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Rockville, MD Building Setbacks & Zoning: Lot Coverage Limits (2026)

Some Restrictions
Compiled from the official code textEditor Martyn O'NeillLast verified September 2026

Key Facts

R-90 zone
25% max lot coverage
R-75 & R-60 zones
35% max lot coverage
R-40 zone
40% max lot coverage
R-400 zone (large lot)
15% max lot coverage
Authority
City of Rockville, not the County

Summary

In Rockville's R-90, R-75, R-60 and R-40 single-unit residential zones, the City's Zoning Ordinance caps building lot coverage at 25%, 35%, 35% and 40% of lot area, limiting how much of each lot buildings and covered porches can occupy.

Sec. 25.2.3.5. Lot coverage. (a) Definition. The percentage of lot area covered by buildings, including covered porches and accessory buildings... Table 7.1.4-1: Small Lot Single-Unit Residential Zone Development Standards. Standard R-90 R-75 R-60 R-40. ... H Lot Coverage (Max.) 25% 35% 35% 40%.

View official code

Full Breakdown

Rockville's Zoning Ordinance defines lot coverage as the percentage of lot area covered by buildings, including covered porches and accessory buildings, excluding historic accessory buildings in the Historic District Overlay zone and accessory dwelling units in any zone (Sec. 25.2.3.5). Table 7.1.4-1 sets the maximum for the small lot single-unit residential zones: 25% in R-90, 35% in R-75, 35% in R-60, and 40% in R-40. The large lot zones are tighter, 15% in R-400 and 25% in both R-200 and R-150 under Table 7.1.3-1. This is a City of Rockville zoning standard, administered independently of Montgomery County.

Violations & Fines

New construction, additions, or accessory buildings that exceed the maximum lot coverage percentage do not meet the Zoning Ordinance's dimensional standards and will not receive building permit approval from the City.

Frequently Asked Questions

Does Montgomery County set Rockville's lot coverage limit?
No. Rockville has its own Zoning Ordinance and Planning Commission; lot coverage maximums are set by the City under Article 7, not by Montgomery County's zoning code.
What counts toward lot coverage?
Buildings, including covered porches and accessory buildings, count toward lot coverage. Accessory dwelling units and historic accessory buildings in the Historic District Overlay zone are excluded from the calculation.
What is the lot coverage limit on Rockville's largest residential lots?
In the R-400 zone, the largest single-unit residential zone, maximum lot coverage is 15% of lot area: tighter than the 25-40% limits in the smaller-lot R-90 through R-40 zones.

Sources & Official References

Other rules in Rockville

Setback RulesSome RestrictionsStructure Height LimitsSome RestrictionsNoise Ordinances: Decibel LimitsSome RestrictionsParking Rules: Loading ZonesSome RestrictionsParking Rules: EV ChargingSignificant RestrictionsFence Regulations: Retaining WallsFew RestrictionsLandscaping Rules: Tree Removal & Heritage TreesSome RestrictionsRental Property Rules: Rent ControlFew Restrictions

All Rockville rules

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Lot Coverage Limits in Nearby Cities

How other cities in Montgomery County handle lot coverage limits.

Gaithersburg, MD
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