OSB and drywall boards are some of the most popular soundproofing materials on the market. They’re both easy to install and will help to shut out the external noises in the home, but which of the two makes the best soundproofing option?
Drywall is a better solution for soundproofing than OSB. Both materials have similar STC ratings and will require double layering to cancel external noise. The key advantage of drywall is the cost. Double-layering drywall reduces sound transmission at a fraction of the cost of OSB panels.
There’s one key aspect of soundproofing that needs to be considered, though and that’s the Sound Transmission Coefficient (or STC) rating of each material. This is basically a measure of the reduction of sound passing through the wall.
1/2″ drywall adds an SCT rating of +3 and 7/16″ OSB offers a rating of +4. So, technically, OSB offers a slightly higher soundproofing but that slight advantage is dissipated by the increased cost.
At the time of this writing, 1/2″ drywall at Home Depot runs about $8-$10 per sheet. 7/16″ OSB is averaging $28 per sheet (check current prices – link to Home Depot).
Now, these prices can fluctuate but as a rule, drywall is going to cost less and that’s a big factor when compared to a relatively small and arguably insignificant difference in STC ratings.
The rest of the article will examine each of these materials in detail and explore their merits and shortcomings.
OSB: A Basic Overview
Short for oriented strand boards, OSB is an engineered wood product made of sheets of compressed wood strands joined with resin and glue.
Dry wood strands are mixed with glue and wax to form thick sheets pressed under high heat. The strands are placed as alternating layers running parallel to give OSB exceptional strength and stability.
The board derives its name from the alternating orientation of the wood strands before they are hot-pressed. The arrangement marks the difference between OSB and the weaker waferboard, which comprises random, homogenous composition.
OSB follows the same manufacturing process as waferboard, but its structure mimics that of plywood. OSB is engineered as an alternative to plywood down to the stiffness and the strength.
These boards have a unique look because they lack a top veneer, and therefore, the small pieces of wood that make up the sheets are visible.
Oriented strand boards come in various sizes ranging from ¼ inches (6mm) to ¾-inch (18.5 mm). The strands are made from fast-maturing, resinous trees, making the end-product eco-friendly.
Interior OSB panels use eco-friendly phenol-formaldehyde and methyl diphenyl diisocyanate as binders. The use of resin makes OSB panels strong, durable, and water-resistant.
Pros of OSB Panels
- OSB panels are solid: Depending on its size, an OSB board can be up to 50 strands thick, which increases its structural strength. The layering makes the boards stiff and increases their load-bearing capacity. Since they are made of small pieces of wood strands, OSB boards are an engineering marvel without soft spots on their surface.
- Available in larger sizes: OSB is made from smaller pieces of wood formed into strands and can be formed into large sheets. Some standard boards measure 8 x 16 feet (2.4 x 4.9 meters), but some can be 24 feet (7.3 meters) in length. Most OSB plants can adjust and make longer boards if necessary because tree sizes do not restrict them.
- Hardy and durable: OSB sheets are manufactured as huge continuous mats, forming an engineered product with no gaps, voids, or laps. The panels resist delamination, deflection, and warping. When used in demanding industrial applications, OSB boards resist shape distortion and racking.
- Eco-friendly: OSB is made from small fast-maturing resinous trees such as poplar, aspen, and southern yellow pine. Most of these trees are farm-raised, lowering the demand for mature wood. The manufacturing process uses up almost the entire tree generating minimal waste.
- Consistent: OSB creates solid and dense panels with a uniform thickness. Similar sized wood strands are mixed with adhesives and wax and compressed under high pressure, up to 1,100 pounds per square inch, to form OSB panels. Some boards have as many as 50 layers of strands, giving them a hefty and solid wood density.
- Good shear strength: While OSB is comparable to plywood in many ways, it outdoes it when it comes to shear strength. OSB shear values are up to two times greater than in plywood, making it the perfect choice for the web of wooden I-joists. It also has excellent nail holding capacity and won’t chip when nailing the edges.
- Versatile: OSB has a broad range of applications, including interior and exterior wall sheathing, roof sheathing, subfloors and underlayment, and furniture making. Manufacturers can reconfigure their production process to create a formulation to suit various budgets, climates, and usage.
- Affordable: Despite its excellent quality, large size, and density, OSB is cheaper than its greatest rival, plywood. OSB panels are between $3 to $5 less expensive than plywood, which translates to a $700 savings on a typical 2,400-square-foot (223-square-meter) home that uses it for sheathing, subflooring, and roof decking.
Cons of OSB Panels
- Heavy: OSB panels are considerably denser than most other engineered wood, such as plywood. OSB is 15% to 20% heavier than similar-sized plywood, making it much more difficult to handle during transportation and installation.
- Low moisture tolerance: Whole OSB panels are remarkably water-resistant and absorb moisture slowly. Unfortunately, they are slow to release the water and, therefore, take longer to dry. Cutting the pieces creates new edges that are vulnerable to moisture and can swell up to 15% of their original size.
