Codes

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Building codes are mostly fire-driven. They arose in the U.S. in the 1800’s when there were a series of catastrophic fires in big cities like Chicago. Insurance companies refused to continue to cover properties unless there was the development of some standards to lessen the chance of and mitigate the effects of fire. Initially codes were local, then regional, and now national, though certain regional codes still apply.

There are two basic approaches to fire safety, passive and active. Passive protection is making the materials of the building more resistant to fire, active is using systems like sprinklers to actually suppress fire.

Two main purposes are to keep the building standing so that people have time to escape, and to keep fire from spreading within the building or to other buildings

OCCUPANCY

The occupancy type is based on usage, and there can be multiple occupancy types in the same building. Our building will fall into type B (business) and may also include type A for an auditorium, and perhaps type A2 for a café. Shop areas may come under the heading of type F occupancies.

At 15 stories our building is classified as a High Rise. A building falls under this classification if it has areas 75’ above the lowest level of fire dept. access.  Our building will probably wind up being between 150 and 180 ft. and its height and area are unlimited as long as it’s construction is type 1A. At this size the building will have to be sprinklered and be of either type 1A or type 1B construction. If lower than 160 ft. and sprinklered then the construction type can be lowered to type 1B.

FIRE RATED CONSTRUCTION

Type classification has to do with the fire resistance of construction materials. It’s based on lab testing, and constitutes a time rating, ie. however long it takes to either compromise the structure or burn through from one area to another.

In type 1 A construction, the building must be made of non-combustible materials (ie. Protected steel or concrete of sufficient thickness) and the components of the building must withstand fire for the following times:

framework – 3 hrs.

bearing walls – 3 hrs.

Non-bearing walls are based on distance from other buildings (see the code)

Floors  -2 hr.

Roof – 1-1/2hr.

Partitions between diff. areas of the building depend on occupancy differences and containing undue spread of fire from area to area. Exterior non-bearing walls depend on “fire separation distances” from adjoining buildings – those areas fronting on street or right of way don’t need to be rated.

Type 1B allows:

framework – 2 hrs.

bearing walls – 2 hrs.

Non-bearing walls are based on distance from other buildings (see the code)

Floors  -2 hr.

Roof – 1hr.

Windows and other openings in outside walls also depend on proximity to other buildings, there are various restrictions on their size and required protection in close proximity to other buildings.

Some common methods of fire protection for type I construction:

fire protected columns

Concrete resistance ratings are based on thickness and the depth of reinforcing steel.

Concrete walls – 5” Thick = 2hr. rating, same for slabs

Masonry and concrete walls have generally good fire ratings, from 1-4 hrs.

A typical 1 hr. interior non-bearing partition wall is 3-1/4” 18 ga. Studs with 5/8 gyp. board on both sides.

Floors/roofs

Corrugated steel and concrete deck systems have good ratings, up to 4 hrs.

Elevator shafts and other vertical shafts must be fire protected, generally a 1 hr. rating.

MEZZANINES AND ATRIUMS

Mezzanines in our building definition (type 1 sprinklered) are allowed to take up ½ of the floor area below them. They must have two route of egress.

Atriums are defined as an opening connecting at least 2 floors and enclosed on the top. Buildings containing atriums must be fully sprinklered, but the ceiling of the atrium itself need not be sprinklered if it is over 55’ high. They must also have smoke control systems. (see section 404 of the IBC) The travel distance through  the atrium cannot exceed 200’. (I’ll discuss travel distance in the egress section)

Railing heights around artriums and mezzanines, like railings everywhere must be at least  42”.

atrium fire protection

INTERIOR FINISHES

In general, sprinklering allows you to offset the use of the most fire resistant materials. This is true for interior finishes for floors, ceilings, and walls. They are divided up into classes, and if the building has sprinklers, the next lower class of materials in generally allowed.

Finish materials must  be securely attached so that they stay up for at least 30 min. @ 200 degrees.

Theaters and auditoriums (occupancy group A) have some special provisions as to the use of flammable materials like curtains.

SPRINKLERS

There are lots of provisions for the specifics of sprinklering; where standpipes should go, how big the supply is, etc… For our purposes it seems sufficient to simply state that it’s a sprinklered building and proceed from there.

MEANS OF EGRESS

Is defined briefly as a “continuous unobstructed path…”, and there are 3 main concepts governing their design:

Flow – exit paths must stay the same size or larger as people move towards exiting the building (like tributaries leading to a river)

Alternate paths – at least two ways out of building in case one is blocked, this is based on occupancy as well, smaller spaces need have only one exit.

Protection – exit areas should be protected and once in a protected (fire rated) area, you shouldn’t have to pass through an unprotected area to get all the way out.

Egress components

The code delineates 3 parts of a system of egress, and there are requirements for each.

  1. Exit access – area to be escaped from adjoining exit. Lower level of protection
  2. Exit – Protected corridor, ramp, or stairway leading out of the building
  3. Exit – discharge – area outside between exit and street or right of way. Could be a courtyard, a ramp, balconies, etc… Usually at or close to grade level.

