L Ratings: Why Don’t Your Specifications Include Them?

One of my pet peeves is people who use code verbiage WRONG.  A fire wall is not the same as a fire RATED wall.  Watch this video and you will see what I mean. The fire wall and some exceptional teamwork saved the lives of the firefighters in that video. A standard fire-rated wall can’t match a continuous fire wall from lowest level to roof. Firefighters understand the parapet acts as a fire wall, able to withstand collapse on one side while protecting the other from fire.

Architects use FIRE WALLS for buildings larger than allowed by the code. This effectively divides one building into multiple segments or separate buildings connected by a rugged structural wall.

So what about fire barriers and smoke barriers?  These are NOT the same either. 

Did you know that a fire barrier should have an F rating? More on that here.  Yeah, well a smoke barrier is required to have a one hour F ratings too. Does this mean all penetrations through fire or smoke barriers must match the wall’s F rating? This is hopefully no surprise to you at this point.  This however this next point might be. 

Did you know that joints or penetrations in smoke barriers require an additional test that fire barriers do not? It is an L ratings and Engineering Toolbox explains it here.  When reviewing firestop submittals, it’s crucial to identify the locations of smoke barriers, their rated assemblies, and the penetrations. First, identify these items. Then, ensure the firestop details received meet the required code test.  When I say YOU, I am talking to all of you- the architect, building official, GC, firestop installer or special inspector. If the trades are self performing their own firestop, then I am talking to each of the trades as well. 

Do you know, if you project has smoke barriers?  If you have them please check your firestop submittals to see if your details cover this code requirement. 

If you are working in a hospital, pay particular attention because smoke barriers may be a requirement to help reduce the nosocomial infection rates.  You know the person who goes into the hospital with a broken arm and leaves with a cast and the worst flu of their life. That is a remedial explanation of nosocomial infection.  Before you think its not a big deal, you should know that nosocomial infections are linked to the death of  as many as 6 children and the subsequent 2019 closure of Seattle Children’s Hospital, so it is serious business. 

L ratings are also important in clean room environments or rooms with FM200 or other similar fire suppression system where room volume is critical tot he life safety measures. 

If you have any questions, feel free to give us a call. We are happy to help if we are able.