Hardiflex boards can be installed
over wood or steel framing. All construction shall comply
with local building codes, including the use of vapor barriers where
required. Unheated spaces above ceilings should be properly
Framing members and other surfaces must
be straight, true, of uniform dimensions and properly aligned. Petronne
steel framing is recommended.
- Hardiflex boards should be installed
on the ceilings first. Application at right angles to the
framing is preferable.
- Unless specified on fire or sound
rated assemblies, horizontal wall application is recommended to give
added strength and reduce the number of joints.
- Starting in the upper corner of the
wall, work across and down. Ends and edges of sheets should be
touching but not forced tightly together.
- Holding Hardiflex board firmly
against the framing, begin fastening in the center of the sheet and
moved outward toward ends and edges.
- Set fasteners heads slightly
indented from the surface without breaking the face paper or
damaging the gypsum core.
- Installed sheet in a brick pattern
with the ends staggered and supported by framing members.
Joints shall not fall on the same studs as those directly on the
opposite side of the wall.
- Cut openings out of full sheets or
lay out joints to fall on the studs nearest the center of the doors
and windows. Where possible, position full sheets to extend
completely above and below openings and avoid
Control joints, as specified and
detailed by the architect, shall be installed in the following situations:
- In ceilings exceeding 2500 sq. ft.
in area and where the framing or furring changes direction.
The distance between control joints shall not be greater than 50 ft.
in either direction.
- In partition, wall and wall furring
runs exceeding 30 ft. in length. Distances between control
joints should not be greater than 30 ft.. Wall or
partition height door frames may be utilized as control joints.
- Opposite of where a control joint
occurs in the exterior base wall construction.
- To coincide whenever possible with
construction joints of the building.
When partitions are erected to span the
full height of the slabs between floors as required for fire or STC
rated assemblies, a perimeter relief joint shall be used at the top to
accommodate normal structural slab or beam movement without loading
and Surface Preparation
These areas should be finished
in accordance with ASTM S 840, the GA - 216 and the
joint compound manufacturer's instructions.
- No treatment of joints shall be done
until the interior temperature has been maintained at a minimum of
50°F for at least 48 hours prior to application of compounds and
until all materials have completely dried. Adequate continuous
ventilation must also be provided.
- Fill and level joints with joint
- Embed tape into the wet compound and
allow to dry. For inside corners, crease the tape and work it
- Apply a second coat of compound
across the joint, feather to approximately 4 inches on each side.
- Apply a third coat of compound and
feather to approximately 6 inches.
- Allow each coat of compound to dry
- Attach corner bead to outside
corners and apply three coats of compound. Feather out each
coat as described in steps 4 - 6.
- Spot cover all fastener heads with
three coats of joint compound applied in different directions.
- Lightly sand the last coat of all
treated areas, taking care no to rough the surrounding gypsum board
paper. Smoothing can also be accomplished with a damp
- Gypsum board must not be used
in areas that are continuously or repeated exposed to excessive
moisture or steam such as saunas, gang shower rooms or swimming
- Gypsum board should not be exposed
to sustained temperatures exceeding 125°F.
- The weight of ceiling insulation
shall not exceed 2 pounds per square foot.
- Sheets should not come in direct
contact with concrete masonry or other surfaces that have a high
for use with radiant heat ceilings.
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