I Finished My Basement

Save Money, Get more Space, Learn Something New and Fun

  • Home
  • About
  • Basement Ideas
  • Getting Started
  • The Major Phases
    • Basement Waterproofing
    • Framing
    • Electrical
    • Drywall Doors & Trim
    • The Bathroom
  • Tools
  • The Book and Videos

What is fire blocking? How do I fire block when framing my finished basement?

by Jason 85 Comments

Not sure how to install fire block? I'm your huckleberry. I know that's a movie quote from somewhere but I can't remember where. I think it means I'm your man or something southern macho like that.

how to fire block a basement wall

If you're reading about fire blocking then I know you must be either:

1. Someone who plans way ahead (kudos to you!)

or

2. Someone who is presently freaking out. Perhaps because you missed a major step in your basement finishing project.

Either way, I know I can help you. During my basement finishing project I was the latter. The guy freaking out.

I remember, it was a Monday. I mentioned to my friend Tom that I was done framing my basement walls and had scheduled my framing inspection for Thursday. He goes, "Cool. You are really doing it." then casually mentions as he walked away. "Don't forget fire blocking - they'll fail you for sure."

WHAT!!!  What the hell is fire blocking? Can I do it in 3 days?

The purpose of fire blocking is two fold. Starve a fire of oxygen and prevent it from spreading. Ironically, fire blocking material does not have to be fire-proof. It just has to keep the fire from getting fuel (air/oxygen).

basement wall with no fire block

Here's my best attempt at visually explaining what fire blocking is and where it goes. In this example there is NO fire block. The fire can get air and move freely. (not good)

When you're finishing your basement, you need to install a fire block in the gap between the top plate of your framed wall and block wall of your house foundation.

basement wall with fire blocking

Ok, same diagram but with fire blocking installed right near the top plate of the wall. That's it, a little strip of drywall. Not that magical.

Believe it or not, that's the best explanation I was able to write after 30 minutes of my hamster brain running. Read these other sections and it will make more sense.  I know, you're probably thinking "what the hell is he trying to say???"

What material can I use as a fire block?

I recommend using drywall as a fire stopping material. You can also use 2x4s, plywood, rigidly packed insulation, fire foam and sometimes sheet metal. I used drywall for my basement. I was a bit short on time so drywall was easiest to cut to the right width and length. It passed inspection without any issues.

How do I "install" fire block?

Fire blocking isn't something you'll see at the Home Depot labeled "fire stopping stuff" or "fire block". It's just material (drywall in my case) that's nailed into the gap between your top plate of your framed walls and the foundation of your house.

So you're going to cut a strip of drywall (or other material) the width of the gap from the block wall to the framed wall, probably 4 to 5 inches. Then push that strip of drywall up into that space.  Take a few nails or screws and secure to the material in there so it doesn't fall. It doesn't have to hold Andre the Giant, just its own weight, so a couple of screws or nails should do it.

If you have small enough gap just use some fire foam and it will expand to fill the space. Plus, it fun to squirt.

Fire Block Space around Holes for Pipes or Wires

fire foam used to fire block holes for electrical wiring

photo from : http://joshbasement.blogspot.com (thanks Josh !)

If you drill a hole in the top plate of a wall so you can run plumbing pipes or wiring you need to stuff some rock wool or insulation in the remaining space.

Yes, even a little tiny space. Don't shortcut it.

If a fire is burning behind your wall and that space is open the fire will suck air into the gap and go burn crazy.

No hole... the fire should just smolder or even go out.  Giving you, your family and your fire department time to react.

Not sure what you can use to fire block? Ask your Inspector!

If you're not sure about what you can use in your area for fire blocking, ask your inspector. Don't be afraid to call, they are there to help you! Call them. Here's what you say. I wrote it down for you.

You:   "Hello, I'm finishing the basement of my house and I have a question about fire blocking ."

Inspector Receptionist:  "Okay, no problem, hang on while I get _____ (Fred).

Fred: "Hello?  What ?  (Fred is a little hard of hearing, due to that one air show he went to where he stood right next to the engine while it "warmed up".)

You: " Yes, Hello... Fred... What material do you recommend for fire blocking if I'm finishing my basement? Is it okay to use drywall?

Fred:  "Yes….yeah... drywall is A-okay! Thanks for checking."

See. That was easy. He even said thanks for checking, so you know you are good to go.

3 Questions, 3 Answers - About Fire Blocking

Q: Do I install fire blocking before or after wall framing?
A:  After. You can also do it as you go along. I didn't even know about it so for me… after was good.

