DRYWALL SYSTEMS

The information given below is to provide all our customers and visitors with useful general information on drywall systems (specifications, construction techniques, usage details and level of services provided).

Drywall is one of the most commonly used building materials and techniques in the world. It is known under different names according to the region where it is used - gypsum board, wallboard, plasterboard, gib, rock lath, gyprock, rigips, etc.The technical specifications of the building materials mentioned above are identical or similar and they are used globally for the finish construction of interior walls and ceilings.

A drywall panel is made of a paper liner wrapped around an inner core made primarily from gypsum plaster, which stands for the semi-hydrous form of calcium sulfate (CaSO4.½ H2O). The raw gypsum (mined or FGD) must be calcinated (via natural gas technology) before use. The plaster is mixed with fiber (typically paper and/or fiberglass), plasticizer, foaming agent, potash as an accelerator, EDTA or other chelate as a retarder, various additives like fiberglass or vermiculite that increase mildew and fire resistance (very important implementation specification) and water. This is then formed by pressing together a core of wet gypsum between two sheets of heavy paper or fiberglass mats. When the core sets and is dried in a large drying chamber, the "sandwich" shaped final product becomes rigid and strong enough for use as a building material.

Drywall is typically available in wide sheets of various lengths. With the rising popularity of high ceilings in new home construction, wider panels have become commonly available as well. Larger sheets make increase time efficiency – the installations are faster, since the number of joints that must be finished is significantly reduced. Often, a sizable quantity of any custom length may be ordered, from factories, to exactly fit ceiling-to-floor on a large scale project.

The most commonly used drywall is one-half-inch thick but can range from one quarter (6.35 mm) to one inch (25 mm). For soundproofing or fire resistance, two layers of drywall are frequently laid at right angles to each other.

Regarding its fire resistance specifications drywall provides a thermal resistance R-value of 0.32 for three-eighths-inch board, up to 0.83 for one-inch board. In addition to increased R-value, thicker drywall has a higher sound transmission class.

Drywall systems are exceptionally time and cost effective, since large surfaces could be completed in short periods of time. In large-scale commercial construction projects, the work of installing and finishing drywall is often split between the drywall specialists who install the wallboard, and those who finish the joints and cover the nailheads with drywall compound.

Drywall is cut to size, using a large T-square. Small features (holes for outlets and light switches) are usually cut using a keyhole saw or a small high-speed bit in a rotary tool – this procedure is followed by fixing the drywall to the wall structure.

Drywall fasteners (drywall clips or stops) are now commonly used in both residential and commercial construction. They have supporting function for interior drywall and are also used to replace the non-structural wood or metal blocking. Saving material and labor expenses, minimizing truss uplift, increasing energy efficiency, simplifying procedures, fasteners are rapidly implemented in the industry, especially in green building developments.

In 1990, the consensus document Levels of Gypsum Board Finish (GA-214-96) was officially introduced. It was created to "precisely describe" and determine the desired finish of walls and ceilings prior to final decoration. This precise description enables contractors to better understand the requirements of architects and building owners in order to guarantee customer’s satisfaction. The specifications also allow the bidder to consider the correct labor and materials for the final finish.

GA-214-96 establishes the following specifications:

Level 0
No taping, finishing, or accessories required.
Usage: Temporary construction or when final decoration is undetermined.

Level 1
All joints and interior angles shall have tape set in joint compound. Surface shall be free of excess joint compound. Tool marks and ridges are acceptable.
Usage: Above false ceilings or other areas which are out of public view where a degree of fire and noise resistance is required.

Level 2
All joints and interior angles shall have tape embedded in joint compound and wiped with a joint knife leaving a thin coating of joint compound over all joints and interior angles. Fastener heads and accessories shall be covered with a coat of joint compound. Surface shall be free of excess joint compound. Tool marks and ridges are acceptable. Joint compound applied over the body of the tape at the time of tape embedment shall be considered a separate coat of joint compound and shall satisfy the conditions of this level.
Usage: As a substrate for tile walls and ceilings as well as in garages, warehouses, and other places where appearance is not a primary concern.

Level 3
All joints and interior angles shall have tape embedded in joint compound and one additional coat of joint compound applied over all joints and interior angles. Fastener heads and accessories shall be covered with two separate coats of joint compound. All joint compound shall be smooth and free of tool marks and ridges. It is recommended that the prepared surface be coated with a drywall primer prior to the application of final finishes.
Usage: Suitable base for heavy-medium textured paint or other thick finishes.

Level 4
All joints and interior angles shall have tape embedded in joint compound and two separate coats of joint compound applied over all flat joints and one separate coat of joint compound applied over interior angles. Fastener heads and accessories shall be covered with three separate coats of joint compound. All joint compound shall be smooth and free of tool marks and ridges. It is recommended that the prepared surface be coated with a drywall primer prior to the application of final finishes.
Usage: "Standard" household and office walls. Used with light or non-textured finishes. Not suitable for harsh lighting conditions which may highlight minor imperfections.

Level 5
All joints and interior angles shall have tape embedded in joint compound and two separate coats of joint compound applied over all flat joints and one separate coat of joint compound applied over interior angles. Fastener heads and accessories shall be covered with three separate coats of joint compound. A thin skim coat of joint compound, or a material manufactured especially for this purpose, shall be applied to the entire surface. The surface shall be smooth and free of tool marks and ridges. It is recommended that the prepared surface be coated with a drywall primer prior to the application of finish paint.
Usage: The skim coat is a final leveling agent suitable to smooth out a surface to be used under the harshest lighting conditions that may otherwise highlight any imperfections under the finished surface. This finish is highly recommended for gloss and entirely non-textured surfaces.