The 12 Violations, Ranked By Frequency
These are the most common 248 CMR violations Pro Build identifies in MA homes — most going undetected for years until a pre-sale inspection or repair triggers code review.
- 1. Water heater TPR discharge pipe incorrect or missing
- 248 CMR 10.13: TPR (temperature/pressure relief) valve discharge must terminate 6 inches above floor, full pipe size, no threads at termination, to drain or outdoors. Most MA installs have missing discharge pipe or copper instead of required CPVC/PEX. Easy fix: ~$120.
- 2. Dishwasher drain hose missing air gap or high loop
- 248 CMR 10.11: prevents drain water siphoning into dishwasher. Required: high loop above counter OR air gap fixture at sink. ~35% of MA installs miss this. Fix: ~$80 (high loop) or $300 (air gap retrofit).
- 3. Water heater expansion tank missing
- 248 CMR 10.13: required on any system with backflow preventer (most MA municipalities require). Thermal expansion damages water heater without tank. Cost ~$180 installed.
- 4. Dielectric union missing at water heater
- 248 CMR 10.11: required where copper meets galvanized or black iron pipe. Galvanic corrosion fails pipe at joint. Common in pre-1985 installs. Fix: $200-$400.
- 5. Gas line not properly supported or secured
- 248 CMR 6.05: gas piping must be supported per spacing requirements (3 ft horizontal CSST, 8 ft vertical). DIY gas work routinely violates. Fix: depends on extent.
- 6. Sewer cleanout missing or buried
- 248 CMR 10.04: accessible cleanout required within 5 ft of building exterior. Lawn fill or landscaping over time buries cleanouts. Fix: locate + raise — $300-$800.
- 7. Vacuum breaker missing on outdoor hose bibs
- 248 CMR 10.14: backflow prevention required on all outdoor spigots. Prevents lawn chemicals from siphoning into drinking water. Fix: $25/bib (DIY).
- 8. Trap arm too long
- 248 CMR 10.06: drain trap arm (between trap and vent) limited to maximum 60 inches on 1.5" pipe. Long horizontal runs without vent fail siphon protection. Common in remodel additions.
- 9. Water heater pan missing or undersized
- 248 CMR 10.13: drain pan required for water heaters in finished living space or above living space. Pan must drain to safe location. Many MA installs use undersized pans or no drain line.
- 10. Pex pipe exposed to UV without protection
- 248 CMR 10.11: PEX must be protected from UV in outdoor or windowed locations. UV degrades PEX, causing eventual failure. Common in attic + basement window areas.
- 11. Improper drain pipe slope
- 248 CMR 10.06: minimum 1/4" per foot slope on 2.5" pipe and smaller. Insufficient slope causes drain stoppages. Common in additions and DIY work.
- 12. Water shutoff missing or inaccessible
- 248 CMR 10.10: main water shutoff required at building entry, accessible without tools. Many MA homes have buried-behind-finishes shutoffs that fail this requirement.
Which to Fix First
If 5+ of these are present, prioritize in this order:
- Safety violations first: TPR discharge (#1), gas line support (#5), water shutoff (#12). These prevent property damage or injury.
- Pending-failure violations next: dielectric unions (#4), expansion tank (#3), trap arm length (#8). These cause equipment failure within 5-10 years if uncorrected.
- Inspection-failing violations: dishwasher air gap (#2), vacuum breakers (#7), sewer cleanout (#6). These will be flagged on any sale inspection and become deal-blockers.
- Slow-degradation issues: PEX UV exposure (#10), drain pipe slope (#11), water heater pan (#9). Lowest immediate risk but worth fixing during related plumbing work.
Pre-Sale Inspection Strategy
For MA homeowners planning to sell within 12 months, the pre-listing plumbing audit pays for itself in avoided last-minute concessions:
- Hire a licensed Master Plumber for pre-listing audit — $200-$400 inspection identifies all 12 plus 30+ other potential issues.
- Fix the safety + inspection-fail items proactively. Buyer's inspection won't flag them; closing isn't delayed by negotiation.
- Document remaining items. Pending-failure items disclosed pre-offer avoid surprise. Disclosure is required under MA real estate law for known defects.
- Get repair receipts in writing with the licensed plumber's MP number on each invoice. Required documentation for some buyer mortgage products.
Frequently Asked Questions
What is 248 CMR in Massachusetts?
248 CMR is the Massachusetts Uniform State Plumbing Code. Adopted by reference into the MA building code (780 CMR), it governs all plumbing work in the state. Master Plumber and Journeyman Plumber licensing are also issued under 248 CMR by the Massachusetts Board of State Examiners of Plumbers and Gas Fitters.
What is a TPR valve discharge pipe and why does it matter?
TPR = Temperature/Pressure Relief. The valve releases water if the heater overheats or overpressurizes — preventing explosion. The discharge pipe routes that water safely to a floor drain or outdoors. Incorrect or missing discharge means the safety valve dumps water in an unsafe location. Required by 248 CMR 10.13.
Why does the dishwasher need a high loop or air gap?
Prevents drain water from siphoning back into the dishwasher. Sink garbage disposal can pressurize the drain; without air break, contaminated water can enter the dishwasher and contact dishes. Required by 248 CMR 10.11 and federal plumbing code.
What does dielectric union do?
Separates dissimilar metals (copper meeting galvanized or black iron) to prevent galvanic corrosion at the joint. Without dielectric union, the joint corrodes and leaks within 8-15 years. Required by 248 CMR 10.11 at water heater connections.
Can I fix any of these violations myself?
Outdoor vacuum breakers (#7) and some pan installations are DIY-friendly. Most others require Master Plumber under 248 CMR. Work over $500 OR involving gas (#5) requires licensed plumber regardless of homeowner skill — civil penalties apply for unlicensed work.
Will the building inspector check for these during a renovation?
Yes for any plumbing rough-in work pulled under permit. Re-inspections after permit work include 248 CMR compliance check. Some violations may be grandfathered if predating the most recent code update, but new work must meet current code.
How much do these violations affect home value?
Pre-listing identification + correction protects sale price. Discovery during buyer's inspection typically results in buyer credit requests of 2-5x the actual repair cost — buyers anchor to perceived risk, not actual fix cost. A $400 dishwasher air gap fix often becomes a $2,000 negotiated credit when discovered late.
What's the difference between Master Plumber and Journeyman Plumber in MA?
Master Plumber (MP) can pull permits, supervise work, and own a plumbing company. Journeyman (JP) works under a Master Plumber's supervision. Both licenses come from the MA Board of State Examiners of Plumbers and Gas Fitters under 248 CMR. Verify either license at mass.gov.
References & Sources
- Massachusetts 248 CMR Uniform State Plumbing Code. https://www.mass.gov/regulations/248-CMR-00000-uniform-state-plumbing-code
- MA Board of State Examiners of Plumbers and Gas Fitters. https://www.mass.gov/orgs/board-of-state-examiners-of-plumbers-and-gas-fitters
- Massachusetts 780 CMR State Building Code. https://www.mass.gov/state-building-code-780-cmr
- Massachusetts Office of Consumer Affairs (real estate disclosure). https://www.mass.gov/orgs/office-of-consumer-affairs-and-business-regulation
