# Drywall, 1/2 or 5/8 on garage separation?



## MASSDRIVER

I have been under the impression the typical fire separation wall in residential construction, single family was 5/8 "firecode" on the garage side.

As a matter of fact, to comply to a resale inspection, I had to rock this certain "illegal" laundry room in a garage, overlaying the existing 1/2" with 5/8", to the sheathing. Requirement by the city inspectigator. Typical in my understanding.

So one street over I do the same thing today, where I had reframed the illegal laundry in the garage, back to the house to comply with mandated off street parking requirement. Inspectigator says I don't have to use 5/8 any longer, been that way since the 2010 residential code that I guess trumps UBC.

So, as can sometimes happen, apparently the right hand knows not the activities of the left.

Can anyone clarify, maybe with the code section to point to?

Kind of a moot point for me as I will probably do it the old way just to spite myself, but just interested in the truth of this conspiracy.

Thanks,

Brent.


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## cda

R302.6 Dwelling/garage fire separation. The garage shall be separated as required by Table R302.6. Openings in garage walls shall comply with Section R302.5. This provision does not apply to garage walls that are perpendicular to the adjacent dwelling unit wall.

TABLE R302.6 DWELLING/GARAGE SEPARATION

SEPARATION

MATERIAL

From the residence and attic	 Not less than 1⁄2-inch gypsum board or equivalent applied to the garage side

From all habitable rooms above the garage	 Not less than 5⁄8-inch Type X gypsum board or equivalent

Structure(s) supporting floor/ceiling assemblies used for separation required by this section	 Not less than 1⁄2-inch gypsum board or equivalent

Garages located less than 3 feet from a dwelling unit on the same lot	 Not less than 1⁄2-inch gypsum board or equivalent applied to the interior side of exterior walls that are within this area

The table does not copy correctly;;;;

http://publicecodes.cyberregs.com/icod/irc/2009/icod_irc_2009_3_par058.htm


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## cda

http://pds.cityofboise.org/media/113372/435_garage_separation_handout.pdf

https://mybuildingpermit.com/Constuction%20Tip%20Sheets/tip%20sheet%2006_09.pdf

http://www.codecheck.com/cc/ccimages/PDFs/CCB3_sample.pdf


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## MASSDRIVER

Thankyouthankyou.  

Brent.


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## mark handler

cda said:
			
		

> R302.6 Dwelling/garage fire separation. The garage shall be separated as required by Table R302.6. Openings in garage walls shall comply with Section R302.5. This provision does not apply to garage walls that are perpendicular to the adjacent dwelling unit wall. TABLE R302.6 DWELLING/GARAGE SEPARATION
> 
> SEPARATION
> 
> MATERIAL
> 
> From the residence and attic	 Not less than 1⁄2-inch gypsum board or equivalent applied to the garage side
> 
> From all habitable rooms above the garage	 Not less than 5⁄8-inch Type X gypsum board or equivalent
> 
> Structure(s) supporting floor/ceiling assemblies used for separation required by this section	 Not less than 1⁄2-inch gypsum board or equivalent
> 
> Garages located less than 3 feet from a dwelling unit on the same lot	 Not less than 1⁄2-inch gypsum board or equivalent applied to the interior side of exterior walls that are within this area
> 
> The table does not copy correctly;;;;
> 
> http://publicecodes.cyberregs.com/icod/irc/2009/icod_irc_2009_3_par058.htm


Residential garage fires comprise about 2 percent of all residential building fires.

http://www.nfpa.org/~/media/Files/Research/NFPA%20reports/Occupancies/oshomes.pdf

It was determined. by the code writers, based on that, we do not need to protect the house from the lower risk, garage

But some jurisdictions, still require 5/8” gyp bd.


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## Pcinspector1

Brent, 1/2" unless the AHJ modifies the table to 5/8 FC.

Could't you get approved with two layers of 1/2" with longer nails or screws? You could stager the joints, you would be a hero!

What about those receptacle box extensions?

Pc1


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## MASSDRIVER

Pcinspector1 said:
			
		

> Brent, 1/2" unless the AHJ modifies the table to 5/8 FC. Could't you get approved with two layers of 1/2" with longer nails or screws? You could stager the joints, you would be a hero!
> 
> What about those receptacle box extensions?
> 
> Pc1


I honestly don't know if 2 layers rate the same as 1 of 5/8. It looks like I'm a retard on fire assemblies in general so I'll brush up on that shortly.

I haven't run into a short box yet, probably just gut a plastic one or put a 1 inch mudring on a metal box if it came to that.

Oh...I'm a hero in general terms. Thought you should know that.

Brent.


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## Builder Bob

two 1/2 inch laers does not equate to 1 layer of 5/8 inch....

