How To Properly Splice Dimensional Lumber For Maximum Strength(Rafters & Joists)

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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[chrisgriffiths]

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.

[ProjectFarm]

What a terrific splice technique! Looking forward to your next video!!

[churumbel]

A year What a great technique . I did it and it worked so good....!
Thank you very much....!

[stevearttus]

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.

[chesterroj]

Retired carpenter 40 years never seen this fantastic

[lectro]

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.

[Ahunter]

Awesome video, was lost on how to extend my board longer with what I have without buying longer boards. Definitely using this.

[FirstSuiGeneris]

I was taught by my grandfather and dad back in the late 60s doing these type of splices.

[toddwheeler]

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.

[herbjohnson]

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.

[mikepatchett]

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.

[Bushman]

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.

[Quickened]

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!

[alpha-male]

This is exactly what I was looking for
Fantastic job
Thanks

[sapelesteve]

Now that is one hell of a strong wood joint! Nice work.... 👍👍😉😉

[harlemsar]

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.

[NotWolf__]

I watched you spinner video and came here you are a legend 🔥🔥

[wgdxerw]

Hi, the Japanese have been using this type of scarf joint for hundreds and hundreds of years, the main feature being that is in the centre of the scarf there is a pair of wedges driven in from other side to lock the scarf joint together, if this is done properly on a beam they’re quite often would put a Mortis and tan joint through it as well which will then lock it all together, I personally would not of joined a piece of 2 x 6 2 x 8 2 x 12 in this manner as there is not enough surface area on the 2 inch thickness, and definitely would not be in an area where there is load being transmitted, stay safe, don’t bridge that gap,

[grahamspencer]

Thanks for the very clear video! I'm going to try it today.

[DATDesign]

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.