Code requirement for deck posts

[Rusty]

It's been a while since I've built a deck and was wondering if the post that the beam sits on has to be 6" x 6". The last time I built one it was Ok to use 4" x 4" posts. This deck will be built in Tuftonboro.

The reason I ask is because on page 7 of the Prescriptive Residential Wood Deck Construction Guide which is based on the 2009 International Residential Code states this: "POST REQUIREMENTS....
All deck post sizes shall be 6x6 (nominal) or larger"

I don't want to make a drawing for the permit using 4" posts and find out that I need 6" posts.


Here is the Guide: http://www.awc.org/publications/dca/dca6/dca6-09.pdf

[jeffatsquam]

Regardless of the code a 4x4 will support the load but a 6x6 will give you many more joining options which is very importune in decks.

A lot of lateral loads there.

The cost of a 6x6 over a 4x4 is minimal as is code

[Rusty]

You're right about the options and price. However I was just wondering if the code requires a 6".

A friend of mine in Wolfeboro built a deck and he said the Code Enforcement Officer required a 6" post with the deck only @ 4 ft off the ground.

I guess I could ask the CEO of Tuftonboro but I would like to know where the requirement comes from if in-fact I have to.

[TheProfessor]

Codes were brought up in another post.
I am not an expert on such.
My understanding is that there are national codes, state codes, and even local codes.

Over a decade ago or longer.
This is how I recall the story.
Spec. House.
Builder constructed a home to sell. Did all the correct permits.
This was about the time that the roof shingle companies manufactured a roof shingle that stated on instructions - that tar/felt paper is not required.
So the roof was put on per manufacturers information.
Except the local building inspector stated in "our" town we require felt/tar paper under all shingles. New roof had to be removed and redone.

Could be an urban myth story. But this was told to me by another builder.

[Great Northern Cleaning]

Built at our camp. And they used 6 x 6 posts!

[Rusty]

Originally Posted by Great Northern Cleaning

Built at our camp. And they used 6 x 6 posts!

That is a very well designed and built deck.
What size are the Band and Rim joist?

I also like the teak color of your camp.

[SIKSUKR]

It may be the view in the photo but what the heck is holding up the right corner of that landing?It looks like just a gusset from the main stair post.

[Rusty]

Originally Posted by SIKSUKR

It may be the view in the photo but what the heck is holding up the right corner of that landing?It looks like just a gusset from the main stair post.

I would say the "HUGE" ledger board is holding up that part of the deck.

That's why I asked what size Band and rim joists were used. They look really big.

[Great Northern Cleaning]

I have been waiting for a reply back from my friend who built the deck..
But no response yet. I believe they are 2 x 10s. I can tell ya this is one
rugged deck...and there is no play or bounce on the top corner of the stairs.

[LIforrelaxin]

The only way to know for sure, what the two CEO is going to require is to speak directly to them. By the way this is what they are there for, it is their job, to not only make sure the rules are followed, but to also make available the information need, to properly plan a project.

Over the years requirements have changed tremendously regarding decks. I remember being told that are deck was built almost to rugged, and that we over engineered it. By today's standards it is not beefy enough.

The bottom line is post specification, my have lots of variables, such has how many posts are being used, over what span. etc. In the deck shown by GNC I have no doubt that 6x6 post where required. That is a fairly decent span for only 3 Posts. And then you look at the bulk of the landing being suported by a single post. Looking at the span if only 4X4 where used I would have suggested at least 4 and maybe 5 posts.

In the end you are likely to be better off just going with the 6x6 posts, they will provide stability, and for a small cost difference take the question out of the equation.

It is likely the 4x4 and 6x6 are both allowed, what you have to show is the engineering wise the structure can support an X lbs. load per square foot of surface area. The question is do you want to do the engineering work to show that your design with 4x4 will support the needed load, or just use 6x6 instead, and not have the question raised.

[Great Northern Cleaning]

Those are 2 x 12s

[Rusty]

That's what I thought.

Thank you and I really like the deck!

[DickR]

In most cases, a 4x4 post has plenty of load-bearing capacity for what it has to carry. More typically, it is a matter of height/diameter limitation. Even when a 4x4 is adequate from the engineering point of view, a 6x6 is so much stiffer that the extra cost is peanuts vs the extra robustness of the structure.

[Rusty]

Just rec'd the answer to my question from the CEO of Tuftonboro:

"I will allow 4x4 post under a deck no longer than six feet in length."

Now I can finalize my drawings to use 6" post.

I would have submitted a drawing with 4" post because that is how I have always built them. Also the deck is only 4ft high.

[BroadHopper]

http://www.nahb.org/reference_list.aspx?sectionID=224

I always refer to the current residential building codes. However as stated in another thread towns are always behind adopting the latest RBC.