Replies

1. 
   jlyda | Feb 22, 2020 02:34am | #1

   The issue is the fire rated assembly needs to be tested and certified by the ULC. In theory if 1/2” is 30 min than another 1/2” should be 1 hr. Your local code authority will require the ULC listing (if like mine). I do not recall seeing a 1 hr listing for 2 layers of 1/2”, but there are a lot of listings. I know they make a 1/2” single layer that’s rated for 1 hr, but the drywall is so expensive you rarely see it. If you go to major drywall manufacturers (like USG) they have almost all the ULC listings available for you to view. You can go through that to select the assembly best fit for your project. You will need to provide your code authority with the listing number for approval. Again, all this is based upon my code authority procedure.

1. 
   jlyda | Feb 22, 2020 03:47am | #2

   Also, recessed lights need to be fire rated as well. I typically install surface mounted fixtures on fire rated ceiling to keep time and cost down.

2. 
   firedudec56 | May 03, 2020 08:04am | #3

   sorry about seeing this so late - if you're using the existing 1/2 inch drywall, you'll need to "prove" it's fire-rated and properly installed. If you add more drywall, the installation has to done according to the listing, usually means the seams can't line up.
   any rating is based on an assembly so just installing 1/2 inch and thinking it "should" have a 30 minute rating may not work if there is nothing to prove it meets a particular approved either UL or FM rated assembly.
   you may want to see about getting a variance to use the existing based on a similar rated assembly with adding more drywall to get an acceptable installation
   good luck

3. 
   MarkkTrrr | May 15, 2022 06:45am | #4

   Try here at https://ndrelectric.com/category/recessed/razor-cct-fr-series, to see some solutions

4. 
   firedudec56 | May 15, 2022 10:37am | #5

   thanks for the info

5. 
   mikemahan3 | May 15, 2022 08:00pm | #6

   Ceiling supports (trusses, joists etc) must be no more than 16” oc