Do you have a sagging floor joist and need to repair it? This video goes through the step-by-step process of 'sistering' a new floor joist beside a damaged one in order to restor the structural integrity of your floor.
I’m a carpenter and general contractor and have been doing structural work for a couple decades. Miracle of miracles, but I find nothing to criticize here. Good work. Where I work, we require full depth blocking, not this diagonal straps. So yeah, can’t believe a diy video on RU-vid is good and informative, not dangerously wrong.
That is high praise Matthew! My father taught me to think things through, get good advice and not cut corners. Thanks for affirming his training. Have a great day.
@@RighttothePointDIY exactly. I’d tell my guys in the morning after we rolled out the tools “before you put your bags on, what are we doing today and how are we doing it?” Sometimes an hour thinking is a worth a day or more working, and generally gives better results than working and not thinking.
@@sli43 good point and you’re probably right, but not knowing if there is some other load directly above it it’s hard to say. Also, the subfloor is attached to the old joist so we’d like to have the old and new function as a single member to prevent the new one from separating since it’s not held in place by the subfloor fasteners: another great reason to use full depth 2x blocking instead of those diagonal braces. Think of the new joist as a supplemental repair, not replacement. And it’s just good practice. But yeah, probably splitting hairs and it’s likely fine without it. I figure if it’s cheap and easy to do and the possible consequences suck, I’m just going to do it.
This is a good common sense approach and a fairly easy solution to a scary problem. I would have no issues doing this in my house after watching this video.
Thanks Jacob! I'm glad it was helpful. I saw that wedge idea online and immediately knew that was going to be so helpful for everyone doing this job. Thanks again for the comment!
Great video. I really like how you read my mind and reminded the viewers that the screws and glue arent the ones bearing the weight..loved your attention to detail
I am a fan of using some paraffin wax on the friction points such as on the new board bottom sides (at the sill ends) to make the final hammering much easier. It won't affect the holding power of the beam, only the assembly. Not much different from the wedges you remove on the top face. Together they would ease final assembly. Good video.
Most excellent video! Thanks for taking the time to make it while you’re glue dries etc.!! I have to do this in my garage. But unfortunately I have drywall and garage door rail ceiling mounts and an attic access hole to deal with! Your unfinished ceiling makes this job so much easier but still challenging! Great work!
Yes, you definitely have a lot more work to do than I did! At times like that I just keep telling myself I got to do it right or I’ll have to do it again. LOL Good luck buddy.
Many Thanks. You covered every detail in both descriptions and illustrations. Actually a better video than the "This Old House" version of floor joist repair IMHO !!!
Thanks. I renamed my channel 'Right to the Point DIY' because too many DIY videos show the no brainer stuff like the drilling and the hammering. We just need to know how it was done right? LOL. Thanks again for the compliment.
Thanks Burt! I appreciate that compliment. If you want to help me get to 1,000 subscribers I would appreciate you subscribing. Trying to build my simple DIY channel. :)
Very much appreciate the level of detail you went in with this video. I will need to do this to some of my sagging floor joists and so this video is super helpful. Fantastic tip regarding using the strong to measure the sag so you know how much you want to jack it up.
Super video. One modification I’d make is this : Don’t Jack it up to meet the string line straight edge. Target the jacked up height to align with the bottoms (at that point across the joist) to be just above the same height of the neighboring floor joists. You want the floor to be flat. The neighboring joists will have decades of sag in them and of you Jack this up to a straight bottom , that may push the top above the two neighboring joists - creating a high point on the floor above.
Not really a viable solution since the height of each floor joist could vary. Maybe run 3 string lines, one on the joist to be repaired and one each on the 2 surrounding joists. Determine the amount of deflection of the 2 joists that are sound then raise the damaged one to the same point.
Thank You I needed this. I'm doing my kitchen right now the floor is up and the owner mutilated the sistering of the joists 5 joists.. The 1st owner used 2x4's on a 2x8 joist patching the cracks lolol I just replaced them which was fairly easy since the floor was up.. Crown up !!! Upon inspection I found 4 more cracked joist in this 1957 year old home in the crawl space which it isn't that bad to work in. You're video just helped me tremendously !!! Great job..
