The Complete Guide to Drywall and Plaster

1. Day 1: Safety, dust and silica

Stage: Day 1

Key points

• Silica dust is the big health risk in finishing and sanding. California limits it: action level 25 ug/m3 and PEL 50 ug/m3, each as an 8-hour average. [S3]
• Employers must assess exposure at or above the action level, keep a written exposure control plan, and run a respirator program under 8 CCR 5144. [S3]
• Dry sweeping, dry brushing and compressed-air cleanup are restricted where they raise exposure; use wet methods and a HEPA vacuum. [S3]
• Table 1 of the rule lists controls for saws, drills, grinders and similar tools. It does not name drywall finishing or sanding, so the general assessment and respirator rules apply (application: verify). [S3] [C] verify
• A NIOSH health hazard report on drywall skim-coat sanding found an unfitted N95 was a failure point; use a fitted half-face P100. [S6]
• Wear safety glasses for cutting, mixing, sanding and overhead work. [P] crew practice [?] unverified
• Keep the work area sealed with plastic and a zipper door; seal return vents. [P] crew practice [?] unverified

Try it

Fit-check a half-face P100 respirator, then set up a sealed plastic doorway with a HEPA vacuum hookup. Supervisor checks the seal and the taped seams.

Practice in 3D

• Tool: Half-face respirator with P100 filters
• Tool: HEPA shop vacuum
• Tool: Plastic sheeting and zip-wall
• Tool: Safety glasses
• Tool: Disposable coveralls
• Tool: Air scrubber (negative air)

Self-check

2. The job and the boards

Stage: Day 1

Key points

• Interior wall and ceiling covering in a house is governed by CRC Chapter 7, section R702 (2025 CRC, effective 1 Jan 2026). [S1]
• Standard board comes in 3/8, 1/2 and 5/8 in thickness in the code table. [S1]
• 5/8 in Type X board appears for garage ceilings under habitable rooms. [S1]
• Water-resistant backing board (ASTM C1178, C1278 or C1396) is a base for tile but is never for direct water. [S1]
• Tub and shower backers come from Table R702.4.2: glass-mat gypsum, fiber-reinforced gypsum, cement-based. [S1]
• Finishes must meet flame-spread and smoke limits in R302.9. [S1]
• Standard board may not be directly exposed to weather or water. [S1]

Try it

Sort six sample pieces (standard, Type X, water-resistant, glass-mat backer, cement backer, lath) by label and say where each is allowed.

Practice in 3D

• Tool: Gypsum board (1/2 in and 5/8 in)
• Tool: 5/8 in Type X board
• Tool: Water-resistant gypsum backing board
• Tool: Tub and shower backer board

Self-check

3. Reading plans and the code table

Stage: Day 1

Key points

• Table R702.3.5 sets board thickness, orientation, framing spacing and fastener spacing. [S1]
• Single-ply 3/8 in board is not allowed on ceilings that get a water-based texture or support insulation; use thicker or sag-resistant board. [S1]
• Board runs at right angles or parallel to framing and all edges land on framing. [S1]
• Adhesives must meet ASTM C557 (foam, ASTM D6464). [S1]
• GA-216 is the application standard (editions 2021 and 2024 are listed); the full text was not read, so use the CRC table as the rule and follow the manufacturer. [S13] [S26] [?] source not opened
• CALGreen dust, waste and VOC rules for this trade: not found. [?] not found
• Check the County and City for the code edition they enforce; adoption dates may differ. [S8]

Try it

Read Table R702.3.5 aloud for: 1/2 in wall, 24 in framing, no adhesive. Answer: screws 12 in max.

