Measure walls and ceilings separately
Large sheets reduce joints but complicate access and lifting.
Calculate sheets, compare formats and uses, then add joints, fasteners, finishing and handling.
| Board | Planning use | Verify |
|---|---|---|
| 1/2 in regular | Typical walls where the assembly permits | Spacing, orientation, fastening, exposure |
| 5/8 in | Ceilings, added stiffness or specific systems | Weight, handling and assembly |
| Type X | Specified fire-resistance assemblies | Complete listed assembly |
| Moisture/mould resistant | Damp locations within product limits | It is not a waterproofing membrane |
Large sheets reduce joints but complicate access and lifting.
Avoid clusters of small pieces at openings; coordinate framing and edges.
Tape, compound, corner bead, primer, sanding and protection are a real part of the job.
Measure stairs, doors and turns before ordering 10- or 12-ft sheets; a lift can change ceiling safety.
The result answers how many; it does not decide thickness, fire rating or fasteners.
These links connect this page to the next useful checks and decisions without repeating the full content.
This section connects envelope, air, fire, structure, water and code instead of treating each project in isolation.
This section covers issues that can block a project, cause a loss or become expensive once concealed.
This section connects water, soil, climate, safety, materials and seasonal use to existing projects.