TABLE 722.6.2(1) TIME ASSIGNED TO WALLBOARD MEMBRANESa, b, c, d

DESCRIPTION OF FINISH  TIMEe (minutes)

3/8-inch wood structural panel bonded with

exterior glue 5

15/32-inch wood structural panel bonded with

exterior glue 10

19/3 -inch wood structural panel bonded with

exterior glue 15

3/8-inch gypsum wallboard 10

1/2 -inch gypsum wallboard 15

5/8 -inch gypsum wallboard 30

1/2-inch Type X gypsum wallboard 25

5/8-inch Type X gypsum wallboard 40

Double 3/8-inch gypsum wallboard 25

1/2-inch + 3/8-inch gypsum wallboard 35

Double 1/2-inch gypsum wallboard 40


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## mark handler

Builder Bob said:
			
		

> two 1/2 inch laers does not equate to 1 layer of 5/8 inch....TABLE 722.6.2(1) TIME ASSIGNED TO WALLBOARD MEMBRANESa, b, c, d
> 
> DESCRIPTION OF FINISH  TIMEe (minutes)
> 
> 3/8-inch wood structural panel bonded with
> 
> exterior glue 5
> 
> 15/32-inch wood structural panel bonded with
> 
> exterior glue 10
> 
> 19/3 -inch wood structural panel bonded with
> 
> exterior glue 15
> 
> 3/8-inch gypsum wallboard 10
> 
> 1/2 -inch gypsum wallboard 15
> 
> 5/8 -inch gypsum wallboard 30
> 
> 1/2-inch Type X gypsum wallboard 25
> 
> 5/8-inch Type X gypsum wallboard 40
> 
> Double 3/8-inch gypsum wallboard 25
> 
> 1/2-inch + 3/8-inch gypsum wallboard 35
> 
> Double 1/2-inch gypsum wallboard 40


1/2-inch Type X gypsum wallboard 25 *x2* =50

5/8-inch Type X gypsum wallboard 40

50 greater than 40, not equal, Better....


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## steveray

CT still requires the 5/8"


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## Pcinspector1

BB & Mark, good info!

Finding 1/2"FC (type-x) drywall is probably going to be a specialty product from a drywall house and regular 1/2" cost you over $10.00 bucks @ the box store = $20.00.

Cheaper to get the 5/8"FC to get the results you need in minutes. Not to mention it might mess with your window and door frame widths costing you more $$.

"That's what speed do!" Jarod Dyson, KC Royals

pc1


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## JBI

5/8" Type X is the _prescriptive_ provision in most IRC based codes. Those Codes generally still allow for a approved deign for a 3/4 hour rated assembly, and UL has many 1 hour walls with 1/2" GWB on both sides.

Methinks your inspectigator needs to read his Code more thoroughly...


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## MASSDRIVER

Sometimes it makes no sense to fight city hall, and 5/8" is standard issue.

Brent


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## fatboy

"Sometimes it makes no sense to fight city hall, and 5/8" is standard issue."

Bingo, install 5'8", then no questions are asked.

FWIW, we amended the 1/2" to 5/8" when we moved over from the 97 UBC to the 2003 IRC.................


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## MASSDRIVER

What's funny is the walls in question are the easyist to do in whatever rock.

If you want to do me a favor make the ceiling 1/2".

Makes me wonder what the point of downgrading is was. Considering the general freak out associated with fire risk.

Brent.


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## mjesse

MASSDRIVER said:
			
		

> Makes me wonder what the point of downgrading is was. Considering the general freak out associated with fire risk. Brent.





			
				mark handler said:
			
		

> Residential garage fires comprise about 2 percent of all residential building fires.http://www.nfpa.org/~/media/Files/Research/NFPA%20reports/Occupancies/oshomes.pdf
> 
> It was determined. by the code writers, based on that, we do not need to protect the house from the lower risk, garage


But how do the statistics factor the percentage of houses without garages? Fire can't start in a place you don't have!?

Just one of the dangers of allowing statisticians input on Code and Standard development. :wink:


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## Pcinspector1

Mass, Covering the I-beam and post with drywall?

Just keepin yo in line! Inspectigator will be back!

pc1


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## MASSDRIVER

mjesse said:
			
		

> But how do the statistics factor the percentage of houses without garages? Fire can't start in a place you don't have!?Just one of the dangers of allowing statisticians input on Code and Standard development. :wink:


Because if you did you would instantly have no need for Gfci, or arc fault, or half the stuff in the Strong tie catalog.

Brent.


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## mtlogcabin

We see this requirement missed a lot since it is hidden in the wall covering portion of the code

IRC Table R702.3.5 foot note d

e.	Type X gypsum board for garage ceilings beneath habitable rooms shall be installed perpendicular to the ceiling framing and shall be fastened at maximum 6 inches o.c. by minimum 17/8 inches 6d coated nails or equivalent drywall screws.


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