How to Pass the California C-35 Lathing and Plastering Contractor Exam

Independent-provider notice: Peerless Institute is not affiliated with, endorsed by, or sponsored by CSLB. Practice examples here are original study material.

Current CSLB C-35 Lathing and Plastering exam outline

The official CSLB C-35 Lathing and Plastering study guide applies to examinations scheduled on or after October 1, 2025. CSLB describes these percentages as approximate. The trade exam is closed book; check the current PDF and your exam notice before testing.

Section-by-section study guide

Use the outline as a checklist, not a promise that every bullet gets an equal number of questions. After a diagnostic, spend extra time on weak high-weight sections.

Planning and Estimating (15%)

CSLB lists interpret plans and specifications, estimate material, equipment, and labor, inspect job sites. Work from a plan or scope sheet: mark assumptions, units, quantities, dependencies, and any information that must be confirmed before estimating.

Lath Preparation and Installation (20%)

CSLB lists coordinate lath and plaster installation, prepare substrates, install metal framing and gypsum systems, install lathing materials, among other topics. Sketch the sequence from preparation through inspection or closeout. For each step, name the prerequisite, a common failure point, and a check before proceeding.

Plaster /Stucco Preparation and Installation (28%)

CSLB lists mix and apply scratch and brown coats, install plaster/stucco systems, install specialty plaster/stucco installations, clean up job sites. Sketch the sequence from preparation through inspection or closeout. For each step, name the prerequisite, a common failure point, and a check before proceeding.

Repairs (17%)

CSLB lists repair plaster/stucco installations. Build a symptom-to-test-to-cause sequence. Practice choosing a diagnostic step before selecting a repair, then explain how you would verify the result.

Safety (20%)

CSLB lists personnel safety, job site safety, cal/osha laws and regulations, personal protective equipment. For each scenario, identify the hazard, the first safe action, and which fact in the prompt changes the response. Verify technical requirements in the current applicable rules, not memory alone.

Two-, four-, and six-week study paths

Two weeks: Use this only if you already have broad recent experience and can practice daily. Diagnose on day one; spend the next several days on Plaster /Stucco Preparation and Installation (28%) and Lath Preparation and Installation (20%); rotate through remaining sections; finish with a timed mixed set and a review of every miss or guess.

Four weeks: Week 1: read the official guide, take a baseline, and build an error log. Week 2: work the highest-weight weak sections using drawings, calculations, or installation sequences. Week 3: cover remaining trade sections and safety. Week 4: take timed mixed sets and revisit weak topics with fresh questions.

Six weeks: Add more depth to each field section and retest a week after first reviewing it. Reserve the last week for mixed practice, the error log, and test-day instructions. These are Peerless example schedules, not CSLB requirements.

Original worked C-35 Lathing and Plastering example

Question: A plaster wall measures 30 ft by 10 ft and contains a 4-by-5-ft opening. What is the net surface area?

Answer: 280 sq ft.

Why: Gross area is 300 sq ft; subtract the 20-sq-ft opening. Add reveals, returns, and waste if the drawings require them.

This is an original study exercise, not a recalled CSLB question.

Choose your next practice step

• C-35 Lathing and Plastering printed study guide — structured reading and review.
• Law and Business exam guide — study this separate required examination too.

Frequently asked questions

What should I study first for C-35 Lathing and Plastering?

Start with a diagnostic, then prioritize weak sections with larger approximate weights. Plaster /Stucco Preparation and Installation is the largest section at 28%, but your own weak areas determine the order.

Is the C-35 Lathing and Plastering trade exam open book?

No. The current CSLB study guide says no reference materials may be used during the exam.

Are these Peerless questions actual state-exam questions?

No. Peerless uses original study questions; this page is based on the public CSLB content outline.

Do I also need Law and Business?

CSLB describes a separate Law and Business exam for contractor-license applicants. Check the official requirements that apply to your application.

Source: CSLB C-35 Lathing and Plastering Examination Study Guide; reviewed October 13, 2026. The official guide and examination notice control if information changes.