Chapter 4 of 520% of exam
Finish Trades
The finish trades cover everything the owner sees and touches after the structure is framed and weather-tight: wallboard and plaster, tile, flooring, paint, cabinets, glazing, and site landscaping. As the general building contractor you rarely swing every hammer yourself, but you must know each trade's code limits, quality grades, and sequencing well enough to coordinate the subs and catch defects before the final inspection.
Drywall, Plaster & Ceilings
Gypsum board (drywall) and plaster form most interior wall and ceiling surfaces. Fastener type and spacing, board thickness, and joint treatment all affect how a wall performs for fire, sound, and racking strength. In wet or high-moisture rooms you must switch from standard board to a moisture- or mold-resistant product, and never install ordinary paper-faced gypsum as a tile base in a shower.
Board thickness by spacing
1/2-inch gypsum board is standard for walls with studs 16 inches on center; for ceilings that must resist sag, use 5/8-inch board or 1/2-inch sag-resistant board, especially where framing is 24 inches on center.
2025 CA Residential Code §R702.3Fastener spacing
Nails or screws are typically spaced no more than 7 inches apart on ceilings and 8 inches apart on walls along framing; screws hold better and are required by many fire-rated assemblies.
2025 CA Residential Code Table R702.3.5No paper-faced gypsum in wet areas
Behind tile in tubs and showers use cement board, fiber-cement, or an approved glass-mat backer, not regular gypsum, so moisture cannot rot the paper facing.
2025 CA Residential Code §R702.4.2Minimum ceiling height
Habitable rooms, hallways, and bathrooms must have a finished ceiling height of at least 7 feet; measure after furring and finish are applied, not to the framing.
2025 CA Residential Code §R305.1Plaster coats
Traditional cement plaster over metal lath is applied in three coats (scratch, brown, finish) to a nominal 7/8-inch thickness on exterior lath, and each coat must be allowed to cure before the next.
2025 CA Residential Code §R703.6Tile & Stone
Ceramic, porcelain, and stone tile need a sound, flat, and (in wet areas) waterproof substrate. Movement in the framing, deflection in the floor, or a missing waterproof membrane are the usual reasons tile cracks or a shower leaks. The general contractor should verify substrate flatness and slope before the tile setter begins.
Waterproof shower pan
Shower floors require a water-resistant, sloped receptor with a membrane turned up the walls; the finished floor must slope 1/4 inch per foot toward the drain.
2025 CA Plumbing Code §411Backer board in wet walls
Wall tile in showers and tub surrounds must be set over cement, fiber-cement, or glass-mat backer board with a moisture barrier or bonded waterproof membrane behind it.
2025 CA Residential Code §R702.4.2Floor deflection limit
Tile floors need a stiff subfloor; ceramic tile is generally limited to L/360 deflection and natural stone to L/720, or the grout and tile will crack.
Industry standard (TCNA / ANSI); confirm with tile manufacturerMovement joints
Provide soft (caulked) movement joints where tile meets dissimilar materials and at changes of plane, such as inside corners and floor-to-wall transitions, to absorb expansion.
Industry standard (TCNA EJ171)Floor Covering
Resilient (vinyl, LVP), carpet, hardwood, and laminate each demand a flat, dry, and clean substrate. The most common callbacks come from moisture in a concrete slab that was not tested, or from wood flooring that was not allowed to acclimate. Sequence flooring after wet trades like paint and drywall mud are dry.
Test slab moisture first
Before gluing resilient or wood flooring to concrete, verify the slab moisture is within the flooring manufacturer's limit, commonly measured by relative humidity probe (often a maximum near 75-80% RH).
Industry standard (ASTM F2170); follow manufacturerAcclimate wood flooring
Solid and engineered wood must sit in the conditioned space for several days so its moisture content matches the home before installation, or it will cup or gap seasonally.
Industry standard (NWFA); follow manufacturerExpansion gap
Leave a perimeter expansion gap (commonly about 3/8 to 1/2 inch) around wood and laminate floating floors, hidden by base or shoe molding, so the field can move.
Manufacturer installation instructionsUnderlayment and vapor retarder
Over concrete or crawlspace framing, install the vapor retarder or underlayment the manufacturer specifies; skipping it voids the warranty and invites moisture damage.
Manufacturer installation instructionsPaint & Coatings (VOC)
Paint protects surfaces and is regulated in California for its volatile organic compound (VOC) content, which contributes to smog. Contractors must select compliant low-VOC products and prepare surfaces properly, since most coating failures trace back to dirty, damp, or unprimed substrates rather than the paint itself.
