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The original item was published from 1/14/2020 6:26:37 PM to 1/29/2020 9:34:36 AM.

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Board of Health

Posted on: January 14, 2020

[ARCHIVED] Guidelines for Determining Bedrooms & Other Rooms in Residential Dwellings Served by Septic Systems


The purpose of this guideline is to provide the public a better understanding of what constitutes a “room” within a residential dwelling for regulatory purposes.  State Title-5 regulation dictates that septic system design is based on the number of bedrooms within a dwelling.  Of all room types, bedrooms have the greatest influence on the number of potential inhabitants that a dwelling can reasonably house.  Regulatory standards identify that a bedroom can support up to two (2) inhabitants.  Some may think the regulation should count the number of bathrooms or laundry rooms for septic design since wastewater enters a septic system from these locations.  But it’s the inhabitants who excrete biological wastes, bathe and launder clothes that create wastewater.   State Title-5 regulation also addresses the composition of a dwelling and the number of bedrooms it should logically possess.  This provision, called Total Room Count, imposes a proportional 2:1 relationship between the total number of rooms within a dwelling and how many of these rooms are considered bedrooms for septic design purposes. 


The following criteria describe the physical attributes to a bedroom.  A functional criterion that the room also poses a reasonable degree of privacy for its occupant(s) is equally important.

A bedroom has:  

•    At least one operable window with a 5.7sqft opening for ample egress to escape in an emergency 

•    50% or more floor space being above grade

•    Door opening of less than 5 feet (60 inches)

•    Dedicated heat of any kind (not including portable)

•    Electricity

•    A degree of privacy

A bedroom doesn’t need to resemble the traditional squared room off a central hallway.  Any odd-shaped or distally located room that meets the prior bedroom criteria is a bedroom.  

These atypical circumstances may include: 

•    A room over an attached garage

•    A basement room that is majority above grade

•    Lofts with limited access 

•    Finished attic spaces or elaborate storage rooms

Any room within a detached structure on the lot where the structure serves an identified function, other than for domicile, which meets the prior bedroom criteria is a bedroom for Title-5 purposes regardless of the detached structure’s isolation from the main house or claimed function.  

Common non-domicile functions for a detached structure may include a:

•    Garage

•    Office

•    Artist studio

•    Woodworking shop

•    Fitness studio

•    Children’s playhouse

•    Pool house

A detached structure that serves a non-domicile function, which happens to have a room that meets the prior criteria of a bedroom, may however NOT be deemed a bedroom for Title-5 purposes, if the detached structure overall lacks any one of the following domestic features.   

These three (3) features include:  

•    Heat

•    Shower

•    Toilet

It goes without saying that having to visit the main house to use the bathroom, bathe, or gather warmth would make the detached structure unconducive for customary habitation.   

Whole House Room Count:

A residential dwelling would be expected to have in addition to a bedroom, at least a living room and a kitchen.  Bathrooms don’t count as a room.  Beyond bedrooms for sleeping purposes, the more inhabitants a dwelling supports - the more rooms that are needed to serve larger families.  Along this same thinking, an excessive number of rooms within a dwelling relative to its inhabitants is conducive to having these spare rooms potentially converted to bedrooms and overtax the dwelling’s septic system. This is the premise to the State’s Title-5 Total Room Count.  For a dwelling that has nine (9) total rooms or more, about half of the rooms would be considered bedrooms, regardless of their physical attributes, and the other rooms a mix of living rooms, kitchens, dining rooms, family rooms or office rooms.  So an eleven-room dwelling (1/2 then round down) would have a 5 bedroom septic design and so on.        

Other Rooms:

An “other room” would be any room within a residential dwelling other than a bedroom as previously defined (above) and/or by the Total Room Count formula.  Bathrooms, closets, hallways, foyers, mudrooms, unfinished attics and unfinished basements are always not counted.  The classification of an “other room” is mainly determined by its structural space with some consideration given to its functional use. 

The following criteria are used in determining the attributes of a stand-alone room.   

•    A room has distinctive physical borders

•    A room most often has a distinct domestic function

•    In an open concept design, where the large space has a small dividing wall, half-wall, pillars, built-in cabinetry or other architectural feature that protrudes into the space or obstructs normal movement within the space, which produces a defined visual demarcation, shall be considered for Title-5 purposes as comprising separate rooms.  

•    Conversely, the lack of any distinctive bump-out, projecting casework or pillars, even though there are regions within the large space serving different functions, would be generally considered as one room.  

•    A bedroom cannot be solely accessible through another bedroom.  The room providing access to the more distal bedroom would be a room.

•    A Loft accessed by a stairwell less than 5 foot (60 inches) wide or a spiral staircase which must be 5 feet wide is a separate room regardless of its openness to the room below, unless the loft is only accessible through a bedroom.

Approved by BoH on 11/21/19

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