Thanks Doug! I appreciate the feedback. Just FYI, I have had some consistent feedback about using nails instead of screws and I understand the concern so that I would have changed. However, the joist is really carrying the weight and the screws were more to just keep in place. Otherwise, I'm pretty happy with how it worked out for me. Again, glad it helped.
Awesome video, nice bright basement and clear instructions! The only changes I would make are moving the jack between the two major knots, hoping to remove both dips. Also after glue and clamping, its much stronger to use three 16D common nails every 16". Finally adding blocking between joists on either side makes them much stronger, as they share the load, and will stop any buckling/ tilting in the future. Good work!
Great feedback Lucas! I appreciate that insight. In retrospect I would have used the nails for their shear strength. Thanks again for the constructive feedback. This helps all of us as we DIY.
@@RighttothePointDIY no problem! I have had a few projects now with sistering joists or failed joists in general. I wish my basement I am currently working on looked like yours!
@@lucasspaniard8430 Thanks Lucas. I have actually completed that basement remodel and it turned out even better than I expected. SOOOOO glad it's done! Now, next project....get the rest of my basement (my workshop) back to some semblance of order!! LOL
Great video. Explaining the little tips like cutting wedge in the end and which direction to force new joist in is very helpful. I noticed in the comments that some were commenting on the fact that the screws used were not structural. If you were replacing a joist that was intended to be doubled up to carry the load, structural screws or bolts would absolutely be required, but since the intended load can be carried by a single joist, any screw or nail will suffice for this purpose. Look forward to more videos.
Yes, I noticed that too, but as you say they’re not necessary here. I’m a carpenter and contractor, so I know what I’m talking about. Id probably use a nail gun with 10D common nail, 12” spacing 1 -1/2” from top and bottom, staggered, which is how my engineer specs this sort of thing. That said, if it’s just the one, I probably wouldn’t bother dragging out the compressor and nail gun. Anyway, this is fine since they’re not in sheer and have little pull-out to resist. I would have liked to see full depth wood blocking though, which would have made pull-out even more irrelevant and make a stiffer floor above.
Very informative and clear. I’m a total newbie so I wish there was more on how to undo and redo the electrical and insulation, but I know that was not the main topic of this video..
Hey Veganator. I totally understand and I applaud you for 'digging in'. If you have to move wires the most important thing is to make sure the breakers feeding those wires are turned off and then, go to the closest fixture (assuming this is in a ceiling) and take it off, disconnect the wire and pull it back past the area of repair. It can get much more complicated but the most important thing, again, is to turn off the breaker feeding that line. If you are uncomfortable at all (and electrical is nothing to be trifled with if you are unsure) then I recommend you get an electrician or someone who knows what they are doing. Good luck!
Great job 👍. As a suggestion to others attempting this job, I recommend selecting joists that are "free of heart." The original joist had the dark line running through the center and the large knots = weaker lumber. Heart wood is perfectly serviceable as stud material but best to avoid for joist or rafter 😊
Beside that the joist is cracked because of the knots the joists were not braced to distribute the weight on the others , I think the most important factor in building a house is to pick the lumber carefully even if you pay more to avoid problems like this in the future. A lot of people have finished basements and have problems like this and they don’t know and if they realize it would be a way bigger job to deal with .... and what I see a lot these day is that a lot of builders and contractors try to cheap out on material and tackle things fast to move to the next job and make money unfortunately.... on daily basis I see inexperienced people do jobs around and take advantage... do it right from the beginning and keep you conscious clear ... good job by the way and thanks for the video.
