CertainTeed drywall - Manual (Page 2)

C e r t a i n T e e d
Gypsum Wallboard Panels
Begin with the butt joints – the areas where the
unfinished ends of ProRoc boards meet.
First, apply a coat of
ProRoc joint compound
over the joint with your
four-inch knife. Then,
press the tape firmly into
the compound by press-
ing your knife over the
tape. Squeeze out excess
compound, making sure that there is enough ProRoc
joint compound under tape to make a good bond.
Allow each coat to dry thoroughly before applying the
next coat (24-hours between coats). If the tape does
lift along the edges after drying; simply cut out the
affected area in the shape of a canoe before applying
the next coat. If the tape lifts in the centre, you must
tear out affected area and re-tape.
Apply a second coat
using a 7” taping knife
and this coat should
extend approximately 4” -
6” beyond each side of
the joint. After the coat
dries approximately
24 hours, sand the area
Apply a third coat using a
12” taping knife and this
coat should be a thin coat
and should extend
approximately 7-12”
beyond each side of the
joint. The further you
feather the compound
out, the harder it will be to see imperfections.
When you are finished, you may want to test the fin-
ishing by holding your 12-inch finishing knife blade
across the joint. If the blade rocks, you’ll know there is
still a hump, which will need further feathering.
SANDING
Do not sand after applying tape, remove small lumps
behind with your knife before applying 2nd coat.
When sanding use 150-180 grit paper and always sand
along the outside edge well, so that the transition
between the compound and the ProRoc boards are
smooth with no imperfections. Then sand the rest of
the joint lightly in order to make smooth. Be careful
not to sand too much off. If too much is sanded off,
you will need to apply additional coats of compound.
INSIDE CORNERS
Inside corners will need to be taped as well. First,
apply a thin layer of ProRoc joint compound on both
sides of the corners using a 2-1/2” taping knife,
extending the compound slightly beyond where the
tape would extend.
Next, fold the tape and
lightly press it into the
corner with your knife.
Once it is in place, using
your 2-1/2” knife or a
corner tool to firmly
embed the tape into the
compound. Allow to dry for 24-hours, then apply a sec-
ond coat using a 7” taping knife to one side of the cor-
ner. You can only do one side of the corner today, as
the compound must dry completely so the other side
can be finished tomorrow. Do the same for the third
coat, using a 12” taping knife.
Measure bead and cut to
right length; a snug fit
from floor to ceiling
(about 1/4” shorter than
the wall height). With a
7” knife apply a
generous amount of
ProRoc joint compound
on either side of corner.
Using even pressure, press
paper / metal bead onto
corner into position,
ensuring it is aligned;
embed it into compound
by running the knife at
45° angle. Let dry for 24-hours. Apply a second coat
with the 7” knife, allowing knife to rest on nose of the
bead. Let dry for 24-hours and apply a third coat. After
another 24-hours, sand the corner to a smooth finish.
FINISHING FASTENERS
You will want to coat each of the nail or screw heads used
to fasten your ProRoc boards with ProRoc joint compound.
After the first coat has dried completely, you will need
to sand and apply two more coats to the fasteners,
sanding between each coat.
Joint treatment and taping
The finishing process requires patience! You should
apply three coats of ProRoc joint compound through
the process and allow 24-hours of drying time
between applications. The first coat is used to embed
the tape, while the two finishing coats feather out the
compound, resulting in a uniform, smooth finished
surface.
A few pointers for easy and safe application:
❏ Always wear a dust mask when sanding
❏ Use only a 150 - 180 grit sandpaper, designed espe-
cially for joint compound
❏ Keep your knife clean by drawing it over the edge
of the mudpan or hawk.
❏ Throw out any dried bits of ProRoc joint
compound… they will leave scratches
❏ Don’t worry about a smooth finish on the first
coat… the finishing coats will take care of that.
❏ Stir joint compound well before use. Add clear
water for desired consistency.
❏ ProRoc joint compound should never be frozen.
In cold weather compound should be at room
temperature 24 hours before using.
TAPING AND FINISHING OUTSIDE CORNERS
Characteristics, properties or performance of materials or systems manufactured by CertainTeed herein described are derived from data obtained under controlled test conditions. CertainTeed makes no warranties, express or
implied, as to their characteristics, properties or performance under any variations from such conditions in actual construction. CertainTeed assumes no responsibility for the effects of structural movement.
™® CertainTeed and the tag line “Quality made certain. Satisfaction guaranteed.” are trademarks of CertainTeed Corporation. All other trademarks are the property of BPB plc or its affiliates and related companies.
NOTICE: The information in this document is subject to change without notice. CertainTeed assumes no responsibility for any errors that may inadvertently appear in this document.
©01/07 CertainTeed Corporation. Printed in Canada on recycled paper. C March 2007 Form #: L-TP-001-E
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