What Is A RMI?

What an RMI Actually Is

If you have searched "what is a RMI" in the context of home safety, construction trades, or environmental work, the answer is this: an RMI is a Radon Mitigation Installer. It is the credential held by technicians who physically install systems that reduce radon gas concentrations in homes and buildings. Radon is a naturally occurring radioactive gas that seeps up from soil and rock and can accumulate indoors. An RMI is trained to design the installation approach, find the pathways radon uses to enter a structure, and build the mitigation system that pulls it out.

The RMI designation is the entry-level, supervised tier of radon mitigation certification. It is distinct from the supervisory and professional tiers (often abbreviated RMS and RMP) and distinct from any state license a jurisdiction may require. This article is about the supervised Radon Mitigation Installer credential only. For related background on the terminology, see our explainers on what RMI stands for and the meaning of RMI.

Who Issues the Credential

The RMI certification is issued by the National Radon Proficiency Program (NRPP). NRPP sets the examination objectives, administers the exam, defines the training and prerequisite requirements, and maintains the certification roster. When a homeowner, real estate agent, or state radon office wants to verify that an installer is credentialed, the NRPP listing is the reference point.

Because NRPP controls the rules, the details can change. Exam delivery, fees, and prerequisites have all been updated in recent years, and candidates should treat NRPP's own pages as the authority for current logistics. Our RMI certification overview and explainer on what RMI certification involves track the credential at a higher level.

What a Radon Mitigation Installer Does on the Job

The day-to-day work of an RMI is hands-on and technical. Most residential mitigation involves some form of sub-slab depressurization: drilling into a foundation slab, creating a suction point, routing PVC piping, installing a radon fan, and exhausting the gas safely above the roofline. But the job is much more than running pipe. A competent installer must:

• Talk with the homeowner about what the work involves, what it will change in the house, and what results to expect
• Diagnose how radon is getting in, including slab cracks, sump pits, floor-wall joints, crawlspaces, and penetrations
• Choose and execute an installation strategy suited to the foundation type
• Work safely around combustion appliances, electrical components, dust, and confined spaces
• Seal, label, and verify the finished system, and document the work
• Behave ethically, including accurate claims and honest recordkeeping

Those six responsibilities map almost one-to-one onto the exam domains described below, which is why the credential feels practical rather than theoretical. If you are curious about the employment side, our guides to RMI jobs and the RMI salary guide cover who hires installers and how to think about earnings.

The Supervision Requirement

The single most important structural fact about the RMI credential is that it is supervised. NRPP requires that an RMI work under an NRPP-certified Radon Mitigation Specialist (RMS) who is employed by the same company. This is not an informal mentorship; it is a condition of holding the certification, and current supervisor documentation is part of renewal.

NRPP has updated its supervisory policy as recently as August 2025, so anyone planning a career move, such as going out on their own, should check the current rules instead of relying on older forum posts. Supervision requirements and any applicable state licensing requirements are separate questions: meeting one does not automatically satisfy the other. Your state may impose its own licensing or registration on top of the NRPP credential.

What the RMI Exam Covers

The RMI exam is built from six official content domains published in the NRPP Candidate Handbook. Their weights total 100%. Here is how they break down and what each demands of a candidate. For a deeper domain-by-domain treatment, see our complete guide to all six RMI exam domains.

Communication (14%) and ethics (7%) are smaller but should not be skipped; they tend to reward careful reading and sound judgment rather than memorization, and they make useful points on a tightly scored test.

Exam Format and Testing Conditions

The exam is delivered through Certiverse with live remote proctoring. Since October 1, 2024, the test presents 95 questions: 85 are scored and 10 are unscored trial items used to evaluate future questions. You will not know which are which, so treat every question as if it counts. You have a two-hour testing limit.

Important conditions to know before you schedule:

• You need valid photo ID, a live proctor connection, and a room scan
• One bathroom break of up to five minutes is permitted
• The platform provides the reference materials SGM-SF-2023 and MAH-2023, along with an in-platform calculator and formulas
• Personal reference books are not permitted, so the open-reference tools are limited to what the platform supplies
• If you do not pass, you must wait 30 days to retake, with a maximum of four attempts in 12 months

Older NRPP documents, including parts of the Candidate Handbook, describe previous delivery arrangements and fee details. Current NRPP web pages supersede those, so always confirm logistics on the official NRPP RMI exam page before booking. For how scoring is determined, our article on the RMI passing score explains why NRPP uses a competency standard rather than a publicly assigned numeric cutoff, and RMI exam dates and scheduling covers booking mechanics.

The Path to Certification and What It Costs

Prerequisites

To become a certified RMI, NRPP requires:

1. Approved measurement training of at least 12 hours
2. Approved mitigation training of at least 20 hours
3. Successful completion of the RMI examination
4. A signed Statement of Professional Responsibility
5. Supervision by an NRPP-certified RMS employed by the same company

Timing matters. Training certificates are usable for two years and exam results for one year, so you should not let the pieces sit idle. Our RMI requirements guide walks through eligibility in more detail, and RMI training covers choosing a course.

Fees

These fees took effect January 1, 2025, and training costs are separate and vary by provider. For a full budget view, including how to think about total outlay, read the RMI certification cost breakdown, and weigh it against the return in whether the RMI certification is worth it.

Keeping the Credential Active

An RMI certification lasts two years. To renew, you must complete eight Category I continuing education hours, which include the applicable four-hour Standards Overview course, demonstrate ethics compliance, and provide current supervisor documentation. The renewal fee is $250.

The standards-course requirement is worth planning for early, since it is mandatory rather than optional elective credit. NRPP details the process on its recertification pages. Treat renewal as an ongoing professional obligation instead of a paperwork afterthought; a lapse in supervisor documentation, for example, can hold up the whole process.

Sequencing Your Preparation by Domain

You do not need an elaborate system. What helps is allocating time in proportion to the exam weights and building from foundational diagnosis toward installation. A sensible order for a candidate coming straight out of training looks like this:

Installation strategy gets the most time because it carries the most weight, but do not let it crowd out the two 17% domains, which together outweigh it. For a fuller plan, see our RMI study guide, and keep the RMI cheat sheet handy for last-minute review. You can also test yourself on realistic questions with the RMI practice tests.

Terms People Mix Up

Because radon certification has several tiers and sometimes overlaps with state requirements, a few distinctions trip people up:

• RMI vs. RMS: The RMI is the supervised installer. The RMS is the supervisory tier that oversees RMIs. They are different credentials with different requirements.
• NRPP certification vs. state licensing: A state may require its own license or registration. Holding the NRPP credential does not by itself guarantee you can legally work in a given state, and the reverse is also true.
• Measurement training vs. mitigation training: NRPP requires both for the RMI path, at 12 and 20 hours respectively.
• Handbook vs. current website: The 2023 Candidate Handbook still supplies the official domain outline, but current delivery, fees, and prerequisites are governed by NRPP's newer web pages.

Other short explainers on this site cover related wording questions, including what RMI is and what RMI means. If you are weighing difficulty, how hard the RMI exam is and the RMI pass rate discussion lay out what is and is not publicly known.

Frequently Asked Questions