Pre-rock drywall, an innovative construction method, offers numerous advantages within the commercial drywall and construction industry, even if it’s unfamiliar to you.
Conventionally, gypsum panels get installed after roofing materials are in place and windows are set up. This process ensures a dry environment for the subsequent installation of drywall and other finishes, protecting them from rain damage once the building’s envelope is sealed.
This precautionary approach is adopted because gypsum boards, being paper lined, react poorly to exposure to the elements, particularly water.
By installing drywall in a dried-in building, you not only shield it from environmental harm but also simplify the installation, avoiding the challenges of fitting around piping penetrations and ducts.
Pre-rock drywall, on the other hand, enables contractors to install drywall before MEP (Mechanical, Electrical, Plumbing) installation and before the building is dried-in. This method employs moisture and mold-resistant gypsum panels designed for exposure to the elements.
Pre-rocking offers a faster, more accessible alternative to traditional installation methods, making it a win-win scenario when the building owner is willing to invest in the higher cost of pre-rock drywall material.
Why Do We Pre-Rock Drywall?
Despite the initial perception of risk, pre-rock drywall installation yields numerous benefits, primarily by allowing early drywall installation in the construction process.
1. Faster, Cleaner Drywall Install Before Mechanical Trades
In traditional construction, drywall installation follows MEP rough-ins, metal framing, and window installation. This often results in drywall panels being awkwardly fitted around ducts and piping, leading to quality and fire-resistance issues.
Pre-rock drywall prioritizes drywall installation, ensuring higher quality and code-compliant gypsum panels. Other trades can then work around the precisely installed drywall, guaranteeing tighter fits and simpler job site installation.
2. Speed Up The Construction Schedule
The most significant advantage of pre-rock drywall is its ability to expedite the construction schedule. Using moisture-resistant drywall, installation can commence earlier in the construction process, even before the roof is completely watertight. This allows wall framing and MEP rough-in trades to finish their work ahead of schedule, saving several weeks or months in the overall project timeline.
When to Pre Rock Drywall
Pre-rock drywall is a viable option for almost any construction project, provided it complies with local ordinances. It is commonly employed in healthcare construction, where timely completion of medical facilities is critical.
Although ASTM C840 mandates keeping drywall dry and protected from the elements, alternative high-performance gypsum wallboard products are available to meet moisture exposure requirements. Pre-rock drywall simply modifies the construction sequence to place drywall ahead of roofing materials, ensuring compliance with the allowable exposure duration of up to 12 months.
As long as construction can conclude within the specified timeframe for pre-rock gypsum panels, this method is a convenient and rapid installation solution.
Top-Down Drywall Installation
Known by several names like “pre-dry-in construction,” “pre-rocking,” “topping out,” or “top-down construction,” this approach coordinates the installation of metal framing and drywall before HVAC, electrical, and plumbing trades commence their work.
While some construction managers may opt to install drywall more extensively, the fundamental concept remains the same: exposing gypsum boards to the elements briefly for faster, safer installation, and finishing for other trades.
Best Pre-Rock Drywall Products to Use
Choosing the right mold-resistant panel is critical because pre-rock drywall will be exposed to the elements for an undetermined period. Most pre-rock drywall utilizes glass mat instead of traditional paper-faced paneling, typically warrantied for up to 12 months of weather exposure.
Additionally, obtaining architect approval for product data and submittals before ordering any material is essential to ensure compliance.
1. Gold Bond eXP Interior Extreme Gypsum Panel
Gold Bond’s eXP Interior Extreme Gypsum Panels are a superb choice for interior applications with moisture and mold concerns, featuring a 12-month warranty for typical weather conditions. They are suitable for pre-rock applications and are compatible with wood or metal studs, boasting the highest mold resistance and water-resistant rating per ATSM D3273.
2. Georgia Pacific DensArmor Plus Interior Drywall
ASTM D3273 compliant, DensArmor Plus Interior Drywall features fiberglass mats instead of paper facings, making it ideal for high humidity environments and commercial construction. With a standard 12-month warranty for typical weather exposure in pre-rock conditions, its reinforced design is perfect for areas prone to abuse, such as dormitories and hospital walkways. The product is also fire-rated and noncombustible per ASTM E136 and BS EN 13501-1.
3. Pabco Glass Interior Drywall
Pabco Gypsum’s Glass Interior Drywall excels in pre-rock conditions, offering the highest moisture and mold resistance rating due to its fiberglass-reinforced core. These panels come in a ⅝” Type X fire-resistant model to meet code requirements and are designed for easy installation and finishing with joint compound, making them ideal for top-down construction in both commercial and residential settings.
4. CertainTeed GlasRoc Interior Drywall Panels
CertainTeed’s GlasRoc Interior Drywall Panels are a versatile choice, boasting mold resistance, moisture resistance, fiberglass reinforcement, and fire rating. They stand out with their innovative face panel featuring tapered edges, providing a superior finish suitable for indoor decoration. These panels are also approved for use in exterior soffits, making them an excellent option for pre-rock drywall applications.
5. USG Glass Mat Mold Tough Interior Drywall
USG’s Glass Mat Mold Tough Interior Drywall is an exceptional choice for pre-rock applications, even warrantied for up to 3 years against manufacturing defects. This GREENGUARD Gold-certified product is low VOC emitting and available in ½” and ⅝” variants to accommodate various commercial or residential rating requirements.
6. Georgia Pacific ToughRock Mold-Guard Drywall
While Georgia Pacific ToughRock Mold-Guard Drywall is moisture and mold-resistant, it’s not recommended for pre-rock conditions. Instead, another of their products, the DensArmor Plus Interior Drywall, is the preferred choice for high-humidity areas like showers, kitchens, and laundry rooms.
Things to Look Out for When Pre-Rocking Drywall
When pre-rocking drywall, be vigilant regarding moisture and mold issues. Despite product certifications for exposure to the elements, moisture damage and mold growth can still occur and pose problems in the future.
Pay attention to excess moisture around window and door openings in exterior walls and be cautious of water pooling in interior wall metal framing tracks, which, when combined with dirt or dust from exposure to the elements, can create ideal mold conditions.
While fiberglass-reinforced drywall is designed to withstand the elements in pre-rock conditions, other building materials may not. Screws, fasteners, and water-absorbent materials like wood and insulation may not be suitable for prolonged exposure to high moisture levels.
Make sure to monitor for excess water absorption or rusting in materials intended for indoor use.
References:
ASTM C840-20 – Standard Specification for Application and Finishing of Gypsum Board
