# flat ceiling 2x4



## darcar (Mar 13, 2012)

Can someone direct me to a code section or other guidline that addresses framing members lying flat for a drop soffit framing?

Framer has used 2x4's flat spanning around 5 foot...


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## steveray (Mar 13, 2012)

I know I can't.....


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## mtlogcabin (Mar 13, 2012)

It will work at 16" OC with a 10 lb live and 10lb dead load or you could just do a few chin ups and see if it holds


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## ICE (Mar 13, 2012)

Actually you could just give it a nudge with your chin and if the soffit survives you've got a winner.


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## brudgers (Mar 13, 2012)

darcar said:
			
		

> Can someone direct me to a code section or other guidline that addresses framing members lying flat for a drop soffit framing? Framer has used 2x4's flat spanning around 5 foot...


  What problem are you seeing with it?


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## steveray (Mar 14, 2012)

The problem (I believe) is that the IRC does not address lumber used in this manner, if the applicant would like to provide verification via an alternative means (span table that addresses it) I am all for it...I know it probably works, but that is not my job....


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## brudgers (Mar 14, 2012)

steveray said:
			
		

> The problem (I believe) is that the IRC does not address lumber used in this manner, if the applicant would like to provide verification via an alternative means (span table that addresses it) I am all for it...I know it probably works, but that is not my job....


 The code is silent on the matter of soffit framing.  Perhaps this is a good example to follow?

  Particularly since you know it ain't broke.

  To put it another way, this a case where you don't believe there is a problem.

  What is gained if you create one?


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## Pcinspector1 (Mar 14, 2012)

I've seen this done in raised ranch homes when the duct is in the garage and 2x4's are framed below the duct for gypsum. We called it a cage frame or fur-downs.

I've seen the span further than 5ft as well.

If the 2x4's span further than 6ft would you need hangers?

pc1


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## JBI (Mar 14, 2012)

Oddly, I agree with brudgers on this one. The span tables are for stuctural loading, the soffit is a cosmetic application.


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## Min&Max (Mar 14, 2012)

I have allowed 2 x 4's installed flat to span a max. of 4ft. Nothing to base it on other than I know of no problem associated with this installation method.


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## jeffc (Mar 14, 2012)

Would anybody ever be up there crawling around? If so, I would be worried about how it is connected to the adjacent framing. A gun nail in withdrawl is only good for about 40 pounds. If we size the joist for a 6 psf dead load (insulation 3 lb, sheetrock 2 lb, wood 1 lb) and 10 psf live load, a flat 2 x 4 (HF) spanning 5' is adequare by 5.5%.


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## steveray (Mar 14, 2012)

Dead load is not structural?



			
				JBI said:
			
		

> Oddly, I agree with brudgers on this one. The span tables are for stuctural loading, the soffit is a cosmetic application.


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## brudgers (Mar 14, 2012)

steveray said:
			
		

> Dead load is not structural?


  It's supporting it's own weight and a little bit of gypsum board.  It's structural to the same degree that door butts and base cabinets are.


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## mark handler (Mar 14, 2012)

JBI said:
			
		

> Oddly, I agree with brudgers on this one. The span tables are for stuctural loading, the soffit is a cosmetic application.









I too agree


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## brudgers (Mar 14, 2012)

I ran the beam as SPF studs, 5' span, 20plf loading.

    Deflection = 0.234"

    That's better than l/240.

    20plf is really really conservative for this application.


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## mark handler (Mar 14, 2012)

StrcuCalc a Structural software program allows you to calc "flat" framing members


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## Architect1281 (Mar 14, 2012)

The NDS and WFCM and the antiquated (used by trained people) wood design manuals had all of these and were "REFERENCED STANDARDS" in the codes for ages.

used by craftsmen who had framing squares and tape measures and knew things like - you need extra joists at tubs, and bearing and non-bearing walls. Trained and maybe even served an apprenticeship

hen along comes the larger volume more expensive "ICC Codes for Dummies Series" where if it ain't in a chart it obviously can't be allowed crowd......................sorry I'm Ranting. Time for my pill.


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## Architect1281 (Mar 14, 2012)

BTW the only load those 4x2's are carrying is 2 psf drywall DL


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## mark handler (Mar 14, 2012)

Architect1281 said:
			
		

> Time for my pill.


  Lithium ?


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## steveray (Mar 15, 2012)

Back to the OP.....I guess there is not!  Everyone has an opinion, but not a basis in code.....as AHJ...your choice, case by case.....


