Accessory Dwelling Units in Montgomery County 103/26/2019
Accessory Dwelling Units in Montgomery County 203/26/2019
Examples of Accessory Structures
Kentlands, Gaithersburg, MDKentlands, Gaithersburg, MD
Accessory Dwelling Units in Montgomery County 303/26/2019
Examples of Accessory Structures
Kentlands, Gaithersburg, MD Kentlands, Gaithersburg, MD
Accessory Dwelling Units in Montgomery County 403/26/2019
Existing ADU Counts
ADUs (SE/CU) • Approved under Special Exception or Conditional Use standards
• Approved prior to May 20, 2013
203
ADUs (Class 3 License) • Meet Limit Use standards• Approved since May 20, 2013
212
Registered Living Units • Generally for family and caregivers• Cannot charge rent• In the process of being relicensed as ADUs
58
TOTAL as of March 19, 2019 473
Accessory Dwelling Units in Montgomery County 503/26/2019
Existing ADUsby Zone
ZONEADU
(SE/CU)ADU
(Class 3) RLU TotalAR 7 2 3 12PD-3 1 1 2PNZ 1 1R-10 1 1R-200 31 45 14 90R-40 1 1R-60 97 84 11 192R-90 51 48 9 108RC 5 3 6 14RE-1 5 9 3 17RE-2 4 12 9 25RE-2C 5 1 6RNC 1 1T-S 1 1 2Total 203 211 58 472** One existing ADU is within the Gaithersburg city limits.
• Currently, only attached accessory apartments are allowed in the R-200, R-90, and R-60 Zones
• 390 (or 83 percent) of ADUs are in the R-200, R-90, or R-60 Zones
Accessory Dwelling Units in Montgomery County 603/26/2019
Existing Residential Detached Zoning
Accessory Dwelling Units in Montgomery County 703/26/2019
Location of ExistingADUs
Accessory Dwelling Units in Montgomery County 803/26/2019
Existing ADUHeat Map
Accessory Dwelling Units in Montgomery County 903/26/2019
R-60 Zone
Accessory Dwelling Units in Montgomery County 1003/26/2019
R-60 Lot Size Distribution
Development TypeMinimum Lot Size for Single-Family Detached
Standard Method 6,000 sf
Optional Method 3,000 sf
Cluster Development 3,000 sf
Average Lot Size 8,000 sf
# o
f Lo
ts
Lot Size Range
Accessory Dwelling Units in Montgomery County 1103/26/2019
R-60 Zone – New ConstructionLot
Lot Area 6,000 sf
Lot Dimensions 60 ft wide by 100 ft in depth
Lot coverage 35%
Principal Structure
Footprint 2,100 sf
Total Area 4,200 sf
Height 35 ft at highest point of the roof
Setbacks 25 ft front8 ft side (18 ft sum)20 ft rear
Accessory Dwelling Units in Montgomery County 1203/26/2019
R-60 Zone – New ConstructionLot
Lot Area 6,000 sf
Lot Dimensions 60 ft wide by 100 ft in depth
Lot coverage 35%
Principal Structure
Footprint 2,100 sf
Total Area 4,200 sf
Height 35 ft at highest point of the roof
Setbacks 25 ft front8 ft side (18 ft sum)20 ft rear
10
0'
60'
20
'
Rear
Fron
t
25
'
2,100 sf footprint
35% of 6,000 sf lotSide
8'
Side
10'
Accessory Dwelling Units in Montgomery County 1303/26/2019
Lot
Lot Area 6,000 sf
Lot Dimensions 60 ft wide by 100 ft in depth
Lot coverage 35%
Existing Structure
Footprint 1,500 sf
Total Area 2,500 sf
Height 35 ft at highest point of the roof
Addition
Footprint 600 sf
Total Area 1,200 sf
Height 2 story
Setbacks 8 ft side (18 ft sum)20 ft rear
R-60 Zone – 2 Story Addition
Accessory Dwelling Units in Montgomery County 1403/26/2019
Lot
Lot Area 6,000 sf
Lot Dimensions 60 ft wide by 100 ft in depth
Lot coverage 35%
Principal Structure
Footprint 1,500 sf
Total Area 2,500 sf
Height 35 ft at highest point of the roof
Addition
Footprint 600 sf
Total Area 1,200 sf
Height 2 story
Setbacks 8 ft side (18 ft sum)20 ft rear
R-60 Zone – 2 Story Addition1
00
'60'
Addition
600 sf footprint
Rear
20
'
Fron
t
25
'
8'
Side
10'
Side
Principal Structure
1,500 sf footprint
Accessory Dwelling Units in Montgomery County 1503/26/2019
R-60 Zone – 2 Story ADULot
Lot Area 6,000 sf
Lot Dimensions 60 ft wide by 100 ft in depth
Lot coverage 35%
Principal Structure
Footprint 1,500 sf
Total Area 2,500 sf
Height 35 ft at highest point of the roof
Accessory Dwelling Unit
Footprint 600 sf
Total Area 1,200 sf (48% of principal)
Height 2 story, 20 ft in height
Setbacks 15 ft side15 ft rear
Accessory Dwelling Units in Montgomery County 1603/26/2019
R-60 Zone – 2 Story ADULot
