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What is blocking? Why do I need blocking when framing a basement wall?

by Jason 45 Comments

This guy is installing blocking, most likely so he can frame in a wall.

This guy is installing blocking, most likely so he can frame a wall underneath of it.

Honestly, I had no freaking idea what the word "blocking" meant when talking about framing a wall.

When I started my basement project my friend Tom was like, "how did the blocking go?"

I played it off real cool, like "yeah, not bad, totally blocked it".  But when I walked off I was thinking "what in the hell is he talking about… blocking?

I had just started framing the first room of my basement, the man office / sports room ( aka the gift wrapping room ).

The first wall was up and I as I rounded the corner to start on framing the second wall it hit me.  Blocking!  I needed some blocking or this wall was not going up.

Blocking for wall framing are short pieces of 2 by 4 that you install between two joists of the basement ceiling.  It's not a "building code" thing and it's not optional, you'll more than likely have to install some blocking to complete your wall framing.

Let's say your ceiling joists (or floor joists, depending on how you look at it) run north and south.  When you go to frame a wall going parallel to those joists then you won't have anything to nail the top plate of the wall in to.

If your brain is about to explode now, please stay calm, I do have a picture. Be sure that you've read the basic how to build a wall post first, so you know some of the terminology.  Once you see what framing blocking is you're going to be like "oh, that.  Yea, I get that."

wall framing blocking installation

This wall is secured to the main joist. If you wanted to move it over a 1/2 foot, you would have to install some blocking before you frame the wall.

Install your blocking before you start building your wall.  You want them at 16" or 24" on center because the drywall guys will expect them to be the same distance apart as your joists.  (they can work around it, but you don't really want them to have to, so keep it consistent)

To install blocking, take your framing gun and "toenail" (nail at an angle) a nail on each side of each end of the 2x4.  The main thing is the be sure that the blocking is flush with the bottom of the joist and straight and flat.  I measured the length of each piece cause I'm a bit of a perfectionist and didn't want a gap.

If you don't have a framing nail gun and are doing this by hand or with screws… I feel bad for you. Like, really bad.  Unless your Mike Holmes and you can swing a hammer like Thor, you aren't going to have fun doing this part.  Check out this framing gun from Bostitch from Amazon, it's got fantastic reviews, great price, free shipping, perfect for finishing your basement.  

They are not that badly priced and you can always sell it to someone else when you're done. Although I wouldn't, cause have a framing gun is like the pinnacle of being bad ass.

basement finishing jason 205That's it.  That's blocking.  See, not that bad, right?  Next up - installing a firewall!

Relax, it's not that bad either, but it totally freaked me out 'cause I thought I had missed my chance to install fire blocking and that I would have to tear down all of my walls.

Cheers - Jason

Hey, dudes and dudettes, do you still have a question? Even after my redonkulous written explanation? I thought you might. Go ahead and ask it in the comments below. I'm just sitting here doing nothing... waiting... for you.

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Questions and Comments

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  1. justin says

    August 21, 2012 at 1:39 pm

    How would you block against a concrete wall? I've got the concrete wall, then the first floor joist is 16" parallel off the wall. I suppose I could nail gun a 2X6 or 2X8 to the concrete, then block off of that, but was hoping to find someone who had some experience with this.

    Reply
    • Jason says

      August 21, 2012 at 9:13 pm

      Hey Justin - Welcome. You should not have to nail your blocking to the concrete wall. I'm guessing that what you need to find is your "sill" plate. It's a piece of wood (about 2" inches high) that is sitting on the very top of your concrete wall. It may be hard to see or covered with insulation, but it should be there. Find that bad boy, that's what you nail your blocking too. Hope that helps, let me know if this is not the answer.

      Jason

      Reply
  2. Brandon says

    October 2, 2012 at 5:10 pm

    I'm about ready to start framing my basement. This issue still has me puzzled a bit based on the situation of my sill plates and how the floor joists are positioned. My joists sit on top of the sill plates, thus I can't add blocking that is flush with the bottom of the joists. If I want the blocking flush with the bottom of the joists, then the blocking will be sitting on top of the sill plate, and I would have no way to nail the blocking to the sill plate because of very tight conditions. Any thoughts?

    Reply
    • Jason says

      October 2, 2012 at 8:18 pm

      Hmmmm... Brandon, I'm fairly good at visualizing and you wrote an excellent description. If your joists are sitting on your sill plates then you are working with a wall that is perpendicular to the joists... in that case, you do not need blocking for framing. Simply nail your wall top plate to the underside of the joists.

