Garage Drywall Inspecting

OK so in a finished garage. All walls, ceilings finished and painted, how can you determine if the drywall id Fire Rated ? How do you report this?

Jim :cool:

Remove a few switch and light covers and you should be able to see if it is 5/8 then it is rated

Not necessarily,

The 5/8-inch, “fire-code” drywall (called Type X) increases a wall’s fire rating to a minimum of 1 hour, from the 30-minute rating for standard ½-inch drywall.
And it’s not just thickness that makes the difference. Type X has a denser core and contains glass fibers that keep it from crumbling in the heat. But because Type X is slightly more expensive—about 75 cents more per sheet—it’s rarely used in residential construction except where the building code requires it—on
walls separating an attached garage from the house, and around the boiler in multiple-family dwellings. If you’re willing to shell out the extra dough, you certainly could use Type X throughout a house, yet it won’t necessarily be safer.

Building codes typically call for the use of fire resistant drywall as firewalls in furnace or utility rooms, attached garages, and ceilings and walls that separate units in condominiums and apartment buildings. Because fire ratings depend on the complete installation, i.e., wallboard, studs, nailing pattern, etc, they are based on the assembly configuration.

The IRC code requires 1/2" rock on the garage side of the garage walls and any supporting structure (steel posts, stud walls, etc). If there is habitable space above the garage then 5/8" is required on the ceiling and any horizontal members such as steel beams. A lot of people spec 5/8" on the walls but the code does not require it.

Design No. U317

August 02, 2010

Bearing Wall Rating — 45 Min.

Finish Rating — See Item 3.

Load Restricted for Canadian Applications — See Guide BXUV7](

  1. Nailheads — Exposed or covered with joint compound.
  2. Joints — Exposed joints covered with joint compound and paper tape. Joint compound and paper tape may be omitted when square edge boards are used. As an alternate, nom 3/32 in. thick gypsum veneer plaster may be applied to the entire surface of Classified veneer baseboard with the joints reinforced with paper tape.
  3. Gypsum Board* 1/2 in. thick wallboard, paper or vinyl surfaced with beveled, square, or tapered edges. Wallboard nailed 7 in. OC with 5d cement coated nails 1-5/8 in. long, 0.086 in. shank diam and 15/64 in. diam heads. When used in widths of other than 48 in., wallboard is to be installed horizontally.

CERTAINTEED GYPSUM INC — Type SF3 (finish rating 15 min) or Type FRPC or ProRoc Type C.

Here is a link to Fire Rated Wood Floor/Ceiling and Wall Assemblies for LP I Joists for your information.
Might come in handy at one point.;_ylu=X3oDMTE1cWVwcjU0BHNlYwNzcgRwb3MDMQRjb2xvA2FjMgR2dGlkA1NNRTAyMl8xNTc-/SIG=14fit3qv2/EXP=1298266790/**http%3A//


The only way to tell for sure is to read the print on the back of each sheet (like from the attic side) If you cant see it, you can’t claim it.

That was my main question. I know all about where and when it is supposed to be used, my question is when you cannot see it. Like the ceilings are all finished, and the drywaller did a good job, so no gaps on the sides of any switch or receptacles and all the backsides are finished. So basically no way to determine what do you say?

Measure the jamb width of the door opening, at least you will be able to tell is it is 5/8" on one side or 1/2".
Remember that the standard frame comes for 3-1/2" studs with 1/2" on both sides or for a 5-1/2" with the same. 5/8" drywall, you would have to add a jamb extension.

Hope this helps. :slight_smile:

If you can’t see it you can’t report it.

Since there is no way to verify this fire separation issue I would not attempt it. Residential construction fire seperation rules with regard to garages have been changed repeatedly and AHJ’s have adopted and dropped these regulations over the years to the point of no coherent sensibility. With respect Marcel I would never advise anyone to try to gauge wall thickness. Any method used has a significant margin of error unless the reverse side is exposed to view or an opening is available where a measurement can be made. Not that big an issue unless a bedroom is directly adjacent to an attached garage.

The only place that I can think of that would give you a good measurement would be at the bottom of the wall. Typically there is a 6 inch curb around the garage floor and the drywall should be run past the bottom sill.