Residential vs Commercial Plumber in SC: Which License You Need

October 30, 2026

Updated October 30, 2026.

In South Carolina, plumbers who work on homes are licensed by the Residential Builders Commission, and plumbers who work on commercial buildings are licensed by the Contractor's Licensing Board as mechanical contractors with a plumbing classification. For a house, condo or small apartment building, you want a plumber with a residential plumbing license (or a mechanical contractor license that covers plumbing). For a store, office, restaurant or larger building, you need a commercial mechanical contractor whose license group covers the size of the job.

Both boards sit under the SC Department of Labor, Licensing and Regulation (LLR), and you can check either kind of license yourself in a couple of minutes. Here is how the two systems differ, which one your project falls under, and what to ask before you sign anything.

What is the difference between a residential and a commercial plumber in SC?

The difference is which state board licensed them and what kind of building they are allowed to work on. The skills overlap a lot, since a pipe is a pipe, but the licensing rules, dollar limits and financial requirements are different.

	Residential plumber	Commercial plumber
State board	Residential Builders Commission (LLR)	Contractor's Licensing Board (LLR)
License name	Residential Specialty Contractor, Plumbing	Mechanical Contractor, Plumbing (PB) classification
When a license is required	Residential plumbing work over $500	Commercial work with a total cost over $10,000 (state rule; some cities require it at any amount)
Size limits	Jobs over $5,000 require a $10,000 surety bond on file	License "group" sets the largest job allowed, from $35,000 (Group 1) to unlimited (Group 5)
Typical buildings	Houses, townhomes, condos, apartment buildings up to three floors and 16 units	Offices, retail, restaurants, schools, churches, larger multifamily

The sections below explain where each of those numbers comes from.

Who licenses residential plumbers in South Carolina?

Residential plumbers are licensed by the Residential Builders Commission, and the state says plainly that "residential plumbing work exceeding $500 requires a license" (SC LLR, Residential Plumber License). That threshold is low. Almost any real plumbing job on a home, from a water heater swap to a repipe, clears $500 once labor and materials are added together.

To get the residential plumbing license, an applicant has to:

Show one year of verifiable experience under the supervision of a licensed individual (SC LLR, Residential Builders Commission licensure).
Pass both the Business Management and Law exam and the Residential Plumbers exam, with only three attempts allowed in a 12-month period (SC LLR, Residential Plumbing FAQ).
Submit a complete credit report, not just a score, according to the same FAQ.

Some applicants can skip the technical plumbing portion of the exam, but never the business and law portion. LLR lists the waiver routes as a plumbing license by exam from North Carolina or Mississippi, a South Carolina mechanical contractor license with the plumbing classification held for at least a year, or certain Master Plumber certifications issued by exam (SC LLR).

What is the $5,000 bond rule?

A residential plumber who takes on a job with a total cost over $5,000 (labor and materials added together) must have a $10,000 surety bond on file, issued in the licensee's own name. With a current bond on file, the FAQ says "there is no contract limit on projects" (SC LLR, Residential Plumbing FAQ). State law sets the same $5,000 bond trigger for residential specialty contractors generally (SC Code § 40-59-240).

Why this matters to you: a whole-house repipe, a sewer line replacement or a tankless water heater conversion can easily run past $5,000. If your quote is in that range, ask whether the plumber's bond is current. For a sense of what jobs actually cost here, see our Greenville plumber cost guide, and if you have had work done recently, you can share what you paid anonymously to help neighbors.

Is a "registered" specialty contractor the same as a licensed plumber?

No. The Residential Builders Commission issues both registrations and licenses. A registration requires documented work experience but no exam is listed for it (SC LLR). Plumbing is handled as a licensed trade: a Tega Cay building department guide notes that residential specialty licenses are required for all mechanical trade work, which includes plumbing (City of Tega Cay contractor licensing guide). If someone offering to do plumbing on your home shows you a registration rather than a plumbing license, ask more questions before hiring.

Can a home builder do the plumbing?

Sometimes. A residential builder who was licensed by passing South Carolina's exam may do work in any of the residential specialty areas, including plumbing. A builder licensed through an exam waiver may only do non-mechanical work and must subcontract plumbing, electrical and HVAC to a properly licensed subcontractor (SC LLR, Residential Builder FAQ). The Tega Cay guide adds that a residential builder license marked "RBW" excludes mechanical trade work. If your general contractor plans to do the plumbing in-house, ask which kind of builder license they hold.

Who licenses commercial plumbers in South Carolina?

Commercial plumbers are licensed by the Contractor's Licensing Board as mechanical contractors, and plumbing is its own classification, abbreviated "PB" (SC LLR, CLB classification list). Other mechanical classifications include air conditioning, heating, electrical and pressure and process piping, so a company can hold several.

Under the state rule updated in 2023, a mechanical contractor license is required when the total cost of construction is greater than $10,000, up from $5,000 before the change (SC LLR, CLB 2023 legislative update). Local rules can be stricter. The Tega Cay guide, for example, says commercial plumbing requires a mechanical contractor license at any amount. Check with the city or county where the building sits.

What do commercial license "groups" mean?