Practice in 3D

• Math: Minimum screw length
• Tool: Drywall adhesive

Self-check

4. Hanging: ceilings first, then walls

Stage: Day 1

Key points

• Check framing: plumb, blocked, rough-ins done and inspected before board. [P] crew practice [?] unverified
• Hang the ceiling first so wall sheets tuck under the edge. [P] crew practice [?] unverified
• Use a lift or T-braces on ceilings. [P] crew practice [?] unverified
• Orient board to the table: perpendicular on ceilings with 24 in framing. [S1]
• All edges and ends land on framing. [S1]
• Stagger end joints; plan layout so ends land on studs or joists. [S1]
• Cut outlets small, then trim. [P] crew practice [?] unverified

Try it

Hang one 4x8 sheet on a mock ceiling frame at 16 in o.c. Supervisor checks that both ends land on joists.

Practice in 3D

• Math: Ceiling sheet count
• Math: Sloped ceiling board length
• Tool: Panel lift (drywall lift)
• Tool: T-brace (ceiling prop)
• Tool: Drywall T-square
• Tool: Drywall stilts
• Tool: Four-foot level

Self-check

5. Fastening to the table

Stage: Day 1

Key points

• Screws into wood: Type W or S per ASTM C1002, penetrating wood at least 5/8 in. [S1]
• Screws into cold-formed steel: at least No. 6; thin steel under 0.033 in needs Type S or bugle-head per ASTM C1513 with at least 3/8 in penetration. [S1]
• Ceiling 1/2 in, 16 in o.c.: screws 12 in max; wall 16 in o.c.: 16 in max; wall 24 in o.c.: 12 in max. [S1]
• Garage Type X ceiling: 6 in max screws, 24 in o.c.. [S1]
• With adhesive, spacing widens (e.g., 1/2 or 5/8 in wall, 24 in o.c.: 24 in screws). [S1]
• Set depth on a test piece so the head dimples without tearing paper. [S7] [?] read in summary only
• Fire-rated assemblies: one summary says 8 in or less; the 2025 CRC garage row says 6 in. Follow the listed assembly (contested). [S7] [?] read in summary only [S1] [C] contested

[S1] [C] verify vs state code Read the row for your board, location and framing spacing. Screw spacing is the maximum.

[S1] Adhesive must meet ASTM C557; foam adhesive ASTM D6464.

Try it

Drive 20 screws into a test board. Supervisor checks dimple depth by feel and spacing with a tape.

Practice in 3D

• Math: Field screws per sheet (spacing grid)
• Math: Adhesive vs. no adhesive fastener count
• Math: Minimum screw length
• Tool: Cordless screw gun (depth-set)
• Tool: Drywall screws
• Tool: Spacing marker (story pole or tape marks)

Self-check

6. Cutting and openings

Stage: Year 1

Key points

• Score the face paper, snap, cut the back paper. [P] crew practice [?] unverified
• Mark outlets from the box; cut small and trim. [P] crew practice [?] unverified
• Check behind the board for wires and pipes before sawing. [P] crew practice [?] unverified
• Rasp cut edges lightly. [P] crew practice [?] unverified
• Rotary cutout tools are fast but throw dust; wear PPE. [P] crew practice [?] unverified
• Seal edges of water-resistant board as the maker says. [S1]

Try it

Cut three outlet openings in a sheet; supervisor checks that the box fits with a gap no larger than the cover plate hides (verify spec). [C] verify

Practice in 3D

• Tool: Utility knife
• Tool: Drywall (jab) saw
• Tool: Drywall rasp
• Tool: Rotary cutout tool (spiral saw)

Self-check

7. Taping and compound

Stage: Year 1

Key points

• Embed tape in a thin coat of compound. [P] crew practice [?] unverified
• Tape types: paper (creased) and fiberglass mesh. [P] crew practice
• Drying-type compound dries by evaporation; setting-type hardens chemically. [P] crew practice
• Mix small batches; low drill speed to avoid air. [P] crew practice [?] unverified
• Knife sizes step up: 6 in, 10 in, 12 in for wider feathering. [P] crew practice [?] unverified
• Thin coats; let each dry before the next. [P] crew practice [?] unverified
• Compound coverage per sheet or per bucket: not found; use the product data sheet. [?] not found

Try it

Tape and first-coat a 4-ft joint. Supervisor checks for bubbles and thickness.

