12.4 Doors, Windows & Finishes

Door and Window Installation

Proper installation follows the flashing, leveling, shimming, sealing sequence. The rough opening must be sized 2 inches wider and 2 inches taller than the nominal unit, providing a 1-inch shim space all around. The sill is leveled first; for doors, a sill pan flashing is installed with end dams before setting the unit. The unit is plumbed and squared with shims placed at hinge locations for doors and at 12-inch intervals for windows. Shims are not placed at random intervals because that can twist the frame.

Once the unit is plumb, level, and square, it is fastened through the nailing flange (windows) or through the hinges and jamb (doors). Flashing tape is applied in shingled order: sill first, sides overlapping the sill, head overlapping the sides. A bead of sealant at the sill and jamb joints completes the weather seal. The gap between the frame and rough opening is filled with low-expansion foam or backer rod and sealant. Never use standard expanding foam, which can bow the frame.

Exterior doors require additional attention to water management. The threshold must be sealed to the subsill with sealant, and the sill pan must extend the full width of the rough opening with upturned end dams at least 4 inches high. Door thresholds should be set at least 2 inches above the adjacent finished grade or deck surface to prevent wind-driven rain from entering at the threshold. For swinging doors, three hinges are standard for doors up to 80 inches; taller or heavier doors may require four. Hinge screws must penetrate at least 1-1/2 inches into framing, not just the jamb, to support the door weight and resist racking.

Commercial Code Notes

For commercial work governed by the 2018 IBC, doors and windows fall under several chapters: Chapter 10 (Means of Egress) sets door widths, swing direction, and panic hardware requirements; Chapter 7 (Fire and Smoke Protection Features) governs fire-rated opening protectives (listed and labeled fire-door assemblies); Chapter 11 (Accessibility) and ICC A117.1 set accessible door clearances, hardware heights, and opening force limits. The 2018 IECC sets the fenestration U-factor and SHGC limits that drive energy compliance.

Window Performance: U-factor and SHGC

The 2018 IECC sets fenestration performance limits by climate zone. Two metrics drive window selection:

• U-factor — rate of heat transfer through the entire window assembly (lower is better). The IECC maximum for most Arizona climate zones is 0.32 or lower.
• SHGC (Solar Heat Gain Coefficient) — fraction of incident solar radiation transmitted through the glazing (lower means less solar heat gain). Arizona's hot-dry climate rewards low-SHGC windows; the IECC sets a maximum SHGC of 0.25 in zones 2 and 3.

Quick Answer: U-factor measures heat transfer through the window (lower is better); SHGC (Solar Heat Gain Coefficient) measures solar radiation transmitted (lower is better in hot climates like Arizona).

Flashing Details for Water Management

Water management at openings follows the shingle principle — each layer laps over the one below so water sheds downward and outward. For windows: the sill pan is installed first with upturned end dams at the jambs; jamb flashing extends over the sill pan; head flashing extends over the jamb flashing. The WRB at the head is cut and folded over the head flashing. Common errors include skipping the sill pan, lapping the head flashing under the WRB (reversing the shingle), and failing to end-dam the sill.

Drywall Installation and Finishing

Drywall (gypsum board) is fastened with screws for steel framing or nails and screws for wood. Joints are taped with paper or fiberglass mesh tape and coated with joint compound in multiple layers. The Gypsum Association defines five levels of finish:

Quick Answer: Level 4 (three coats over tape, sanded smooth) is standard for residential flat or low-gloss paint. Level 5 adds a full skim coat for high-gloss paint or critical side-lighting conditions.

Flooring Types

Common residential and light-commercial flooring: hardwood (solid or engineered, nailed or floated), laminate (floating, click-lock), tile (ceramic or porcelain on cementboard or membrane), carpet (tack strip or glue-down), luxury vinyl (floating or glue-down), and polished concrete. Subfloor flatness tolerances vary; tile and floating floors require a flatter subfloor than carpet. The Tile Council of North America (TCNA) specifies a maximum 1/4-inch variation in 10 feet for tile installations. Expansion gaps are required at perimeter walls for floating floors, typically 1/4 to 3/8 inch, covered by baseboard. Hardwood flooring must acclimate to the interior humidity before installation (typically 3 to 5 days with HVAC running) to minimize seasonal movement.

Paint and Coatings

Interior paint types include latex (water-based, flexible, low odor) and alkyd or oil (harder finish, longer dry time). Paint systems use a primer (adhesion promoter and stain blocker) followed by one or two topcoats. Exterior coatings require UV and moisture resistance. Elastomeric coatings bridge hairline cracks and are used on stucco. Surface preparation (cleaning, sanding, priming) has more impact on durability than topcoat quality.

On the B-1/B-2 commercial general building trade exam, Doors & Windows carries 5 of 100 items and Finishes carries 6 of 100 items.