Massachusetts Plumbing Code

Adopted Code

Local jurisdictions may amend the state code further. Always confirm with the authority having jurisdiction before submitting for permit.

How the Massachusetts Code Is Organised

248 CMR is the Massachusetts State Plumbing and Gas Fitting Code, written directly by the Board of State Examiners of Plumbers and Gas Fitters. It is not a model code with amendments; it is an independently drafted regulation covering plumbing and gas fitting in one document. That combination is unusual — most states separate fuel gas into a distinct code adopted from NFPA 54 — and it means one regulation and one board govern both trades.

What It Changes About Sizing

248 CMR is among the more restrictive US codes on approved materials, and that is where it bites hardest. Piping materials routinely accepted under the IPC in neighbouring states may not be permitted, so a material selection valid in Connecticut or New Hampshire can fail here even where the sizing arithmetic is identical. Venting provisions also diverge from both model codes.

Licensing in Massachusetts

The same board licenses plumbers and gas fitters, with apprentice, journeyman and master tiers in each. Because gas is inside the plumbing code, a plumbing licence does not automatically convey gas fitting authority: the gas credential is separate and separately examined. Massachusetts also maintains its own continuing-education requirement tied to code cycle changes.

Cities That Do Something Different

Massachusetts enforces 248 CMR statewide through local inspectors, with less municipal amendment than in states that adopt model codes — the state code is comparatively uniform. Boston has additional permitting process requirements rather than substantively different technical rules.

What Out-of-State Contractors Get Wrong in Massachusetts

1. 1Specifying a material because it is IPC-approved. Massachusetts maintains its own approved-materials list and it is narrower.
2. 2Assuming a plumbing licence covers gas work. The gas fitting credential is separate, even though both sit in 248 CMR.
3. 3Looking for an IPC or UPC chapter reference. Massachusetts drafted 248 CMR independently; the numbering has no model-code equivalent.
4. 4Bringing a New England regional design across the border unchanged. Massachusetts is the outlier among its neighbours, not the norm.

Massachusetts in Practice

Our sizing calculators state the edition and table they use: pipe sizing, drainage slope, gas line sizing. Check them against the MA edition in force before relying on a result.