Leave a space between the butt boards from 1/16" to 1/4". The space need not be uniform. Should the space be more than 1/4", roll the ButtTaper on each end of the two boards separately and use a setting compound on the first two coats. If a space is not left by the sheet rockers, wet the butt joint and pull a space with the ax side of a drywall hammer, your finishing or utility knife. The reason for the space is to allow the boards to absorb the water more readily and for the ButtTaper tool to follow its line of operation. Further, the USG Construction Handbook recommends leaving a space between all drywall to allow for wood shrinkage.

In cases where spraying the butt joint or repair with the water bottle is not appropriate such as on wooden floors, use thinned all purpose joint compound or a slow drying setting compound instead of the water. Apply the compound into the space between the boards and wipe off the excess. Wait a few minutes and then roll the butt joint with the ButtTaper tool creating the tapered edge. Finish the butt joint as instructed. Keep the ButtTaper in a bucket of small water to prevent compound drying.

If it becomes difficult to create the tapered edge while rolling the ButtTaper, spray more water and roll again. 5/8" drywall requires more water absorption than 10.

With the ButtTaper system, you have an option of using or not using the 1/2" tape. As a drywaller you know when compound is applied in the interior of a board, the compound will not crack, but it will crack if tape is not used on a seam. Tape is used on seams to bind the two boards together.

The tape prevents the movement of the boards between the studs or joists. The backer board in the ButtTaper system also binds the two boards together, much better than the tape does.

Depending on the type of drywall, the rolling action of the ButtTaper may cause the facepaper to slightly curl at certain points. To rectify this situation, apply the compound into the tapered edge and with the corner of your finishing knife wipe the compound into the space between the boards with a slight angle of the knife to the drywall, and then wipe the excess off the face of the drywall. This will leave the compound at the center of the tapered edge, and will hold the facepaper down. Allow to dry, and proceed with another two coats of setting compound prior to applying the final coat. This occurs mainly on LaFarge and Georgia-Pacific drywall with very little on National Gypsum, and none with USG drywall.

Joint compound is not an adhesive, it does bind, but not to the extent that coarse drywall screws do, and joint compound is affected by humidity and temperature. The 4" backer board behind the butt joint in between the studs or joists is the binder between the two boards, and is stronger than 2-16 tape. Joint compound because of its low binding characteristic requires a wide tape (surface area) to bind the boards. With the use of the backer board, the drywall now is essentially thicker. Look at it this way...you are not doing a butt joint, you are repairing a fissure in the drywall.

Therefore, the 1/2" wide tape is not required but should you use it, you may immediately apply the second coat of setting compound. The use of the setting compound such as Easy-Sand, Durabond, etc., for the first two coats speeds the finishing process. As setting compound has minimal shrinkage, apply it well into the tapered edge, tape it, and then immediately apply the second coat. Third coat with a finishing compound or a setting compound once the setting compound has set. Setting compound adheres better to drywall than joint compound, is stronger, and is not affected by humidity.

Butt joints should not be placed over window or door openings as recommended by the drywall manufacturers. Always make sure that even on a small butt joint, that it is on a backer board or stud and not on a header. Refer to this study for drywall failure caused by wood shrinkage: http://www.umass.edu/bmatwt/publications/articles/detailing_for_wood_shrinkage.html

There is no sagging of the drywall with the use of a 4 to 6" backer board. On walls, the backer board will overhang the lower board at the top of the board by 3" and 1-1/2" from the upper board to the lower board. Screw the overhanging board to its adjacent board on the backer board if you so desire. The backer board weighs less than the compound with the ButtTaper system. On ceilings, use a 4 to 6" wide by 48" long backer or longer. If a longer backer is used, extend it over the adjacent board, and apply screws to the backer board on the adjacent, or if using a 48" long backer on a ceiling, next to it affix a 6" backer that extends over the adjacent board.

Use the backer board, and end the butt joint boards in between the RC-1 channel and the Rigid-X grid.

