Taping drywall joints on garage.

[KLuce]

I see that R309.2 in the 2003 International Residential Code book (still being used in Indiana) does not mentioned taping drywall joints for its separation requirements. What am I missing?

[Jerry Peck - Codeman]

This is the 2006 IRC code section you are referring to: (underlining and bold are mine)
- R309.2 Separation required. The garage shall be separated from the residence and its attic area by not less than 1/2-inch (12.7 mm) gypsum board applied to the garage side. Garages beneath habitable rooms shall be separated from all habitable rooms above by not less than 5/8-inch (15.9 mm) Type X gypsum board or equivalent. Where the separation is a floor-ceiling assembly, the structure supporting the separation shall also be protected by not less than 1/2-inch (12.7 mm) gypsum board or equivalent. Garages located less than 3 feet (914 mm) from a dwelling unit on the same lot shall be protected with not less than 1/2-inch (12.7 mm) gypsum board applied to the interior side of exterior walls that are within this area. Openings in these walls shall be regulated by Section R309.1. This provision does not apply to garage walls that are perpendicular to the adjacent dwelling unit wall.

That states that the garage and residence "shall be separated" by "not less than" 1/2 inch gypsum board minimum (or its equivalent, as properly filled and taped joints would make the gaps in the joints 'equivalent'). Garage ceilings under habitable rooms shall have even greater separation - the gypsum board used shall be 5/8 inch Type X minimum.

The Gypsum Association (GA) on their web site ( http://www.gypsum.org/ ) has an online library with their design/installation/application/finishing manuals available for download on it ( http://www.gypsum.org/download.html ).

One of the available manuals is "APPLICATION AND FINISHING OF GYPSUM PANEL PRODUCTS (GA-216-07)" ( http://www.gypsum.org/pdf/GA-216-07.pdf ) which, on page 5 in section "4. Application of Gypsum Panel Products - General Provisions.", addresses joint gaps in 4.6.7 to a greater extent than even finishing, this addresses the prefilling of gaps before taping and finishing. If the gap a joint is 1/8 inch or less it does not require prefilling, wider gaps require prefilling. This is to ensure that the joints are equivalent to the gypsum board.
- 4.6.7 When gaps occur at gypsum panel product joints, they shall be not greater than 1/4 in. (6 mm) and shall be prefilled with joint compound as specified in Sections 4.6.7.1 and 4.6.7.2.
- - 4.6.7.1 Gaps not greater than 1/8 in. (3 mm) shall be prefilled with either ready-mix or setting-type joint compound.
- - 4.6.7.2 Gaps greater than 1/8 in. (3 mm) shall be prefilled with setting-type joint compound.

Then, on page 16, in section "19. Finishing of Gypsum Panel Products.", taping and finishing is addressed (which is in addition to any prefilling addressed above).
- 19.4 Taping and finishing shall be done using the hand tools designed for this purpose, such as broad knives or trowels with straight and true edges, or mechanical tools designed for this purpose.
- 19.5 Tape shall be applied either by applying compound to the joint (buttering), pressing in the tape, and wiping off the excess compound, or by mechanical tools designed for this purpose.
- 19.6 The second coat shall be applied with tools of sufficient width to extend approximately 3 ½ in. (90 mm) beyond the center of the joint center. Compound shall be drawn down to a smooth even plane.
- - 19.6.1 After drying or setting, treated surfaces shall be sanded or otherwise smoothed as needed (See Section 19.1.1.1) to eliminate high spots or excess compound. When sanding the joints, care shall be taken not to raise the nap of the gypsum board paper.
- 19.7 Where a third coat is specified, it shall be applied with tools that will permit feathering of the joint treatment edges approximately 6 in. (150 mm) from the center of the joint.

Note that in 19.7 it states "Where a third coat is specified," indicating that there is an option of having the third coat, but not an option for buttering the joint and embedding the tape or applying the second coat over the tape.

However, before continuing with the taping and finishing of the gypsum board, let's go back and review the code requirements for "sealing" that wall and how it addresses "openings" in that wall.
- R309.1 Opening protection. Openings from a private garage directly into a room used for sleeping purposes shall not be permitted. Other openings between the garage and residence shall be equipped with solid wood doors not less than 13/8 inches (35 mm) in thickness, solid or honeycomb core steel doors not less than 13/8 inches (35 mm) thick, or 20-minute fire-rated doors.
- - R309.1.1 Duct penetration. Ducts in the garage and ducts penetrating the walls or ceilings separating the dwelling from the garage shall be constructed of a minimum No. 26 gage (0.48 mm) sheet steel or other approved material and shall have no openings into the garage.
- - R309.1.2 Other penetrations. Penetrations through the separation required in Section R309.2 shall be protected by filling the opening around the penetrating item with approved material to resist the free passage of flame and products of combustion.

Note that in R309.1.2, where there is a penetration through the wall, such as an electrical cable or a plumbing pipe, the gap around the penetration is required to be sealed "to resist the free passage of flame and products of combustion". With that standard set, we can now determine which level of gypsum board finish provides that same level of resistance to be able "to resist the free passage of flame and products of combustion".

Okay, with that standard set, let us continue with the level of finish of gypsum board on those same walls and ceilings.

Manual GA-214 covers finishing and taping of the installed gypsum board, "Recommended
Levels of Gypsum Board Finish, GA-214" ( http://www.gypsum.org/pdf/GA-214-07.pdf ). Here is a brief review of the levels of finish and why the lowest levels of finish would not be suitable for a garage:
- III. LEVELS OF FINISH. The following levels of finish are established as a guide for specific final decoration. The minimum requirements for each level shall be as described herein.

