An overview for single family dwellings
Basement/Attic Finish

Permit needed for:

1. Bath exhaust fans
2. New Supply outlets
3. Duct
4. Clothes dryer exhaust
5. Changing of furnace flue vent

BATH EXHAUST
Bath exhaust fans are required in all restrooms. Duct must be increased to 4” diameter instead of 3” diameter, if there is an elbow and the duct is more than 3’ long. The exhaust duct must terminate outside of the house.

COMBUSTION AIR
The mechanical code most frequently ignored during remodeling is the combustion air requirements to the furnace room. As walls are built and finished, the combustion air supplied to the furnace and water heater is decreased. When this happens, some provision must be made to replenish this lost volume of air. This may be accomplished by either one of two methods: high/low grills or outside air.

High/Low Grills:
By adding the total input BTUs of the furnace and water heater (marked on nameplate), you can calculate the size of combustion air grills to be installed (within 12” of ceiling and floor). These grills are installed through the walls to replenish the combustion air volume to the furnace room.

Outside air:
An alternative method is to provide an opening into the furnace room from the outside of the house to replenish the combustion air. The total input BTUs will determine the size of opening from the outside.

Consult with a registered Heating Contractor or an Inspector with the Department of Building & Safety for assistance in these calculations.

DRYER EXHAUST DUCTS:
Dryer exhaust duct must be metal and have a smooth interior surface wherever it is concealed. You may use 6’ of flexible duct connected to your dryer if it is not concealed in the wall or ceiling. Dryer exhaust ducts may be 25’ long using two 90 degree elbows. Each additional 90 degree elbows will decrease the length of the duct allowed by 8’. Do not use screw to fasten dryer duct. You may use short pop rivets or a strong “furnace” or “foil” tape.

FURNACE:
If you are building walls or doors close to your furnace, you must maintain proper clearances. Thirty inches is required in from of the furnace for access to repair. The sides and back of the furnace will have clearance ratings marked on the name plate. These are usually 1". A door may be built no closer than 6" in front of a furnace (provided the door opens to provide 30" clearance". The supply duct extending horizontally away from your furnace must be 1" away from combustibles for the first 3'. The furnace flue pipe requires 6" clearance to combustible if it is single wall pipe. One inch clearance is required for type "B" double wall flue pipe.

FURNACE ACCESS:
You may not have a furnace in a bedroom or a bathroom (shower or tub room). You may not pass through a bedroom or a bathroom to access the furnace room.