- What Are the TSI Exam Domains?
- Domain 1: Project Safety (13%)
- Domain 2: General Work Practices and Communication (7%)
- Domain 3: System Materials (10%)
- Domain 4: Tools and Equipment (6%)
- Domain 5: Materials Installation (27%)
- Domain 6: Membrane Seaming (22%)
- Domain 7: Flashings and Accessories Installation (11%)
- Domain 8: Job-Site Housekeeping (4%)
- Domain Weights at a Glance
- How Domains Map to the Online Eligibility Exam
- Prioritizing Your Prep by Domain Weight
- Frequently Asked Questions
- The TSI exam covers exactly 8 domains drawn from the NRCA Thermoplastic Systems Installer Job Task Analysis dated May 2020.
- Materials Installation (Domain 5, 27%) and Membrane Seaming (Domain 6, 22%) together account for nearly half of all assessed competencies.
- The online eligibility exam contains 60 multiple-choice questions with audio support and is available in English or Spanish.
- You need at least 24 months of thermoplastic installation experience, including pipe penetration and curb flashing, before you can sit for the assessment.
What Are the TSI Exam Domains?
The TSI Certification issued by the National Roofing Contractors Association (NRCA) is built around a formal Job Task Analysis (JTA) completed in May 2020. That JTA identified every critical task a working thermoplastic installer performs on a low-slope job site, then grouped those tasks into eight content domains. Every question on the 60-item online eligibility exam, and every skill assessed during the hands-on performance evaluation, traces directly back to one of these eight areas.
Understanding the domain structure is not just helpful - it is the most efficient path to certification. When you know that Domain 5 and Domain 6 together represent nearly half of all assessed content, you can allocate your study hours accordingly rather than treating every topic as equally important. This guide breaks down all eight domains, explains what each one actually tests, and shows you how to sequence your preparation for maximum return.
If you are still exploring whether this credential is right for you, the article What Is TSI Certification? covers the big-picture value proposition before you dive into domain specifics.
Domain 1: Project Safety (13%)
Domain 1: Project Safety
Weighted at 13% of the JTA, safety is the third-largest domain. The NRCA treats safety knowledge as a baseline expectation for any credentialed installer.
- Fall protection systems, including guardrails, personal fall arrest, and safety monitoring
- Hazard communication, SDS interpretation, and chemical handling for adhesives and solvents
- Electrical safety near rooftop HVAC equipment and lightning protection systems
- Personal protective equipment (PPE) selection and inspection
- Emergency response procedures and first-aid awareness on elevated work surfaces
Questions in this domain often present scenario-based situations: a crew member notices a damaged harness, or a foreman must decide how to stage materials near a roof edge. The exam rewards practical decision-making, not just recitation of OSHA regulation numbers. Review the full breakdown in the TSI Domain 1: Project Safety (13%) Complete Study Guide 2026.
Domain 2: General Work Practices and Communication (7%)
Domain 2: General Work Practices and Communication
At 7%, this domain covers professional conduct, job-site coordination, and the documentation skills that keep a thermoplastic project on track.
- Reading and interpreting project drawings, specifications, and manufacturer installation guides
- Communicating installation requirements to crew members and general contractors
- Documenting daily work progress, material usage, and weather conditions
- Understanding warranty requirements and how installation deviations affect coverage
Do not underestimate this domain simply because it carries a smaller weight. Misreading a specification or failing to document a deviation is one of the most common causes of warranty disputes in commercial roofing. For a deeper look, visit the TSI Domain 2: General Work Practices and Communication (7%) Complete Study Guide 2026.
Domain 3: System Materials (10%)
Domain 3: System Materials
Weighted at 10%, this domain tests your ability to identify, evaluate, and handle the materials that make up a complete thermoplastic roofing assembly.
- Distinguishing TPO, PVC, and KEE membrane types by composition and performance characteristics
- Insulation board types (polyisocyanurate, EPS, XPS) and their thermal properties
- Cover boards, air barriers, and vapor retarders - when each is specified and why
- Fastener types, pullout values, and substrate compatibility
- Adhesives, primers, and caulks - proper application conditions and shelf-life requirements
The online exam uses audio to read questions aloud, which means terminology you can recognize visually must also sound familiar when heard. Study material names the way they appear in manufacturer literature, not informal job-site shorthand. See the TSI Domain 3: System Materials (10%) Complete Study Guide 2026 for a full material inventory checklist.
Domain 4: Tools and Equipment (6%)
Domain 4: Tools and Equipment
The smallest domain at 6%, Tools and Equipment still appears on every exam because equipment errors cause both installation failures and safety incidents.