Q: What if I don't install fire blocking?
A:  You will fail your framing inspection. Well, you "should" fail. Not a huge deal, you don't get penalized or anything - you just have to install the fire block before they will pass you. In most areas they'll come back for another inspection at no extra charge.

Q: What is horizontal fire blocking?  Do I need to worry about it.
A:  So, the fire blocking we've been talking about is vertical. It stops fire from moving up. Horizontal fire block stops fire from moving sideways. My county did not require horizontal fire blocking. It wasn't even mentioned at all in the building codes. Check your code, but it seems like it's not required in many areas for basement finishing - check your code though.

basement finishing jason 205I hope that helps. I know for me fire blocking was a tricky topic to grasp at first.

You're doing awesome! Keep going with your basement finishing! It's going to be so worth it.

If my awesome explanation wasn't good enough, although I can't see how that would be, feel free to leave a comment or question below this post.

Cheers - Jason

More Firey Links : 

  • Links about framing your basement.
  • Do you enjoy spending too much for power tools? Don't click here then.
  • If you only buy 1 book on framing, here it is.
  • How to buy lumber for your basement project.
0
Your Best Email >> *

Signing you up... Come on internet,it\'s GO TIME!

Signing you up... Come on internet,it\'s GO TIME!

Signing you up... Come on internet,it\'s GO TIME!

Questions and Comments

Click here to ask a question or leave a comment.

  1. Nick says

    October 31, 2012 at 8:38 am

    I installed fireblocking before framing as recommended by the inspector. I simply cut 8 foot drywall sheets into strips and screwed them to the floor joists (or blocking going the other direction) along where my exterior framing would go. Then the top plate of the wall was screwed to the joists through the layer of drywall.

    I think Jason's way might be easier in the long run since I may have to shave off drywall and make it even with my top plate where I left it a little too wide.

    You'll also need to make sure to fireblock any exterior wall framing that runs under a soffit, it's the same idea, but visually is different and for some reason was hard to wrap my head around.

    Reply
    • David says

      June 30, 2018 at 8:36 am

      Having not done it until after, I guarantee doing it first like you did is indeed faster if you left curtain insulation in place and pulled your walls out a bit. This creates a void bigger than what can be covered by a 2x4, plus...you have to block the area behind the stud "in the shadow of the stud". You can't fill that space with fireblock foam as it is only for gaps up to 1/2" . That means notching the drywall too. Ugh. I am using Rockwool in my situation (ok by inspector) and drywall for horizontal (every ten feet rule).

      Reply
    • Ranbir says

      November 6, 2020 at 1:32 am

      Do you have to fire block inside walls or just exterior. how do you fire block the windows and doors framing.

      Reply
  2. Jian from Toronto ON says

    November 8, 2012 at 1:26 pm

    Hi Jason, Thanks for everything you posted on your website. I am about to remodel my basement myself. Luckly, I found your website, and now I am learning and digesting from your DIY day by day. The drawings and picture in regard to fire blocking are very helpful.

    Reply
    • Jason says

      November 8, 2012 at 2:01 pm

      Jian - That is awesome! I'm so glad it's been helpful, theres more on the way. You've got the perfect attitude, make some progress each day, each week and before you know it you're looking at a great finished basement for a third of the price. Plus a primo set of tools and skills to boot. Have fun! - Jason

      Reply
  3. Jon says

    November 28, 2012 at 7:14 pm

    FYI
    The walls of my basement came with insulation already on the walls so I'm framing my walls on the outside of the insulation. The inspector here (Colorado) says the insulation on the walls can act as the fireblock so I don't need to add anything special...YAY!

    Reply
    • Jason says

      November 28, 2012 at 7:52 pm

      Thats... interesting.... I'm not sure how that qualifies as fireblock for the vertical space? But, if they say ok, then it should be good. No big deal if they aren't being clear, they'll just tell you what you need at the framing inspection. - Jason

      Reply
  4. Dan says

    December 9, 2012 at 2:52 pm

    Jason, I a bit slow...do you mean that the sheetrock should go on all the vertical ceiling boards (and horizontal boards, if required)? Dan

    Reply
    • Jason says

      December 11, 2012 at 9:00 pm

      Dan - I'm not 100% sure I'm following your question. For fire blocking you do need to install it along the entire perimeter behind your wall, there shouldn't be any gaps where a fire could spread vertically. If you have a picture email it to me and I can probably comment more better. - Jason

      Reply
  5. Jeff says

    January 29, 2013 at 6:43 pm

    Hi Jason,
    Is 1/2" thick drywall acceptable for fire blocking in the stud cavities or does it need to be 5/8"?
    Thanks....Jeff

    Reply
    • Jason says

      January 29, 2013 at 7:38 pm

      Hey Jeff - 99% sure 1/2" is okay. It was fine in Loudoun County, VA. - Jason

      Reply
  6. Jared says

    February 9, 2013 at 8:08 pm

    Hello Jason,

    You post was awesome and just what i needed. I was like you and freaking out that I had finished my framing with no fire-blocking. Thank you so much for your post! I just wanted to say thank you for your drawings and pictures also, they helped me understand exactly what I needed to do.