      Am I under thinking this? Hopefully that helps, if you're still stumped or I'm not fully comprehending, shoot me a picture "jason AT ifinishedmybasement.com" - Jason

      Reply
      • KevinB says

        October 11, 2016 at 6:15 pm

        Jason. I think I know exactly what Brandon is talking about since I just ran into this myself. Here is a picture which describes the scenario.

        http://imgur.com/a/G7AC6

        The wall in this case is parallel with the joists so you need blocking between the sill plate and the 1st I-Joist. But the bottom of the I-Joist isn't even with the sill plate. It's 1.5 inches lower so you have to bump it up a bit to do the blocking correctly above the flanges. TJI recommended to not nail blocking into the flanges but instead above them so that they sit on the flanges.

        Reply
        • Jason says

          October 18, 2016 at 9:04 pm

          Ah... yes, good diagram. Yes, you would definitely want to level the blocking (not have it angled). My only concern with that diagram is that the drywall for the ceiling doesn't have a level block to nail to on the end. If you toe-nail the blocking to the "flange" then you have a solid backing to secure the ceiling drywall. - Jason

          Reply
        • Ted says

          March 29, 2018 at 8:05 pm

          I basically have the same issue, except my I joist is about 1/8 of an inch lower. If I angle it to be flush with the I joist, will I have issues puttin up the wall. Or should I make the blocking level leaving a 1/8 difference, when putting up drywall. Any suggestions?

          Reply
  3. nilou says

    July 22, 2013 at 7:51 pm

    when I build the framing do I need to do electrical and HVC the same time?

    Reply
    • Jason says

      July 23, 2013 at 8:11 am

      Framing first, then electrical and HVAC. For the most part they are separate phases. You'll have to get your framing inspection done "before" you start your electrical work. If you have a lot of HVAC work to do, like adding a whole new trunk line, then you may have some framing to do to accommodate that. Good question. - Jason

      Reply
  4. Mike says

    November 27, 2013 at 8:58 pm

    Hey,
    Great article...went to turn the corner framing and the said "Oh #$%@". So now I know about blocking. I was having a heck of a time trying to toenail with the framing gun and was read to give up, but decided to try screws with a cordless driver. I had some 3.5 inch deck screws left over from a fence project, and they did the trick! I highly recommend using screws if the space is tight and if you are not used to toenailing upside down.

    Reply
    • Jason says

      November 29, 2013 at 9:49 am

      Good suggestion Mike - My framing gun was definitely too big to work in tight spaces. Screws to the rescue. - Jason

      Reply
      • Mike says

        May 4, 2014 at 10:01 pm

        Some of my joist areas were so tight that I couldn't even get a cordless driver in there. I went to lowes and picked up the "BOSTITCH PN50 Mini Impact Nailer", which is basically an air-powered palm nailer that allows you to drive a single nail at a time...it was a life saver, and only 40 bucks.

        Reply
        • Jason says

          May 5, 2014 at 7:22 am

          Mike - That's a great tip. There were definitely a few times I had to do something similar. I turned my hammer sideways and smacked away for 10 minutes, a $40 palmer nailer would have been well worth the money. Plus it's just so bad-ass that you could nail something with the palm of your hand. - Jason (here's a link to that same Bostich PN50, if anyone else needs one)

          Reply
        • cris longfield says

          November 16, 2015 at 10:11 pm

          good one Mike im more into finish work ===but the framing helps when its straight & level when most needed Learned blocking way back its a necessity

          Reply
  5. Chris says

    December 5, 2013 at 9:01 pm

    Hey, Jason, yours is my new go to site during my basement renovation. I have a neat one. My house is sixty plus years old. And a previous owner, used mortar to build a pretty ramp up the exposed edge of the sill plate and the top of the cinder block wall, so it slopes up and back at forty five degrees. I hope I don't have to chisel all that out of the forty foot wall requiring blocking

    Yours truly

    Chris Stallaert

    Reply
    • Jason says

      December 9, 2013 at 4:59 pm

      Hey Chris - Ummmm.... a ramp of mortar? That's very interesting. Interesting is the nicest term I can give it. Thanks for visiting the site and good luck on your basement renovation! - Jason

      Reply
  6. Pete Koutoulas says

    January 25, 2014 at 2:27 pm

    Is there a particular reason why you suggest toenailing the blocking to the joists? Why not just nail through the joist from the other side, straight into the blocking? Seems easier to me.

    Reply
    • Jason says

      January 26, 2014 at 2:15 pm

      Pete - Good point, actually I had to toe nail where the blocking meet the sil plate because you can't get to the other side. But where it met the joist, I could have just nailed through. I think the reason I didn't is that my joists bottoms (they're engineered, not all one pieced) are pretty thick and I wasn't sure my nail/screw would go all the way through. - Jason

      Reply
      • Pete says

        February 4, 2014 at 1:53 pm

        Thanks for the reply. That makes sense. I was wondering if I was overlooking something. Thanks for sharing your experiences here. Great tutorials.