Practice in 3D

• Math: Joint tape length
• Tool: Joint compound (drying type)
• Tool: Paper joint tape
• Tool: Fiberglass mesh tape
• Tool: 6-inch taping knife
• Tool: 10-inch taping knife
• Tool: 12-inch taping knife
• Tool: Mud pan
• Tool: Hawk (mud or plaster)
• Tool: Setting-type joint compound
• Tool: Drill paddle mixer
• Tool: Metal corner bead
• Tool: Paper-faced corner bead
• Tool: Corner finishing trowel

Self-check

8. Finish levels 0 to 5 (GA-214-2021)

Stage: Year 1

Key points

• Level 0: no taping or finishing; temporary work. [S4]
• Level 1: tape embedded; concealed areas such as plenums and attics. [S4]
• Level 2: tape embedded and wiped; one coat on fasteners; tile substrate, garages. [S4]
• Level 3: one coat on joints and angles, two on fasteners; heavy and medium textures. [S4]
• Level 4: two coats flat joints, one on angles, three on fasteners; smooth walls with flat paint. [S4]
• Level 5: Level 4 plus a skim coat over the whole surface; gloss, dark paint or critical light. [S4]
• Priming before decoration is recommended at Levels 3 to 5. [S4]
• A design professional specifies the mock-up for Levels 3 to 5; on a house without one, agree a mock-up in writing. [S4]

[S4] The levels come from GA-214, not GA-216. GA-216 is the application and finishing standard; its text was not read. The "typical use" column is the research summary of S4; confirm in the standard.

Try it

Name the level for: bathroom with semi-gloss paint, garage, hall with orange-peel texture. Answers: 5, 2, 3.

Practice in 3D

• Math: Coat passes by finish level
• Tool: Raking light
• Tool: Skim-coat trowel

Self-check

9. Sanding and dust control

Stage: Year 1

Key points

• Use a pole sander with HEPA vacuum hookup and a fitted P100 respirator. The NIOSH report measured the lowest exposure with a power sander connected to a HEPA vacuum; it recommends pole sanding but did not measure it. [S6]
• Wet sanding sponges cut dust for light work. [P] crew practice [?] unverified
• Check with raking light between passes. [S4]
• Use the finest grit that still works. [S4]
• Run an air scrubber before, during and after. [P] crew practice [?] unverified
• Disposable coveralls come off in the sealed area; bag them. [P] crew practice [?] unverified
• No dry sweeping or compressed-air cleanup. [S3]

Try it

Sand a 4-ft joint with HEPA hookup. Supervisor checks dust on a black card held 2 ft away.

Practice in 3D

• Tool: Pole sander with HEPA hookup
• Tool: Drywall sanding screen
• Tool: Wet sanding sponge
• Tool: HEPA shop vacuum
• Tool: Raking light

Self-check

10. Prime, texture and paint-ready

Stage: Journeyman

Key points

• Prime after sanding and dust-clean. [S4]
• Joint compound flashes through paint if not primed. [S4]
• Texture: hopper sprayer, then knock down; test on scrap. [P] crew practice [?] unverified
• Level 3 is the minimum for heavy and medium textures. [S4]
• Ceiling texture needs 1/2 in board at 16 in o.c. or 5/8 in at 24 in o.c. (or sag-resistant). [S1]
• Check under raking light before paint. [P] crew practice [?] unverified

Try it

Prime a 4x4 test area and inspect for flashing under raking light.

Practice in 3D

• Tool: Drywall primer-sealer
• Tool: Texture hopper sprayer
• Tool: Knockdown knife

Self-check

11. Wet areas and tile backers

Stage: Journeyman

Key points

• Water-resistant board is a base for tile but never directly exposed to water. [S1]
• Do not install it over a Class I or II vapor retarder in tub or shower compartments. [S1]
• Seal cut edges per the manufacturer. [S1]
• Tub and shower backers must come from Table R702.4.2. [S1]
• Level 2 finish is the tile substrate level. [S4]
• Cement backer dust is a silica concern: cut wet or with dust capture. [S3]
• Waterproofing membranes: not covered by this research (tile trade). [P] crew practice [?] unverified

Try it

Read a backer board label and say what it is and whether it fits a shower wall.

Practice in 3D

• Tool: Water-resistant gypsum backing board
• Tool: Tub and shower backer board
• Tool: Moisture meter

Self-check

12. Fire-rated assemblies and garage ceilings

Stage: Journeyman

Key points

• Garage ceiling under habitable rooms: 5/8 in Type X, perpendicular, 24 in o.c., screws 6 in max. [S1]
• A listed assembly (UL/GA design) may require more; follow its listing. Listing details: not found. [?] not found
• Interior finishes must meet R302.9 flame spread and smoke limits. [S1]
• Keep joints on framing and do not swap thickness. [S1]
• County wildfire (Ch.7A / R337) text covers exterior elements; no drywall-specific rule found. [S8]
• Fire-rated spacing: sources disagree (8 in vs 6 in); use the listing. [S7] [?] read in summary only [S1]

Try it

Layout a garage ceiling with 5/8 in Type X on 24 in joists and count screws per sheet (answer 32).

Practice in 3D

• Math: Type X garage ceiling screws
• Tool: 5/8 in Type X board

Self-check

13. Plaster and lath

Stage: Master

Key points

• CSLB C-35 covers plaster coatings, lath and related metal studs and channels. [S2]
• Gypsum plaster takes 3 coats over metal lath, 2 coats over other permitted bases. [S1]
• Min finished thickness (from face of base): 5/8 in expanded metal lath, 1/2 in gypsum lath. [S1]
• Plain gypsum lath: 3/8 in at 16 in o.c. or 1/2 in at 24 in o.c. max supports; run at right angles. [S1]
• Veneer plaster: up to 3/16 in in one coat within the total thickness. [S1]
• Bag yield, cure and mix specifics: not found; use the product data sheet. [?] not found

[S1] [C] verify vs state code

Try it

Check lath spacing on a mock wall: 3/8 in lath on 19.5 in framing fails (margin -3.5 in).

Practice in 3D

• Math: Gypsum lath support spacing check
• Math: Plaster volume for a thickness
• Tool: Metal lath (expanded or wire)
• Tool: Gypsum lath (plain)
• Tool: Gypsum plaster (3-coat / 2-coat)
• Tool: Darby (plaster float)
• Tool: Hawk (mud or plaster)

Self-check

14. Take-offs and math

Stage: Year 1

Key points

• Wall area = 2(L+W)H minus openings. [P] geometry
• Sheets = ceil(area / sheet area x waste); 4x8 = 32 sq ft. [P] geometry
• Waste factors (about 10 percent) are rule of thumb: unverified. [P] crew practice
• Slope length = run x sqrt(1 + (rise/12)^2). [P] geometry
• Screws per sheet from spacing grid (a grid estimate; a 4x8 sheet at 16 x 16 in edge plus field is about 28 screws, versus 18 from the field grid alone), minimum screw length = thickness + 5/8 in in wood. [S1]
• Plaster volume = area x thickness / 12. [P] geometry
• Use the calculators to cross-check hand math. [P] crew practice [?] unverified

Try it

Take off a 16x12x8 room with a door and one window; compare with the calculator.

Practice in 3D

• Math: Wall area net of openings
• Math: Sheets to order with waste
• Math: Ceiling sheet count
• Math: Whole-room board take-off
• Math: Load on a panel lift or carry

Self-check

15. Failure modes and quality checks

Stage: Journeyman

Key points

• Wrong finish level for the paint or light is the costliest miss. [S4]
• No mock-up at Levels 3 to 5 when one is specified. [S4]
• Paint or texture without primer; joints flash. [S4]
• Ends not on framing, too few or too far fasteners. [S1]
• Overdriven or torn-paper fasteners. [P] crew practice
• Ceiling hung after walls. [P] crew practice
• Dust spread to unprotected rooms. [S6]
• Check under raking light before primer. [S4]

Try it

Walk a finished wall with a raking light and mark five flaws.

