Drywall (gypsum board) comes in a few standard thicknesses and sheet sizes, and the right choice depends on where it goes: walls, ceilings, a garage, a basement or a bathroom. This guide covers the sizes you can buy, which thickness to use where and what the building code requires, and shows how choosing longer sheets cuts the number of joints you have to tape. For sheet, screw and joint compound quantities, use the drywall calculator.
Standard drywall sizes
- Width: 48 in is standard. 54 in sheets are made for 9 ft walls, where two sheets hung horizontally cover the full height with one seam.
- Length: 8, 9, 10, 12, 14 and 16 ft. Home centres stock 8 and 12 ft; longer sheets are a supplier order and need two or three people to hang.
- Thickness: 1/4, 3/8, 1/2 and 5/8 in, described below. Specialty boards (moisture- and mould-resistant, abuse-resistant, sound-damping, lightweight) come in the same sizes.
- Edges: the long edges are tapered so tape and compound can be bedded flush; the cut or factory ends (butt joints) are not, which is why butt joints are harder to finish.
Which thickness to use where
| Thickness | Typical use | Notes |
|---|---|---|
| 1/4 in | Curved walls, covering old plaster or paneling | Flexible; usually doubled on tight curves. Not for new framing on its own. |
| 3/8 in | Overlay and repairs, some partitions | Lighter than 1/2 in; check whether your code allows it on your framing spacing. |
| 1/2 in | Standard for interior walls; ceilings on 16 in framing | The everyday board. Sag-resistant 1/2 in ceiling board is made for 24 in ceiling framing. |
| 5/8 in | Fire-rated (Type X) assemblies, garage ceilings under living space, ceilings on 24 in framing, better sound control | Stiffer and heavier. Type X has a fire-resistant core; plain 5/8 in board is not fire-rated. |
Code requirements that decide the thickness
- Garage to house. The IRC requires at least 1/2 in gypsum board on the garage side of walls and ceilings separating an attached garage from the house, and 5/8 in Type X on the garage ceiling where there is a habitable room above (R302.6). Walls that support that ceiling need 1/2 in board too.
- Under stairs. Enclosed accessible space under stairs must have its walls, soffit and any ceiling covered with at least 1/2 in gypsum board (R302.7).
- Framing and fasteners. IRC Table R702.3.5 sets the maximum framing spacing, orientation and fastener spacing for each thickness. Screws are typically spaced about 12 in apart on ceilings and 16 in on walls; check the table in your code edition or the board maker’s instructions for your framing.
- Showers and tubs. Behind tile in shower and tub areas the IRC calls for cement, fibre-cement, fibre-mat reinforced cementitious or glass-mat gypsum backers (R702.4.2), not ordinary drywall. Moisture-resistant board is for the rest of the bathroom.
Long sheets mean fewer joints
| Room (walls only) | 4 x 8 ft sheets | 4 x 12 ft sheets |
|---|---|---|
| 10 x 12 ft, 8 ft ceiling | 16 sheets, 8 butt joints | 8 sheets, 0 butt joints |
| 12 x 14 ft, 8 ft ceiling | 16 sheets, 8 butt joints | 12 sheets, 4 butt joints |
| 12 x 14 ft, 9 ft ceiling | 16 sheets 54 in wide, 8 butt joints | 12 sheets 54 in wide, 4 butt joints |
| 16 x 20 ft, 8 ft ceiling | 20 sheets, 12 butt joints | 16 sheets, 8 butt joints |
Butt joints are the hard part of taping, because the ends are not tapered and the compound has to be feathered wide to hide the hump. In a 12 x 14 ft room with 8 ft ceilings, 4 x 12 ft sheets need fewer sheets to carry and hang than 4 x 8 ft, and remove the butt joints on the 12 ft walls entirely. The trade-off is weight and handling: a 12 ft sheet of 1/2 in board is half as heavy again as an 8 ft sheet, and it must fit through the door and up the stairs. When butt joints are unavoidable, stagger them so they do not line up on the same stud on neighbouring rows.
Ceilings, basements and garages
- Ceilings: hang ceiling sheets first and perpendicular to the joists. On 24 in framing, or where heavy insulation or water-based texture will load the board, use 5/8 in or a 1/2 in sag-resistant ceiling board.
- Basements: keep the bottom edge about 1/2 in off the concrete floor so it cannot wick water, and consider mould-resistant board. Fix moisture problems in the foundation first; board will not fix them.
- Garages: beyond the fire separation rule above, many owners use 5/8 in throughout for impact resistance. Detached garages have no separation requirement, but check local rules.
- Sound: heavier and thicker board, two layers, and resilient mounting all reduce sound through a wall; thickness alone makes a modest difference compared with insulation and sealing gaps.
Worked example: 12 x 14 ft bedroom
Walls: 2 x (12 + 14) = 52 ft of wall, 8 ft high = 416 sq ft. In 4 x 12 sheets hung horizontally that is 12 sheets for the walls; the ceiling is 168 sq ft, or 4 more 4 x 12 sheets (5 if you avoid a thin strip). Use 1/2 in board on the walls and, if the ceiling joists are 24 in apart, 5/8 in or sag-resistant 1/2 in on the ceiling. The drywall calculator adds screws, tape and compound for the same room.
Frequently asked questions
What size does drywall come in?
Sheets are 48 in wide (54 in for 9 ft walls) and 8, 9, 10, 12, 14 or 16 ft long, in 1/4, 3/8, 1/2 and 5/8 in thickness.
What thickness of drywall for walls?
1/2 in is standard for interior walls in houses. Use 5/8 in Type X where a fire-rated assembly is required.
What drywall is required in a garage?
For an attached garage the IRC requires at least 1/2 in gypsum board on the garage side of the separation walls and ceiling, and 5/8 in Type X on the ceiling if there is a habitable room above (R302.6).
Is 5/8 drywall better for ceilings?
It sags less between joists, especially on 24 in framing. A 1/2 in sag-resistant ceiling board is the lighter alternative.
How far apart should drywall screws be?
Typically about 12 in on ceilings and 16 in on walls, per IRC Table R702.3.5 and board makers’ instructions; set heads just below the surface without breaking the paper.
Sources
- International Code Council, 2021 International Residential Code (IRC). Requirements are paraphrased with their section numbers; local codes and amendments may differ, so confirm with your building department. Sections R302.6 (garage separation), R302.7 (under-stair protection), R702.3 and Table R702.3.5 (gypsum board application and fastening), R702.4.2 (backers for tile in tub and shower areas).
- ASTM C1396, Standard Specification for Gypsum Board: the product standard for the board types and sizes described (not reproduced).
- Sheet and joint counts: our arithmetic, shown in the table caption.
Last reviewed: 24 October 2026. Numbers in the tables are our arithmetic from the sources listed; code sections are summarised, not quoted. How we check our work: methodology and corrections. Spotted an error? Please let us know.