    You da man!

    Reply
    • Jason says

      February 10, 2013 at 8:01 am

      No problem Jared, thanks for commenting. That's what makes the writing fun for me. - Jason

      Reply
  7. Ed says

    July 21, 2013 at 2:02 pm

    Hi - Thanks for your article. I understand that 1/2" drywall would be acceptable to use as fire blocking where I am located. However, it shows the 1/2" drywall tight to the joists and then extending to the exterior perimeter sill plate, then the top plate of the basement framing fastened through the 1/2" drywall into the joist above (top plate of basement framing would be under the drywall). Even though the basement wall will not be a load bearing wall it seems odd to fasten through the drywall to catch the joist - do you or anyone on here have any experience with this method and its long term viability?

    Reply
    • Jason says

      July 21, 2013 at 6:14 pm

      Hello Ed - Although I haven't seen it done this way too often it would seem to me that should work just fine. It sounds like what you're describing is that they drywalled the ceiling first then framed the wall. In this way the fire-blocking is already in place? Once the walls were framed you would just have to drywall the walls and you're good to go. Seems okay.

      Anyone else seen this? Please chime in. Good luck with your project! Cheers -Jason

      Reply
      • Robert says

        February 10, 2015 at 3:52 pm

        Hi Jason,

        I put my fire block (1/2 drywall in first then caulked with fire resistant caulk to fill gaps along the concrete wall. I then built my walls and nailed them in place. I used a 6' level and a straight 2x4 to determine how wide to cut my drywall (fire block) so that I would not have to trim the drywall after the walls were in place. This passed in Stafford county VA.
        Thanks,

        Robert

        Reply
        • Jason says

          February 12, 2015 at 12:45 pm

          Yes, this is definitely an option for fire blocking. Good idea checking with you building department. - jason

          Reply
  8. Tom Bennett says

    August 25, 2013 at 11:24 am

    Jason, great article and your writing style is very easy to understand and makes perfect sense. Now my wife and I can stop discussing fire blocks on our project...she won. I had to laugh at the very beginning when you talk about the statement "I'm Your Huckleberry". The movie was Tombstone and it was what Doc Holiday (Val Kilmer) said to Johnny Ringo during the movie. It's in reference to Huckleberry Fin of the Tom Sawyer books, Huck Fin being Tom's back up and best friend. Doc was Wyatt Earp's very good friend in the movie.

    Reply
    • Jason says

      August 27, 2013 at 4:53 pm

      I'm glad someone has my same level of movie intelligence, knowledge of history and recall. Thank you for the wonderful compliments on my writing, I really appreciate the feedback. Clearly you're a man of great character and savvy.

      As for the fire blocking - like you I always let my wife win arguments - this makes getting permission for my annual 4 day golfing trip to Orlando that much easier.

      Cheers - Jason

      Reply
  9. Steve says

    October 3, 2013 at 12:00 pm

    Very entertaining writing style!
    In Colorado, horizontal fire blocking is also required, or draft stopping, especially after these huge fires we've had. They're slightly different, but go together. The principle is that only 100 sq ft of wall or ceiling should be air-flowing. So less than every 12 linear feet of wall, there should be a sealed barrier (on the outside walls, preventing air from flowing along between the basement wall and the framing. Like you've said, you can do it with wood (2x or 2 1x) or drywall or structural board, and seal the seams with fire caulk or compressed (packed) fiberglass insulation.
    And you've already covered the vertical blocking--separating the cavities in between the floors from the walls, and from each other. With these huge fires, one of the things that happened is that a deck caught fire, the fire entered the area inside the exterior wall under the first floor and...spread like crazy, resulting in the loss of the whole house and fuel for the next house down the street. Embers that could start new fires were flying up to 1/2 mile!

    Reply
    • Jason says

      October 3, 2013 at 3:17 pm

      Steve - Great info. I didn't even think about fire creeping in from the outside but you're 100% right. These seemingly small fire blocking tips can be the difference between a small fire and the total loss of your home. - Jason

      Reply
  10. frank says

    October 10, 2013 at 12:42 pm

    Hi, Jason,,

    I am not sure I understand correctly

    "Then the top plate of the wall was screwed to the joists THROUGH THE LAYER OF DRYWALLl."

    any picture will be helpful.

