Residential Code Requirements

This section contains general residential building code requirements. Please refer to the Building Codes for more detailed information. This information is intended as a guide and does not relieve the applicant from complying with all applicable code requirements.

  • Ground snow load: 25 psf
  • Wind design speed: 115 mph
  • Topographic effects: No
  • Special wind region: No
  • Wind-borne debris zone: No
  • Seismic design category: A
  • Subject to damage from weathering: Severe
  • Frost line depth: 30 inches
  • Subject to damage from termites: Moderate - Heavy
  • Decay: Slight - Moderate
  • Ice barrier underlayment required: Yes
  • Flood hazards: Originally May 2, 1983;
  • Currently October 16, 2012, Revised February 18, 2015
  • Air freezing index: >1500
  • Mean annual temp: 55
  • Elevation: 154
  • Altitude correction factor: none
  • Coincident wet bulb: 74
  • Indoor winter design dry-bulb temperature: 70
  • Outdoor winter design dry-bulb temperature: 17
  • Heating temperature difference: 53
  • Latitude: 39
  • Daily range: M
  • Indoor summer design relative humidity: 50%
  • Summer design gains: 36
  • Indoor summer design dry-bulb temperature: 75
  • Outdoor summer design dry-bulb temperature: 91
  • Cooling temperature: 16
  • Structures less than 5’-0” from property line
  • Residential dwelling equipped with sprinkler system but less than 3’-0” from property line
  • One (1) hour fire resistance wall assembly;
  • 5/8 inch Type ‘X’ gypsum board each side of stud wall or equivalent
  • Shall be installed from the foundation up to the underside of roof sheathing
  • New construction, Demo and Rebuild structures
  • Additions constituting more than 50% increase in square footage inclusive of an unfinished basement
  • ADU without free-flowing access (i.e. case opening) from attached principal dwelling shall have a wall separation with minimum One (1) hour fire resistance construction
  • Access door in-between shall have minimum 45 minute fire resistance construction
  • One (1) hour fire resistance wall assembly;
  • 5/8 inch Type ‘X’ gypsum board each side of stud wall or equivalent
  • Shall be installed from the foundation up to the underside of roof sheathing
  • Requires a Maryland registered Engineer or Architect signed & sealed construction drawings 
Bedroom window

Minimum window required -  
Minimum net clear opening -

Minimum net clear opening height -

Minimum net clear opening width -

Maximum still height -

One 
5.7 sq. ft 
24-inches 
20-inches 
44-inches
HallwaysMinimum width -3 feet
StairwaysMinimum clear width - 
Minimum headroom - 
Minimum tread - 
Maximum riser -		3 feet 
6 ft 8 in 
10-inches 
7 3/4 inches
GuardrailMinimum height + required at walk surfaces over 30-inches above grade or stairs with 4 or more risers36-inches
RailingMinimum height 
(required at least one side of stair)		34 to 38-inches
PicketsMaximum clear spacing between pickets4-inches
Working space around electric equipmentMinimum width - 
Minimum in front -		30-inches 
36-inches
Ceiling heightHabitable rooms - 
Other areas - 
Under beams & ducts -		7 ft, 0 in 
6 ft, 8 in 
6 ft, 4 in
BathroomsWater-resistant gypsum backing board used as the base or backer for adhesive application of ceramic tile or other required nonabsorbent finish material 
Emergency Escape 
And Rescue Openings		At least one Emergency Escape and Rescue Opening is required for basement and habitable attic 
Fire stoppingAll duct chases, bulkheads, laundry chutes, metal flues, tub traps, and all shafts at each floor 
Fuse boxDo not locate fuse box in clothes closets 
Smoke detectorsOne (1) required on each level, plus one (1) in each bedroom and one (1) outside each sleeping area. Each shall have internal battery back-up plus being hardwired. 
Exterior stud walls2x4 or 2x6, P.T. sole plates in contact with masonry or concrete 
Wall coveringsDrywall - ½ inch 
Paneling - 
(Maximum smoke density - 450 
Maximum flame spread - 200		 
Habitable roomsMinimum area - 
Minimum horizontal dimension -		70 sq. ft. 
7 feet
Garage SeparationAttached garage separation from residence and attic minimum 1/2" gypsum board. Habitable rooms above garage minimum 5/8" Type "X" gypsum board.  
Non-combustible floor sloped to overhead door with 4" minimum elevation to residence floor.  
Minimum 20 minute or 1-3/8" solid wood door with self-closer. No openings into sleeping areas.