Drywall Basics: Measuring, Prep and the Different Types
From: DK - Do It Yourself Home Improvement
Drywall is the standard wall covering in the United States, covering three out of four interior walls in our homes. While it takes practice to properly finish drywall, it does not require many tools and is fairly straightforward. If you are planning to alter or build any walls in your home, you will need to know the basics of drywall.
Drywall is a specific type of sheeting material made of gypsum sandwiched between paper. Also referred to as wallboard, plasterboard, or gypsum board, drywall started to replace plaster as the typical interior wall finish in the United States more than 60 years ago. It is less expensive than plaster, and much easier to attach to stud walls. The panels are typically screwed to wall studs and the joints between panels are filled with joint compound, which is then finished to a flat surface.
- If you have a home built before 1950, you may have plaster walls.
- Plaster is heavy, and it needs a solid, well-anchored base made of strips of wood or metal wire, called a lath, to support its weight.
- Over time plaster can dry out and lose its holding strength, or the lath beneath can pull away from the framing. If you see your plaster walls sag, you may need to repair them.
Plastering and Drywalling Options
Plastering a masonry wall
A traditional method for preparing a large area of wall, ready for decorating (Image 1).
Plastering a stud wall
A smooth finish over untapered board, achieved by plastering across the entire surface (Image 2).
Layers of compound fill the joint, which is then sanded to provide a smooth finish (Image 3).
Preparing to Use Drywall
Drywall developed as an alternative to plastering walls. Some say the name drywall is characteristic description of the material. Unlike the plaster-and-lath wall surface that is completely moist and must be left to dry, drywall only has its joints that are moist from joint compound and they dry much more quickly than plaster.
Even with the benefits of drywall installation and repair over plastering, you still may decide to take on plaster repairs if you live in an older home or if you are restoring a home to its original materials.
Before you even begin to drywall or plaster your walls, make sure you have a flat working surface. When taking on the task of drywalling your home, the most important objective is to achieve a smooth finish. Each step in the multi-step drywalling process is designed to help you achieve this. The first part is making sure your stud walls are framed correctly. If the walls are not flat, the drywall panels will show the imperfections. It will be very difficult to overcome this type of imperfection through finishing techniques. It must be fixed prior to drywalling.
Drywall is available in 4' and 4-1/2' widths, and ranges in length from 8' to 16'. Due to the rectangular shape of the pieces, it is recommended that you hang the sheets parallel to the floor to reduce the amount of finishing work required. You will save time and money on the tape and joint compound needed to finish a larger number of vertical seams. If you are able to transport the larger-sized sheets, buy sheets that are the width of the wall, if possible. This will further reduce the amount of taping required.
Measuring for Drywall
When planning to use drywall materials, first determine the total square footage of the walls and ceiling that you are aiming to cover. Include the window and door openings, and always estimate high. Never buy exactly what you think you may need to just finish the project. This will save you time spent traveling back and forth to the home center during the project.
If you are using the standard 4' x 8' sheets of drywall, divide the square footage number by 32 (4 x 8 = 32). This will provide an estimate of the number of sheets you will require. You will also need about 400 feet of tape for every 1,000 sq ft of drywall. And you will need about 150 lb of joint compound. Make sure you estimate for the fasteners you plan to use, and rent any equipment and scaffolding that is needed to finish ceilings.
For ceilings and walls with 16" on-center framing use standard 1/2" drywall. For 24" on-center framing, use 5/8" drywall.
Types of Drywall
There are many types of drywall available at your local home center. From thicknesses that range from 1/4" to 5/8" to wall sizes that start at 4' x 8', there is a drywall product that is designed to suit your interior wall needs. If you are finishing a garage or another area where a fire rating is required, look for fire-resistant drywall. If you need to finish a wet wall, make sure you use a product that is able to handle more than average moisture content.
The most typical drywall used in standard interior applications is 1/2" drywall in 4' x 8' panels. It is also available in 1/4", 3/8", and 5/8" thicknesses.
Sometimes called greenboard, due to its color, this has the same gypsum core as drywall, but with a water-resistant facing. It is typically used in wet areas such as around a bathtub. Not waterproof.
This type of drywall has a core with additives that contain fires well. Fire rating for panels is measured in time. Due to its tougher core, it can be more difficult to cut.
When you have an arch or a curved wall, 1/4" flexible drywall is the best type to choose. It has a stronger paper face than regular 1/4" drywall and is more resistant to cracking.
Sometimes called concrete backerboard or the brand names of Durock and Wonder Board, it is used as a surface for ceramic tiles. It is not a gypsum-based product, as it has a solid concrete core.
This is a mold-resistant board used for tiling. It has a glass face and an acrylic coating that prevents moisture from entering the wall cavity.
Copyright 2009 Dorling Kindersley Limited
Text copyright 2009 Julian Cassell and Peter Parham