- - Level 0:
- - - No taping, finishing, or accessories required.
- - - - This level of finish may be useful in temporary construction or whenever the final decoration has not been determined.
- - - - (Jerry's note: Obviously, this Level 0 finish is not going to meet the standard the code set for sealing that wall.)

- - Level 1:
- - - All joints and interior angles shall have tape set in joint compound. Surface shall be free of excess joint compound. Tool marks and ridges are acceptable.
- - - - Frequently specified in plenum areas above ceilings, in attics, in areas where the assembly would generally be concealed or in building service corridors, and other areas not normally open to public view. Accessories optional at specifier discretion in corridors and other areas with pedestrian traffic.
- - - - Some degree of sound and smoke control is provided; in some geographic areas this level is referred to as “fire-taping.” Where a fire-resistance rating is required for the gypsum board assembly, details of construction shall be in accordance with reports of fire tests of assemblies that have met the fire-rating requirement. Tape and fastener heads need not be covered with joint compound.
- - - - (Jerry's note: Obviously, this Level 1 finish is not going to meet the standard the code set for sealing that wall. The finish level description itself states that it only provides "some degree of ... smoke control", and the code standard is "to resist the free passage of flame and products of combustion", which is not met with a Level 1 finish.)

- - Level 2:
- - - All joints and interior angles shall have tape embedded in joint compound and wiped with a joint knife leaving a thin coating of joint compound over all joints and interior angles. Fastener heads and accessories shall be covered with a coat of joint compound. Surface shall be free of excess joint compound. Tool marks and ridges are acceptable. Joint compound applied over the body of the tape at the time of tape embedment shall be considered a separate coat of joint compound and shall satisfy the conditions of this level.
- - - Specified where water-resistant gypsum backing board (ASTM C 630) is used as a substrate for tile; may be specified in garages, warehouse storage or other similar areas where surface appearance is not of primary concern.
- - - - (Jerry's note: This Level 2 finish states it is applicable for garages where appearance is not a primary concern. Additionally, with the fasteners and accessories covered in joint compound along with the tape being covered with a layer of joint compound, its ability to meet the code standard of "to resist the free passage of flame and products of combustion" in enhanced. Thus, the Level 2 finish would be the lowest level of finish which would meet the requirements set forth in the code, however, it is also implying that one would only use this low level of finish in a garage if one is not concerned with appearance, meaning that this Level 2 finish would only be used in a minimum standard no-frills house.)

- - Level 3:
- - - All joints and interior angles shall have tape embedded in joint compound and one additional coat of joint compound applied over all joints and interior angles. Fastener heads and accessories shall be covered with two separate coats of joint compound. All joint compound shall be smooth and free of tool marks and ridges. Note: It is recommended that the prepared surface be coated with a drywall primer prior to the application of final finishes. See painting/wall covering specification in this regard.
- - - Typically specified in appearance areas which are to receive heavy- or medium-texture (spray or hand applied) finishes before final painting, or where heavy-grade wall coverings are to be applied as the final decoration. This level of finish is not recommended where smooth painted surfaces or light to medium wallcoverings are specified.
- - - - (Jerry's note: This Level 3 finish would be suitable provided that the walls where not going to be given an application of paint without some type of heavy-bodied hiding ability type coating is to be applied prior to painting. This Level 3 finish would only be used in a just-above-minimum standard no-frills houses where a heavy bodied texture was going to be applied and then painted.)

- - Level 4:
- - - All joints and interior angles shall have tape embedded in joint compound and two separate coats of joint compound applied over all flat joints and one separate coat of joint compound applied over interior angles. Fastener heads and accessories shall be covered with three separate coats of joint compound. All joint compound shall be smooth and free of tool marks and ridges. Note: It is recommended that the prepared surface be coated with a drywall primer prior to the application of final finishes. See painting/wall covering specification in this regard.
- - - - This level should be specified where flat paints, light textures, or wall coverings are to be applied.
- - - - In critical lighting areas, flat paints applied over light textures tend to reduce joint photographing. Gloss, semigloss, and enamel paints are not recommended over this level of finish.
- - - - The weight, texture, and sheen level of wall coverings applied over this level of finish should be carefully evaluated. Joints and fasteners must be adequately concealed if the wallcovering material is lightweight, contains limited pattern, has a gloss finish, or any combination of these finishes is present. Unbacked vinyl wallcoverings are not recommended over this level of finish.

- - Level 5:
- - - All joints and interior angles shall have tape embedded in joint compound and two separate coats of joint compound applied over all flat joints and one separate coat of joint compound applied over interior angles. Fastener heads and accessories shall be covered with three separate coats of joint compound. A thin skim coat of joint compound trowel applied, or a material manufactured especially for this purpose and applied in accordance with manufacturer’s recommendations, shall be applied to the entire surface. The surface shall be smooth and free of tool marks and ridges. Note: It is recommended that the prepared surface be coated with a drywall primer prior to the application of finish paint. See painting specification in this regard.
- - - - This level of finish is highly recommended where gloss, semi-gloss, enamel, or flat paints are specified or where severe lighting conditions occur.
- - - - This highest quality finish is the most effective method to provide a uniform surface and minimize the possibility of joint photographing and of fasteners showing through the final decoration.

To summarize, the lowest level of finish for gypsum board which would meet the standard and requirements set forth in the code would be a Level 2 finish, unlikely found on all by the lowest level minimum standard housing, which is as follows:
- "All joints and interior angles shall have tape embedded in joint compound and wiped with a joint knife leaving a thin coating of joint compound over all joints and interior angles. Fastener heads and accessories shall be covered with a coat of joint compound. Surface shall be free of excess joint compound. Tool marks and ridges are acceptable. Joint compound applied over the body of the tape at the time of tape embedment shall be considered a separate coat of joint compound and shall satisfy the conditions of this level."

Hopefully this information is helpful.

Codeman