    Thanks

    Frank

    Reply
  11. Cliff says

    January 18, 2014 at 4:05 pm

    Jason,

    Can you walk us through fire stopping soffits? I can't seems to visualize it at all. I'm also in Loudoun County so I'm glad to hear I don't need to fire stop horizontally.

    Thanks,
    Cliff

    Reply
  12. Geoff says

    April 19, 2014 at 1:31 am

    Hey Jason,

    I'm wondering about fire stopping for a basement in which we plan on having an open/painted/industrial looking ceiling (In other words... no drywall... just rafters, pipes, wires, etc. shown bare). I'm still in the planning stages of my project so I'm not in a rush but I'd love to hear your thoughts.

    Thanks,
    G

    Reply
    • Jason says

      April 20, 2014 at 9:30 am

      Hi Geoff - Okay, here's the deal with fire blocking your basement with a no drywall ceiling. It's the same as if you had a drywalled ceiling. Fire blocking is for the ceiling space behind your basement walls (which I'm presuming are going to be drywalled). There will be a 3-5" space between your concrete wall and the framed-drywall walls. It's that ceiling space that MUST be fire blocked with drywall or some other material.

      The reason is that that space is hidden. Because the drywall for the wall goes up to the ceiling the space behind it is hidden. IF your design has some kind of openness to the top of the walls then perhaps you would not need fire-blocking. Any concealed space must have fire stopping materials at the top to prevent the spread of fire to the next floor.

      Hope that helps to explain it. It's a great question - and I really like the no drywall ceiling option - let us know how it turns out.

      Cheers - Jason

      Reply
  13. Daniel Hofer says

    May 6, 2014 at 1:42 pm

    Thanks! Starting in a month or so.

    Reply
  14. Ran Parikh says

    September 9, 2014 at 10:58 am

    My family member did basement without permit. When he went back to get CO, the city is giving hard time to pass inspection without fire stopping. walls are up and painted. Is there any other way to install fire stopping without destroying walls??

    Reply
    • Jason says

      September 10, 2014 at 4:42 pm

      Bummer... that's a common issue that trips people up who don't get permits. There's no way that I know of where you can add fire-blocking without removing some drywall.

      This page talks in more detail about some of your options for fire-blocking after drywall has been installed. Good luck! - Jason

      Reply
  15. Don says

    September 22, 2014 at 1:43 pm

    Jason,

    I am finding myself in trouble before I get these permits started to finish my basement. Last year my pipes were blocked solid from the Kitchen to the Basement from 50 years of bacon grease and who knows what else from the previous owner. My friend and I tore out the Cast Iron and Copper piping and installed PCV in a day but needed support for the new 2" pipes so we built an open frame, 2x6 studs and 24" apart along the wall to the existing cast iron stack for the plumbing. My friend and I didn't know anything about fire blocking until I read what I need to do for finishing my basement this past week. From what I see from the town here in NJ and on other websites, people are attaching 3/8 plywood, Drywall, or a 2x4 before putting up the framing to go between the floor and the Fire blocking. I see what you did in that one picture which looks similar to my situation where you had existing framing but no Fire blocking and you added Drywall and Spray Fire resistant foam underneath the 2x4. Will or did it pass code for you?
    Thanks,
    Don

    Reply
    • Jason says

      September 23, 2014 at 4:27 pm

      Hello Don - Yes, I used drywall and some spray foam for fire blocking and both methods passed code. I've also worked with guys who like to use rock wool, and that has passed. I can't comment specifically on NJ - but I would guess their allowable methods for fire blocking are similar.

      Hopefully that helps - good luck with finishing your basement! - Jason

      Reply
  16. Jaysen says

    March 30, 2015 at 8:22 pm

    I am finishing my basement that had the insulation attached to the exterior concrete walls. I have put up the exterior walls and was wondering how to do the fire blocking. I looked at putting a 2X4 in between the studs horizontally, but that left a gap below between the studs where the plastic over the insulation compressed and also left noticeable gap behind the studs. I believe that defeats the purpose of fire stopping, but it does block gap to the trusses above. Any suggestions on how to approach this with out tearing down the walls and starting over

    Reply
    • Jason says

      April 4, 2015 at 10:21 am

      Hi Jaysen - Yes, I have suggestion. In fact I did my fire blocking AFTER framing as well and I also had insulation on the exterior walls as you are describing.

      What you want to do is use drywall as your fire blocking material. You just need to cut long strips of drywall 3 to 4" wide. I didn't even need to nail the drywall strips to anything they just fit snuggly between the top place of the framed wall and the sill plate (wood beam) on top of the exterior wall.