3 stages of egress

Some General Requirements for exits:

Ceiling ht. – 7-6” min.

Elevators, moving walkways, or escalators not allowed as means of egress if they don’t have their own emergency power source

Exit corridors have to maintain their width around any obstructions

The number of exits and egress sizes are based on occupancy loads for specific areas, (that is the maximum number of people allowed).  Use table 1004.1.1 in the IBC to determine the occupancy loads which are based on type of use of areas or on known numbers like seats in theater spaces.

room occupancy estimates

When egress paths come together the down stream path should be big enough to carry both combined. Vertical egress – stairs, are considered to work in sequence, so that the people on the lowest levels have gone out first clearing the way for upstairs people to exit.

Caution: don’t always know what an area will be used for in the future, may have to allow for higher occupancy rate than planned for.

The widths of paths are dependent on how many people will use, (occupant load), the relative danger of the type of occupancy, and whether the path is a stair or some other means of egress.

Using table 1005.1 – our building : stairways – .2” per occupant, other components – .15” per occupant

Doors – min. 3’x 80”

Stairs – min. 44” wide and 80” high. Treads – min. 11”, risers – min. 4”, max 7” No more than a 12’ rise between floors, if more, need a landing. Landings must be the width of stairs in both directions, straight landing – min. 48” long. Handrails req. both sides, protrude not more than 4-1/2”.

Areas of refuge are not req. but are a good thing to consider. (These are protected areas where people who can’t get down stairs can wait for assistance. (see ADA guidelines for specific dimensions and req.) Must provide space for at least 2 wheelchairs, and generally protected by 1 hr. firewalls.

Roof access is req. in buildings more than 4 stories.

Ramps in path of egress:

Not to exceed 1 in 12 slope (8%), max vertical rise – 30” between landings, min. width of 44”.  Rise of more than 6” req. handrails both sides, landings at least width of ramp and min. 60” long.

Exit access travel distance:

The distance someone has to travel to get to the closest exit – taken from the farthest point in the room or group of rooms along most likely route of egress. In our building type with sprinklers – 300 ft.

Occupancy loads determine the number of exits required for a given floor area. The number of people using an area is assumed from the number of seats in theater or other space with fixed seating, or estimated based on usage. A safe occupancy is determined from the code based on people per sq. ft.

There are a lot more specific requirements, but these seemed the most salient.

ACCESSIBILITY

Compliance with the code does not equal compliance with the ADA guidelines – need to consult both. Remember to provide access not just for wheelchair users but the sight and hearing impaired as well.

Guiding concept: Universal Design – making buildings accessible to the widest range of people possible.

Some basic requirements:

-Accessible parking should be the shortest distance from the main accessible entrance, spaces are 8’ wide with 3’ zone to side.  For every six spaces must provide one van space, which is larger.

-Accessible routes should not seem second class, paths should share or be as close as possible to general circulation areas. Exterior pathways should connect to public transport in as short a distance as possible.

-One main accessible entrance, and 60% of total entrances should also be accessible.

-Ramps: no more than 1:12 pitch with max. 30” rise between landings.  Need to be at least 36” wide and must have railings on both sides which should be between  34 and 38” high. Landings must be at least 60” long.

-Doors: at least 32” clear space when open. (In practical terms this actually a 34” door, so that door itself doesn’t narrow the opening).

-Corridors: at least 36”

-Bathrooms: at least one accessible stall, with 32” min door and able to accommodate a 5’ diameter turning circumference, w/ handrails to the side and back of commode.

-Sinks: less than or equal to 34”, with at least 29” clearance underneath.

-work surfaces:  28-34” high, at least 27” underneath, at least 19” deep.

-Assembly areas: Wheelchair spaces should be provided in different areas to avoid segregation, the number of spaces provided depend on total occupancy load (see table 1108.2.2.1 of IBC)

-In rooms with operable windows, at least one should be accessible.

ENERGY

These requirements are detailed in the  International Energy conservation Code (IECC)

It has to do mostly with building envelope requirements, and these are based on geographic area. There are two approaches you can take; go by the prescriptive code, which delineates specific R and U ratings for walls, windows, floors, etc… Or use modeling software to achieve a total envelope rating (based on energy costs) by mixing and matching trade-offs in different areas.  I was unable to get my hands on the IECC in time to write this, so I don’t know what the specific requirements are for building envelopes are in our area, but I hope to track it down soon.

There is also a general lighting electric use requirements of 1W/sq. ft. for buildings of our type, and this is an average, so some areas can use more than others.

That’s a general overview of what seemed like the most relevant parts of the code for this project, my sources for this report were these books:

“Building Codes Illustrated, A guide to Understanding the 2006 International Building Code” by Francis Ching and Steven Winkel. (all of the diagrams reproduced here are from this source)

The 2006 IBC code.

“International Building Code Companion”, by R. Dodge Woodson

The ADA Facilities Compliance Workbook

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