Many home improvement projects involve some type of drywall repair. Learning how to properly install drywall and finish tape the drywall to a smooth flat finish is a learned art, which can be achieved with the help of a few tips I will share here.
It is important to understand the drywall product and how it should be used. Residential drywall comes in different thicknesses, ¼”, 3/8”, ½”, and 5/8”. There is also a 1” thick product that is used for a fire wall in some multi-family buildings. There are different types of drywall, such as green-board, which is moisture resistant, newly introduced lightweight drywall and mold resistant drywall.
Typically ¼” drywall is used to go over a structurally sound but cosmetically damaged wall, or for covering curved walls because it’s bendable. The 3/8” thickness can also be bent slightly and was used in some home construction many years ago, but it is not used much today. The most common drywall product used residentially is by far ½”. In the city of Chicago and in applications where a fire rating is important 5/8” drywall is used.
Installing drywall is relatively easy as it is commonly available in 4’ by 8’ sheets, although 10’ and 12’ lengths are available as well as 5’ widths. Typically it is installed horizontally with the length running across the framing members. It should be glued and screwed for maximum bonding but nailing with ring shank nails is acceptable. Cutting drywall is done by scoring the face with a utility knife, snapping it and then cutting the backside paper. A short narrow stiff bladed saw called a key hole or drywall saw can also be used as well as a Roto-Zip cutting tool.
There are two basic types of “mud” or taping compounds used for finish taping of drywall. The first type comes pre-mixed and it will dry over time, usually in 24 hours. Secondly is a powder type you mix with water, which sets in a defined time period. The technique to apply either is the same, except the open time, which is the time you can work with the product before it sets or starts to harden. I prefer the setting type.
Having the proper tools is important to the successful completion of any job. I recommend you have a metal taping trough, a stiff putty knife as wide as the bottom of your trough, a 6” blade with medium flexibility, and a 12” cement finisher’s trowel. I recommend the cement finishers trowel for a few reasons. First it’s easier to get the feel of, it’s less flexible than a typical 12” taping blade and you can use it to perform both taping and finishing concrete as long as you clean it well.
USG makes a great taping/patching product called Sheetrock EZ-Sand which comes in a 5 minute, 20 minute, 45 minute, and 90 minute setting time. I use the 20 minute and 45 minute product almost all the time. A little trick to make any of it set faster is to mix it with hot water instead of room temperature water.
A lot of beginners think,” I will just put a whole lot on and sand it smooth”. This not only is a waste of the product and sandpaper but a lot of work, especially if you are taping a large area.
The proper technique is to place your tape over the seams or hole, extending past the edge the width of the tape. I use the self adhering nylon mesh tape, which I have found to be easier to work with. Mix up the “mud” to a peanut butter consistency, and using a 6” taping blade spread the mud over the patch area to a depth that just covers the tape. Don’t worry about blending or feathering it out right now. All you need to accomplish in the first coat is to just barely cover the tape.
After that coat is set take your taping blade and run it over the first coat of mud knocking down any ridges or loose material. Mix up another batch of mud, to the consistency of mayonnaise. Now we will work on feathering it out. Place one side of your 6” blade on center of where the tape would be and the other edge to the outside of it and spread your mud. Repeat this on all four sides of the patch.
After that coat sets use your 12” trowel to knock down any ridges or loose material. At this point if you have not gotten carried away with the thickness of the mud you have applied you should still be able to see a faint outline of the mesh tape in some areas. Mix up another batch of mud. This time you want it to be little looser or runnier than mayonnaise. Using your 6” knife spread it all over the existing patch area. Now take your 12” trowel, holding it at about a 45 degree angle to the wall, beginning a couple inches outside the patch area slide it across the area. When you get the first side done resist the urge to take the trowel off the wall, instead with a curving motion continue to the other side until all sides are done. You may have to stop and start again if you have placed too much mud on the wall. The more continuous the motion you use the better the finish. Your objective with this coat of mud is to fill in any voids and finish the feathering process.
After the final coat has dried totally, usually 24 hours, you can sand it. Using 120 grit drywall screen sand paper and the appropriate size sanding pad lightly sand the area. When you think you have it smooth run the palm of your hand over it and you should be able to feel dips or ridges, if any. If you need to add another coat of mud, do so carefully and then sand it again.
After it’s totally dry use a clean and lightly damp sponge or rag to wipe the entire area to remove any dust. Give that moisture 30 minutes to dry and then prime and paint the area.
There you have it, all you need to know to take care of your drywall projects. As with many projects following the steps in order is critical to a quality finished project.
Watch this video for a hands on lesson on how to patch a hole in drywall. Contractor John on YouTube