      You are correct that you do not want ANY gaps behind your wall - you can use some rock wool to fill any holes or spaces that are too small to cover with drywall.

      Hope that helps out - you should be fine but just to double check you might want to call or look up your local building department to ensure they accept drywall as a fire blocking material.

      Good luck!

      Jason

      Reply
  17. Drew says

    April 15, 2015 at 2:47 pm

    I too have the majority of my walls framed before learning about fire blocking. The building inspector in Ohio said that drywall cannot touch the foundation walls. In that case is there a trim to go around the drywall or a special type of drywall (i.e. cement) that can be used to fireblock? Is there a reason you can't just use Rockwool along the whole exterior of the wall instead of struggling to fit drywall or plywood pieces to the top plate and behind studs?

    Reply
    • Jason says

      May 11, 2015 at 3:42 pm

      Hi Drew - Not touch the foundation?? That's a first for me. I guess technically mine was touching the "sill plate" not the foundation but still. Yes, from what I've read and heard from other rock wool is acceptable, even all the way around to fill in major gaps. I would call the inspection office and confirm but that may be the best solution for you (others in Ohio, may want to double check this). - Jason

      Reply
  18. Steve says

    September 25, 2015 at 12:56 am

    Thanks for the insight. My basement framing is about an inch from the concrete, so if I was to do the same as the pictures post above would there not be gaps behind the 2x4? Also in my case, my foundation only runs up about 90% of the wall. If i was to attach the drywall to the underside of the top plate the front edge of the drywall would be pressed up against wood and not concrete. It doesn't seem effective? Am I missing here?

    Reply
  19. Theodore says

    December 18, 2015 at 3:02 pm

    Hi Jason, Excellent site. I'm currently finishing my basement and getting stuck on fire blocking above the main electrical panel. I often find examples online of one or two discreet wires or a plumbing pipe penetrating the basement wall's proposed top plate. But above the electrical panel, there's 20+ armored cables going up and into joists. My first challenge will be to frame a wall around this mess. And after that, I've no idea how to fire block 20+ penetrations. They're so close together that it won't be individual penetrations. Any suggestions?

    Reply
    • Jason says

      December 21, 2015 at 10:08 am

      Hi Theo - The framing part is a whole topic in itself, but to fireblock those gaps between the wires and the framing you just need a bit of rock wool. This stuff is soft like insulation and (wearing gloves) you can just pull a bit off and gently place it into any air gaps. Good luck! - Jason

      Reply
  20. Matthew Lemmon says

    February 2, 2016 at 2:26 pm

    Some of the exterior walls in my basement are half concrete half exterior framed, do I have to install fireblocking on these walls? Basically I'll be installing fireblocking between the top plate of the wall I built and the 2x6 exterior wall the builder put on top of the concrete 1/2 wall?
    Thanks

    Reply
  21. Daniel says

    March 17, 2016 at 11:02 pm

    I framed in front of my existing insulation. How do I fire block every 10 feet along the studs?

    Reply
    • Cal says

      March 22, 2016 at 2:01 pm

      Following. I did same thing. I did not know about this requirement when I started project. Will I just have to run particle board behind wall now?

      Reply
  22. david says

    April 20, 2016 at 9:28 pm

    Is this only need on framing up against the exterior walls? I'm trying to figure out where I need it. I put 2" XPS right on the concrete and will be framing right up next to that, so there really won't be any gaps like in your pictures.

    Reply
    • Jason says

      April 25, 2016 at 4:01 pm

      If there are no gaps then you're good to go. But if there's even an 1/2 inch, you should fill it. - Jason

      Reply
      • Aaron says

        May 30, 2016 at 2:16 am

        I realize there will not be gaps between the rigid foam and framing but don't inspectors assume that in a fire the hot gasses melts the foam almost instantly , therefore leaving a gap? Don't they require the fire blocks to go through the foam and to the foundation or sill plate?

        Reply
  23. Kirk Varra says

    September 13, 2016 at 12:30 am

    "ill be your huckleberry" is a quote from Doc Holiday. a huckleberry is a little flower typically left on a grave. Doc Holiday would say "ill be your huckleberry" before a gun fight. He was basically saying that he would be the flower on their grave. so yes, manly. good article on fire blocking by the way.

    Reply
  24. Rick says

    September 13, 2016 at 10:01 am

    Awesome, helpful and hilarious post, thanks!!

    Reply
  25. Erich says

    November 8, 2016 at 5:36 pm

    Our contractor failed inspection because horizontal fire blocking was not installed at the top of the metal furring. The building is all concrete block and bot a basement. It is one story and she said to install wood fireblocking within the top of the furred space. The roof framing is wood trusses. In the building code fire blocking is only related to combustible construction. Do you think that because the trusses are wood and the rest of the building is not is what is triggering the requirement for fire blocking? The building is one story, utility building with concessions that servsd premade food, a small office for the park director and restrooms with no interior furring.

