How To Properly Splice Dimensional Lumber For Maximum Strength(Rafters & Joists)
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- Опубліковано 10 лют 2025
- How to properly splice or join two pieces of dimensional lumber (2x4, 2x6, 2x8, 2x10, or 2x12) for maximum strength to create a much longer board for rafters and joists when longer pieces of lumber are unavailable or have to be special ordered. DIY carpentry and save. Scarf joint variant. Replacing termite damaged or rotten rafters and joists. Enjoy the video!
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What a terrific splice technique! Looking forward to your next video!!
Thank you very much!
I agree! Thanks for the idea
Sorry is ''terrific'' another word for ''bad job'' (don't look like that btw)? it's a foreign language it's kind of difficult with some meanings
Agreed. And dare I say…
Elegant simplicity.
@@dennis-s You're thinking of terrible. Terrific means a great job.
I think I will employ this technique on a boat stringer with 3/4" plywood. this splice will be laminated over with another layer and epoxied and fiberglassed , so the jointery will be staggered, and layered over.. rather than nails 1/4 wood dowels also epoxied, there are no nails or screws in my build, no place for water to enter.
This is the best method for splicing I have found, locking itself in place, I can see the advantage to this method.
Thank You.
Thank you. That's the best joinery I've ever seen. I'll be using it.
A year later..... What a great technique . I did it and it worked so good....!
Thank you very much....!
I watched your video about a year ago and was very impressed with how well the cuts fit. I need to span 20', with a 10' center post, and was going to use LVL beams. But, since I will have a 6x6 post in the center, I could use double 2x10's with this type of splice, and they would sit over the 6x6. I wasn't comfortable with overlapping the 2x 10's and having one joint on each section not sitting on the center post beam. On a 10' span this should be very sturdy on a carport with a metal roof.
Thank your very much, i´m doing a wood ceiling in Colombia, we are not really big on timber construction (we like concrete and bricks), this splice will help me a lot.
I Lived in an Old House which had Wall Posts which were Spliced like this.
So this Method has been around for 100 Years at Least.
Impressive Wood Join Method.
True, old work around here looks just like this. 100+ years thru 8.1 earthquake
A post and a beam are not the same. A post can be small compared to a beam.
Great instructions. Clear and concise
Awesome video, was lost on how to extend my board longer with what I have without buying longer boards. Definitely using this.
Excllent! easy to follow and very usefull on many projects. Thank you!
Awesome technique, thanks for that. I assume if you have any further strength concerns you can add a sister or two across maybe 2x that splice section
When determining how long the joint should be, I've heard it should be 3X the width of the material.
2x4 = 10.5"
2x6 = 16.5"
Etc.
I've read 2xs I use this theory often. 16 penny nail has shear strength of 1600lb
Great video. I actually have to do this and was wondering how.
Retired carpenter 40 years never seen this fantastic
That's a cool splice. I've never used that method, but it looks sound. The only other advice I'd give when doing this, is to make sure the carriage bolt heads are positioned on the side of the board where the crown is up if there is one, and there usually is. In fact one might consider engineering a specific crown on a board so long, depending on application. In your case, it's not needed because of the support of all the jack rafters. The last time I built a hip roof that size, I used LVL beams for the hips, but it was a free standing carport that needed additional support...
I might also add a piece of glued and screwed, half inch plywood to each side of the splice, just for added shear strength, but I like your splice overall!
Correct. Head of bolt crown up. The good thing is, the jack rafters lined up in the spliced area, which adds more support. Glad you liked the splice!
Very good.....I have been looking at the best way to join some joists and this looks like a winner 🎉........
@5:32 The torque washer is made to be used on the head end of a carriage bolt, hence the square hole. They are designed to keep the bolt from spinning when tightening the nut on the other end. A flat or fender washer is used under the nut. Depending on application, a split lock washer may be used between the nut and fender or flat washer.
Wow, so cool; I'm from The Bahamas.
