# According to the IRC, are decks floors?



## Jobsaver (Oct 18, 2010)

Buelligan's thread, _Deck ledger attachment on brick veneer walls_, gives rise to this question: According to the IRC, are decks floors? I remain in a near perpetual state of disagreement with deck builders who use single band joists as girders, and hang all girders on nails or bolts to wooden posts. What are the bearing requirements for deck floor joists? What is the bearing requirement for the deck girders? Are girder span charts for floors (R502.5) applicable to decks? What are footing requirements for posts?

I believe decks constructed for SFH's ashould be constructed according to the same criteria as other "living areas" in the home.


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## RJJ (Oct 18, 2010)

The requirements in the IRC are for dry application. If you want a guide look at AF&P for deck details. How long have you been an inspector?


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## Jobsaver (Oct 18, 2010)

I have a decade of inspection experience, (mechanicals and some building),  but have just this year become the primary framing inspector for my ahj.


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## Jobsaver (Oct 18, 2010)

RJJ: Thanks. Found it on AF & PA website link to www.awc.org:

DCA 6 - Prescriptive Residential Deck Construction Guide - 2009 IRC Version Free Download - PDF

Includes guidance on provisions of the International Residential Code (IRC) pertaining to single level residential wood deck construction. Provisions contained in this document that are not included in the IRC are considered good practice recommendations.


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## peach (Oct 21, 2010)

2009 IRC addresses it.. 502.2.2.1 (50 psf)


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## Jobsaver (Oct 21, 2010)

We are still using the 2006. Still that is interesting (50 psf): The _DCA 6 Prescriptive Residential Deck Construction Guide - 2009 IRC Version _listed above builds to 40 psf. Go fiqure?


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## Mac (Oct 22, 2010)

Using the reference standard that is either included in your current IRC or been locally adopted is primary concern. DCA 6 in whatever year version is very good.

I find NYS IRC 502.2.2 (Decks) to be helpful, but foundations are less clear due to 403.1.4.1, which gives decks "... adjoining but not supported by a dwelling..." an exception from frost (depth) protection requirements.

With the standard joist & girder span tables, here in NY we manage to assemble minimum standards for decks. Not perfect, but adequate.


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## mtlogcabin (Oct 22, 2010)

If it is an open deck (no roof) I use the snow load which is higher than the 40 psf. A lot of homes are vacant in the winter and decks are not shoveled


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## Jobsaver (Oct 22, 2010)

mt:   Another good argument for regional codes.


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## Jobsaver (Oct 22, 2010)

mtlogcabin said:
			
		

> If it is an open deck (no roof) I use the snow load which is higher than the 40 psf. A lot of homes are vacant in the winter and decks are not shoveled


How much does one cubic foot of snow weigh?


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## smeismer (Oct 22, 2010)

Jobsaver said:
			
		

> How much does one cubic foot of snow weigh?


  Snow varies in density from a very light powder that might be 7% water to a dense heavy snow that might be in excess of 80%.  You can't figure snow load on volume, it must be done on a weight basis.


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## mtlogcabin (Oct 22, 2010)

Depends on if it is a dry snow (10 pcf) or a wet snow (compacted 30 pcf or more)  either one will weigh the same if it is on a deck or a roof. An open deck will accumulate the snow sliding off the roof so the snow drifting loads can increase significantly in some areas.

http://www.reade.com/Particle_Briefings/spec_gra2.html


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## Jobsaver (Oct 22, 2010)

mt:  Great chart. Thanks.  Also, good point on the snow sliding off the roof.


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## JBI (Oct 22, 2010)

" mt: Another good argument for regional codes. "

With regard to things like snow loads, wind loads, thermal zones... the Codes ARE regionalized.

NYS has several different snow load zones - up to 80psf in the Adirondack North Country.

Another current thread mentions CMU houses in Florida. Well if you're going to live on a sandbar that gets pounded by hurricanes annually, unless you really like rebuilding with wood year after year, CMU seems like a good idea. ;-)


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## Jobsaver (Oct 23, 2010)

JBI said:
			
		

> With regard to things like snow loads, wind loads, thermal zones... the Codes ARE regionalized.


This is true.


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## RJJ (Oct 23, 2010)

JBI especially in Vermont. Snow is often wet and heavy! White face near JBI has the same condition. In the front of the book there is a section for frost, wind,etc to be established by local AhJ. You need to identify your conditions. Condition here in PA  change quite a bit from my location to Jeff's which is 1 1/2 hr drive from south to north. Soil condition change as well. Fact is change just happens and you need to learn the local condition. I would not be able to apply what MT or JBI have in my ahj's. We are all slightly different.


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## mtlogcabin (Oct 23, 2010)

Our snowloadranges from 46 psf to over 100 within a 30 mile radius, The IRC maps are useless for us.


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## RJJ (Oct 24, 2010)

That is true! only a guide Mt. or a starting point. The base elements of the code we can all start with. Then we need to identify the local conditions or extremes. I could never apply a condition like a 100psf in my area. However, we do get hurricane winds.


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## Belly John (Nov 1, 2010)

1. Stop making multiple posts for the same question.

Just resetting your router does not always give you a new IP address. Your external IP could've still been the same. That or like you just showed here, you were probably asking the same question.


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