Drywall: A Basic Overview
Drywall panels are made of gypsum (calcium sulfate dihydrate) sandwiched between two sheets of thick paper. Drywall is also known as gypsum, plasterboards, wallboards, or gypsum plaster. It’s the standard building material for ceiling and wall surfaces.
Drywall was invented by Augustine Sackett at the turn of the 19th century and quickly overtook plaster and lath as the choice building material for walls and ceilings. Drywall came in modular sheets that allowed the contractors to install and finish them in record time.
A drywall panel comprises a gypsum core wrapped with several layers of facer and backer papers. During production, a dense slurry of liquid gypsum is transferred to continuous paper sheets. Aerated gypsum layer comes next, followed by another layer of thick gypsum slurry covered by more paper sheets.
The gypsum filled sheets are compressed into panels with a uniform thickness and a taper that runs lengthwise before they’re cut into various sizes. A gypsum board’s front side uses a white face paper and a light brown back paper.
Drywall panels are often 4-foot (1.2-meter) wide but can range from 8 to 16 feet (2.4 to 4.9 m) in length. The thickness varies from ¼-inch (6 mm), ½-inch (12 mm), 3/8-inch (9mm), to 5/8-inch (15mm), but the ½-inch (12 mm) boards are used in house walls and ceilings.
There are four types of drywall:
- Regular drywall
- Mold resistant drywall
- Moisture resistant drywall
- Type X or fire-resistant drywall.
Pros of Drywall
- Fire-resistant: Drywall comprises gypsum, a non-flammable mineral, bound between sheets of paper. In crystalline form, gypsum contains a large amount of water despite the individual molecules being dry. When the drywall is heated, the water in the crystals starts to vaporize on reaching its boiling point. The resultant water cools the drywall and limits the spread of fire.
- Easy installation: Drywall comes in similar-sized panels and is easy to install with the right equipment. Since you only require a good drywall screw gun to install drywall, it’s a popular choice among DIY enthusiasts. However, it takes a bit of skill to tape and seal all the joints that result.
- Drywall provides soundproofing and temperature insulation: While a standard drywall panel can muffle sound, its rigid nature allows sound waves to pass through it. However, the drywall cost is low enough to allow you to double layer the panels without incurring a fortune in costs. That’s what makes drywall a choice soundproofing and insulation material.
- Cheap and affordable: The average price of a 4 x 8 (1.2 x 2.4 m) feet drywall panel is about $11 at the time of this writing. However, the cost depends on the types, as the thicker, soundproofing drywalls cost up to $60 a sheet.
- Drywall is available in various sizes: While the standard drywall sheets are 4-foot (1.2-meter) wide, they can be 8 to 16-feet (1.2 to 4.8 m) in length. That allows you to pick the most suitable drywall panel sizes when soundproofing large wall surfaces.
- Drywall doesn’t require finishing: Each drywall panel comes with a white front face that doesn’t require additional finishing. You can leave the walls unpainted to save on costs, or you can paint them any color you wish.
- Structural strength: The gypsum core creates a robust and stiff board that can support shelves and frames without buckling or breaking. Since drywall is softer than solid wood, it’s easier to drill and install shelves and cabinets.
- Easy to repair: You can cut out a damaged portion of drywall with a regular saw and glue a fresh piece in its place. A simple paint job will disguise the joint and keep your soundproofing intact.
Cons of Drywall
- Delicate and easily damaged: Drywall buckles under impact and is easily pierced by the everyday sharp objects in the home. Joints tend to crack, and the tapes come off, especially when improperly installed.
- Drywall is not water and moisture resistant: Drywall is highly susceptible to water damage and mold infestation. It cannot be installed in high moisture areas such as bathrooms or basements.
- Drywall is heavy: The standard 4 x 8 feet, ½-inch (1.2 x 2.4 m, 12mm) thick drywall panel weighs more than 50 pounds (22 kg). You’ll often require a drywall jack to install drywall on the ceiling.
Which One Should You Choose?
Ideally, the choice between OSB and drywall for soundproofing boils down to your budget. Both materials have similar soundproofing qualities and require double layering.
If you’re working on a tight budget, opt for the more cost-effective drywall. If your budget allows, opt for the more durable OSB boards.
Typically, OSB and drywall boards have almost similar soundproofing capacities, but OSB is a more superior engineered wood product. It’s made from small chips of wood that are compacted into dense, thick boards.
Drywall is made of a gypsum core that’s bound by sheets of paper, giving it a smooth white face. It’s highly delicate and susceptible to water damage, but it’s highly affordable.
Therefore, the choice boils down to your budget and preference. If your budget allows, you can choose the slightly better, more durable OSB panels. If on a budget, the more affordable drywall will serve you well. It’s also arguably more aesthetic. In the end, though, the sound damping ratings between these two are negligible.