Great splice, thank you for sharing
Thanks for watching John!
Really good demo, thank you!🇨🇦
You're welcome!
this guy rocks I was gonna replace my roof decking. I m gonna do that
That's one awesome splice! I'm making some stairs for a garage loft, and the stringers are a tad over 16'. There was no way I was hauling 16' boards in my 5' box Tacoma. 12' is the longest I felt comfortable hauling, but this joint looks super strong and makes me feel better.
Very strong Craftsman style joint. You can omit all the glue and fasteners, with a dowel at the center point. Hold the joint slightly over closed (lapping) hole saw through a scrap on the top of the left hand side, the right hand (lapper) , and into scrap supporting the (lapper) the dowel is now a (pin) trying to hold the joint over closed, preloaded resistance to deflection I would still glue up 2xanything. makes a beautiful joint in exposed raftering functional or not. Thank you for the cool video, and for triggering a fond old stream of thought.
can you explain this further, link to a picture or something?
Skill Builder has a good video that shows the purpose of the pin tell me what you are trying to do with this joint, and I will try to help. I am not an engineer@@nickmacaroni
Well explained. Thank you!
Thanks for this. Much appreciated.
I have a 8x4 beam to repair it situ. Can this be done with a jigsaw and long blade? The end of the wood is rotten. But, it's load bearing. Thank you 🙏
Awesome tip!!! Thank you for posting.
This is exactly what I was looking for
Fantastic job
Thanks
Glad you found the video helpful!
Great work and awesome technique! Thanks for nice sharing! Have a wonderful day!
Thank you! You too!
Scarf joints have been used by timber framers for hundreds of years. You're right, they are the best. And even better, look up "locking scarf joint".
Great video . Thanks 🙏
Now that is one hell of a strong wood joint! Nice work.... 👍👍😉😉
very good and simple too. i hate it when people overcomplicate stuff for no reason or to use as little fasteners possible make no sense in todays world where everything is available
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Fascinating presentation, thank you! 👍
Glad you enjoyed it!
I tried it and it works great
Nice job 👍
A really clean finish, I would go one step further and recess the bolt (planning an exposed truss finish)
Very helpful, thank you for sharing.
How well would it work to use truss plates on the sides instead of nails driven through?
Brilliant video
Great video and demonstration! Thanks!!!
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Masterful. Will this work on my front rim joist for my new deck. I need to either splice the joist making it about 18 inches longer or make it shorter by digging a new footing and moving it in (shorter) by about 18 inches. Would appreciate any suggestions if you can understand my description of what i'm trying to do
Genius. Thank you for sharing this.
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that's really a great method
Nice work. Just wondering. What type of termite treatment are you using ? My home has a same problem. Termites eating the upper structure.
@@VC-THE-MAN_87 The damage to my rafter was done decades ago. When I removed the rafter, it was carefully inspected and there was nothing alive inside. You can buy termite granules and sprinkle them around the entire perimeter of your home every 6 months make sure you water them in thoroughly
I love this channel
Great to hear Dave!
To insure the two boards are nested tightly, screw a block to the board faces just past the joint and put a clamp across the gap.
This applies pressure to the glued surfaces insuring a tight bond.
Excellent idea!
Great Video. Explained it really well. Muz AU
Thank you, Sir!
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Great tip and detailed video.
I watched you spinner video and came here you are a legend 🔥🔥
Good stuff!
WOW you got some 🌞 bro.TY
That was pretty slick. Awesome! I'm needing to do a 24ft span on a elevated platform,using a 2 by 10. What would the measurement s be on that? Thank you
Om doing the same next week on my workshop roof
I was taught by my grandfather and dad back in the late 60s doing these type of splices.
A warning to folks using this technique. It should only be used for non load bearing applications unless the joint is supported at the splice accordingly? Never exceed the span tables clearly outlined in the codes unless approved by an engineer or building department. Long fascias or barge rafters are a great application for this technique. It's a form of a " Scarf Joint " BE very careful.