- Automatic hot-air welders: temperature settings, speed calibration, and maintenance checks
- Hand welders and nozzle types for detailing work at penetrations and corners
- Screw guns, drill bits, and plate-setting tools for mechanically attached systems
- Probe and seam probers for quality-control testing of completed welds
- Cutting tools, chalk lines, and layout equipment for sheet positioning
Exam questions here often focus on troubleshooting: what happens when a welder runs too hot, or how you verify a completed weld passes pull-test requirements. The TSI Domain 4: Tools and Equipment (6%) Complete Study Guide 2026 provides scenario walkthroughs for common equipment problems.
Domain 5: Materials Installation (27%)
Domain 5: Materials Installation
This domain covers every phase of putting the system together from substrate preparation through final sheet placement.
- Substrate inspection and preparation: deck type identification, moisture assessment, and surface cleaning
- Insulation layout patterns, staggering joints, and securing layers to prevent thermal bridging
- Membrane sheet layout: determining sheet orientation, managing slope direction, and minimizing field seam length
- Mechanically attached systems: fastener spacing patterns, plate placement, and pull-test requirements
- Fully adhered systems: adhesive application rates, open times, and proper roll-out technique
- Ballasted systems: stone size, weight distribution, and wind uplift considerations
- Pipe penetration and curb flashing details - these are explicitly required in the prerequisite experience and heavily tested
The prerequisite for the TSI certification specifically calls out pipe penetration and curb flashing details as required experience. That is a direct signal that these subtopics appear prominently in both the online exam and the hands-on performance assessment. Candidates who have done this work repeatedly in the field still benefit from studying the NRCA technical documentation to ensure their field habits align with the standardized procedures the assessors evaluate.
Practice questions mapped to this domain are available at TSI Exam Prep's practice test platform, where you can filter by domain to focus your repetitions efficiently.
Domain 6: Membrane Seaming (22%)
Domain 6: Membrane Seaming
Hot-air welding is the defining skill of a thermoplastic installer, and this domain tests every aspect of creating a watertight, durable seam.
- Seam preparation: cleaning, priming, and verifying proper overlap width (typically 1.5 inches minimum weld width)
- Automatic welder setup: preheat time, temperature calibration for ambient conditions, and speed settings
- Hand-welding technique for T-joints, inside corners, pitch pockets, and areas inaccessible to automatic equipment
- Seam inspection: visual checks for edge bleed and consistent bead, probe testing, and cut-sample evaluation
- Defect identification and repair: blisters, voids, and edge lifts - causes and correct remediation procedures
- Environmental conditions: how temperature, humidity, and wind affect weld quality and required parameter adjustments
For the hands-on performance assessment, candidates either complete a mockup evaluated by an NRCA Qualified Assessor or submit approved photo and video media. Either way, seam quality is a primary evaluation criterion. Assessors look for consistent overlap width, proper edge bleed, and clean T-joint construction - details that separate a credentialed installer from an uncertified one.
Domain 7: Flashings and Accessories Installation (11%)
Domain 7: Flashings and Accessories Installation
Flashings and accessories carry 11% of the JTA weight and represent the most failure-prone areas of any low-slope thermoplastic system.
- Termination bar installation: proper fastening schedules and sealant application at exposed edges
- Pre-fabricated accessories: walkway pads, pitch pockets, pipe boots, and prefabricated corners
- Field-fabricated flashing: inside and outside corners, T-joints at penetrations, and curb cap details
- Drain sumps, overflow drains, and the membrane integration technique for each
- Parapet walls and edge metal systems: cleat attachment, metal integration, and counter-flashing sequences
Flashing failures account for a disproportionate share of roofing warranty claims. The exam reflects this reality by devoting 11% to a topic that covers a comparatively small physical area of any roof system. Understanding why each flashing detail is sequenced the way it is - not just memorizing the steps - is essential for both the multiple-choice questions and the performance assessment.
Domain 8: Job-Site Housekeeping (4%)
Domain 8: Job-Site Housekeeping
The smallest domain at 4%, housekeeping covers material storage, waste management, and end-of-day site conditions.
- Proper storage of membrane rolls: temperature requirements, protection from UV exposure, and moisture control
- Adhesive and solvent storage: flammability ratings, container labeling, and disposal regulations
- Scrap membrane and packaging disposal: environmental compliance and site-cleanliness standards
- Securing materials and equipment at end of shift to prevent weather damage and theft
Four percent still represents roughly two or three questions on a 60-question exam. These are among the most straightforward questions on the test - candidates who have worked professionally on commercial roofing sites typically answer them correctly without intensive study.
