The stuff is known by many names: gyprock, gypsum board, sheetrock, drywall, and simply wallboard. I have also called it a few other more colourful names that cannot be repeated here. One thing is certain: at some point most of us will end up working with this building material.
Types of Drywall
Drywall consists of a gypsum core with a coarse paper backing and smooth paper face. Standard thickness is 1/2 inch but it is also available in 5/8 inch.
Standard: Can range in length from 8 feet to 12 feet. Eight foot sheets are much easier to handle, but using longer sheets will reduce the number of butt joints. 5/8 inch sheets are recommended for ceilings as they have less tendency to sag. However, they are considerably heavier than 1/2 inch sheets.
Fire Code: This product is 5/8″ thick and is usually required by code in furnace rooms and attached garages where the wall or ceiling are shared with the house. Check with your building department.
Blue Board and Green Board: These products may vary from manufacturer to manufacturer,, so check the product specifications at your local building center. Some products just have moisture-resistant paper which is suitable for skim coating with plaster but are not designed for prolonged exposure to moisture. Such a product can be used as a backer for tile, but is not recommended for high humidity locations such as bathrooms. Cement board is always the best choice as a backer for tiles in wet areas like showers.
In other products, both the core and paper are water and mold resistant, suitable for high humidity areas such as bathrooms. However, water resistant should not be confused with waterproof. Again, cement board is the best choice for wet locations.
Compound: (commonly referred to as “mud”) Pre-mixed compound is available in pails, ready to use. However, this type of compound usually requires longer drying times, usually 24 hours. This means a typical job will often take at least three days. Mixes are also available. There is a little more mess associated with these as water needs to be added and mixed. However, these mixes will harden quickly (20 minutes, 45 minutes, or 90 minutes) so multiple coats of mud can be applied the same day. Because they set up faster, application needs to be quick.
Tape: Paper tape is usually the choice of professionals. Mesh tape is easier for the do-it-yourselfer as it is self-sticking. Mesh is also stronger, which is why some professionals will opt for it over paper.
Corners: For outside and inside corners, look for the ones with the paper attached. These do not need to be screwed or nailed. There are also plastic beads available for odd angles, as well as flexible beads for curved corners such as arches. Standard corners can be crimped, nailed or screwed though screws should always be used to avoid nail pops.
Screws: Fine screws are used for metal framing, coarse screws are used for wood. Use longer screws for thicker drywall, or for ceilings for greater holding strength. However, screws that penetrate too deep into wood may be more likely to pop if the wood shrinks or twists.
Drywall knives are used for applying compound. Start with the narrowest knife (6″) for the taping coat and work up to the widest knife (12″-14″) for the finish coat. There are also specialized drywall tools for applying compound to the inside and outside corners. I found the inside corner tool useful, while the outside tool, for me, was a waste of money. Neither is necessary.
Sanding screens used for drywall are basically stiff mesh. I recommend using a vacuum attachment to help control the dust. Sanding sponges also do a fine job, but there is a lot more mess to clean up afterwards.
A sharp utility knife is essential for cutting the drywall. A keyhole saw is useful for quickly cutting out for junction boxes., although this too can be done with a utility knife.
A power spiral saw can effectively replace the hand tools, but will result in more dust. However, there is no better tool for cutting around junction and device boxes. With the drywall held in place with a couple of screws, plunge the zip tool into the drywall at the outside edge of the box and simply trace around the box for a nice tight fit. Be careful you don’t nick the wires inside the box, though. Once the hole is cut, install the rest of the drywall screws.
A small rasp can be used to create bevelled edges where the ends of two sheets butt together.
Drywall Gun OR Drywall Clutch Bit: Drywall guns are designed to install the screws without breaking the face paper. If you are going to be hanging a lot of drywall, a dedicated tool such as this is a worthwhile purchase. For smaller projects or occasional use, the same result can be achieved by using a drywall clutch bit, or dimpler on a standard drill. The bit has a clutch mechanism that stops the bit rotation once the screw is just below the surface of the drywall.
- Drywall should be hung perpendicular to the framing. In other words, for vertical studs, drywall should be hung horizontally. This way, there is no need to attach screws through the beveled factory edges, and there will be fewer butt joints when longer sheets are used. Screwing into the studs is also considerably easier as the screws are installed across the width of the sheet (4 feet) rather than blindly along the length. In my first basement project, I hung the drywall vertically to completely avoid any butt joints at all since the ceiling height was less than eight feet.
- Drywall screws are typically spaced one foot apart. Check your local building code for specific requirements but you should be using about 45 screws per sheet.
- Leave a space between the bottom of the drywall and a concrete floor, to prevent any moisture from wicking up into the drywall.
- Hang the ceiling drywall first. The wall sheets will help support the edges of the ceiling and prevent future sagging.
- When using metal framing, install a wood strip to provide a nailing surface wherever you plan to attach trim. That way you can use finishing nails and have smaller holes to fill than if you used trim screws. The nailing strip should be as thick as the drywall and about a half inch less in width than the trim you plan on using. Simply butt the drywall up against this strip. (Thanks to Aaron for this tip)
- Typical application of compound is in 3 coats: First coat is the taping coat. Only use enough compound to embed the tape and fill the screw holes. Second coat is the fill coat. The final coat is the finish coat. Allow each coat to dry completely.
- When sanding, use long smooth strokes whenever possible. Don’t over-sand. I often find myself doing a fourth coat because I tend to sand too much.
- To get rid of sanding marks for a smooth finish, I will sometimes go over the joints with a damp sponge. This also cleans up some of the surface dust.
- Vacuum the surface of the drywall so that it is clean and dust-free.
- Use a primer high in “solids” content. Repair any imperfections before painting the top coat.
These are some basic tips. For more complete, professional advice, there are a number of books available, such as this one: