Drywall Fiberglass Tape

Should I or should I not use fiberglass tape for my drywall? If you talk to your local drywall contractor or hardware store owner, they will tell you the use of fiberglass tape for your drywall project may not be the best course of action.

A paper tape is the preferred for its rigidity and lack of movement during the mudding process. This lack of movement means that your mud will go on more uniform and there will be less chance of cracking years later in your drywall. Fiberglass tape, as with any tool, has its pros and cons.

The main area of your drywall in which a fiberglass tape is the most problematic is the seam. The seam is the drywall backbone. You want any backbone to be solid and strong. A fiberglass tape seam has a tendency to move ever so slightly during drying.

This movement will cause a hairline crack to appear in the seam in time, because the mud coating is just not strong enough to secure the joint. That is the main difference between the use of paper tape and fiberglass tape.

Of course fiberglass tape is easy to use. You un-roll, stick it in the seams, and mud. The sticky tape goes down the seam quickly and easily. There is no fighting with paper tape to get it to stay in the seam. Most weekend warriors who have never put up drywall use fiberglass tape because all of the self help books and websites recommend it. There is a skill level needed to properly use paper tape.

The Mud

The most common mistake with novice dry-walling is the use of joint compound with fiberglass tape. The type of mud you use along with the type of tape you use will affect the overall strength of your seam. Fiberglass tape is used best with a gypsum plaster.

Gypsum plaster is much stronger than regular joint compound. A line of fiberglass tape covered with a veneer of gypsum plaster creates a rigid overcoat. The subsequent coatings with the gypsum bonds to the tape and board and increases the strength of your seam.

Aside from the movement of the tape, the problem with using joint compound and fiberglass tape is the top coatings. Joint compound is just not as rigid as gypsum. Over the fiberglass, joint compound will not add much more holding power to the tape and board underneath. With no tough over-coating, the likelihood of cracks developing increases. As a rule of thumb you should use fiberglass and gypsum or paper and joint compound. Just expect to pay more for fiberglass and gypsum.

Do Professionals use Fiberglass Tape?

Yes they do, for repair work. When a house is being built the shock and movement of construction that is invisible to the naked eye will often show up years later in the drywall in the form of cracking. These cracks often appear around doors, windows, and corners. This is where the professionals pull out their roll of fiberglass tape and get to work.

To repair a crack the drywall they first fill in the crack in with a “hot mud”. Hot mud is a richer mixture of plaster to create a quicker drying time. After your crack is filled cut your fiberglass tape into enough sections to cover across the crack. The pieces should measure around 3 inches. Do not overlap when laying them across your crack. After it has set, glue a piece of paper tape down the fiberglass covered crack with joint compound. Always remember your two top coats.

So don’t go out take your fiberglass tape back to the hardware store. Fiberglass tape is not all that bad. It is just knowing when and how to use it.

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