Domain Weights at a Glance
| Domain | Name | JTA Weight | Approximate Questions (60-item exam) |
|---|---|---|---|
| 1 | Project Safety | 13% | ~8 |
| 2 | General Work Practices and Communication | 7% | ~4 |
| 3 | System Materials | 10% | ~6 |
| 4 | Tools and Equipment | 6% | ~4 |
| 5 | Materials Installation | 27% | ~16 |
| 6 | Membrane Seaming | 22% | ~13 |
| 7 | Flashings and Accessories Installation | 11% | ~7 |
| 8 | Job-Site Housekeeping | 4% | ~2 |
Approximate question counts are based on the 60-item exam format and published domain percentages from the NRCA Low-Slope Roof Systems Exam Content Outline dated November 2020. The actual distribution may vary slightly.
How Domains Map to the Online Eligibility Exam
The TSI certification uses a two-part format. The first component is the online eligibility exam: 60 multiple-choice questions with audio narration, available in English or Spanish. This exam is administered through NRCA PROCertification's online platform - no third-party testing center like Pearson VUE or Prometric is involved. You will need valid government-issued photo ID to access the exam session.
The second component is the hands-on performance assessment conducted by an NRCA Qualified Assessor. This can take place on a physical mockup or through approved photo and video media submission. The assessor's compensation is negotiated separately and is not included in the certification fee, so factor that into your total cost planning. The full cost picture - including the $799 member and $1,599 nonmember certification fees, $199/$399 retake fees, and renewal pricing - is detailed in the TSI Certification Cost 2026: Complete Pricing Breakdown.
Key Takeaway
Your eligibility exam result is valid for 12 months. If you pass the online component but have not completed the hands-on assessment within that window, you will need to retake the eligibility exam before proceeding. Plan both components in advance to avoid paying an unnecessary retake fee.
Domain 5 (Materials Installation) carries even more weight on the online exam - 37% according to the published Exam Content Outline - compared to its 27% share in the JTA. This difference reflects the online exam's specific emphasis and is another reason to treat Domain 5 as your primary study priority.
Prioritizing Your Prep by Domain Weight
Most candidates have real job-site experience across all eight domains before they ever register. The challenge is converting that experience into reliable multiple-choice performance and consistent hands-on execution under assessment conditions. A weight-based study schedule helps bridge that gap efficiently.
Domain 5: Materials Installation + Domain 6: Membrane Seaming
- Review NRCA technical documentation for mechanically attached, fully adhered, and ballasted systems
- Study automatic and hand welder parameters for varying ambient conditions
- Complete targeted practice questions for both domains at the TSI practice test platform
- Sketch pipe penetration and curb flashing sequences from memory, then compare to specification drawings
Domain 1: Project Safety + Domain 7: Flashings and Accessories
- Review fall protection system selection criteria and PPE inspection checklists
- Study termination bar schedules, pitch pocket construction, and drain integration details
- Practice scenario-based safety questions that require a decision rather than a fact recall
Domains 2, 3, 4, and 8 + Full Review
- Work through material identification exercises for TPO, PVC, and KEE membranes
- Review specification-reading and warranty-documentation requirements
- Take a timed 60-question practice set simulating full exam conditions
- Identify any domains where your score falls below your personal target and review those sections
The TSI Study Guide 2026: How to Pass on Your First Attempt provides a more detailed week-by-week approach including specific topic lists within each domain. If you are wondering how challenging the exam is in practice, How Hard Is the TSI Exam? Complete Difficulty Guide 2026 walks through the cognitive complexity of the question formats you will encounter.
Frequently Asked Questions
Based on the published Exam Content Outline, Materials Installation carries 37% of the online eligibility exam's emphasis, which translates to approximately 22 of the 60 multiple-choice questions. This is significantly higher than its 27% share of the Job Task Analysis, making it the single most important domain to master before exam day.
The hands-on component conducted by an NRCA Qualified Assessor focuses on performance skills rather than knowledge recall, so it most directly reflects Domains 5 (Materials Installation), 6 (Membrane Seaming), and 7 (Flashings and Accessories Installation). However, safety practices (Domain 1) and housekeeping (Domain 8) are observable behaviors that an assessor may note during any skills evaluation.
Yes. The online eligibility exam is available in both English and Spanish, and audio narration of questions and answers is provided in both languages. This accessibility feature is built into the NRCA PROCertification platform and does not require a separate request or additional fee.
The TSI online eligibility exam is scored on a pass/fail basis overall - there is no domain-by-domain pass/fail breakdown reported to candidates. If you do not pass, you may retake the exam by paying the retake fee ($199 for NRCA members, $399 for nonmembers). Use your preparation time to identify which domains felt weakest during your practice sets and concentrate your review there before retesting.
The current domain framework comes from the Thermoplastic Systems Installer Job Task Analysis dated May 2020 and the Exam Content Outline dated November 2020. NRCA periodically revises its JTAs to reflect industry changes, so candidates approaching renewal should verify whether an updated JTA has been published. Renewal itself requires documented system-specific work experience plus technical and safety training - not a retake of the original 60-question exam - and carries a $199 member or $399 nonmember fee.