Retaining Walls: Cambridge vs Somerville
How do retaining walls rules compare between Cambridge, MA and Somerville, MA?
Cambridge has fewer restrictions than Somerville.
Cambridge, MA
Middlesex County
Retaining walls over 4 feet tall in Cambridge require engineered drawings and a building permit; walls over 2 feet count toward fence height if topped by a fence.
View full Cambridge rules →Somerville, MA
Middlesex County
Retaining walls over 4 feet require a Somerville building permit and engineered plans, with drainage, property-line, and historic-district review considerations under the Massachusetts Building Code.
View full Somerville rules →Key Facts Comparison
| Fact | Cambridge | Somerville |
|---|---|---|
| Engineer Required | Over 4 feet | - |
| Guardrail | Over 6 feet | - |
| Fence Height | Walls over 2 ft add to total | - |
| Flood Zone | ConCom review | - |
| Building Code | 780 CMR | - |
| Permit trigger | - | Over 4 ft or surcharge |
| Code | - | 780 CMR |
| Engineer required | - | Walls over 4 ft |
| Drainage | - | Weep holes and backdrain |
| Failure fine | - | From 300 dollars |
Highlighted rows indicate differences between cities.
Cambridge FAQ
Does a 3-foot retaining wall need a permit in Cambridge?
Yes, any retaining wall needs a building permit; only walls over 4 feet require engineered drawings.
Can I put a fence on top of my retaining wall?
Yes, but the combined height counts against the zoning fence limit if the wall is over 2 feet tall.
Somerville FAQ
Do I need a permit for a short rock wall?
Decorative walls under 4 feet without surcharge generally do not need a permit, but check setback and drainage before building.
Can I build directly on the property line?
No. Retaining walls must be set back on your side; any encroachment or shared structure requires a written agreement and survey.
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