Garage wall shared w/ house question on fire barrier/wall

[kevmor99]

I posted this earlier but it was deleted when some topics got erased. Anyway, I think I know the answer but I just wanted to confirm:

Are there any restrictions on placing a new electrical outlet on the wall shared between an attached garage and the house? I started reading (IBC 711.3.2) that states that electrical outlets need to be 24" apart, max 16 square inches of openings for 100 sq inch area, etc. but this doesn't apply to residential garages, correct?

I think I misinterpreted the wall as a "firewall" or fire barrier when that term is actually used for defining a wall between separate multi-family dwelling units, hotels, etc.

Here's IBC 711.3.2 for reference:

IBC 711.3.2:

1. Steel boxes that do not exceed 16 square inches (4” x 4”) may be installed provided the total area of openings does not exceed 100 square inches for any 100 square feet of wall area.

2. Boxes on opposite sides of a wall shall be separated as follows:

a. By a horizontal distance of not less than 24”.

b. By a horizontal distance not less than the depth of the wall cavity where the wall cavity is filled with cellulose loose-fill or mineral fiber insulation. (Not standard fiberglass insulation)

c. By solid fire-blocking complying with section 716.2.1. (Not practical for back to back boxes)

d. By other listed materials and methods. (This would include fire stop pads inside boxes or outside that covered all 5 exposed sides)

3. Listed box assemblies that have been tested for use in fire rated assemblies can be used in accordance with their listing and instructions.

 

[BillK]

I think I misinterpreted the wall as a "firewall" or fire barrier

You did not misinterpret it at all. That wall is most definitely a fire wall. Not sure what that means in terms of putting outlets in it and running wire. I am sure an electrician will educate us shortly

 

[AntonLargiader]

There has always been confusion about the garage wall requirements, and most of what I have read mirrors this article:

https://www.buellinspections.com/myths-fire-rated-walls-doors-house-garage/

That said, if the receptacle placement is going to be a weak area in the wall assembly then do something different, but I don't see it as being the weakness if the rest of the wall is only 20-minute rated at best.

 

[larry4406]

On our new construction homes, we have outlets and switches on the wall common with the garage/house with outlets/switches on both sides of the wall. Garage side is hung with 5/8 Type-X drywall while interior side is normal 1/2" drywall.

Right or wrong, issue never comes up during inspections.

 

[Zeke]

You have entered a gray area in the NEC. There is some more info on the UL site but residential (SFR) is included in these rules.

 

[TRWham]

On our new construction homes, we have outlets and switches on the wall common with the garage/house with outlets/switches on both sides of the wall. Garage side is hung with 5/8 Type-X drywall while interior side is normal 1/2" drywall.

Right or wrong, issue never comes up during inspections.

Even the type X is probably unnecessary, but we do the same thing. The only place that becomes an issue in most single family residential applications is the ceiling of a garage if the space above is habitable. We have also been asked to add a layer to a pull down attic stair in a garage that was otherwise 1/2" drywall ceiling, but they didn't really care what that additional layer was- even 1/4" plywood would have been enough, but we used 1/2" drywall. That same project had an elevator, but there were no special requirements for the hoistway (e.g. shaftliner) as far as fire code was concerned.

 

[Baydog]

A simple solution in a fire code wall is to make sure any box for receptacles and switches are not in the same stud bay as a box on the other side. That way the fire rated barrier is maintained. You'll likely also need to fire-caulk any holes made in the sill and top plate for running wires.