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OSB Versus Sheetrock In A Garage: Pro, Cons, And Fire Code


OSB or sheetrock in a garage?

A common debate is whether to use OSB or sheetrock in a garage. With the exception of some fire rating necessities, it really boils down to personal preference. 

Both OSB and Sheetrock can be used to cover the walls in a garage. Fire-Rated OSB and sheetrock each meet the fire code requirements for attached and unattached garage spaces. Beyond this, it is highly a matter of personal taste.

Garages can be attached to the house or can be detached buildings separated from the living area.

Let’s take a look at the materials and their advantages and disadvantages in garage use so you can make an informed decision. 

What are OSB and Sheetrock?

OSB and sheetrock are two very different products with various applications. Although both can be used to cover garage walls, their different properties may help you determine the right choice for your space. 

OSB: 

OSB, or oriented strand board,  is made from strands of low-density hardwoods and softwoods pressed together. Chemicals such as Phenol-formaldehyde and methylene–diphenyl-isocyanate (MDI) resins are used to bind the strands, and a petroleum-based wax is used as an additive to provide temporary water resistance (source). 

OSB is available in several thicknesses and grades. The grades are based on their mechanical performance and moisture resistance. OSB/0-2 is designed for dry conditions, while OSB/3-4 are load-bearing boards used for humid conditions.

Sheetrock: 

Sheetrock, also called drywall, is composed of gypsum core sandwiched between 2 heavy paper faces. One face is smooth and is considered the finish surface, while the other is the backing face. 

Drywall is sold in many sizes and thicknesses, but the typical drywall board is 4x8 feet board and 1/2 inch thick. A 5/8 inch thickness will provide more sound control and a 1-hour fire rating, which is code for some garage wall applications. 

What are the Code Requirements for Garage Walls?

The biggest factor to determine what product you can use on the walls of your garage is the fire code requirements of garage walls. The International Residential Code (IRC) has specific codes depending on the location of the garage and the wall you are covering.

Garages are full of flammable material. Oil and gas can leak from vehicles; Flammable liquids such as oils, gas, paints, and thinners are often stored in garages. In addition, heaters, boilers, and electrical panels are commonly located in garages, all of which pose fire risks. 

Needless to say, making sure your home is safely protected from the various potential fire hazards in the garage is not a bad idea.

The 2012 IRC calls for 1/2 inch gypsum board (sheetrock) between the garage and attic space and support walls that are attached to the dwelling. These must be fully taped and sealed and reach from rim joist to roof (source). 

If there is a finished room above the garage, it should be separated with a 5/8 inch, 1-hour fire-rated gypsum board. Even detached garages situated within 5 feet of the house must have 1-hour fire-rated material on the interior of all walls that are facing the dwelling. 

One other code requirement related to garage wall covering is the energy efficiency code that requires the building’s thermal envelope (basically all exterior walls) to be insulated to limit air leakage, or infiltration (source).

See Make A Garage Energy Efficient: Improve Comfort, Pest Control.

Air sealing between the garage and living quarters is also required for protection against dangerous gases, such as carbon monoxide, and for energy savings. These insulation codes would necessitate some sort of covering to protect the insulation and provide a tighter seal. 

All of these codes may make it seem like only sheetrock can be used in a garage, but really the fire-rating codes only apply to certain walls. You could potentially use different materials on the walls not adjacent to the dwelling.

Plus, there is a fire-rated OSB on the market. 

What is Fire-Rated OSB?

Fire Rated OSB, such as LP FlameBlock sheathing, is comprised of 2 parts. One is the typical OSB layer, comprised of strands of wood products resined together.

The other part is a non-combustible, fiberglass-reinforced Pyrotite treatment that makes the product meet fire code. It can withstand flame spread and burn-through for 1-2 hours, depending on the product. 

LP FlameBlock is considerably more expensive than either sheetrock or regular OSB, but if you want the benefits of OSB with the code adherence of drywall, it is a viable option.