Practice in 3D

• Tool: Raking light
• Tool: Straightedge

Self-check

16. Licensing, permits and inspections

Stage: Journeyman

Key points

• CSLB C-9 Drywall covers installing gypsum board and its metal framing, taping, finishing and texture. [S28]
• C-35 covers lathing and plastering; C-26 merged into C-35 in 1998. [S2]
• A Class B contractor may take framing or carpentry alone; other trades only if the job needs at least two unrelated trades other than framing/carpentry, or by holding the license or subcontracting. [S11] [S12]
• Permit triggers for drywall: not found. County says most repairs and alterations need a permit; verify. [S8] [C] verify [?] not found
• Inspection order for this trade: not found (confirm locally). The County page states only that all building permits require inspections and the types vary with the scope of work. [S27] [?] not found
• CALGreen requirements for the trade: not found. [?] not found

Try it

Write the classification you would sub out for a drywall-only repair job and confirm with CSLB.

Self-check

17. Montecito, County and City of Santa Barbara

Stage: Master

Key points

• Montecito is unincorporated County of Santa Barbara; the City is a different jurisdiction. [S8] [S9]
• County: most repairs, alterations and retrofits need a building permit (stated by a nonprofit guide; verify). [S8] [C] verify
• High Fire Hazard Area: County amendments to CBC Ch.7A and CRC R337 exist (2022 editions named); no drywall rule found. [S8]
• City adopted amendments including the 2025 WUI Code on 2 Dec 2025 (no effective date found); not for Montecito. [S9]
• City construction hours 7:00 a.m. to 8:00 p.m. daily; stricter for some projects. [S10]
• County Board of Architectural Review: the County BAR packet (updated 31 Jul 2026) lists projects in the Montecito Community Plan area as subject to BAR, and lists "Interior alterations" under exemptions from BAR. [S31]
• County construction hours: the Montecito Association FAQ (undated, not the County) says construction may take place 7:00 am to 4:30 pm Monday to Friday only, and cites County Code Section 40-2 for amplified noise audible within 100 feet of a property line. [S32] [C] verify
• County stormwater, coastal zone, hillside and debris-flow rules, fees: not found. [?] not found
• Interior-only drywall and plaster work is exempt from BAR under the County packet; any exterior change is not covered by that exemption. [S31] [C] verify

Contacts

• City of Santa Barbara Community Development, 630 Garden St., Santa Barbara 93101; (805) 564-5578. City only. [S10]
• City Enforcement Hotline (equipment noise) (805) 897-2676; City Police Dispatch (805) 882-8900. City only. [S10]
• County permitting page: countyofsb.org Permitting Home (opened; navigation links only, no phone numbers or rules on the page). [S27]
• County Planning and Development 568-2000 and zoning violation hotline 568-3558, written without area code on the Montecito Association FAQ (805 is the local code; confirm before relying). [S32] [C] verify County Building and Safety direct number: [?] not found

Open questions to ask the County (Building and Safety)

1. Which code edition applies to permits filed now, and since when?
2. Does a drywall re-hang or plaster repair of a given size need a permit?
3. County construction hours for Montecito.
4. Confirm that the BAR interior-alterations exemption covers your scope (answered in the County packet; confirm for your parcel).
5. Required inspection sequence for board and insulation.

Try it

Call the County Building and Safety division (number: see Contacts; the Building and Safety direct line was not found) and ask the four open questions; log answers.

Self-check

18. Master topics: specifying and coordinating

Stage: Master

Key points

• Specify finish level per room in writing before taping. [S4]
• Build a mock-up with final paint under real light. [S4]
• Coordinate with paint, tile, electrical and insulation trades. [P] crew practice [?] unverified
• Fire-rated assemblies: match the listing, not the guess. [P] crew practice [?] unverified
• Silica: assessments, plan, competent person. [S3]
• Research gaps: GA-216 text, plaster yield, compound coverage, County rules. [P] crew practice [?] unverified

Try it

Write a one-page finish spec for a room: level, primer, paint sheen, light, mock-up.

Self-check