Fiberglass drywall tape is popular for drywall work and plaster repair.
But there are big problems with it. One professional's opinion.
The truth is, fiberglass tape has its place, but - please! not on your drywall
seams.
Yes, my view of this is controversial. And I have my (good) reasons.
Actually, people who use fiberglass tape instead of paper tape for drywall taping are helping me make a living.
As a drywall finisher and a plaster repair specialist, I have made
thousands of dollars over the years repairing drywall seams taped with
fiberglass. Thanks, folks.
What happens? Drywall seams need a RIGID tape to stay
closed. Especially over butt joints, the fiberglass taped seam
will wiggle ever so slightly some time down the road after finishing,
and presto! a hairline crack develops right down the middle of the
joint.
The tape isn't broken. It's just that the drywall mud overcoat is
not rigid enough - tough enough - to add the strength necessary to
permanently secure the joint.
How do I know this? Well, for one thing, I have noticed that the
long, recessed drywall seams tend to stay taped better. With
those seams, the mud overcoat is thicker because it is filling the
valley where the tapered edges of the drywall come together. You
get some extra toughness.
I understand the allure of fiberglass tape. Slap it down on that
crack and mud 'er up. No blisters, etc. So easy and
comfortable, especially for the novice taper. And every
do-it-yourself website and magazine article promotes it.
Yes, it is harder to learn to use paper tape properly. For the newcomer
to drywall taping, there are issues of laying the mud on evenly, wiping
the tape down properly, avoiding humps on the butt joints, and so on.
These are learnable skills, and they pay big dividends after the job is
finished and painted. Nothing is more irritating to the customer
or homeowner living in his new home/addition than to see cracks
developing in his new walls or ceilings.
As I said in the beginning, there IS a place for fiberglass tape.
First of all, it the tape of choice for plasterboard seams under veneer
plaster. This is what it was developed for in the first
place. It works very well in this setting, because veneer plaster
is far harder and tougher than drywall compound.
But, there is a place where fiberglass tape can help in the drywall
trade, and that is in the repair end of the business. Around
doors and windows, cracks in the drywall are common. A little
extra movement in the framing there and you get these unsightly defects.
When I repair such cracks, I want some extra insurance. What I
will do is use short pieces of fiberglass tape - maybe three inches
long or so - and place them in a bed of mud ACROSS the crack and
parallel to each other. I wipe out the excess mud, just as I would with
paper tape.
When this first layer of tape is hard, then I lay down a line of paper
tape right across the fiberglass and centered on the underlying crack.
Now I have double insurance: the glass for lateral strength and the
paper to keep it tight to the surface. This usually takes care of
such cracks, or any cracks you are particularly concerned about. (Don't
forget two or more topping coats.)
I do the same operation or a variant of it on bad plaster cracks.
One last point. I've emphasized toughness of the compound you
use. For that reason, I like "hot mud", a setting type joint
compound more like plaster for strength. If you are unsure of
yourself and your speed, it would be good to use hot mud with a longer
setting time, like an hour or 90 minutes. Mix small batches and
don't forget to wash your tools and pans well between batches.
Good luck!
Edwin Brown is a licensed and bonded drywall and plaster repair
specialist with 35+years experience. He works on the west coast of the
US. For more complete information, browse his website at
http://www.plaster-wall-ceiling-solutions.com
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