Watch this short video demonstration of how fast a home can be engulfed in flames using traditional construction materials compared to Fireblock OSB.

LP® FlameBlock® Fire-Rated OSB Sheathing Live Test

Let’s look at the general pros and cons of OSB vs. sheetrock to learn more. 

OSB vs. Sheetrock: A Comprehensive Comparison

OSB and sheetrock both offer some advantages and disadvantages as wall covering in your garage space. Insulating and then sheathing your garage walls with either material can provide a more comfortable environment.

OSB vs sheetrock pros and cons of each.

Advantages

OSB

  • Lighter than sheetrock
  • Easy to hang and attach to walls with only a few screws
  • Cleans easily and hides dust
  • Tough material that resists damage from garage activity
  • Can attach shelves, hooks, and other fasteners anywhere on the surface
  • Regular OSB is roughly half the cost of sheetrock
  • Easy to remove to access wiring, etc. behind the wall
  • Slightly more resistant to moisture

Sheetrock

  • Non-combustible material provides good fire protection
  • Easy to cut with sharp knife
  • Easy to paint for a finished look
  • Fire-rated sheetrock is considerably cheaper than fire-rated OSB
  • Slightly better sound barrier than OSB

Disadvantages

OSB

  • Can swell and shed wafers over time if not sealed and painted for water protection
  • Looks less “finished” with its textured surface
  • Harder to paint—must apply primer and multiple coats of paint to cover fully
  • Must purchase expensive Fire-Rated OSB to meet code requirements

Sheetrock

  • Difficult to hang, tape, and mud
  • Heavier to handle than OSB
  • Can’t hang things anywhere—must plan extra blocks or anchors for shelving, hooks, etc. 
  • Accessing behind panel damages drywall and must be patched to repair
  • Susceptible to mold, rot, and water damage

In the end, the material you choose really comes down to the preferences you have for the garage space. If you want a finished look in your attached garage for a reasonable price, sheetrock may be the way to go.

However, if you are using your attached or detached garage for woodworking, repair work, and other heavy duty shop activities, OSB (fire-rated as necessary) is probably the better option. It can withstand more abuse and offers endless opportunities to attach things to the walls.

Moisture is another issue and OSB does get the edge here but only slightly. Neither of these materials are really designed for high moisture situations.

There are moisture-resistant varieties of each and those may be worth looking at. I ended up installing a dehumidifier in my garage to offset condensation and moisture issues.

Effect On Home Value

Before leaving this discussion, one more important consideration must be reviewed. The finish material of your garage can actually affect your home value. 

Although a finished garage—one with insulation, covered and painted walls, lighting, air conditioning, flooring material, etc.—doesn’t really add much value to a home appraisal, it can affect the way potential buyers perceive your home. 

A study found that 85% of buyers want garage space, and when that space is nicely finished, it adds curb appeal by making the garage stand out from the typical dingy, cluttered space (source). 

If you want to create a better impression on potential buyers, go with sheetrock. It looks more polished and can be painted to look like any other room in the home.

Along with a thorough cleaning and organizing of the garage, you may be able to add some “subjective value” to your home.

Conclusion

How you plan to use the space should mostly determine which product you decide to use. OSB is tougher and easier to hang, while sheetrock is easier to paint and looks neater.

Fire-Rated OSB offers a great alternative to sheetrock, yet for a higher price tag. Regardless of which product you decide to use, your garage will be more comfortable and usable with finished walls.

Just don’t forget the potential value bump for a nicely finished garage when selling. Sheetrock gets a little edge in this regard.

Paul

As a homeowner, I am constantly experimenting with making the structure of my house more energy-efficient, eliminating pests, and taking on DIY home improvement projects. Over the past two decades, my family has rehabbed houses and contracted new home builds and I've learned a lot along the way. I share my hard-learned lessons so that you can save time and money by not repeating my mistakes.

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