Blue face paper engineered for plaster bond and controlled water absorption per USG
Key features
UltraLight rigid base positioning for veneer plaster systems per USG marketing
Tapered long edges for joint reinforcement consistent with Sheetrock joint treatment systems
Technical specifications
| R-Value | 0.45 |
|---|---|
| Thickness | 0.5 in |
| Width | 48.0 in |
| Length | 96.0 in |
| Coverage | 32.0 sq ft/pack |
| Material | Noncombustible gypsum core with specialized blue face paper for veneer plaster applications per USG Imperial Base |
| Fire rating | UL classification as to surface-burning characteristics and noncombustibility per USG; core is noncombustible gypsum per typical listings |
| Sound rating | Acoustic performance is assembly-dependent; gypsum finish layers contribute to STC in tested partition assemblies (ASTM E90). |
| Density | Nominal 1.25–1.35 lb/sq ft per USG; planning calculation uses 1.25 lb/sq ft unless job submittal states otherwise |
| Construction type | ASTM C1396 1/2 in. gypsum base for veneer plaster per USG |
| Application area | Veneer plaster base for interior systems where Imperial gypsum base is specified; follow USG plaster system literature |
Product details
Veneer plaster systems bond chemically and mechanically to a specialized substrate; swapping standard face-paper drywall for Imperial gypsum base breaks the plaster contractor’s workflow, risks bond failure, and voids the warranty chain on high-end plaster specifications.
UltraLight Imperial Base ships with distinctive blue face paper engineered for controlled water absorption and plaster bond; USG lists a nominal 1.25–1.35 lb per square foot range—YEARS plans at 1.25 lb per square foot unless the submittal states otherwise, about forty pounds on a four-by-eight sheet.
Compliance highlights include ASTM C1396 for gypsum base for veneer plaster, UL surface-burning classification language, and GREENGUARD Gold; USG’s performance table lists Moisture Resistance: No—do not spec this as a wet-area board without engineering approval.
Fastener spacing, screw set, and joint reinforcement follow USG veneer plaster literature, not generic drywall schedules; coordinate the plaster bidder before locking gypsum quantities.
Store panels flat and dry; wrinkled blue face paper telegraphs through thin veneer coats and triggers expensive reskim work.
Documents & certifications
Technical data sheet
Manufacturer-tested R-value, coverage, fire notes, and handling—use for submittals, RFIs, and field QA.
Download PDF (opens in new tab)Certifications & compliance
GREENGUARD Gold; UL classification per USG; ASTM C1396 gypsum base for veneer plaster
Frequently asked questions
Can I finish Imperial Base like regular drywall?
Can I finish Imperial Base like regular drywall?
It is engineered as gypsum base for veneer plaster systems per USG; follow the specified plaster system rather than treating it as standard ready-mix drywall mud finishing unless approved.
Is Imperial Base mold tough?
Is Imperial Base mold tough?
USG’s Imperial product page lists Moisture Resistance: No—select Mold Tough or other systems when the spec demands enhanced moisture performance.
Why is nominal weight a range?
Why is nominal weight a range?
USG publishes 1.25–1.35 lb/sq ft; use the submittal for the exact shipment and adjust crane picks to the master-pack label.
Does this replace cement board?
Does this replace cement board?
Only when the veneer plaster or tile system documentation explicitly allows gypsum base; wet-area tile often still requires cementitious backers per TCNA.