1.      WORKMANSHIP

Gypsum board shall be installed by mechanics skilled in this trade in accordance with CSA A82.31, ASTM C-840, or Gypsum Association GA216 Specification and the following standards.

2.      COLD WEATHER APPLICATION

Gypsum board and joint filler shall not be applied to surfaces that are damp or contain frost.  In cold weather, ensure heating is provided to maintain a temperature of at least 10ºC., but not in excess of 14ºC., for seven days prior to and during application of boards and joint treatment, and for at least four days thereafter.  (See Note 14)

When temporary heating equipment is employed, ensure precautions are taken to avoid local concentration of heat by means of deflectors or protective screens.  Ensure suitable ventilation is provided to ensure normal drying conditions.

3.      GENERAL APPLICATION

Plan the installation to avoid butt-end joints if possible, to reduce the amount of joint finishing.

Do not locate joints on same stud on opposite sides of partitions.  Stagger end joints occurring on same side of partitions. Keep vertical joints at least 300mm (12”) from the jamb lines of door, window and other openings.
Cut sheets to fit accurately; butt edges of boards in moderate contact; do not force into place.  Remove ragged edges or burrs with rasp or sandpaper.

Isolate gypsum board from exterior metal windows and door frames.   If not covered by any other means, use rigid PVC ‘J’
molding at junction between board and frames.  (See Note 15)

Gypsum board shall be cut by scoring and breaking, or by sawing, working from the face side.  When cut by scoring, the face paper shall be cut through with a sharp knife or sharp instrument.  The gypsum board shall then be snapped back away from the cut face. Cut outs for pipes, fixtures, or other small openings shall be scored in outline on both sides before knocking out, or shall be cut out with a saw.

Except when the spacing of nailing members does not exceed 400mm (16”) on center, in single layer construction, and for the first layer of multiple layer construction, all ends and edges of gypsum board shall occur over fastening or nailing members.  This is not required for edges at right angles to framing members in horizontal application.

Gypsum board 12.7mm (1/2”) or 15.9mm (5/8”) thickness, attached to ceiling supports which are spaced more than 400mm (16”) on center, shall be erected with the length of the sheet at right angles to the supports.

4.      MAXIMUM SPACING OF SUPPORTS

Maximum spacing of vertical supports for gypsum board shall be in accordance with the following table.

Table 9.5/1

5.      GYPSUM BOARD SCREW CHANNEL AND Z-BAR WALL FURRING

Install screw channels or Z-Bars attached to masonry or concrete surfaces at 400mm (16”) or 600mm (24”) o.c. as specified and not more than 100mm (4”) from corners and openings.

Secure flanges to wall with hardened nails, power actuated fasteners or equivalent fastening.  Maximum spacing shall be 600mm (24”) centers alternating to opposite flanges.

6.      SINGLE LAYER APPLICATION

6.1      Joints

6.2      Screw Application

6.3      Spacing

6.4      Nailing

6.5      Curved Surfaces

6.6.     Nail and Adhesive Application (to Wood Studs)

6.7      Adhesive Application - Gypsum Board to Concrete

7.      DOUBLE LAYER APPLICATION

7.1      General

7.2      Screw Application

7.3      Nailing and Adhesive Application

7.4      Nailing Application with no Adhesive used Between Layers

7.5      Adhesive and Screw Application

8.      WATER RESISTANT GYPSUM BOARD APPLICATION

Fasten water resistant gypsum board to supports using screws at the conventional spacing, except where ceramic wall tile of more than 6mm (1/4”) thickness will be used, space nails at 150mm (6”) and screws at 200mm (8”) centers.  (See Note 22)

Erect the board horizontally with the paper bound edge at the tub or shower receptor.  Leave 6mm (1/4”) space.  Avoid cut edges within the shower or tub enclosure, except at corners, and where recessed fittings or plumbing services are required.

When water resistant gypsum board is installed on steel studs and the finish application is a tile surface, a minimum of 20-gauge steel is required.

Do not use joint compound or tape on joints or corner beads within areas to be tiled.  (See Note 21)

9.      ABUSE RESISTANT GYPSUM BOARD

9.1      General

9.2      Application

10.  GLASS MAT WATER RESISTANT GYPSUM ORTILE BACKER BOARD APPLICATION

10.1    General

10.2    Application

10.3    Finishing

11.  REINFORCED CEMENTITIOUS BOARD (CBU) APPLICATION

11.1    General

11.2    Application

12.  RESILIENT CHANNEL AND GYPSUM BOARD APPLICATION

Erect resilient channel transversely across framing members, spaced at 400mm (16”) for 12.7mm (1/2”) board and maximum 600mm (24”) centers for 15.9mm (5/8”) board; and within 150mm (6”) of wall/ceiling junctures.  Secure bottom flange of channel on wall installations.

Install a 75mm (3”) strip of 12.7mm (1/2”) gypsum board at floor level and install the face layer on ceilings and walls as described for single layer application above.

Screws in second (face) layer shall penetrate the first (base) layer of gypsum board.