    Reply
    • Jason says

      November 9, 2016 at 4:44 pm

      Hi Erich - I can't say for sure. I only comment on basements and this sounds like a shed or out building for food, etc, which could have completely different code. Sorry I couldn't be of more help. - Jason

      Reply
  26. Doug says

    February 16, 2017 at 4:14 pm

    "I'm your Huckleberry..." Val Kilmer as Doc Holiday in the movie 'Tombstone" with Kurt Russell, 1993. You're old.

    Reply
    • Jason says

      February 18, 2017 at 9:22 am

      Guilty as charged, and happy for it, the alternative is not as enticing. - Jason

      Reply
  27. Wayne Hoffman says

    May 18, 2017 at 8:56 am

    Do you need to install Fire Blocking at top of basement wall if you don't drywall the ceiling? The basement will not be finished some contractors use spray foam and stud out the wall and cover with drywall. Your drawings all show a drywall ceiling.

    Reply
    • Jason says

      May 24, 2017 at 11:32 am

      I would double check with your local area ordinances but most likely, "no", since the area behind the wall is no longer hidden by the drywall of the ceiling. That's my best guess based on what I've read about the reasons for fire blocking in the first place, again, double check. - Jason

      Reply
  28. Steven says

    August 17, 2017 at 1:00 pm

    What about spray in insulation into 2x4 wall and joists in basement? Is the spray foam considered fireblocking material? It fills all vertical and horizontal gaps in the wall and joist.

    Reply
  29. Bill says

    August 20, 2017 at 3:01 pm

    I have my permits and outlines in place, bought my wood and my inspector said don't forget to fireblock FIRST! I asked specifically what he wanted and his reply was 1/2 inch drywall cut in 1 foot strips (as long as needed) nailed to the ceiling joists out to the sill plate, then build the wall up under that. Sounds fine but in many places I have to come down under steel beams or pipes, etc so that doesn't exactly work, my plan id to try and do his method wherever possible but in some areas I may have to just cut and insert up under the top plate as you have done. I hope he doesn't fail us but it's the only way I see it working in some areas.

    Reply
    • Jason says

      August 21, 2017 at 8:55 am

      You should be ok, as long as you've tried to address all of the open areas with a fire-blocking solution. Let us know how it turns out. - Jason

      Reply
  30. Mike says

    December 23, 2017 at 7:27 am

    Thanks for the information, this was very helpful. I found out about fire block after I got done with the framing. Of course it was a co worker that told me about it. ???

    Reply
  31. Lissette says

    February 15, 2018 at 1:09 pm

    Great job on explaining everything but I am still confused. I bought my house four years and ago and closing day found all of the sheetrock in the basement was molded. We removed everything and when the inspector came she said it needed fireblock. She talked alot about Roxul and said we could stick it up there. If I buy the long roll and use as my insulation, when I get to the top area would I just put it across as I would a 2x4? I would appreciate any guidance.
    Thank you! NJ

    Reply
    • Jason says

      February 26, 2018 at 3:20 pm

      Hello Lissette - Yes, I know its confusing, it's a very difficult concept - until you've got it - then it appears to be a simple fix. I'll try my best to explain. Fire blocking designed to slow down the spread of fire from one floor of your house to the next. The drywall that is your ceiling is a form of fire-blocking.

      Typically inspectors are looking for fire-blocking in the gaps between the foundation wall and the framed wall of your basement - specifically at the top of that wall area. Suppose a fire started "behind" of your basement walls - it would quickly race up to the next floor of your home - unless you stuff something in there to slow it down / block it. That can be drywall or Roxul or other substance approved by your local jurisdiction - each area in the country may have different approved materials.

      Hope that helps!

      - Jason

      Reply
  32. Mike Tulloch says

    March 25, 2018 at 10:08 am

    Complete kitchen remodel in an 1880s story and a half farm house.
    Balloon frame construction. Opening up interior and exterior walls and ceiling reviled a perfect example of chimney walls inside and out connected to ceiling truss bays. Completely frightening. Fire blocking being installed both vertical (there are no sill plates anywhere) and horizontally (although each room runs joists different directions "wall bays" connect ceiling spaces). This site was a great help in tackling a non basement problem of huge proportions!

    Reply
  33. David says

    July 4, 2018 at 7:05 pm

    I’m thinking about buying a house and it hasa finished basement . It’s not up to code how do I put the fire block in since the basement is already finished .