A commercial license group is the largest bid or job a contractor is allowed to take on, and each group comes with financial requirements. These are the mechanical contractor limits from the same 2023 LLR update:

Mechanical group	Bid and job limit	Surety bond amount listed by LLR
Group 1	$35,000	$7,000
Group 2	$100,000	$15,000
Group 3	$200,000	$30,000
Group 4	$400,000	$60,000
Group 5	Unlimited	$300,000

The update also lists working capital and net worth figures for each group. The practical takeaway: a Group 1 plumbing contractor should not be bidding a $150,000 restaurant build-out. Ask which group the contractor holds before you sign.

Which plumber license do I need for my project?

Go by the type of building first, then the size of the job. The Residential Builders Commission's definition of residential covers buildings no more than three floors tall, with no more than 16 units in an apartment building (SC LLR, Residential Builder FAQ). Anything bigger, or anything that is not a dwelling, generally falls on the commercial side.

Your situation	What to look for
Single-family home, townhome or duplex	Residential plumbing license, or a mechanical contractor license with PB
Residential job over $5,000 (repipe, sewer line, major remodel)	Residential plumbing license with a current bond, or a mechanical PB license whose group covers the job
Rental house you own	Same as a home: residential plumbing license
Condo or apartment building, 3 floors or less and 16 units or fewer	Residential plumbing license; ask the HOA or property manager if they require more
Apartment building over 3 floors or over 16 units	Commercial mechanical contractor with PB classification
Office, store, restaurant, church or warehouse	Commercial mechanical contractor with PB, in a group that covers the job size
Gas line for a grill or range	Ask first. The Tega Cay guide says gas cooking equipment requires a mechanical PB license, residential or commercial; your local rule may differ

If your project sits on the line, such as a home with a business in it or a mixed-use building, call your local building department before you hire. They are the ones who will issue the permit, and they can tell you which license they will accept.

Can a residential plumber do commercial work, or the other way around?

A residential-only plumbing license does not cover commercial jobs above the state threshold, so a residential plumber should not be running your restaurant's plumbing build-out. Going the other direction is more flexible. The Tega Cay guide lists a South Carolina mechanical contractor license as one of the accepted licenses for residential plumbing, as long as the classification matches the work and the group limit covers the job's value (City of Tega Cay). That is why you will see plenty of Upstate companies that serve both homeowners and businesses holding a commercial mechanical license.

Neither license is "better" for a homeowner. A company with a commercial license is not automatically more skilled on a home job, and a residential-only shop may do nothing but houses all day. What matters is that the license is active, covers plumbing, and fits the size of your job.

How do I check which license a plumber has?

Look it up on the state's free license lookup. It takes a few minutes and tells you more than any logo on a truck.

Ask the plumber for their South Carolina license number and the exact business name on the license.
Go to the SC LLR license lookup.
Pick the right board: Residential Builders for home plumbing licenses, Contractors for commercial mechanical licenses. If you don't find them under one, try the other.
Confirm the status is Active and the name matches the company you are hiring.
Read the classification. For residential, look for plumbing. For commercial, look for PB.
For a commercial job, ask for the license group and make sure its limit covers your project's total cost.
Note the expiration date, especially if the job will run for weeks.

Every plumber listed in our directory has already been checked against LLR records, with the license number, the name on the license and the date we checked shown on the profile. Our how we verify page explains the process. One honest limit: we confirm an active contractor license, and we do not verify insurance or confirm that a license covers your specific job. That last step is yours. For a broader hiring checklist, see how to find a good, licensed plumber in South Carolina.

Does the license type matter for permits in Greenville County?

Yes, because the permit application asks for it. Greenville County's residential and commercial plumbing permit forms both ask for the plumbing contractor's name, license number and license expiration date (Greenville County residential plumbing permit; Greenville County commercial plumbing permit). A plumber who holds the right license can pull the permit. One who doesn't may ask you to pull it yourself, which is a red flag worth stopping on.

State law also limits how much a local government can pile on. Once a residential specialty contractor has passed a commission-approved exam in their trade, "no additional examination may be required by a county or municipality" (SC Code § 40-59-240). Permit rules and fees still vary by jurisdiction, so the City of Greenville, Greenville County and nearby towns may each handle the paperwork a little differently.

Questions to ask your plumber about licensing

Ask these before work starts, and get the answers in writing on the estimate when you can:

What is your South Carolina license number, and is it residential or commercial (mechanical)?
Does the license include the plumbing classification?
Is the license in the same business name that is on this estimate?
For a home job over $5,000: is your residential bond current?
For a commercial job: what is your license group, and does it cover this contract amount?
Will you pull the permit under your license?
Will the work be done by your own licensed staff or by a subcontractor? If a subcontractor, what is their license number?
Can you send a current certificate of insurance? (Licensing and insurance are separate. Ask for both.)

A good plumber will answer these without hesitation. Rules and dollar thresholds do change, so if anything here doesn't match what you're told, check the LLR pages linked above or call your local building department.

Compare licensed plumbers near you

Ready to get quotes? Browse our Greenville plumbers or Taylors plumbers, where every listing shows the South Carolina license we checked and the date we checked it. Shortlist two or three, confirm the license type fits your job using the steps above, and compare written estimates.