Can screw your 2x4 jack together in a T shape to make a strong-back for less bowing/flex. I recall that you can sister or scab on a smaller piece over a crack so long as you extend 3' or 4' on either side of the crack and glue and bolt it. This can help for a quicker fix and possibly avoid moving plumbing and electrical. I like the idea posted about rotating the joist in the middle of the joist bay with a notch in the sill or just relying on the floor flexing in the middle easier. Seems like rotating next to the joist would create a jacking effect on the floor screws/nails in the old joist that could lead to squeaking. Also like the wood glue in the crack and in the sistering vs thick construction adhesive. I would have left the jack in to let the glue dry to counteract the memory/bend from that crack/sag. The old joist (and floor) will want to go back to where it was for the past 20 years. I would also add solid blocking. 14' is a LONG span. The blocking would take some of the spring out of the floor (which can show up in the ceiling drywall seams over time) Loved your video. Sucks to run wire or plumbing to new spots only to find that there's a structural problem that requires pulling it all out. Damn the builder for picking that joist and putting it in the middle!!
Good points. Thanks for sharing. I thought about the shorter piece to repair but didn’t want to worry about it possibly failing again and the amount of effort it would’ve taken versus just buying a whole new joist made me decide on putting an entire new joist in. I agree the builder should never have installed that joist in the first place. It was such an inferior piece of Lumber and it was just a matter of time before it failed. Thanks for the comment.
I had to repair several 2x9 joists that an idiotic plumber notched out on the bottom, slap bang in the middle. Structural engineer recommended sistering but I had to use 12mm high tensile bolts and glue (bolts spaced at 400mm in a zig zag pattern) - was written in bold not to use screws or nails. I guess everyone's situation is different, but I would always recommend getting a professional to do the calculations. Like the tips on getting the new lumber into place 👍
@@abgaming8249 RU-vid is putting ads on my videos because I’m not yet a RU-vid partner. Therefore I’m not getting anything for the ads. I would rather there not be ads but if they’re going to do them anyways I would rather have that money go into my pocket than theirs. Make sense? LOL
I had to sister a joist back in the day. I built a pool table in the basement and had to notch the joist to get it up the stairs 😉 No pool tables were harmed during the procedure...
Repaired a cracked beam in my basement the same way. I did put a large bead of glue on the top to glue it to the underside of the plywood subfloor as well, yes it was messy.
Cool! I never thought about gluing the top. It would be mess but hey, at least you stuck it out and finished the repair! (sorry, love puns). LOL. Thanks for the comment!
I was wondering that same thing - about gluing the top. I will do.this and will be able tonscrew the upstairs subfloor into the new sistered joist, but if you could not do that,a messy glom of glue might help avoid squeaks. I have also seen taking a 20° angle off the inside top to slide it in the other way (bottom in first). Fantastic video - good level of detail in your description and great editing! 🔨
Suggestion: allow the adhesive to set (24 hours) before removing the jackpost. This will allow better distribution of load to each lamination of your built-up beam.
I could be wrong but I disagree with waiting 24 hours for the glue to setup before removing the jack. The glue is added for additional strength but will crack easily if 1/8 natural settling is going to occur. I'd rather have the glue adhere between the 2 beams in its natural state to lesson any stress on the glue and seal the beams together in their more natural state. I think that's what the maker of this video intended as well.
I liked your video and how you explain the procedures in fixing a floor joist. There is one concern that wasn't address is the thickness of the new sister joist. The existing looked like 2x10 over time it can shrink to 9 1/4 possibly. Your new joist is running fatter than that. Possibly need to trim the fat on the sister to match the existing. Especially at the beams trying to rotate joist would be hard
Thanks for the comment Michael. As to the shrinkage i’ve never really heard of that before. When I put this new joist in it didn’t take much to beat it into place and they seemed to match up well. If that other joist had shrunk that much I sure didn’t notice it. But, regardless I appreciate the comment. Something to consider.
@Jessyjames60 a 2x10 measures in at 1 1/2”x 9 1/4” today’s lumber is not what it used to be. Look at today’s 2x4 that’s 1 1/2”x 3 1/2” back in the day they were true 2x4. I have a house built in 1900 and the studs are true 2x4. Anyway your 2x10 didn’t shrink to 9 1/4”. Now if you buy pressure treated it’s possible while it’s still wet to be slightly swelled past the 9 1/4 and it will shrink a little as it dries out but it’s def never a true 10” wide...