    Reply
    • Jason says

      July 8, 2018 at 11:02 pm

      Hey David - You'd need to remove the drywall to install the fire blocking. How do you know it wasn't installed correctly?

      -Jason

      Reply
  34. David says

    July 4, 2018 at 7:19 pm

    How do you cut into a finished basement wall that doesn’t have fire block in order to install it?

    Reply
  35. Coby Call says

    July 25, 2018 at 8:02 pm

    I am finishing my basement and I have attached continuous insulation (xps) to the basement concrete walls and ran it all the way to the floor joists. I have framed in front of the foam insulation and it is pretty tight to the foam. The places that are gapping from the foam I was going to add Dow fireblock spray foam. In the 2x4 channels I am going to put Roxul Rockwool. My concern is that I have not ran anything (plywood, Sheetrock, etc) to the concrete and am concerned that the inspector won’t pass what I have done with the foam being flammable. Do you think I need to cut out 1/2” section of foam at the top of the stud wall and run it to the concrete wall to pass as fireblocking or is what I am doing sufficient? Thanks.

    Reply
    • Jason says

      August 2, 2018 at 8:06 pm

      Coby - Here's my amateur take on your question. A lot of the approved fireblock methods (ex. wood) are still flammable, but are meant starve the oxygen from the fire. I'd say you've accomplished that, but who knows what the inspector will say. Prior to ninjaing, yes that's a word, out a 1/2" around the top, I'd call the inspector and ask.

      -Jason

      Reply
  36. Jay says

    January 14, 2019 at 8:38 am

    Nice article. Im finishing my basement now and i have a question similar to the one posted here but not answered. There's an existing 2in xps foam all around my basement. Floor to ceiling. Im putting up the framing now. Is it code to just put the fireblock against the xps foam? Or do i need to cut the xps and slid in the fireblock against the concrete walls? Thanks

    Reply
    • Jason says

      January 14, 2019 at 8:12 pm

      Hey Jay - Good question. It's my understanding that ICC 718.2.1 permits cellulose insulation as a fire block. That said, it sounds like you have the vertical fire block covered but need the horizontal space between the XPS and wall. You can use 2x, drywall, plywood, rockwool, etc...

      Hope that helps,
      Jason

      Reply
  37. Jason says

    February 4, 2019 at 8:41 pm

    Finally someone who cares about fire block as much as I do!

    Reply
  38. George says

    April 5, 2019 at 11:34 am

    fireblock.. if I install 2" xps board against my basement concrete block, and then put the 2x4's against that, do I just put in rockwool above the top of the wall and against the exterior wall/ soffit?

    Reply
  39. David Cooper says

    June 7, 2019 at 2:50 pm

    My home is 15 years old, has an unfinished basement. Do I need to have fire blocking installed?

    Reply
    • Jason says

      June 9, 2019 at 10:22 pm

      Hey David - not if your basement is unfinished.

      - Jason

      Reply
  40. Eric L says

    November 5, 2019 at 11:24 pm

    You just saved my bacon! Done with stud walls in basement, and realized I had not planned for fire blocking. Was trying too hard . . .trying to get it above and behind my top plate. What a relief to see I can screw it to the underside of the top plate, and hit the gaps behind the studs with great stuff fireblock. THANK YOU!!

    Reply
    • Scott says

      March 18, 2021 at 1:10 am

      Thanks I believe you just answered my question.

      Reply
  41. carlos franco says

    January 14, 2020 at 10:22 pm

    Carlos from Toronto
    Hello Jason,
    I did my son's basement several years ago, and so great full to have read your article about fire blocking. I used 1 x 4 wood to cover the gaps and fire resistant foam/caulking to cover small areas all around the perimeter of the wall. When the inspector came the only comment he made was to place a fire block collar around the new 4 inch and a 2 inch PVC drain pipes running down from the main floor to the basement. When smoldering fire occurs around the area of the PVC pipe , it will melt the pipe creating a gap for air to seep in and fuel the fire. With a fire collar ring installed, the collar will expand when heated and will close the gap blocking air passage. I installed the fire collar rings as instructed by the inspector sent him a photo of the collar installation and passed the inspection. And you are right the inspectors are there to help you. Thank you again Jason.

    Reply
  42. Craig says

    February 3, 2020 at 8:09 am

    Question...
    What if my Framed wall is more than a foot away from the block wall? That situation would render the use of dimensional lumber out , is that a case where you would recommend the use a piece of drywall positioned between the studs and long enough to reach the block wall?
    What if the wall separates a finished space and an unfinished space. Would those call for a backing layer of drywall or OSB on the unfinished side?