When the butt joint with the second layer is on a stud, use a thin bead of drywall adhesive with minimal screws. Alternatively, leave the second layer in between the studs, use drywall adhesive with 1 5/8" cement board screws. Cement board screws adhere well in double layer applications, better than laminating screws as they have a nip that penetrates the drywall, and sink into the drywall without tearing the drywall paper.

The ButtTaper system permits the drywall curvature to remain. Be sure to properly attach the drywall butt joints on the stud, use drywall adhesive with screws or nails, create the tapered edge, and then finish pressing your 8" finishing knife into a slight curve on the final coat. The result is that the curve of the wall remains intact. Using 1/4" "High-Flex drywall in a double layer application, leave the second layer butt joint in between the studs, adhering it to the first layer with a thin coating of drywall adhesive, and secure it with 1-5/8" cement board screws.

Cut a square or rectangle on the repair, apply backer boards around the repair, leave a small space between the new drywall patch and the old drywall, and finish as previously instructed for butt joints. Another method is to use drywall as the backer board with a thin coating of setting or all purpose joint compound to hold the drywall backer to the drywall and use 1-5/8" cement board screws to secure the drywall backer until the setting or joint compound sets.

Using 1-1/4" coarse drywall screws with 1/2" drywall and 7/16" backer board will result in the screws penetrating the backer board, and tearing the vapor barrier. Affix scrap drywall to the rear of the backer or use 5/8" plywood as the backer board with 1" or 1-1/4" drywall screws.

Cut the backer board to the length of the wall, preferably 6" wide. Use Durabond on the first two coats. The paint on the old wall will become loose when sprayed with water, thus scrape it off before applying Durabond. Should you not be able to produce a backer board the length of the wall, use 48" long backers, and splice them together at their junction with a 6" long strip.

The ButtTaper works on all types of drywall including Dens-Armor Plus, Dens Shield and Hi-Abuse XP. On the latter three, presoak the butt joints or repairs, wait one minute, spray with water again, and then use the ButtTaper to create the tapered edge.

Your drywall crew should have a cordless circular saw to cut the OSB backer board less than 4 feet long when required on smaller butt joints or score the OSB on both sides with a utility knife, and then snap it for a clean break. Prior to starting a large job, rip your backer boards with a circular saw into 4 to 6" wide by 48" long strips. If more than one 4' x 8' sheet of backer is required for your butt joints strips, clamp a few 4' x 8' sheets together, and then cut the strips. The time allocated to this will be saved by the sheetrockers when installing the drywall.

On your belt use three hammer holders; one for the ButtTaper tool, another for the water bottle, and the third for your finishing knife. This way you can do the butt joints from stilts.

The ButtTaper tool does not require any maintenance as it contains two sealed stainless steel bearings, and is totally rust proof.

If you have any rips between two boards, and if one end of the rip board has the factory tapered edge then only ButtTaper the other side without the factory tapered edge and use 2-1/16" tape on the tapered edge. If the rip does not have a factory edge then create the tapered edge with the ButtTaper. Be sure in either case to use a backer board behind the drywall rip.

To gain speed in doing a number of butt joints, spray all the butt joints with water in one area such as in a room, then spray each one prior to using the ButtTaper tool. This double watering will facilitate the pressure required for the ButtTaper tool. Roll all the butt joints with the ButtTaper, and then begin the finishing for all your butt joints.

If you are not using the 1/2" tape on the tapered edge created by the ButtTaper, the tapered edge can be minimal in depth. All you have to do is create a slight curl on the two edges of the butt joints.

The ButtTaper's tapered edge is similar to the tapered edge that was used in 1950's and 1960's in the Rock Lath Plastering System. The Rock Lath was 3/8" thick by 16" wide drywall with a plaster veneer system without using any tape. The ButtTaper system is superior because it incorporates a backer board behind the drywall which the Rock Lath did not.