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## Architect1281 (Mar 15, 2012)

No the rant was based on code

the CFD's Chart Laden DIY manual is for "STRUCTURAL LUMBER"

the photo and resultant construction in not "Structural" - no load path to follow

R301.1 Application. Buildings and structures, and all parts

thereof, shall be constructed to safely support all loads, including

dead loads, live loads, roof loads, flood loads, snow loads,

wind loads and seismic loads as prescribed by this code. The

construction of buildings and structures in accordance with the

provisions of this code shall result in a system that provides a

complete load path that meets all requirements for the transfer of

all loads from their point of origin through the load-resisting elements

to the foundation. Buildings and structures constructed as

prescribed by this code are deemed to comply with the requirements

of this section.


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## Architect1281 (Mar 15, 2012)

Mark thanks for the suggestion worked wonders

However the long term effect was the above post was entered prematurly - meant to refer to the construction depicted as JUST DEAD or Mostly Dead


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## JBI (Mar 15, 2012)

If you want to question anything about the install, it would be reasonable to ask about the additional dead load on the main floor joists.

The code desn't specifically address the bedding requirements for ceramic floor tile, does that mean it can't be used?

Ben has provided the calculations that would be appropriate to make a determination, and clearly there is no issue viewing these as 'ceiling joists' based on span and load - and his factor of safety was very high in this instance. Had they put the 2x4s on edge, there is still no mechanism in the Code to rate them for span. The span tables start at 2x6. And again, the span tables are for joists and rafters not soffits.

If the project looks like mark handler's photo, I'd say much ado about nothing.


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## Mule (Mar 15, 2012)

darcar said:
			
		

> framing members lying flat for a drop soffit framing?


I don't quite understand what you are describing. The key word soffit leads me to believe that this is the exterior of the building. And you have rafter tails that the framer is nailing to and then the 2X's go back into the exterior portion of the wall. Am I on the right track?


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## JBI (Mar 15, 2012)

And lest we forget... I'm the guy that turned 'attic stairs' into a 500+ long thread here a while back.


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## JBI (Mar 15, 2012)

Mule - See photo above in Mark Handler's post.


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## Mule (Mar 15, 2012)

For some reason the photo didn't load the first time I read the thread.... Thanks.

We treat them like ceiling joists as far as loading because they are supporting sheetrock. We also look at if they are nailed or screwed. If just nailed I would think that the weight would tend to pull the nails downward.


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## brudgers (Mar 15, 2012)

Mule said:
			
		

> For some reason the photo didn't load the first time I read the thread.... Thanks.  We treat them like ceiling joists as far as loading because they are supporting sheetrock. We also look at if they are nailed or screwed. If just nailed I would think that the weight would tend to pull the nails downward.


  If you treat them like ceiling joists, do you treat vertical furring as studs?


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## Mule (Mar 15, 2012)

Anything over four feet we consider a joist.


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## Pcinspector1 (Mar 15, 2012)

Mark's #14 post is what I see in the field around duct work.

The 4ft rule is good, after 6ft I would consider the use of a hanger or other support?

pc1


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## brudgers (Mar 15, 2012)

Mule said:
			
		

> Anything over four feet we consider a joist.


  Anything over four legs, Abe Lincoln considered a tail...


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## Mule (Mar 15, 2012)

brudgers said:
			
		

> Anything over four legs, Abe Lincoln considered a tail...


Huh???? Never heard that before!    Usually I can follow your humor but you lost me on this one! It was humor wasn't it?


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## Mule (Mar 15, 2012)

Okay I had to google it! You are VERY old!!!!


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## Architect1281 (Mar 15, 2012)

Not old just paid attention in school Yeah Brugers!


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## Big Mac (Mar 15, 2012)

Was that a one-room or two-room school house?


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## brudgers (Mar 15, 2012)

Big Mac said:
			
		

> Was that a one-room or two-room school house?


  It was the one where you arrived on the short bus.


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## Big Mac (Mar 15, 2012)

Sorry brudgers, you must have me confused with someone else.  They didn't have buses when I was in school.  We had to walk to and from school.  Uphill.  Both ways.  For miles.  That was even before buckboards.


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## brudgers (Mar 15, 2012)

Big Mac said:
			
		

> Sorry brudgers, you must have me confused with someone else.  They didn't have buses when I was in school.  We had to walk to and from school.  Uphill.  Both ways.  For miles.  That was even before buckboards.


  I meant "where one arrived in a short bus."  So yes I had "you" confused with "I."

  The length of the  bus, however, was correct.


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