Gypsum wallboard panels, Joint treatment and taping – CertainTeed drywall User 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.

March 2007 Form #: L-TP-001-E

CertainTeed Corporation
P.O. Box 860
Valley Forge, PA 19482

Professional: 800-233-8990
Consumer: 800-782-8777
www.certainteed.com

F i n i s h i n g G u i d e