Historically, a number of building codes were used throughout North America, but several of these codes have been combined. The most prominent codes used now are those published by the International Codes Council (ICC) ®, NFPA 5000®, Building Construction and Safety Code®  published by the National Fire Protection Association, and the National Building Code of Canada  published by National Research Council Canada. Canada’s Constitution gives the ten provinces and three territories jurisdiction over construction. Some cities also have this authority through a special relationship with their provincial authority. In general, construction classifications are based on the types of materials used in the construction and on the fire-resistance ratings of major structural components.

It is important to remember that fire resistance ratings are a measure of how long structural assemblies will maintain their load-bearing ability under fire conditions, not of how easy or difficult it will be to fight a fire in that building. Most building codes have the same five construction classifications that are described in NFPA® 220, Standard on Types of Building Construction , but may use slightly different terms to name the classifications. The five types of building construction listed in NFPA® 220 include:

• Type I – Fire-Resistive
• Type II – Noncombustible
• Type III – Ordinary
• Type IV – Heavy Timber
• Type V – Wood Frame
  

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Type I Construction – Fire-Resistive

Known also as fire-resistive construction, Type I construction maintains its structural integrity during a fire. Fire-resistive construction consists mainly of reinforced concrete with structural members, including walls, columns, beams, floors and roofs that are protected either by blown-on insulation or automatic sprinklers. The fire-resistive compartmentation, provided by partitions and floors, tends to retard the spread of fire through the building. These features allow time for occupants to exit the building and firefighters to conduct interior firefighting.

Limited combustibility of the materials of construction, makes the primary fire hazards the contents of the structure and the interior finishes. This allows firefighters to launch an interior attack with greater confidence than in a building that is not fire-resistive. The ability of fire-resistive construction to confine the fire to a certain area can be compromised by openings made in partitions and by improperly designed and in-adequately dampered heating and air-conditioning systems.

Strengths:

• Resists direct flame impingement
• Confines fire well
• Little collapse potential from the effects of fire alone
• Impervious to water damage

Weaknesses:

• Difficult to breach for access or escape
• Difficult to ventilate during a fire
• Massive debris following collapse
• Floors, ceilings and walls retain heat
  

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Type II Construction – Noncombustible

Type II construction, also known as noncombustible construction, is made of the same types of materials as fire-resistive construction except that the structural components lack the insulation or other protection of Type I construction. Type II construction has a fire-resistance rating on all parts of the structure including exterior and interior load-bearing walls and building materials. All-metal buildings also fall into this classification. Materials with no fire-resistance ratings, such as untreated wood, may be used only in limited quantities. Again, one of the primary fire protection concerns is the contents of the building. The heat buildup from a fire in the building can cause structural supports to fail. Another potential problem is the type of roof on the building.

Noncombustible or limited combustible construction buildings often have flat, built-up roofs. These roofs consist of a combustible or noncombustible roof deck covered by combustible felt, noncombustible insulation and roofing tar. Fire extension to the roof can eventually cause the entire roof to become involved and fail.

Strengths:

• Almost as resistive to fire as Type I construction
• Confines fire well
• Almost as structurally sound as Type I construction
• Impervious to water damage

Weaknesses:

• Difficult to breach for access or escape
• Difficult to ventilate during a fire
• Massive debris following collapse
• Floors, ceilings and walls retain heat
• Steel components subject to weakening by fire
• Steel components subject to weakening by rust and corrosion

Type III Construction – Ordinary

Known also as ordinary construction, Type III construction requires that exterior walls and structural members be made of noncombustible or limited combustible materials such as concrete blocks or day tile blocks. Interior structural members including walls, columns, beams, floors and roofs are completely or partially made of wood. The wood used in these members is of smaller dimensions than that required for heavy-timber construction. See the Type IV-Heavy Timber construction that follows.

The primary fire concern specific to ordinary construction is the problem of fire and smoke spreading through concealed spaces. These spaces are between the walls, floors and ceiling. The heat from a fire may be conducted to these concealed spaces through finish materials, such as gypsum drywall or plaster, or the heat can enter the concealed spaces through holes in the finish materials. From there, the heat, smoke and may spread to other parts of the structure. If enough heat is present, the fire may actually burn within the concealed space. These hazards can be reduced considerably by installing fire-stops inside these spaces to limit the spread of the combustion by-products (heat, smoke, etc)

Strengths:

• Resists fire spread well from the outside
• Relatively easy to vertically ventilate

Weaknesses:

• Interior structural members vulnerable to fire involvement
• Fire spread potential through concealed spaces
• Susceptible to water damage
• Walls can retain heat

Type IV Construction – Heavy Timber

Also known as heavy timber construction, Type IV construction has exterior walls made of noncombustible materials (masonry). Interior structural members, including beams, columns, arches, floors and roofs are made of solid or laminated wood with no concealed spaces. This wood must have dimensions large enough to be considered heavy timber. These dimensions vary depending on the particular code being used.