Absolutely loved the video, amazing explanations. Just one question, i was shopping for screws but that warning on the box had me confused of which screws to use. The one you used said "for use in any non-structural construction project" floor joists arent considered structural or are they referring to something completely different? thank you once more!
Hey there. Yes, in a previous comment somebody also pointed that out. The thing here to remember is these screws are really just holding the two beams together. The joist is carrying the weight of the floor vertically. I just held it in place with the screws. Think of it this way: I could’ve taken the other joist totally out and it would’ve been just fine. So really it’s just holding it to the other joist. It’s not really holding any sheer weight from the floor.
Thanks Lning. As I mentioned in the video, some do connect the host with bolts but I don’t believe it is necessary to hold the weight. The jack is a 3 1/2 ton jack but I certainly wasn’t lifting with near that much force.
This is the nicest video I have seen so far, very clear instructions. One question, could you have used just one 2x4 instead of two and did you join the two 2x4 by nails. I have a bottle jack with a very small dia face, and I am afraid of using two 2x4. Thanks
Thank you for the compliment. I would not recommend using just one 2 x 4 because it can bend very easily. One thing you could do, is put a small flat piece of steel on top of the bottle jack that would fit under the two by fours. That way it would be lifting on both of them.
@@RighttothePointDIY I think the operative word here is "structural". I think that when sistering the screws are subjected to shear forces, meaning forces that happen because the weak joists will "try" to sag more than the new one, resulting in the two joists slightly sliding against each other.. Nails are good at resisting shear forces. The will tend to deform before they break. Standard screws are not so good for that. Structural screws are supposed to be stronger against shear forces. On the other hand glue is excellent against shear forces so standard construction screws might well be adequate for you case.
Fortunately for me these were new wires for the apartment I was wiring in. I was able to disconnect them at one place pull them out and then just re-thread them through. If that’s not convenient for you, you’re going to have to put in a junction box somewhere around that joist and join them together. Obviously make sure you cut your power and make the connections correctly.
When I sister a joist I notch both end so I don't lift the sub floor when installing and a few shims at both ends gets it nice and tight, Pl premium on top and side with the same screws you were using add blocking on both sides and call it good.
Good vid 👍 what do you recommend for tighter areas where you cant run a full length piece through but still want the best result in terms of floor sag?
Hey Aaron. Well, I’m not a licensed contractor but in the case where you can’t run the full length, get a piece that is as long as you can fit in and then bolt it in.
@Volkan i’m not sure I understand your comment but it appears that you are saying the new joist you would put on would not reach the beam or the sill plate on either side. If that is the case, I don’t think it would really help all that much. It has to be supported on the ends to give it the lateral strength you would want. However, if connected correctly (I would use carriage bolts to secure the new joist to the old one) it could help the existing joist from sagging anymore. But again, I’m not really sure I understand your comment clear enough though.
Pretty well done. Smart to go full length, to screw and glue. This will hold up very well. Not much to critique- maybe add some block bracing but that is about it. Adding a few (3) posts in the center with a thick 2"x10"x 12' or 20' on top that spans multiple beams would add a ton more support. That would get you a post every 4 or
Thanks DG. I thought about the block bracing but in the end didn't think it necessary with the other joist braced like it was. As to adding other posts, the house is over 40 years old and the only joist sagging was this broken one so I don't think it would be needed and would have really limited the use of that room (made that space into an apartment). I ended up hanging two layers of 5/8" drywall on that ceiling for sound proofing (We are renting it as an Airbnb) and there have been no cracks or movement whatsoever. We are pretty happy with the result. Thanks again for the comment!
@@RighttothePointDIY No worries. I am sure it will be "good enough." I do music and 5/8" is fine but for isolation, you do what is called an Acoustical Drop Ceiling. You can still use your 5/8" but then add a drop ceiling under it and include an air gap. A guitars top is solid wood, yet it still resonates. Sit in your car with the window closed and try to hear someone in a nearby phone booth- you won't hear a thing. Two layers of glass and a AIR mass in between you. You can also coat the materials with a treatment. You can go deep with it. In a pinch- do your 5/8" but add another 5/8' under it separated by some air. It will be much quieter.
