Drywall Thickness Guide: 1/2 vs 5/8 vs Specialty Boards

The short answer first

For 95% of GTA residential interior walls, you want 1/2 inch standard drywall. For most ceilings under living space, 5/8 inch Type X. For bathrooms and laundry, 1/2 inch green board moisture-resistant. The exceptions are interesting, but the defaults cover almost everything. If you want help spec'ing the right board for your project, our drywall installation team will walk through it on a free site visit.

1/2 inch drywall — your default

Half-inch panels are the workhorse. Lightweight, fast to hang, code-acceptable for almost every interior wall, and inexpensive. We use 1/2 inch on bedrooms, hallways, closets, basements (walls only — not ceilings), home offices, and most living areas in normal residential construction.

5/8 inch Type X fire-rated

Fire-rated panels have glass fibres in the core that hold the gypsum together longer when exposed to heat. The Ontario Building Code requires 5/8 inch Type X in several common locations: garage walls and ceilings adjacent to living space, mechanical rooms, party walls between dwelling units, and the ceiling of a basement that contains a furnace. We see this constantly in Toronto laneway suites and Mississauga finished basements.

Even when not strictly required, we often install 5/8 inch on basement ceilings under living space — partly for fire-resistance, partly because the heavier sheet sags less between joists. The cost difference is small (about $4–6 more per sheet) and the wall is noticeably more solid.

Green board (moisture-resistant)

The paper face is treated with a wax-resin coating to resist water vapour. It is not waterproof — it is moisture-resistant. Use it in bathrooms, laundry rooms, mudrooms, and garages with poor air sealing. Do not use it behind tile in a tub surround or shower — that requires cement board or a waterproofing membrane.

Cement board

Real waterproof backing for tile. Required behind tub surrounds, shower walls, and any tile installation that will see direct water. We score and snap it on site, fasten with corrosion-resistant screws, tape the seams with alkali-resistant mesh tape, and mud with a thinset rather than joint compound.

QuietRock and damped panels

Viscoelastic damped panels for sound reduction. Common applications: home theatres, condo party walls, shared townhouse walls, music rooms, podcast studios. A QuietRock 545 panel on each side of a standard wood-stud wall raises STC from about 33 to about 56 — roughly the difference between hearing a normal conversation through the wall and hearing only the very faintest bass. Our residential drywall crews install these regularly in Vaughan and Oakville custom basement theatres.

Abuse-resistant board

Fibre-reinforced gypsum core — much harder to dent or punch through. Used in commercial corridors, schools, hospitals, daycares, and any high-traffic public space. We do not see much of it in residential except for occasional pet-heavy households or homes with multiple kids.

Mould-resistant board

Inorganic fibreglass face instead of paper. Resists mould growth even when wet. Use in basements with humidity history, around plumbing, in crawlspaces, and any chronically damp area.

Sag-resistant ceiling board

Specifically engineered to not sag between widely-spaced joists or trusses. Useful when ceiling joists or trusses are spaced 24 inches on centre with no strapping — though we prefer to add strapping and use standard 5/8 inch instead. If your ceiling is already sagging or shows screw pops, our ceiling repair service handles the cut-out and replacement.

Common mistakes

• Using 1/2 inch on a ceiling with 24" joist spacing. The drywall sags between joists. Either go to 5/8 inch or add strapping.
• Using green board behind tile. The tile mortar and grout will fail before the wall does. Always cement board or waterproof membrane behind tile.
• Skipping Type X in code-required locations. Inspectors catch this and you re-do the wall. Just buy the right sheet.
• Buying 5/8 inch for everything. Heavier, more expensive, harder to lift overhead. Use it where it matters and 1/2 inch elsewhere.

Picking the right board is half the battle. Hanging it square and taping it tight is the other half — that is where we come in. See our taping and mudding service for what happens after the board goes up, and our taping levels post for picking between Level 4 and Level 5. For real-world pricing, check the cost breakdown or request a written quote.

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