Low-VOC architectural coatings
Interior architectural coatings must meet CALGreen and California Air Resources Board VOC limits, such as roughly 50 g/L for flat and 100 g/L for nonflat paints; keep the product data sheets for inspection.
2025 CALGreen §4.504.2Surface preparation
Clean, dull, and dry the surface before coating; remove efflorescence, grease, and loose material, because paint bonds to a sound substrate, not to contamination.
Manufacturer / industry standard (SSPC / PDCA)Prime bare and repaired surfaces
New drywall, bare wood, and patched areas need a primer or sealer so the finish coat builds evenly and does not flash or peel.
Manufacturer application instructionsCoverage and coats
Estimate about 350-400 square feet of coverage per gallon per coat on smooth surfaces; textured or porous surfaces cover less, and most jobs need two finish coats.
Manufacturer coverage dataLead-safe work
In pre-1978 housing, disturbing paint requires certified lead-safe (RRP) practices to contain and clean up dust that may contain lead.
Federal EPA RRP Rule (40 CFR 745)Cabinetry & Millwork (NAAWS Grades)
Cabinets and architectural millwork are specified to a quality grade so the owner, designer, and shop agree on materials, joinery, and finish before fabrication. The North American Architectural Woodwork Standards (NAAWS) define three ascending grades that a general contractor should be able to read on a spec sheet.
NAAWS grade ladder
NAAWS defines Economy (basic, lowest cost), Custom (the most common commercial grade), and Premium (highest quality, tightest tolerances and best material matching); Custom is the default if the spec is silent.
North American Architectural Woodwork Standards (NAAWS)Cabinet blocking and anchoring
Install solid backing or hit the studs when anchoring wall cabinets; screws must reach framing, because a loaded upper cabinet can pull out of drywall alone.
Manufacturer / industry standardCountertop overhang support
Unsupported stone or quartz counter overhangs beyond roughly 10-12 inches need brackets or corbels to prevent cracking at the seam.
Industry standard (fabricator)Moisture and finish
Millwork should be delivered and installed only after the building is dry and conditioned, so panels and joints do not swell, shrink, or telegraph.
NAAWS; manufacturerWindows, Skylights & Doors
Fenestration is regulated for three separate reasons: energy loss (U-factor and SHGC), human safety at impact-prone locations (safety glazing), and life safety in bedrooms (emergency escape and rescue openings). The general contractor must confirm all three, because an inspector will reject a beautiful window that fails any one of them.
Safety (tempered) glazing locations
Use tempered or laminated safety glass in hazardous locations: in and next to doors, in tub and shower enclosures where the glass bottom is within 60 inches of the standing surface, and in large panes near the floor.
2025 CA Residential Code §R308.4Emergency escape opening size
Every sleeping room needs an egress window with at least 5.7 square feet of clear opening (5.0 at grade level), a minimum 24-inch clear height, and a minimum 20-inch clear width.
2025 CA Residential Code §R310.2.1Egress sill height
The bottom of the emergency escape opening may be no more than 44 inches above the finished floor so an occupant can climb out.
2025 CA Residential Code §R310.2.2Energy U-factor limit
Prescriptive fenestration in most climate zones is limited to a maximum U-factor around 0.30 and a solar heat gain coefficient (SHGC) around 0.23; verify the NFRC label matches the plans.
2025 CA Energy Code (Title 24, Part 6)Skylight flashing and rating
Skylights must be flashed per the manufacturer and meet the same energy label requirements; unit skylights carry an NFRC U-factor and SHGC just like windows.
2025 CA Residential Code §R308.6 / Energy CodeLandscaping
Finish work extends to the site: grading, drainage, hardscape, and irrigation. California regulates landscape water use tightly, so on many new and renovated landscapes the contractor must design to a water budget and install efficient irrigation. Grading away from the building protects everything built inside it.
Positive drainage away from building
Finished grade must slope away from the foundation, commonly at least 6 inches of fall within the first 10 feet, so water does not pool against the structure.
2025 CA Residential Code §R401.3Water-efficient landscape (MWELO)
New and rehabilitated landscapes above the size threshold must meet the state Model Water Efficient Landscape Ordinance water budget, adopted through CALGreen.
2025 CALGreen §4.304 / MWELOIrrigation controllers and sensors
Automatic irrigation systems generally require weather- or soil-moisture-based smart controllers and rain shutoff so the system does not run during rain.
2025 CALGreen §4.304.1Backflow protection
Irrigation connections to the potable supply need an approved backflow prevention device so fertilizer or pond water cannot siphon back into drinking water.
2025 CA Plumbing Code (backflow provisions)Test your knowledge
Practice questions on Finish Trades