@@MOAB-UT Thanks for the info. I actually used a 1/2” layer of fiber board and then, between the 1st and 2nd layers of 5/8” I put this special sound proof caulking. It never really hardens and makes a sound deadening layer. It is pretty quiet now. Plus I put heavy blown acoustic popcorn on the ceiling. It works!
@@RighttothePointDIY It works! Padding and carpet upstairs would help as well. Besides air, mass matters. Density matters. Decoupling surfaces like ceilings and walls make a big difference. Here is a video: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-pio6rNd9tAc.html&ab_channel=HomeRenoVisionDIY
I have joists that extend out that holds a balcony. The balcony needs to be replaced so the contractors want to cut the joist at the stucco and run 15 ft boards through the stucco and attached them to the existing joints under the living room. I suspect they will do the same -- glue and screw the joist together. One of my big complaints, because I just had a new fence built, is that contractors don't bother to pick out lumbar, They go to lumbar stores, take whatever lumbar the employe sets out, and then the contractor uses whatever lumbar they have. They don't care what shape the lumbar is in. So what could happen --- the new wood could have these irregulars in them and a few years down the line they will have to be replaced. There is a house down the block that is getting built with rotting lumbar -- no kidding - and the inspector is passing the job. I feel sorry for the person who buys that house. You better believe when this job get done I am picking out my own lumbar. Thanks for the video.
Wow! That’s pretty crazy. I will tell you I used to have a house that had a balcony that was done a similar way. I think the key there is the lumber that they choose to make sure they have the crown at the top to avoid sagging. Also, because it’s going to be free hanging, they need to make sure they have enough going into the house and that they bolt it together when they sister it to the existing joists.
@@RighttothePointDIY @Right to the Point DIY I am not sure what a "crown" means but I am going to find out. The joists now sticks out 5.5 ft so they are going to make it 5 ft and then extend the wood passed the stucco 10 ft. The balcony will be on the 5 ft. part. I supposedly have a very competent builder coming to give me an estimate and I am doing my homework before they come out because I never know how knowledgable they are or will they use that knowledge on my balcony. After all the balcony "doesn't sit on their property". Thanks for the tips.
@@RighttothePointDIY When I was at the lumbar store he recommended Pine and I see that pressure-treated is a whole lot more expensive but pressure treated wood is toxic. I probably need abut 12 of these 15 ft long. Do you actually think the contractor is going to take the time and look for that "crown" part? One contractor didn't want to work with me because I wanted to pick the wood out and now I am so sorry I didn't do this for my fence I just had built.
Thanks for the comment. I don’t really know if it makes much difference. It did not settle that much. The reality was the glue may not even have been necessary since the majority of the weight is carried by the new beam.
I notice sagging floors under a load barring wall along with other weight such as kitchen cabniets, fridge, countertops, etc. It's all supported by a single 2x10x10 16" on center. Would you suggest I sister another joist to reinforce the joist or just take a beam down through the area to level it with the other beams. I'm okay with doing both, just wanted your idea.
Hey Zachary. Based upon what you said (the LBW and heavy appliance load on the top floor) you may want to do exactly that. It sure can't hurt and won't take you that much extra work. Good call.
So how would you do it if the bad joist got dry, split, bowed out, smooshed into the beam and dropped the subfloor 1 1/4”? Jacking only bows it out more without lifting the subfloor. Two stories of plaster walls above with a brick chimney that’s been removed to below the roof line. I know I need to strengthen the bad joist before I can jack it up and sister it. Screw a couple 2x4 pieces to the side that’s not being sistered?
That sounds like a pretty significant job. Without really seeing the situation I think what you could do is get a large 6” x 6” beam that is close to the length of your joist you need to replace and put it up against the bottom of the floor alongside the defective joist. Then jack it up in at least two places and lift the floor to completely take the weight off of the old joist. Then, remove the old broken joist and put the new joist in. You may even want to put in a double joist in place of the old joist to make sure you have sufficient strength for all that weight above. When you have the new joist(s) in place you could then slowly let the weight off the jacks and lower the temporary 6x6 beam. With all that said this is all just a suggestion without really seeing the situation. You may need a professional to come in if it is more complicated.