        Reply
  7. jason says

    February 16, 2014 at 7:48 pm

    So I have a section of duct that comes off the main and runs for about five feet inside the rim joist/sill box where it attaches to the floor vent on the floor above. I obviously can't block in this part of the sill box. How do I frame the exterior wall at this part?
    Thanks
    Jason 2

    Reply
    • Jason says

      February 17, 2014 at 8:52 am

      Hey Jason - Good question. So is the bottom of the duct even with the bottom of the ceiling? Absolutely no room for even a 1x4 block? If it was just a foot or so you could get away with no blocking, but at 5 feet the ceiling drywall would sag, we need to have something to nail the drywall into. Maybe a 1/4 inch of plywood attached the bottom side of the joist and then you'd have to get creative and use a piece of 1/4" drywall just for that section? I think I'm envisioning what you're saying but if you want to send a picture that might help.

      Jason

      Reply
  8. Jeff says

    March 31, 2014 at 4:52 pm

    I've been reading along and took your advice and just built a wall. Funny how hard that first one was. Now moving forward with the basement, I had a concern about building a wall that butts up to my foundation. I'm not finishing the outside walls and don't know if I need to put any kind of barrier between the foundation wall and the wood stud? Also if anybody has good ideas on how to cover the insulation between the rim joist I'm all ears as I want to paint my ceiling when done. Love the blog it's be a real life saver.

    Reply
  9. Shawn says

    April 4, 2014 at 6:50 am

    First I want to say thank you for the strength . You are an inspiration, if I used two top plate for my wall like the builder did, do I still need to fire block. I'm confused . I have pictures I can send you. Thanks in advance for the answer.

    Reply
    • Jason says

      April 4, 2014 at 9:26 am

      Hi Shawn - Yes, the fire-blocking is for "behind" the top plates. Having 1 or 2 top-plates doesn't matter. It is confusing, until you get it, then it's easy. When I say behind I mean between the top plate(s) and your basement foundation. You are basically "blocking" the top of that empty space with a fire stopping material. - Jason

      Reply
  10. Umer says

    July 21, 2014 at 10:49 am

    Hi Jason,.
    Awesome site...thx..looking forward to building that first wall...but
    the area where i want to start need blocking, but the area above the sill plate is drywalled..and there is wood behind the drywall....so...i would think that i would remove the drywall and then install the blocking?
    i can email you a pic too if that would help visualize.
    thx...Umer.

    Reply
  11. Matt Kiesel says

    June 19, 2015 at 2:25 pm

    Jason,
    So I really appreciate your website, I have decided to use steel studs to frame for the convenience and seems there may be less errors. But I have two questions.
    1. For blocking my joist have a lip to them. The bottom looks like a T would my blocking go above this lip? There is a blue plastic water pipe attached to the lip as well running to the other water spout. So just curious your thoughts there.
    2. Since, I'm using steel studs could I just purchase the previous palm nailer for the blocking or use 3.5 deck screws with a typical drill?

    Reply
    • Jason says

      June 29, 2015 at 9:16 am

      Hi Matt - Congrats on starting your basement! I wish I could answer you steel (metal) stud questions but I'm afraid that's outside my knowledge zone. I've only built with and support lumber framing. Good luck! - Jason

      Reply
  12. Brian says

    August 29, 2015 at 11:06 am

    Jason - Don't know if you're still monitoring this blog, but thought I'd ask you a question and see if you're still out in cyber space! I need to install blocking into a tight space above my foundation, between the outer rim joist and the next joist in towards the basement room (does this make sense?). It's a fairly large space, but the opening between the inner joist and the foundation is only about 5-6 inches so I cannot toenail into the outer rim joist. I'd only be able to attach the blocking with a nail/screw to the inner joist and I'm stumped on how to attach the block to the outer rim joist. Any advice at all on how I can add blocks?

    -Brian

    Reply
    • Jason says

      August 30, 2015 at 8:09 pm

      Hi Brian - Yes, I'm definitely still here and monitoring for any basement finishing questions. It's a bit tricky to answer this particular question without seeing a picture but I think I get what you're saying.

      Make sure you couldn't possible attach the blocking to your "sill plate" - that should be wood and run along the top of your foundation - it may be hidden by insulation, that's typically what you would toe-nail to on the outside (so to speak). If that doesn't seem to work- email me a picture and I'll take closer look.

