Life Safety

Why a Four-hour Fire Rating Matters

A fire rag­ing through your prop­er­ty is a night­mare sce­nario. A blaze can start for many rea­sons and its effects can be dev­as­tat­ing. That’s why build­ing with mate­ri­als that are Four-hour Fire Rat­ed is a smart choice.

What Is the Four-hour Fire Rating?

In 1905, the Nation­al Board of Fire Under­writ­ers (NBFU) includ­ed pas­sive fire pro­tec­tion in its build­ing code. The NBFU bestowed the des­ig­na­tion fire­proof build­ing” to struc­tures that were built using non-com­bustible mate­ri­als, includ­ing brick, stone, iron and steel. These ear­ly reg­u­la­tions, how­ev­er, did not con­sid­er how exact mate­ri­als of vary­ing thick­ness actu­al­ly per­formed when exposed to flame and extreme heat.

Today, the advan­tages of non-com­bustible con­crete mate­ri­als are well known. For exam­ple, con­crete block will not emit nox­ious gas­es or vapors in the event of a fire and lim­it­ed heat trans­mis­sion main­tains mod­est tem­per­a­tures on one side of the wall even when tem­per­a­tures reach 2,000 degrees F on the oth­er. Even with con­crete, how­ev­er, there is vari­abil­i­ty in fire resis­tance that results from the com­po­si­tion and thick­ness of the mate­r­i­al.

In order to deal with the vari­abil­i­ty with­in cat­e­gories of build­ing mate­ri­als, archi­tects and con­trac­tors need to rely on fire resis­tance rat­ings. To help mat­ters, the Inter­na­tion­al Build­ing Code has insti­tut­ed a time-based def­i­n­i­tion of fire resis­tance. Fire resis­tance, accord­ing to the code, is The peri­od of time a build­ing ele­ment, com­po­nent or assem­bly main­tains the abil­i­ty to con­tain a fire, con­tin­ue to per­form a giv­en struc­tur­al func­tion, or both.”

How Is a Fire Rating Earned?

Wall com­po­nents are usu­al­ly test­ed using ASTM Stan­dard E119. The test­ing is excep­tion­al­ly rig­or­ous and includes two phas­es: fire expo­sure and water hose test­ing.

The fire expo­sure phase mea­sures the abil­i­ty of load-bear­ing wall assem­blies to pre­vent pen­e­tra­tion by flame and super-heat­ed gas­es over a peri­od of time. As part of the test­ing, the wall assem­bly is loaded into an oven, tem­per­a­ture sen­sors are placed on both sides of it and gas flames blast away at one side of the wall.

The water hose test­ing pro­vides an indi­ca­tion of how well the wall sys­tem will hold up under actu­al fire con­di­tions, includ­ing direct fire expo­sure, falling debris, and high-pres­sure/high-vol­ume water streams from a fire hose.

At the con­clu­sion of the test­ing, the wall sys­tem receives a one‑, two‑, three- or four-hour rat­ing to indi­cate how long it should hold up dur­ing a fire.

What Makes the Four-hour Fire Rat­ing So Impor­tant?

There is no good news when an uncon­trolled fire breaks out but wall assem­blies built with four-hour fire rat­ed mate­ri­als offer some excep­tion­al pro­tec­tion that can mean the dif­fer­ence between a dev­as­tat­ing out­come and a trag­ic one.

Increased Time for Safe Egress

Evac­u­at­ing from a burn­ing build­ing and escap­ing from the dan­gers of smoke and fire can take some time. If a fire breaks out in a mul­ti-sto­ry build­ing or one in which occu­pants with mobil­i­ty impair­ments need to be assist­ed, the extra time afford­ed by fire-resis­tant mate­ri­als can make all the dif­fer­ence.

Pro­tec­tion for Fire­fight­ers

Fire­fight­ers need to com­bat the blaze and search for any indi­vid­u­als who may have been left behind. Enter­ing a build­ing in the advanced stages of a fire comes with incred­i­ble risks, and those are increased if the wall sys­tems of the build­ing do not have a high fire pro­tec­tion rat­ing.

Main­tain the Integri­ty of Load-bear­ing Walls

Fire and smoke inhala­tion are the obvi­ous dan­gers when we think about build­ing fires, but col­laps­es also pose a very real threat. The longer the load-bear­ing walls are able to with­stand the fire, the low­er the like­li­hood of some­one being the vic­tim of a build­ing col­lapse.

Lim­it the Spread of the Fire

Fire can be very dif­fi­cult to con­tain and caus­es the most dam­age when it can spread through­out a build­ing or, worse, start a blaze in a neigh­bor­ing one. Four-hour fire rat­ed walls can con­tain the flame for a longer peri­od of time, allow­ing fire­fight­ers greater oppor­tu­ni­ty to extin­guish it before it spreads.

How Bautex Passes the Four-hour Fire Rating Test

Con­crete is non-com­bustible but the fire rat­ing of CMU blocks varies accord­ing to thick­ness and the types of aggre­gates used in the man­u­fac­tur­ing process. Engi­neers and con­trac­tors seek to increase the fire rat­ing of mason­ry walls by var­i­ous means, includ­ing increas­ing thick­ness, spec­i­fy­ing dif­fer­ent aggre­gate blends, fill­ing the inner core, and adding a plas­ter or wall­board fin­ish.

Foam has very good insu­lat­ing prop­er­ties but, on it’s own, it is com­bustible.

To avoid the com­pli­ca­tions usu­al­ly face with con­crete and foam, Bau­tex Sys­tems has devel­oped a pro­pri­etary wall sys­tem with a four-hour fire rat­ing. The wall sys­tem com­bines a cement-based mix­ture with a unique mix of expand­ed poly­styrene (EPS), a prod­uct that has found increas­ing appli­ca­tions in con­struc­tion­al mate­r­i­al engi­neer­ing thanks to its ther­mal effi­cien­cy, mois­ture resis­tance, and reduced weight.

The inno­v­a­tive Bau­tex wall sys­tem pro­vides supe­ri­or fire pro­tec­tion while still allow­ing for an effi­cient, sin­gle-con­trac­tor instal­la­tion process.

Everyone Deserves to Be Safe

Every­one deserves the safe­ty pro­vid­ed by four-hour fire rat­ed build­ing mate­ri­als. Thank­ful­ly, with the Bau­tex Sys­tem, pro­vid­ing that lev­el of fire pro­tec­tion has nev­er been sim­pler. Learn more here.