    Reply
  43. Bill Wertz says

    April 28, 2020 at 11:59 pm

    Hi. Thanks for the info. I have a question. My walls have an insulation blanket over them, so I will be setting my framed exterior wall about 6" away from the poured foundation. I also installed ceiling strapping prior to framing my walls. How would you recommend installing the fire block in this situation?

    Reply
  44. Prem Jain says

    July 21, 2020 at 10:44 am

    Jason,
    Your information is very useful. Thanks. I have a finished basement with dry walls and a drop ceiling. It is without Fire Blocking. Can I do Fire Blocking without damaging dry walls and drop ceiling grid/ tiles?

    Reply
    • Prem Jain says

      August 1, 2020 at 11:46 am

      Jason,
      Your information is very useful. Thanks. I have a finished basement with dry walls and a drop ceiling. It is without Fire Blocking. Can I do Fire Blocking without damaging dry walls and drop ceiling grid/ tiles?

      Reply
  45. Sharon Desrosiers says

    November 4, 2020 at 1:54 pm

    Just put up 5/8 in fire coded sheetrock in ceiling in my garage but I have a place on the side of furance that I can't hang the sheetrock, what do I do.

    Reply
  46. Jason Roberts says

    January 11, 2021 at 9:03 pm

    I bought a house with the framing already done. They used 1/2” plywood for fire blocking. The inspector said it needed to be 3/4” plywood. What do you think is the easiest way to fix this?

    Reply
    • Jason says

      February 2, 2021 at 9:45 am

      Jason, I would add 1/4" to the existing 1/2" plywood to give you the full 3/4" the inspector is looking for.

      - Jason

      Reply
  47. Scott says

    March 18, 2021 at 1:04 am

    Ok my walls are 2 and 1/2 inches from the concrete I plan to use 1/2 drywall for fire block nailed to my top plate. Can I fill the space behind my 2 x 4 stud white fire foam because I cans attach any thing to the concrete wall with nail , I can’t get back their. Or could I screw another short price of drywall to the other drywall fire block. I hope this makes sense. Thank you in advance.

    Reply
  48. Bret says

    April 16, 2021 at 10:03 am

    Here is the sad part about this. Fire block isn’t required in the walls that are part of the storage and HVAC, hot water and electrical area of the basement. This is where a fire is most likely to start. Then it can travel down the open floor joists and subfloor throughout the entire basement storage are fueled by the stacked personal items like Xmas trees, and all the stuff people keep.

    But walls that are framed away from the basement wall need to have a fire block even when there is no electrical or plumbing in the wall. Truth is, once firefighters arrive , if a fire starts in the basement and is fully engaged they aren’t going to try and save anything cosmetically, they will brake the drywall and spray water into the spaces between the ceilings of the basement and sub floor. If the floor has I joists and has been burning for a several minutes, many departments will not go inside at all but rather contain the fire from the outside until they can asses the structural integrity of the floors they need to walk on.

    Our building department requires 5/8 x drywall or 3/4” plywood be installed vertically every 10’ and horizontally along the entire gap. When we frame exterior basement walls we use a 2x6 top plate on the 2x4 wall to close the gap at the top in those areas. The. We use rock wool around plumbing and fire caulk in the electrical and small gaps.

    I’ve seen one fire in a modern home that had I joists. The fire department arrived and said, this home is registered as having I joists. We cannot go inside. They broke the exterior Windows and pumped water into the home until no visible smoke and flames. Then they carefully entered using ladders to walk on and finished up the fire fighting.

    Reply
  49. Roman says

    June 23, 2021 at 8:46 pm

    Hey Jason,
    Thanks for the article, this was very valuable.
    You are mentioned in the post "drywall the width of the gap from the block wall to the framed wall, probably 4 to 5 inches." Is that possible with 2 to 3 inches from the block wall to the framed wall?

    Reply
  50. Tom says

    July 6, 2021 at 8:13 pm

    For horizontal blocking in a basement, does the fire block have to go all the way down to the floating foundation floor. Can pressure treated 1x8's be used for fire blocking?

    Reply
  51. AJ says

    July 13, 2021 at 3:32 pm

    Hi Jason,
    I am starting to finish my basement and like you I just heard about fire blocking after I started framing. I stopped framing, should I have all the electrical wires put into place before I fireblock everything. I am not sure if it's easier to have the electric work and framing done before or after fireblocking. Any advice will be appreciated
    Thanks

    Reply
  52. Reynolds T says

    July 23, 2021 at 6:08 am

    Thanks for the great information, this was very helpful. I found out about fire block after i done with the framing.

    Reply

Leave a Question or Comment Cancel reply

Your email address will not be published. Required fields are marked *

iFMB Privacy Policy
© 2015 iFinishedMyBasement.com