USG IMPERIAL Interior Ceiling Gypsum Base Sag-Resistant - Manual

Preparation Protect this product from moisture during storage and on the job. In cold weather, heat the interior of the building
to a minimum of 55 °F (13 °C) for an adequate period before the application of plaster, while basecoat and
finish is being applied and until the finish is dry. Air circulation should be kept at a minimum level during joint
finishing. Under normal working conditions, joints of veneer plaster systems may be treated by applying I
MPERIAL ®
Brand Type P (pressure-sensitive) or Type S (staple) to the joints and then applying the veneer plaster basecoat
or finish to preset the tape.
Use S HEETROCK ® Brand Joint Tape and S HEETROCK ® Brand D URABOND ® Setting-Type or E ASY S AND ™ Lightweight
Setting-Type Joint Compound to treat all joints and internal angles for veneer plaster systems when the
following conditions exist:
– rapid drying conditions due to low humidity, high temperature or excessive evaporation
– metal framing at 24
Љ o.c. is specified (single or double layer)
Installation I MPERIAL Brand Sag Resistant Gypsum Ceiling Base may be installed either perpendicular (preferred) or parallel
to the framing. All ends and edges should be placed over framing members except where edge joints are
perpendicular to framing. Use maximum practical lengths to minimize end joints. Over steel studs, arrange
direction of installation so that the lead edge of the base is attached to the open side of the stud flange first.
Bring ceiling base panels into contact with each other, but do not force into place. Fit abutting ends and edges
neatly; stagger end joints; arrange joints on opposite sides so they occur on different studs.
Begin driving fasteners in center of panel and work toward ends and edges, holding gypsum base in firm
contact with framing. Space fasteners as shown in the table and not less than 3/8
Љ from edges and ends of
panel. Drive fastener heads flush with surface without breaking face of paper. If ceiling base appears to be
loose from framing, install additional fasteners. Float vertical and horizontal interior corners by placing fasteners
8
Љ out from corner. Where framing is parallel with the corner, attach one panel to corner framing and float the
abutting panel. Cut and fit the panel neatly around pipes and other openings. Remove loose face paper around
cuts and use quick-setting plaster to close openings.
Maximum spacing Base and finish assembly Framing spacing (1)
1/2 Љ 12.7 mm One layer, 1-coat system 16 Љ or 24Љ (2) 406.4 mm
One layer, 2-coat system 16 Љ or 24Љ (2) 406.4 mm or 609.6mm (2)
Two layer, 1 & 2-coat system 24 Љ 609.6 mm
(1) For perpendicular or parallel application to framing. Perpendicular is preferred for maximum strength
(2) Setting-type joing compound must be used with metal framing when framing is spaced 24
Љ (609.6 mm) o.c.; this applies to both one- and
two-layer systems.
Control Joints Apply control joints, where required, over the face of the gypsum base. Cut to required length with fine-toothed
hack saw. Cut end joints square, align and butt together slightly gapped. Attach the control joint to the base
temporarily with 9/16
Љ rosin-coated staples spaced 12Љ o.c. along each flange. Complete the installation of the
control joint with fasteners (nails or screws) driven through the control joint flange into the framing on each side
of the joint. The protective plastic tape over the open groove should be left in place until finishing is completed.
Metal Trim Fasten ceiling base in normal manner but omit fasteners at framing member where metal trim is to be installed.
Leave a space 3/8
Љ to 1/2Љ wide between edge of base and face of jamb or wall. This provides space for hard-
ware and allows for expansion when trim is used for perimeter isolation. Slip trim over edge of base with
expanded mesh flange on face side. Fasten to base by nailing or stapling 12
Љ o.c.
Vinyl Trim Slip vinyl trim over ceiling base with long flange behind base. Install the base with the trim firmly abutting the
surface.
I
MPERIAL
®
Brand
Interior
Ceiling Gypsum Base
Application Tips
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