Heavy Timber construction was used extensively in old factories, mills and warehouses. Traditional Heavy Timber construction is rarely used today in new construction except for decorative reasons. The use of Heavy Timber construction with glue-lam beams is growing.

The primary fire hazard associated with Heavy Timber construction is the massive amount of combustible contents presented by the structural timbers in addition to the contents of the building. Although the Heavy Timbers remain stable for a long period under fire conditions, they give off tremendous amounts of heat and pose serious exposure protection problems for firefighters.

Strengths:

• Resists collapse due to burn time of large dimension columns and beams
• Possible to vertically ventilate during the early stages of a fire
• Manageable debris following collapse

Weaknesses:

• Tremendous radiant heat causes potential for flame spread to other nearby structures
• Susceptible to rapid interior flame spread
• Large open spaces make search difficult and getting lost a significant hazard
• Water management may be an issue due to large volumes required for exposure protection and fire control

Type V Construction – Wood Frame

Also known as Wood Frame construction, Type V construction has exterior walls, bearing walls, floors, roofs and supports made completely or partially of wood or other approved materials of smaller dimensions than those used for Heavy Timber construction. Wood frame construction is the type commonly used to construct the typical single-family residence or apartment house of up to seven stories. This type of construction presents almost unlimited potential for fire extension within the building of origin and to nearby structures, particularly if the nearby structures are also wood-frame construction. Firefighters must be alert for fire coming from doors or windows extending to the exterior of the structure.

Strengths:

• Easily breached for access, ventilation or escape
• Resistant to collapse from earthquakes due to lightweight and flexibility
• Collapse debris is relatively easy to manage

Weaknesses:

• Susceptible to fire spread from outside
• Susceptible to rapid flame spread inside
• Susceptible to total collapse due to fire or explosion
• Susceptible to water damage

Non-standard Construction

(sometimes referred to as Hybrid Construction)

In many parts of North America, local building codes allow non-standard buildings to be constructed under certain circumstances. These structures do not conform to any of the standard construction types listed in NFPA® 220. Some non-standard structures are allowed to be built on large properties that are in very remote areas. Others are simply new construction concepts that are not yet recognized by national building codes. Even these innovative structures must conform to local zoning and land-use standards. One example of non-standard construction are Manufactured Homes.

Other forms of non-standard construction are allowed in certain jurisdictions. To protect yourself and your fellow firefighters, you must be aware of what types of structures are being built in your area of responsibility. In other words, you must pay attention to what is going on in your response district and make frequent preincident planning surveys of construction sites.

Attic, Basement Void Space Considerations

There are aspects of the building construction that make it difficult for firefighters to get the line where it needs to be. Areas that present access issues like basements, attics and void spaces present issues that need to be addressed by the Incident Commander.
Basements are below-grade spaces. Basements are built in a variety of forms however the main consideration is there access and egress. It is easier to identify basements on the method of access: walk-out, look-out, walk-up. Walk-out basements have access points to the outside meant for access and egress from that level. Look-out basements have windows but don’t allow for regular exterior access. Walk-up basements are below grade and access and egress are via stairs interior and exterior. It is imperative that Incident Commanders evaluate the ventilation profile of basement fires, both current and future.

The latest UL studies have found that water applied via the interior basement stairs had a limited effect on cooling the basement or extinguishing the fire. However, water applied through and exterior window or door, quickly darkened down the fire and reduced the temperatures throughout the building and no fire or hot gases were “pushed” up the interior stairs.

Attics and voids are usually not meant for normal human occupancy and have restricted or no access. They usually have unprotected structural elements. The lack of fire protection in these spaces allows for the fire to spread at a more rapid pace. Consideration should be given to the structural stability of the involved systems, and possible collapse concerns. Further, when opening up spaces it should be understood that each opening presents a new flow path for gasses to move and the possible effects on the energy production of the fire.

If the attic space eaves can be accessed with the hose stream from the exterior, that is where we should start flowing water….it has been proven to be the best method to apply water into the attic space and apply water on the actual materials that are burning.