Lot Area 6,000 sf
Lot Dimensions 60 ft wide by 100 ft in depth
Lot coverage 35%
Principal Structure
Footprint 1,500 sf
Total Area 2,500 sf
Height 35 ft at highest point of the roof
Accessory Dwelling Unit
Footprint 600 sf
Total Area 1,200 sf (48% of principal)
Height 2 story, 20 ft in height
Setbacks 15 ft side15 ft rear
10
0'
Side
15'
60'
ADU Structure
600 sf footprint
15
'
Rear
Side
15'
Fron
t
Side
8'
Side
10'
25
'
Principal Structure
1,500 sf footprint
Accessory Dwelling Units in Montgomery County 1703/26/2019
Lot
Lot Area 6,000 sf
Lot Dimensions 60 ft wide by 100 ft in depth
Lot coverage 35%
Principal Structure
Footprint 1,500 sf
Total Area 2,500 sf
Height 35 ft at highest point of the roof
Accessory Dwelling Unit
Footprint 600 sf
Total Area 600 sf (24% of principal)
Height 1 story, 15 ft in height
Setbacks 8 ft side (18 ft sum)12 ft rear
R-60 Zone – 1 Story ADU
Accessory Dwelling Units in Montgomery County 1803/26/2019
Lot
Lot Area 6,000 sf
Lot Dimensions 60 ft wide by 100 ft in depth
Lot coverage 35%
Principal Structure
Footprint 1,500 sf
Total Area 2,500 sf
Height 35 ft at highest point of the roof
Accessory Dwelling Unit
Footprint 600 sf
Total Area 600 sf (24% of principal)
Height 1 story, 15 ft in height
Setbacks 8 ft side (18 ft sum)12 ft rear
R-60 Zone – 1 Story ADU1
00
'60'
Fron
t
25
'1
2'
Rear
ADU Structure
600 sf footprint
10'
Side
8'
Side
Principal Structure
1,500 sf footprint
Accessory Dwelling Units in Montgomery County 1903/26/2019
R-90 Zone
Accessory Dwelling Units in Montgomery County 2003/26/2019
R-90 Lot Size Distribution
Development TypeMinimum Lot Size for Single-Family Detached
Standard Method 9,000 sf
Optional Method 4,000 sf
Cluster Development 5,000 sf
Average Lot Size 12,000 sf
Lot Size Range
# o
f Lo
ts
Accessory Dwelling Units in Montgomery County 2103/26/2019
Lot
Lot Area 9,000 sf
Lot Dimensions 75 ft wide by 120 ft in depth
Lot coverage 30%
Principal Structure
Footprint 2,000 sf
Total Area 3,500 sf
Height 35 ft at highest point of the roof
Accessory Dwelling Unit
Footprint 700 sf
Total Area 700 sf (20% of principal)
Height 1 story, 15 ft in height
Setbacks 8 ft side (25 ft sum)12 ft rear
R-90 Zone – 1 Story ADU
Accessory Dwelling Units in Montgomery County 2203/26/2019
R-90 Zone – 2 Story ADULot
Lot Area 9,000 sf
Lot Dimensions 75 ft wide by 120 ft in depth
Lot coverage 30%
Principal Structure
Footprint 2,000 sf
Total Area 3,500 sf
Height 35 ft at highest point of the roof
Accessory Dwelling Unit
Footprint 700 sf
Total Area 1,400 sf (40% of principal)
Height 2 story, 20 ft in height
Setbacks 15 ft side15 ft rear
Accessory Dwelling Units in Montgomery County 2303/26/2019
R-200 Zone
Accessory Dwelling Units in Montgomery County 2403/26/2019
R-200 Lot Size Distribution
Development TypeMinimum Lot Size for Single-Family Detached
Standard Method 20,000 sf
Optional Method 6,000 sf
Cluster Development 9,000 sf
Average Lot Size 17,000 sf
# o
f Lo
ts
Lot Size Range
Accessory Dwelling Units in Montgomery County 2503/26/2019
R-200 Zone – 1 Story ADULot
Lot Area 20,000 sf
Lot Dimensions 100 ft wide by 200 ft in depth
Lot coverage 25%
Principal Structure
Footprint 3,800 sf
Total Area 4,500 sf
Height 40 ft at highest point of the roof
Accessory Dwelling Unit
Footprint 1,200 sf
Total Area 1,200 sf (27% of principal)
Height 1 story, 15 ft in height
Setbacks 12 ft side (25 ft sum)12 ft rear
Accessory Dwelling Units in Montgomery County 2603/26/2019
Lot
Lot Area 20,000 sf
Lot Dimensions 100 ft wide by 200 ft in depth
Lot coverage 25%
Principal Structure
Footprint 3,800 sf
Total Area 4,500 sf
Height 40 ft at highest point of the roof
Accessory Dwelling Unit
Footprint 1,200 sf
Total Area 2,250 sf (50% of principal)
Height 2 story, 25 ft in height
Setbacks 12 ft side (25 ft sum)12 ft rear
R-200 Zone – 2 Story ADU
Accessory Dwelling Units in Montgomery County 2803/26/2019
Examples of Teardowns
Accessory Dwelling Units in Montgomery County 2903/26/2019
Examples of Teardowns
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