Drywall is not a single product. The type of board, the thickness, the moisture resistance rating, the fire rating, and the type of joint compound all affect the performance and longevity of the installation. A contractor who specifies materials thoughtfully — using the right board for each application — is doing the job correctly. One who uses standard drywall everywhere is cutting corners in wet areas and potentially creating code violations.

“The most common material mistake I see is standard drywall installed behind tile in a bathroom. The homeowner sees a beautiful tile job. What’s behind it is a water sponge. Two or three years later, the grout starts failing, water gets behind the tile, and the drywall is black with mold. The right board type costs maybe $3 more per sheet. It’s never worth skipping.”

— Yolanda Ferris, licensed drywall finisher and plastering specialist with 18 years of experience in residential and commercial drywall installation and finishing in the local area

Questions About Board Type

Close-up of drywall sheets stacked in a large warehouse in London.

What type of drywall board will be used in each area?

There are several types of gypsum board, each appropriate for different applications:

Standard gypsum board (regular drywall):
The most common type. Appropriate for interior walls and ceilings in dry, conditioned spaces. Not appropriate behind tile or in high-humidity environments.

Moisture-resistant board (MR board / greenboard):
Has a moisture-resistant facing paper. More resistant to humidity than standard board. Appropriate for bathroom walls where tile will not be installed (painted surfaces only). Not appropriate behind tile — greenboard absorbs water through cut edges and will fail behind a wet tile installation.

Glass mat gypsum board (e.g., DensArmor, DensShield, Georgia-Pacific Dens products):
Uses glass mat facing instead of paper. Truly moisture and mold resistant. The appropriate choice behind tile in wet areas (shower surrounds, tub surrounds, wet-zone bathroom walls).

Cement board / fiber cement board:
A non-gypsum substrate made of cement and aggregate or fiber cement. Completely inorganic — not affected by moisture at all. The most durable substrate behind tile in the highest-moisture applications (shower floors, steam showers).

Fire-rated (Type X) gypsum board:
5/8″ thick with glass fibers added to the core. Required in specific locations by building code — most commonly in attached garages (ceiling and wall adjacent to living space), stairwells in multi-storey homes, and mechanical rooms with certain equipment.

Soundboard / sound-dampening drywall:
Specialty products (QuietRock, SilentFX) that significantly reduce sound transmission. More expensive than standard drywall but meaningful in bedrooms, home offices, or shared walls.

Ask your contractor to specify which board type is being used in each area and confirm it’s appropriate for the application.

What a good answer looks like: A board type specified for each area — standard in dry areas, glass mat or cement board behind tile, Type X where code requires it.

What thickness is being used?

The most common residential drywall thicknesses are:

1/2″ (12.7mm): Standard for most residential wall applications. Also used on ceilings with 16″ joist spacing.

5/8″ (15.9mm): Used for Type X fire-rated applications, on ceilings with 24″ joist spacing (provides better sag resistance), and in areas where increased soundproofing is desired.

3/8″ (9.5mm): Used for curved surfaces and as a second layer in double-layer applications.

Ask what thickness is being specified for each application and why.

Questions About Joint Compound

Interior construction with metal framing and drywall panels

What type of joint compound will be used for each coat?

Joint compound (“mud”) comes in several types with different properties:

Setting-type compound (hot mud):
A powder that hardens through a chemical reaction — not drying. Sets in a defined time (20 minutes, 45 minutes, 90 minutes, etc. depending on the product). Much harder and stronger than drying-type compound once set. Used for embedding tape on the first coat and for repairs where strength is needed. Can be topcoated sooner than drying-type compound.

Drying-type compound (all-purpose, lightweight, topping compound):
Hardens by evaporation. Shrinks as it dries. All-purpose compound is used for all coats; lightweight compound shrinks less and is often used for finish coats; topping compound is the smoothest-flowing type for finish coats.

A professional finishing sequence often uses setting-type compound for the tape coat and drying-type compounds for subsequent coats. Ask what compound type will be used for each coat.

Will fiber-mesh tape or paper tape be used?

Two types of joint tape are common:

Paper tape: The traditional choice. Embeds well in compound, creates a very strong bond, and is preferred by most professional finishers for flat joints. Requires setting-type or all-purpose compound to embed properly.

Fibre-mesh (fibreglass) tape: Self-adhesive, easier for beginners to apply. Slightly more prone to cracking in flat joints because it doesn’t embed as deeply. More appropriate for repairs than new installation according to many professionals.

Ask which tape type is being used and why. A finisher who exclusively uses fibreglass mesh where paper tape is the better choice may be taking a speed shortcut.

What corner bead is being used?

Corner bead protects and defines outside corners (the 90-degree corners where two walls meet). Types include:

Metal corner bead: Traditional, very durable. Requires careful installation to avoid rust bleeding through compound.

Vinyl corner bead: Lighter, doesn’t rust. Slightly less rigid than metal.

Flexible corner bead: For curved or non-90-degree corners.

Paper-faced metal bead (Trim-Tex and similar): A composite that bonds to compound like tape while providing the rigidity of metal. Preferred by many high-end finishers for its crack resistance.

Ask what corner bead type is specified and confirm it’s appropriate for the application.

Questions About Primer

Is primer included in the drywall scope?

Many drywall contractors prime the finished surfaces before handing off to the painter. Others do not. Ask whether priming is included and what product is being used — a quality PVA drywall primer is appropriate for new drywall surfaces. Skipping primer and painting directly over joint compound leads to flashing (uneven sheen caused by different paint absorption rates between compound and paper facing).

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