Garage/habitable room separation

[Sifu]

This may seem a little elementary but I have never had to deal with this before. I found a builder installing 1/2" regular drywall between a garage and a habitable room above, where 5/8" type X is required. I am looking to see if anyone has an opinion as to if there is an equivalent, for example adding another layer of 1/2" regular or if the only way to go is to require the 5/8" type X. The requirement is not a rated assembly, just a panel. My guess is go the 5/8" but if there is an alternative I would like to know.

 

[steveray]

I know the newer I codes reduced it to 1/2".....we are still 5/8" here.......and it would most likely be the walls and ceiling.....

 

[brudgers]

My personal opinion is that requiring 5/8" Type 'X' on a single family building site is asinine. And the fact that 13D sprinklers provide only 10-15 minutes of life-safety protection, only makes it moreso.

 

[imhotep]

This may seem a little elementary but I have never had to deal with this before. I found a builder installing 1/2" regular drywall between a garage and a habitable room above, where 5/8" type X is required. I am looking to see if anyone has an opinion as to if there is an equivalent, for example adding another layer of 1/2" regular or if the only way to go is to require the 5/8" type X. The requirement is not a rated assembly, just a panel. My guess is go the 5/8" but if there is an alternative I would like to know.

2009 IRC

Requirement is for not less than 5⁄8-inch Type X gypsum board or equivalent.

TABLE 721.6.2(1) gives 5/8" Type X a time of 40 minutes. It also gives Double 1/2-inch gypsum wallboard 40 minutes. Lots of footnotes to deal with in terms of edge support and framing spacing.

 

[rogerpa]

The requirement for 1/2" gypsum on the garage ceiling with habitable space above only lasted 1 cycle (2000). The requirement for 5/8" type X gypsum was added in the 2003 IRC (R309.2).

 

[Sifu]

Thank you imhotep, that is the equivalency I was looking for. My old jurisdiction only required 1/2", this newly created jurisdiction requires 5/8". I have just started to enforce codes in this new jurisdiction and have never actually caught anyone doing less than code since my old jurisdiction was only 1/2". The way I read IBC Table 721.6.2(1) double 1/2" is acceptable if on 16" center, edge supported, perpendicular and finished. Excellent!

 

[SCBO1]

If you apply another layer of 1/2" drywall, direction, fastener length and fastener spacing should be checked as well as ceiling joist span having additional DL.

pc1

 

[mtlogcabin]

The way I read IBC Table 721.6.2(1) double 1/2" is acceptable if on 16" center, edge supported, perpendicular and finished

Maybe however you may want to tighten up the screw pattern so the assembly would be equvilant to the IRC requirements for Type X 5/8" gypsum board

TABLE R702.3.5

MINIMUM THICKNESS AND APPLICATION OF GYPSUM BOARD

footnote

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.

 

[TJacobs]

I'd allow a layer of 3/8" or 1/2" over the 1/2" they have already installed, all joints staggered. Tell the builder they used their mulligan...

 

[steveray]

Roger...didn't it go back to 1/2" in 06 or 09? I thought I saw that?....as my signature suggests, we are on some form of 03.....

The requirement for 1/2" gypsum on the garage ceiling with habitable space above only lasted 1 cycle (2000). The requirement for 5/8" type X gypsum was added in the 2003 IRC (R309.2).

 

[Codegeek]

2012 says 5/8 inch Type X on garage ceiling with habitable room above, otherwise it's 1/2 inch.

 

[steveray]

Thanks CG....I knew there was something different, but I hardly have time to keep up with my stuff....nevermind the stuff we mayor may not adopt....we were told last week I think by the State that we will be switching to our amended 2009 IECC on Friday......nothing like a heads up!!!

 

[Sifu]

I caught this guy on his third house under the newly adopted codes. I assumed ( yea, I know what assume spells) everyone knew the requirements, in fact the next door jurisdiction had a pretty big law suit over just this issue some years back before I moved here. This guy knew he had to do it there but figured for some mysterious reason he didn't need to do it if there were no inspections. Usually the board is stocked at the insulation inspection where I can at least see it on site but some area inspectors will fail these guys if the board is in the house for the insulation inspection (not me) so sometimes it isn't there. The reason I looked for an equivalent was to go back and bring the first two houses into compliance since they are almost at final stage. His mulligan was definately used! When asked by another builder early on about how I would verify 5/8" type X I told them it was sometimes difficult without additional inspections but that unless I had reason to suspect non-compliance in the area it wasn't too big a concern. Well, now I suspect! I will be looking a little harder at others to make sure there aren't more doing the same thing.

 

[mtlogcabin]

Usually the board is stocked at the insulation inspection where I can at least see it on site but some area inspectors will fail these guys if the board is in the house for the insulation inspection

That is crazy. For what reason and what code section would apply? I have worked highrises where the drywall is stocked before the walls are built

 

[Sifu]

No idea. If the builders are telling the truth, some have been turned down and told to remove the board. I have heard some crazy stuff since I came here. Mostly stuff that demonstrates that some of the inspectors have never been builders or maybe even ever worked in the industry before. Kind of like some of the code writers???? Of course as a former GC I do take what I am told by the builders with some healthy skepticism. However, it wouldn't be a total suprise to find out that a builder was somehow trying to conceal some defects with stocked board either. One thing I learned long ago, you have never, never seen it all!

 

[rogerpa]

The requirement for 5/8" type X or equivalent (when habitable rooms above) has not changed since it was added in '03. Don't forget that habitable space above also triggers the requirement that "Where the separation is a floor-ceiling assembly, the structure supporting the separation shall also be protected by not less than 1/2-inch (12.7 mm) gypsum board or equivalent."

Gypsum (1/2" min.) is only required on the garage ceiling if (when) the the 1/2" gypsum (or equivalent) on the common wall does not extend to the under side of the roof sheathing.

2009 added "Garages located less than 3 feet (914 mm) from a dwelling unit on the same lot shall be protected with not less than 1/2-inch (12.7 mm) gypsum board applied to the interior side of exterior walls that are within this area. Openings in these walls shall be regulated by Section R309.1. This provision does not apply to garage walls that are perpendicular to the adjacent dwelling unit wall."

In the 2012 IRC these requirements have been moved to Table R 302.6, but remain unchanged. A new twist in '12 is the requirement for sprinklers in some private garages.

You can find "equivalent" assemblies in GA-600.

 

[steveray]

I gues I did not clarify...in CT it is 5/8" seperation everywhere, no 1/2"...