      Cheers - Jason

      Reply
      • Mono says

        February 17, 2018 at 8:29 am

        I have a similar situation to Brian. My solution was to lay a PT 2x4 parallel to the sill plate and lag screw through it to tie into the sill. That gave me a nailing surface I could reach to toe nail in my block, and with the wall framed, it extended out enough to serve as a fire block between the framing and sill space.

        Reply
  13. Troy says

    February 22, 2016 at 5:55 pm

    Blocking on the new engineered joists. Flush with the bottom still or higher up on the joist?

    Reply
  14. Mike says

    February 25, 2016 at 7:18 pm

    Great article. Thank you very much for the blocking technique.

    Reply
  15. Melanie says

    August 31, 2016 at 4:35 pm

    Great info! I want to do as much myself and this really helped! Need advice though - hvac is currently vented from the ceiling. Is it better to run the venting down the walls to the floor? I live in a cold climate will this help keep the basement cozier?

    Reply
  16. Rachael says

    October 26, 2016 at 12:06 am

    Hey Jason. YOU'RE REALLY FUNNY! You should have a TV show or somethin. I'm a TOTAL NEWBY with all this stuff. My boss at work told me to Google "blocking" and "framing" - and THANK HEAVENS - Your site popped up!! Or it could've been a very dry and boring night. Thanks!

    Reply
    • Jason says

      November 1, 2016 at 6:52 pm

      Thanks Rachael - My sister is always telling me that I should try stand-up comedy. Maybe for my birthday I'll write 5 minutes of stuff and give it a shot! - Jason

      Reply
  17. Prter says

    December 28, 2016 at 3:14 pm

    What do you do when a duct is in the way of a 2x4 block

    Reply
  18. Mike says

    February 19, 2017 at 3:46 pm

    Finishing a basement, how to control temperature in basement different from the house

    Reply
  19. Jason Harris says

    April 4, 2017 at 11:23 pm

    Thanks for the great site Jason. I'm working on my basement as well and confused about the blocking between the open web joists and the foundation. Below are some links to the different setups that I have. Under a cantilevered section, I could just make my wall talker and attach to the top of the joist, however that would not be possible in a majority of the basement. Reading the comments above, it sounded like I should try and attach to the sill plate and then find a way to level off the blocking below, but I'm just not sure how I would go about doing that. Any help would be greatly appreciated. - Thanks!

    In case it helps, my plan is to install 2" XPS and a 2x4 wall, so I would still be a 1/2" from the bottom of the floor joist with my top plate.

    Cantilever
    https://drive.google.com/open?id=0B2GACLKRK7GzMWVJUm54YUpTd2s

    Standard
    https://drive.google.com/open?id=0B2GACLKRK7GzQklFT3hoTmdOYzg

    Line Drawing
    https://drive.google.com/open?id=0B2GACLKRK7GzeGNyUTZDbVphOHM

    Reply
    • Jason says

      April 13, 2017 at 9:39 am

      Hi Jason - Good news! All of this and more is answered in my video explaining in detail about blocking. That video and much more is available for purchase and instant access over here. If the video doesn't answer your question - I'll personally investigate your specific issue and give you my best advice. - Jason

      Reply
  20. Jignesh Padia says

    July 13, 2017 at 12:53 am

    Hi Jason,

    My contractor has left gaps anywhere from one inch to half inch between the floor joist and the top plate of the basement wall frame. Should I be concerned?

    Reply
    • Jason says

      July 16, 2017 at 9:16 am

      Hi Jignesh - I wouldn't be overly concerned, it's not uncommon to have a small gap. I can't tell for sure without seeing some pictures but as long as the framing passing inspection - you should be just fine. - Jason

      Reply
    • Tony says

      February 15, 2020 at 12:13 pm

      He probably built the wall on the floor as one piece and then raised it in place. This requires a gap, otherwise the wall won't swing up and fit. As long as it is shimmed, it should be fine.

      Reply
  21. Tom says

    November 16, 2018 at 5:23 pm

    I am remodeling a 11' clothing closet. I found out the previous owner did not nail the top plate to ceiling joist, he glued it and toe nailed on each end. If he chose to nail the top the ceiling joist, then the dept of closet would be too shallow, so he moved the top plate about 3 in out. The ceiling joist are 2 x 4, can I do the blocking between the joists with 2x4, so I can have something to nail the top plate up.

    Reply
    • Jason says

      November 25, 2018 at 11:16 am

      Hey Tom - Lots of folks block between joists. Have at it.

      - Jason

      Reply
  22. Curly says

    March 11, 2020 at 6:42 pm

    how many blocking’s are needed for a 12’ top plate? Also, how can one add the blocking after the top plate is in place and wall is finished (insulated, dry walled, etc.)?

    Reply

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