13.  ACCESSORIES

13.1    Corner Beads

13.2   Casing Beads and Miscellaneous Trim

13.3   Aluminum moldings

14.  GYPSUM BOARD FINISHING – LEVELS OF FINISH

Gypsum board shall be finished in accordance with the following levels of finish.  (See Notes 26 and 27)

14.1   Levels of Finish

15.  ACOUSTICAL SEALANT

Seal joints between sound rated gypsum board partitions and floor, and joints where partitions abut walls or vertical surfaces of other materials; with acoustical sealant specified to prevent noise transmission and to provide required sound rating.

Seal joint between edge of gypsum board (both layers on two layer application) and adjoining surfaces on both sides of sound rated partitions, prior to taping and filling, with bead of sealant (two beads at two layer application).

Extrude a full 9mm (3/8”) diameter bead (two beads at two layer application) into each joint between first layer of gypsum board and floor or other adjoining surface to effectively block airborne sound transmission.

Seal joints around penetrations in sound rated partitions using glass fiber insulation to fill joints completely. (See Note 29)

16.  ACOUSTICAL INSULATION

Install sound insulation blankets between studs in sound rated partitions of thickness to provide sound rating required.  Install insulation tightly between studs as indicated and/or scheduled full height of partitions.  (See Note 30)

17.  MINERAL WOOL INSULATION

Install mineral wool insulation within fire rated partitions as indicated and/or scheduled, between steel studs. Install tightly between studs full height of partitions.  (See Note 31)

18.  GLASS MAT EXTERIOR GYPSUM SHEATHING BOARD APPLICATION

18.1    General

18.2    Sheathing

18.3    Wood Framing

18.4    Metal Framing

18.5   Joint treatment

19.  CUTTING AND FITTING

Include all cutting and fitting of gypsum board to accommodate recessed items in partitions and/or furring including, but not necessarily limited to, mechanical and electrical equipment (electrical cabinets), (fire hose cabinets), (electrical receptacles) and other recessed fixtures as indicated or required.

Notes to Specifier:

1. Water resistant gypsum board is not suitable for use in areas of excessive moisture, such as swimming pools and showers.
   Water resistant board should be used only as backing for ceramic tile in tub recesses without a shower and in areas where low humidity and moisture may be present.
2. There are other limitations on the use of water-resistant gypsum board:
   • It is not designed  for exterior  use and requires  weather-protected  storage.   Sustained  exposure  to moisture  can be detrimental to the board.
     It is not recommended for standard ceiling joist widths.  Because of the core additives, this product has a greater propensity to sag than does standard gypsum board when applied on ceilings. 12.7mm(1/2”) can span 305mm(12”oc) and 15.9mm(5/8”) can span 406mm(16”oc).
   • Attachment of water-resistant board to resilient channels is not recommended where ceramic tile is to be applied, as finish since flexing of the resiliently mounted may cause the tile to loosen.
   • Water-resistant board should be applied only to wood or steel framing.   Application directly to plaster, or another water- absorbent surface can lead to failure.
   • Water-resistant board should not be installed over a vapor barrier or on a wall which acts as a vapor barrier.  With a vapor barrier on one side of these panels and tile on the opposite, it is not possible for entrapped water to escape.  Also, the adhesive used with the tile may not develop a full bond because the vehicle carrying the adhesive cannot evaporate.
   • Joints in water-resistant board should not be taped or filled with joint compound in bath or shower enclosures which are to receive tile.  Conventional joint compounds are water-sensitive and will cause tile to delaminate if exposed to moisture.
3. The local availability of plain and Type ‘X’ or Type ‘C’ water-resistant board should be checked by the Design Authority with the gypsum board manufacturer or supplier.
4. Glass mat tile backer board or reinforced cementitious board may be used in lieu of water resistant gypsum board.  Joints must be taped and filled as per glass mat tile backer board or cementitious board manufacturer’s directions.
5. When Type ‘X’ or Type ‘C’ board is used to achieve a specific fire rated construction, the length and type of screw or nails employed  in  assembling  the  fire  test  design  assembly  shall  apply  and  should  be  specified  accordingly  in  the  project specifications.
6. Joint compound may be used as an adhesive.  The Design Authority should check with the compound manufacturer.
7. If aluminum moldings are required, the particular type(s) of moldings and/or trim required should be specified in the project specifications.
8. Use of acoustical sealant should be confined to concealed joints as required to prevent noise transmission through or at the perimeter of gypsum board partitions.  Exposed joints to be caulked should be specified under the applicable sealant section in the project specifications.
9. Acoustical sealant, insulating tape and acoustical insulation are generally installed in gypsum board partitions which are required to be sound rated.   The actual thickness of insulation and location of sealants and/or tape should be specified in the project specifications as necessary to provide the required sound rating.
10. Other associated  items, i.e. sheet lead for X-ray partitions; sheet lead for sound baffles; polyethylene vapor barrier on interior of exterior walls or other items, should be specified in the applicable sections in the project specifications.
11. Grouting of door frames is not a requirement of this gypsum board section (when installing frames in steel stud partitions) and if required, the grout should be specified in the project specifications, using materials as follows:
    ”Grouting for filling pressed steel door frames shall be one part hardwall plaster to not more than 2 ½ parts sand byweight, or 22.7 kg(50 lb.) hardwall plaster to 0.028 m3 (1 cu.ft.) perlite or vermiculite aggregate.”
12. Non-combustible mineral wool insulation is required within some fire rated partitions to obtain fire rating.  The Design Authority should check applicable U.L.C., U.L., or W.H. design test assemblies being used and include mineral wool insulation in the project specification if required.
13. Do not use nails to install reinforced cementitious board.
14. Temporary heat and ventilation is normally provided by the General Contractor under Division 1 – General Requirements and does not form part of the work of this section.
15. Any condensation forming on the metal of the window and door frames will damage the gypsum board and cause paint discolouration.
16. In fire rated construction, the method of apply the wallboard in the fire test assembly shall apply and if the spacing of screws is other than specified in Part 3, Item 6.3, the spacing should be specified accordingly in the project specifications.
17. When Type ‘X’ fire rated gypsum board is used to achieve a specific fire rated construction, the spacing of screws in the fire test design assembly shall apply and should be specified accordingly in the project specifications.
18. Where fire rating construction is specified, the adhesive shall be non-combustible to conform to that used in the applicable fire test assembly.
19. Type of base and face boards required and the method of application should be specified in the project specifications.  (See Part 4 – Guide Specification.)
20. For fire resistance rated construction, the methods of application shall apply and should be specified accordingly in the project specifications.
21. These standards do not recommend taping and filling of joints in water resistant wallboard board behind ceramic wall tile.
22. If supports exceed 400mm (16”) o.c. at ceramic tiled walls, two rows of blocking should be provided between the studs; one at mid-point, the other approximately 25mm (1”) above top of bathtub or receptor.  Blocking is required in all cases if tile is more than 6mm (/4”) thick.  Maximum support spacing to be 600mm (24”) o.c.  Specify such blocking in the appropriate section of the project specifications.
23. If aluminum moldings are to be used, they should be specified in the project specifications.  Refer to Part 2 – Products for type of moldings.
24. Joint filler, tape or corner beads should not be used on joints within areas to receive ceramic tile.
25. The Design Authority should ensure the following requirements have been met when specifying reinforced cementitious board.
    • Steel stud framing meets the design criteria for the intended use, and must be 0.84 mm  (0.033”) or heavier.
    • Steel stud framing shall meet AISI S201-07.
    • Studs are furred out flush with face of receptors and heavy gage anchor plates.
    • Wall framing lumber shall be of a suitable grade for its intended use.   It shall be a nominal 38 x 89mm (2” x 4”) or equivalent and shall bear the grade stamp of a recognized inspection agency.
26. The Design Authority should indicate the required Level of Finish for each area on a Room Finish Schedule.
27. The use of flat paint finish is recommended on gypsum board.  The Design Authority must indicate on the Room Finish Schedule which surfaces are to have an eggshell, semi-gloss or high gloss paint finish and also specify in the project specifications a skim coat for such surfaces.  Medium to dark colored paints perform best over a Level 5 finish.  No level of finish is designed to true up a wall surface that is uneven due to deviations in the substrate or framing.  Sanding between coats may be required, but care should be taken not to sand the exposed paper face.  This will cause the paper fibers to break and create uneven suction across the face of the board.  Some applicators sponge between coats.  A high solid latex primer coat should be applied to equalize surface suction.  When dry, the surface should be inspected for any blemishes or discrepancies and repaired.  At this point, the surface is ready for final decorating.  All joint treatments must be thoroughly dry before applying any decoration.  A damp sponge should be used to remove dust before decoration
28. In applications where gypsum board extends above ceiling, joints require taping only.   If other than taping is required then treatment of such joints shall be specified in the project specifications.  This does not include fire rated partitions which require to be finished in accordance with fire rating design assembly.
29. Foam gasket tape should be used between sound partitions and acoustic tile or other finished ceilings in lieu of acoustical sealant to avoid staining.
30. Specify any additional or special requirements for sound resistance rated construction.
31. Fire-rated construction should duplicate the materials and methods used for the tested assembly.
32. Grouting of door frames is not a standard requirement of these Standards and if required, grouting should be specified in the project specifications.  Refer to Part 2 – Products.
33. Casing trim at junction of floor level and gypsum board partitions is not normally installed unless specified or indicated on the drawings.
34. There are a variety of acceptable spray or roll on finishing products available on the market.  It is recommended that such products be previewed on a scale mock up to determine the acceptability of finish as required. Trowelled on application by a skilled tradesperson remains the most recommended means of achieving proper Level 5 finish.
35. Control joints shall be installed where a wall or partition runs in an uninterrupted straight plane exceeding 30 linear feet (9100mm).
36. Control joints in interior ceilings with perimeter relief shall be installed so that linear dimensions between control joints do not exceed 30 ft (9100mm) and total area between control joints does not exceed 2500 sq.ft. (84m2).