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Drywall

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You may know the stuff by many names: gyprock, gypsum board, sheetrock, drywall, and simply wallboard. I have also called it a few other more colorful names that I can’t repeat here. One thing is certain: at some point most of us will end up working with this building material.

Drywall

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 24 inch on center stud framing as well as for ceilings as they are more rigid than 1/2 inch sheets. However, they are considerably heavier than 1/2 inch sheets. But because they have more mass, they also reduce sound transmission between rooms.

Fire Code, or Type X: 

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, don’t confuse water resistant with waterproof. Again, cement board is the best choice for wet locations such as showers.

Quiet Rock, SoundFX, etc:

For soundproofing purposes. These products have a membrane sandwiched between gypsum that reduces sound transmission.

Supplies

Joint 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. The mixes cure chemically and are much harder than the pre-mixed compound, which air dries.

Tape

Paper tape is usually the choice of professionals, because they claim it makes for a stronger joint. Mesh tape is easier for the do-it-yourselfer as it is self-sticking. When using mesh tape, choose a joint compound mix for the taping coat. Because it cures harder it is more resistant to cracking.

Corners:  

There are a lot of choices here. You can find metal outside corners that have to be nailed or screwed. Also available are metal outside and inside corners with the paper attached. They can be installed with just mud, no nails or screws necessary. Flexible beads bend easily for curved corners such as arches. My personal favorite is drywall corner trim that comes in a roll and can be used for both inside and outside corners.

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.

Tools

Drywall knives 

For applying compound.  Start with the narrowest knife (4″) for the taping coat and work up to the widest knife (12″-14″) for the finish coat.  There are also specialty 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 

These 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.

Cutting tools

A sharp utility knife is essential for cutting the drywall.  A keyhole saw is useful for quickly cutting out for junction boxes.

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. Then 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, a drywall clutch bit, or dimpler on a standard drill can achieve similar results.  The bit has a clutch mechanism that stops the bit rotation once the screw is just below the surface of the drywall.

A few tips

There are plenty of resources available that will provide better instruction than I can. Here a few pointers to keep in mind:

  1. 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 you are installing the screws across the width of the sheet (4 feet) rather than blindly along the length. In my first basement project, the ceiling height was less than 8 feet. I hung the drywall vertically, completely avoiding any butt joints at all.
  2. Drywall screws are typically spaced one foot apart.  Check your local building code for specific requirements but you should be using about 30 screws per sheet (5 screws per stud)
  3. Leave a space between the bottom of the drywall and a concrete floor, to prevent any moisture from wicking up into the drywall.
  4. Hang the ceiling drywall first. The wall sheets will help support the edges of the ceiling and prevent future sagging.
  5. 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)
  6. Typical application of compound is in 3 coats:  First coat is the taping coat.  If using mesh tape, setting compound must be used for this coat.  Second coat is the fill coat.  The final coat is the finish coat.  Allow each coat to dry completely before knocking down any rough spots and sanding.
  7. 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.
  8. 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.
  9. Vacuum the surface of the drywall before painting so that it is clean and dust-free.
  10. Use a quality primer.  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 these:

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