratzer]

Max cant.is 2' as already conveyed by others.
You may also wish to investigate the width and depth of the poured piers the post are resting on.In this area the min. width is 12" and 3' deep.They could also be sinking.

[rbunzel]

I can't tell from the pictures but is the ledger board bolted into the brickwork? If it is then a 2" cantilever shouldn't be a problem as the potential uplift on the joists/ledger boards shouldn't be huge even with a keg party. I regularly see 30" overhangs here but they usually are on larger spans. If you concerned I would make sure all the joist hangers have the proper number of screws or nails and there is a bolt between even joist on the ledger board. "As always if you are still concerned contact a structural engineer to the review the deck and attachments" ;-}

//Rick

[rwand1]

I would concur with Cheremie re the posts. But you didn't tell us where you are located because climatically speaking you may be in a frost prone area. If the posts are below grade directly in contact with soil even though they maybe sitting on concrete at the base the wood could be lifted out of the ground by the frost adhering to the wood (adfreezing). Frost will lift the wood up and in the spring it could drop back down. Or if the posts are set on piers the piers may not be deep enough or the footing not large enough to carry the load resulting in movement.

[James D Mosier]

Focusing on the left side of the deck for a minute, isn't 13ft too much span for 2x8s?

[nishanf]

Thanks for the replies!

Raymond - I'm down in Atlanta.
Rick - The ledger board is bolted to the brickwork.
Cheremie - The width of the footings appear to be about 12", but I can't tell the depth. Also the post looks to be sitting just on the edge of the footing (not centered).
James - isn't the span length really 11" between the posts which would be ok for 2x8?

In my prior research, I came across these two references from a post on this forum.

http://buildingcodes.jocogov.org/documents/Deck%20Book.pdf
http://www.taunton.com/finehomebuilding/pdf/Deck-Joist%20Layout.pdf

Both of them suggest a max cantilever of 2-3' but also no more than 30-40% of the total joist length. That's my main concern for the right hand section. The cantilevered section in only about 25-27", so overall that's probably ok along the left side of the deck. But what about the tilting right hand side. Here the cantilevered part is again 25-27", but the back span is only 32". So to address the tilting problem, should we shore up the footing first or address the excess cantilevered section (by moving the post out?) or both? The builder will take a look, of course, but I want to get some independent opinions as well.

Also - this is the second time that section has tilted. The first time the support post warped crazily, which we attributed to a wood defect. That post was replaced. Now I'm not so sure it wasn't a construction defect.
Thanks again for all the advice.

[Paul W. Abernathy]

Originally Posted by pabernathy

Where I am the Maxium Canti. is 2' MAX.

One of the rules used is the amount of Cantilever should be no more than one fourth of the joist's span.....But in our area for example no more than 2' regardless.

No more than 1/4th of the JOISTS SPAN....( ie: 25% )

[rwand1]

What is the decking? Spaced board, solid sheating? Is that factored into the issue? Is it permissible to double the joists? You could also provide solid blocking between joists. Why move the posts if not necessary, other then provide new pier for right end? My opinions.

[rwand1]

I also don't like the way the staircase header is attached at beam end. It is not framed properly for my liking. the stringer is resting on the cantilevered section from what I can see in the first photo. Seems to me, this area could do with 2 addtional posts.

[robarm]

Max. cantilever span for a 2x8 is 34".
The cantilever can not be more than 1/2 the span of the joist from the house to the beam. IRC Table R502.3.3(2).
This deck looks like it was built in Gwinett CO. since they require independent support at the brick veneer. I'll be in Gwinett Tue. 05/30/06. I will come by and take a look. Call me at 404-932-0867

[John Allingham]

Nishanf
In my area a permit would be required for an elevated deck such as this. Was a permit approved and issued?

[nishanf]

Raymond - The decking is composite board. Also I'll take a closer look at the stairs.

Robarm - thanks for the offer. I'm actually in fulton county right off exit 6 on the 400. If you're still interested let me now and/or I'll give you a call tomorrow.

John - I don't know about the permit. I can ask the builder.

thanks,
nishan

[Joe Funderburk, CMI]

Another good resource:

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

(I don't see the 25% rule you guys are stating. This source says 3 feet.)