Complete Guide to Drywall Sizes and Thickness

A typical residential home may have several different types of drywall throughout it depending on location (bathroom, garage, etc.), and varying in size and thickness. This article is designed to help you select the appropriate size, thickness, and type of drywall or cement board that you’ll need, whatever your specific project may be.

Drywall Size/thickness

Drywall typically comes in four different thicknesses: ¼”, ⅜”, ½”, and ⅝”.

½” is by far the most standard size, and is probably what 90% of your home’s walls are constructed with.

⅜” is also a common size, but ½” has really taken over as the accepted industry standard. ⅜” is more commonly used nowadays for repair purposes.

The thicker ⅝” drywall is the standard for ceilings. You don’t want to use ½” or ⅜” for ceilings, as over time it will sag downwards in between rafters. Also, ⅝” is the standard thickness for fire-resistant or fire-code drywall, commonly found in garages.

¼” drywall is relatively uncommon, and can be used for repairs or for curved areas, where you can double up two sheets to make a standard ½” sheet.

As far as lengths, the standard sheet size is 4’ x 8’. This is what will be most commonly used for residential home construction or remodeling purposes. Smaller sheets are also available for patches or repair purposes, and larger sheets (4’ x 12’) are typically available as well at most big box hardware and home improvement stores.

Very large sheets of drywall are produced as well, for commercial or industrial purposes, but are typically only available to private contracting companies.

When determining how much drywall you’ll need for your project, make an effort to use as big a sheet as possible - any seams will have to be taped and made flush with joint compound, so the fewer seams you can get away with, the better.

Also, another thing to consider is weight. Drywall is heavy and can be very awkward to lift and hold in place, even if you’ve got helpers with you. For reference, a standard ½” 4’ x 8’ sheet weighs in at just over 50 lbs.

Types of drywall/cement board

Now that you’ve got an idea of the different sizes of drywall and their various uses, you’ll need to know which specific type of drywall you’ll need for your project.

There are essentially four different types available: regular, mold-resistant, moisture-resistant, and fire-resistant.

For general use (i.e. non-kitchen or bathroom), you can get away with using regular drywall. The core of regular drywall is made of gypsum, sandwiched between layers of paper. Both the gypsum and the paper are organic materials that are prone to the growth of mold and other living organisms.

Mold-resistant drywall uses paperless backing to inhibit the growth of living organisms. For general purposes such as bedrooms, hallways, and living and dining rooms, mold-resistant drywall is recommended over regular drywall. The only downside is that it’s a bit pricier.

For ‘wet’ areas such as kitchens or bathrooms, do not use regular or mold-resistant drywall - it will rot out over time due to moisture. For these areas, moisture-resistant cement board such as HardieBacker has become the industry standard and is by far the best choice. Like drywall, the most common size for cement board is also ½”, but it is also available in ¼”, ⅜”, and ⅝”.

A moisture-resistant drywall, or ‘greenboard’ used to be commonly used for wet areas, but has virtually been replaced by the far superior cement board.

Fire-resistant drywall is generally used in commercial or industrial locations such as apartments, office buildings, or schools, where fire-rating requirements have to be met. Also, ⅝” thick fire-resistant drywall can be used to help minimize the transfer of sound between walls, although specific sound-reducing drywall has recently been introduced to the market.