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Opening between deck boards

Mr. Inspector

Mr. Inspector

SAWHORSE
Joined
Nov 28, 2009
Messages
4,657
Location
Poconos/eastern PA
They have 1" openings between the 2x6's that makes up the deck floor. Seems like it could be a tripping hazert to me, but can't find a code section abut it. 2009 IRC
 
ANSI has 1/2" requirement I believe, but I have never found anything in the IRC.....ALOT of shrinkage in the PT decking these days.....

I have even tried the lumber co paperwork to see if I could find anything enforceable there and no luck....
 
I promote the 1/2" maximum from ANSI A-117.1 as the maximum for this gap when teaching and consulting in the decking industry.
 
There you go, they were probably taught the 1/2" gap and installed them that way. After they dried out, some places would have an inch.

We've always installed PT tight on decks and in 4wks, there would be at least an 1/8" gap everywhere (using 5/4x6PT). Some places would have 1/2".
 
For years the contractors used the hand drive nails diameter for spacing then pulled the nails from the gap. A 1-inch space would save you a couple of deck boards on a large deck I'd think?

Could also promote snow and water displacement?

pc1
 
"If you space it 1/8" on install, it will be 3/4" the next month.....If you pull it as tight as you can it might only gap out to an eigth if you are lucky..."

Yes. I definitely agree a best practice is to butt the decking as tight as possible because of the shrinkage that will occur. Still, this document may provide a good basis for requesting a correction to the present 1" spacing.
 
If the boards are air dried there will be minimal shrinkage but if they are PT boards then a 6" board could shrink as much as 1/4 inch

Deck Boards

Many carpenters use 16-penny nails to space deck boards.

This creates a

1⁄8-inch-wide gap that forms a collection

zone between boards and on top of every joist (

). It’s nearly impossible to remove leaf litter from

such a narrow gap. And once the organic matter is in there,

it can induce rot in the deck boards and in the joists below.

My way around this problem is to install decking with a

wider,

3⁄8-inch gap. Organic matter won’t collect in this

larger space, but will simply fall through. (Some customers

express concerns that such a wide gap will catch a woman’s

high heel. I’ve found that once I explain the benefit —

extending the longevity of the deck — they readily accept

the gap. And how many women wear stilettos to a barbecue?)

The larger space also allows air to circulate and dry

out the decking and joists. And on top of joists, where

debris still collects, the space is wide enough to be raked

clean with a screwdriver. The same rules apply to composite

 
"You cannot enforce common sense, and ANSI A-117.1 does not apply to SFD"

I was referring to whomever constructed the deck, not what could be inspected. Hence my comment "not addressed".
 
I usually clamp a rack of boards at a time and screw them down. you do ned to have some idea of the moisture content. i've blown a rim off when the wood was very dry and we got rain. I've also had the gaps stay slammed tight up against the house on the north side, not a good thing. I now intentionally gap rows near the ledger and rim to assure drainage and clamp the field.

Structurally I'm not sure we shouldn't require a roof over those structures but that's a whole othere kettle of fish.
 
Rick18071 said:
It's a house. I can only enforce what's in the code. I will have to let it go.
Click to expand...
I disagree whole-heartedly.

When there is no prescriptive method provided for in the IRC, it is an alternative and subject to approval by the Building Official. Installation of spaced decking on an exterior floor is not provided a prescriptive method in the IRC. Therefore ALL exterior decking of this sort is an alternative. Alternatives must be reviewed to determine if they provide equivalent performance as to that in the code. (R104.11) The only flooring in the IRC would be that with no gaps what-so-ever. Rather than be that restrictive, and allow NO gaps, an authority can rationally look to the ANSI and admit that if 1/2 inch gaps are acceptable there, then they are probably acceptable for a home.

If they insist on installing the decking with larger gaps than can be logicially justified using published standards, then use R104.11.1 and let them perform tests at their expense to provide evidence that 1/2" gaps are equivalent to the non gapped floor sheathings prescriptively provided in the IRC.

I'm not saying I would push the issue like this...but you absolutely can if you wish to.

Elevators aren't in the IRC either...and I don't think you would say, "It's a house. I can only enforce what's in the code. I will have to let it go."
 
I forgot to mention. MtnLogCabin has it dead correct. As a former deck builder, I know his comment to be absolute truth. I learned from tearing down hundreds of old decks to always gap the boards about 1/4". This allows debris to fall through.

Great addition to the discussion, Mtlogcabin. It's obvious you've spent some time in the trenches.
 
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