If a hip rafter gets overspanned, it isn't a hip rafter. I don't know anyone who would use this joint and not sister a six foot piece spanning the joint when not applied as a hip.
You are correct to caution. There is a tremendous potential for DIY naïveté to create a far less than adequate joint. However, I would have confidence in my own work. Use of the proper glue, clamping scheme, and a precisely crafted joint would be stronger than the wood.
The span is a separate issue, glued or not. You don’t want to run amok the code.
@@MrLgmurphysr 👍💯% my thoughts as well
This is great. I wish you would have given measurements for different size boards, but what the heck? I'm only building a firewood shed. This I quick and easy. The only issue today is finding straight boards !
0 90⁰0000000pppppppppppp0pp⁰ⁿ
This man is a master craftsman.
Very good to know!
Glad you enjoyed the video! Thanks for watching
Thank you for this video. 😊 though I would like to ask if this is also applicable to beams with direct weather exposure? Best to use galvanized bolts? The embedded bolt heads should also be sealed?
Maybe as a hip, as long as the jack rafters are laid out properly and matching on each side of the hip. I've always been taught to upgrade to engineered lumber in that situation.
Man's splice is stronger than the rest of the board....
IIt was called a scarf joint. Used on ships.
That's really super
It's called a scarf joint...pretty strong for sure...😉
Awesome splice! I am curious if this meets ANSI/BOCA code and if inspected by the friendly and pleasant local enforcement officer, would it pass?
Well, code says all joints must occur over a support. This would be at best an engineered solution. Scarfing can "approach" the strength of an unmolested timber but it cannot duplicate or exceed it. If carefully located at the point of lowest bending moment in a beam they can perform well enough that an engineer might be game to stamp it. The poster here doesn't appear to know that, and in a floor under varying loads that point is a moving target. I've seen split scarfs in heavy timber, don't fool yourself. Also, there is no approved wood to wood field glue joint. A structural glue joint is done under controlled conditions and under third party audit. In other words, glue is not magic schmoo. Field applied glue can make assemblies stiffer (a qualitative thing) but not reliably stronger (a quantitative thing). In my working carpenter world this would be a quick way to fail an inspection.
this is where youtube shines, and it's crazy they don't promote the best ideas more. instead of useless Vtubers.
Saw this in Jamaica years ago
I would be inclined to support the splice with a plywood plate on both sides that would be 1/2 again longer than the length of the splice.
Yes I was thinking mostly the same with a double the length splice of plywood. Maybe 1/2" perhaps.
As well not knowing the application is to use Gr 8 ready rod with nylocks for ends a slight piece out of the overlap wood , should be more the okay for this.
Thanks for the very clear video! I'm going to try it today.
As a rule of thumb, such splices should be within the first ⅓ of the overall span. For example, if your overall span is 18', then the splice(s) should be within 6' (at most) from the ends. So while a 6-6-6 splice should work, a 5-8-5 splice would be better, and a 4-10-4 better yet. A single 10-8 splice would be horrible. The closer to the ends the better. As splices are located more and more toward the center of the span, they become more stressed and more prone to failure.
Thanks well done!
Cool tip! Thanks!
Thanks for watching Karl!
Awesome super help thanks!
I assume this would also work for wall studs?
in Instead of using Carriage bolts, would a simple dominos and glue be strong enough, say I was doing this with some 2x4s for a frame to screen in a small lanai?
You are a brilliant physicist, what did you want to become as a child?
Thanks for this video. Super clean, clear explanation on how to.
Nice, I like it.
Nice video
Thank you Ed!
If scarfing and not supporting on a post, always best to sister another full length board in and screw it tight. This will exceed the load capacity of the original beam.
Cool joint. . . always love a learning "New way" .. I do the V splice, takes more fastening... never glued em tho. At first i thought u were beveling the cut but you're plumb here, , , hurricane clip brackets and "buckets" too? Do you crown your boards? Lots of love for the greatest skill. We got to where we made games out of it all and threw up some showplaces.
oh bOLted too lol dam...