Hey Steven. Yeah, fortunately, they were not holding the weight of the floor as much as just holding the new joist to the old. The new joist was what is holding the vertical load.
I wish I could have seen you removing the wires. Did you disconnect from the breaker box and pull them out through the holes of the joists? Is there a max number of holes I can drill to reinstall the wires and maintain strength?
Thanks for the questions Derek. How you deal with the wiring really depends upon how accessible your wiring is and where it originates and terminates. So, in my case I only had to disconnect my wiring from two places (a run to a ceiling fixture and a run to a wall switch) and pull it back and then drill the hole I needed I’m the new joist to rerun it. However, my whole basement was exposed studs and easy to access. In extreme cases where you can’t access the termination or origination points of the wiring (the breaker box or outlet) you may need to actually cut the wiring and put in a junction box to splice it back. Obviously do that with great care or get a licensed electrician to do that part if you are not experienced enough. As to how many holes you can drill, it’s my opinion that the fewer holes you have to drill the better. I drilled one 1/2” hole with my auger bit and ran my two wires through this single hole. That single hole should not impact the strength of the joist much at all. I recommend making the holes as small as possible without hurting the wiring when you’re running them through. Hope that helps.
When you jacked it up so the board can be leveled with the string line. What did you put in between so it can stay leveled when you released the jack? Did you put metal plates?
Hey there Armando. I don’t know if I quite follow the question. While it was jacked up I put the new floor joist in, glued it and screwed it to the existing joist, and then let the jack down. It’s that new joist that keeps it in place and stops it from sagging back to the level it was before.
Thanks for the comment Paul. Technically it would be easier but it didn't take a lot of hammering to get it in place with the amount I had it jacked up. Also, you don't want to jack a floor up too much as you can unseat nails and even damage flooring that may be on top. The amount I had it raised worked just fine.
I also suggest using the GRK R4 screws. Much better on load handling as they are framing screws. Pricier but way better, otherwise 16d nails are more than enough. The glue is super important. That joist wont go anywhere :D
Hey Matras, I’m not sure however it just makes sense that if you let it dry with the beam jacked up and then let it down it would possibly stress it. Again, not to sure. The reality is it didn’t settle that much so Letting the glue dry after the jack is released is just fine.
@@RighttothePointDIY - Definitely would want to let the glue dry while the other ones is jacked up. That way when it’s released the stress is captured by the beam which is the whole point of the exercise. In reality is this going to make any big difference? Probably not but why not do it correctly. Great video
@@condor5635 The thing to remember here is that the weight of the ceiling is being held by the wood, not the screws or the glue. I could’ve probably not glued it at all if it still would’ve been effective. The joist itself is holding the weight. I wanted to let it down while the glue is drying just so the glue didn’t crack afterwords when I released the jack. It only settled about an 1/8 of an inch when I released it.
Hey Anthony. I would take a rotted joist out and, more importantly figure out how it rotted to make sure it didn’t happen to the new one. There is no extra expense to sister verses replace as far as I can tell.
Thanks for the note. I have explained this in a few of the different comments but the reality is the screws are only holding the old joist to the new one. They are under literally no shear weight. I probably could have not even used any adhesive because the only purpose of both it to hold the new joists to the old. The weight of the floor coming down on the joist is being bore by the ends of the joists. When I did the video I didn’t outline that like I should have.
That is tougher. You will probably need to jack up the floor on the joists on either side of that one, take out that old joist and then put the new one in. A lot more work but doable.
You could have sistered that broken joist more easily by using 3/4 inch plywood on both sides of that broken joist, and glued and screwed it in place. This is what the city code inspector said would be sufficient to fix the overscan and damaged floor joist issue.
Hey there Paul. Thanks for the note. I've had that suggestion a few times and have responded by stating that the screws are not holding any 'shear' weight. They are just holding the new joists to the old one. The shear weight is being taken by the joist itself.