This is good for single pitch roof too ?
24 ft
2x12
I'm sure it works but that doesn't mean I don't wanna see strength tests.
Awesome trick to know
In the future I may make another and put a load on it to compare to one that was uncut.
LOL...Framed a few in my day. That would be an exceptionally difficult joint to cut on a job site. I like how you switched from layout to poof: assembled joint. Gee, how long did that take? An hour?
Cutting was fairly easy. I used a hand saw on the ends of the cuts, the small cuts that were angled. Then I did a pocket cut using the circular saw for the straight length. Once that was done I simply laid it on top of the other piece of wood, traced it and then cut it the same way. About 30 minutes
Can we use this scarf joint in vertical columns?
@@richardatanacio4049 I would only use it for that purpose if you had three together and you made sure the joints were far apart from each other
Are there any load tests for these types of joints?
For my use, which was a hip rafter, strength will not be any problem at all. If you're going to be placing a lot of weight on the center of the lumber, then clearly you want to place a support under the area
It looks perfect for a ridge or hip. I'm just curious if it has any significant load ability for something like a joist. Something like 2 sistered with the joints offset come to mind. Just spit-balling here. I'd hate to see someone think this is a suitable solution for a floor joist. @@electronicsNmore
Do you realize the tremendous forces in the hip rafter? What could possibly go wrong?@@electronicsNmore
Is there away to do for 2 by 2?
if you want it really strong, use a wedged tabled splice joint
thank you
You're welcome
Do you know how to properly join 2 6x6 *(5 1/2 X 5 1/2)* barn poles together end to end if you needed to lengthen a pole?
I was wanting to use a shed roof on a small summer cottage I am planning but the planned width was 16' and that is the maximum length of boards I could get locally so I was resigning myself to do the traditional gable roof. Perhaps I could use a splicing method along these lines to make 20' rafters. I was looking into some sort of gusset plate methodology. Would you prefer splicing over using a metal plate? Would either pass code? Thanks for sharing this method!
For a common rafter, you can probably just glue/nail as shown in the video, then take a strip of 3/4" plywood that's a little longer than the splice area and nail it over the splice area on both sides. That rafter will never come apart.
@@electronicsNmore That sounds even easier and that makes sense. However, given the price of plywood here on the east coast of Canada, the metal plates might be less expensive! 😒 Thanks!
Why would you ask this idiot if it will pass code? You have to be kidding...
Would this work on a tool handle
That's much simpler than other methods
Wow! Talk about good timing, I have to make 22 foot joists in order to upgrade our Philippines built homes ability to stand up to Pacific Ocean Typhoon shooting gallery.
Our front door faces Taiwan. High tide raises up under our floors twice a day. So both home Footings and the roof rafters must get special treatment. The typical galvanized joist hangers, Hurricane Strapping, strong wood glue together with your technic I am working on it right now.
Interesting. A scarf joint on a plank on a boat generally mates the wide dimension at an 8/1 - 12/1 thickness to length ratio.
Can this be used to splice two 2x4x8 to span 12 feet? I need to small storage loft in my shed. The span would 12'. The shelf on top of the loft will be 3 feet in width.
Yeah sure, why not. And then load up a few thousand pounds just for good luck. What could possibly go wrong? You people are idiots. If you had a sore foot, would you ask the janitor if it's OK?
Guys, I need y'alls help with this.
How do you use a table saw to initially cut these marks. I'd get a band saw blade or circular cut here, but not a table saw
Thank you
This is a variation of the scarf joint common in timber framing.
It would be a simpler than the scarf for the average layman to build correctly and therefore a great alternative.
I skipped parts of the video, so not sure if it was mentioned. Make sure both boards are crowned up once the whole piece is assembled.
concise!
It’s called a scarf joint. I’m not sure if that was mentioned, throughout the entire video.