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splicing 2 x 12's

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Forum topic by brucea posted 06-01-2019 09:39 PM 527 views 0 times favorited 25 replies Add to Favorites Watch
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brucea

6 posts in 48 days


06-01-2019 09:39 PM

Topic tags/keywords: joining question

I am planning to build a shade structure at my koi pond.
I want to know what is the best way to splice together 2 – 2×12’s, end to end.
The roof of this structure is going to be about 28 feet long.
The posts are going to be spaced about 24 foot apart.
So I am looking to find a way to splice the 2×12’s without using side mounted plates.
I want the finished product to look like it is one piece of wood.


25 replies so far

View SMP's profile

SMP

1177 posts in 324 days


#1 posted 06-01-2019 10:45 PM

I’d go with a standard scarf joint.

View John Smith's profile (online now)

John Smith

1879 posts in 581 days


#2 posted 06-01-2019 11:25 PM

The posts are going to be spaced about 24 feet apart.
- brucea

are you saying you will have a 24 foot span of unsupported lumber ??
will the boards be on the edge or flat side ?
not really understanding your design here.

.

.

-- I am a painter. That's what I do. I paint things --

View Richard Lee's profile

Richard Lee

244 posts in 1194 days


#3 posted 06-02-2019 12:17 AM

Iron plates on both sides bolted thru.

View ibewjon's profile

ibewjon

680 posts in 3212 days


#4 posted 06-02-2019 02:40 AM

LVL’s might work, you can buy in 28’. I don’t know about how weather resistant they would be or if you can get in treated form.

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brucea

6 posts in 48 days


#5 posted 06-02-2019 03:44 AM



I’d go with a standard scarf joint.

- SMP


I am planning to build a shade structure at my koi pond.
I want to know what is the best way to splice together 2 – 2×12 s, end to end.
The roof of this structure is going to be about 28 feet long.
The posts are going to be spaced about 24 foot apart.
So I am looking to find a way to splice the 2×12 s without using side mounted plates.
I want the finished product to look like it is one piece of wood.

I should have said that they are going to be made of redwood on edge.
I will be putting one on each side of a 6×6 post.
They will have 2×4 going perpendicular with a shade cloth covering for the roof structure.
- brucea


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brucea

6 posts in 48 days


#6 posted 06-02-2019 03:51 AM



I’d go with a standard scarf joint.

- SMP

Thanks
I looked up scarf joint types, on the internet.
Would you recommend a table scarf joint?
Are they hard to made?

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brucea

6 posts in 48 days


#7 posted 06-02-2019 03:55 AM



The posts are going to be spaced about 24 feet apart.
- brucea

are you saying you will have a 24 foot span of unsupported lumber ??
will the boards be on the edge or flat side ?
not really understanding your design here.

Yes I plan on going 24 feet without support.
They will be on edge.
I am not carrying much of a roof load.
There will be four beams, two on each side.
.

.

- John Smith


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brucea

6 posts in 48 days


#8 posted 06-02-2019 03:58 AM



Iron plates on both sides bolted thru.

- Richard Lee

Sorry no thanks, I will pass on this idea.
I work in the steel industry and I want to keep it looking natural.

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brucea

6 posts in 48 days


#9 posted 06-02-2019 03:59 AM



LVL s might work, you can buy in 28 . I don t know about how weather resistant they would be or if you can get in treated form.

- ibewjon

Yes they will be exposed to the weather.
I am using redwood.

View ibewjon's profile

ibewjon

680 posts in 3212 days


#10 posted 06-02-2019 04:25 AM

Ahhh, now you tell us. Hide stainless steel inside like a loose tennon, spanning the scarf joint

View HerringImpaired's profile

HerringImpaired

12 posts in 128 days


#11 posted 06-02-2019 04:48 AM

How about a Finger Joint Router bit? I wouldn’t put too much load on it though….

-- "My greatest fear is that upon my demise, my wife will sell my tools for what I said I paid for them."

View CWWoodworking's profile

CWWoodworking

528 posts in 598 days


#12 posted 06-02-2019 04:53 AM

Can’t clear span 24’ without being a truss. Will sag regardless of joint or metal.

View John Smith's profile (online now)

John Smith

1879 posts in 581 days


#13 posted 06-02-2019 12:23 PM

CWW – that is what I was thinking.
no matter what kind of joint used, there must be an engineer’s formula
for an unsupported span in that “sagulator” thing (or whatever it is called)
that is mentioned here sometimes.
is just not a good idea. (IMHO).

Bruce – you asked: “are they hard to make”.
well, that depends on you, your skill level, tools available, and a large flat
work area to handle large boards like this.

if you insist on the open 24’ span, this is what I would recommend.
I am not an engineer by any means, just an example of the scarf joint.
I am in no way endorsing the project or anything else – just the joint alone.
If I were doing it – I would make a table jig and use a hand-held router
with a large bottom bit to make the 24” long scarf on each board.
each scarf must be 100% identical in order to make a successful joint.
I would use structural grade two part epoxy for the adhesive. (not a casting resin).
redwood will absorb epoxy like a sponge. so a few wet coats to saturate the grain
and a slightly thickened epoxy for the final coat would be a good idea prior to assembly.
maybe even a layer of fiberglass mat in the joint.
regardless what adhesive you use, there will be a noticeable glue line in the joint.
so if you are planning on leaving it all natural, you need to take that into consideration.
totally your call. good luck in your project.
some photos of your methods used and final project would be nice to see.

.

-- I am a painter. That's what I do. I paint things --

View TomM's profile

TomM

15 posts in 3832 days


#14 posted 06-02-2019 12:28 PM

My first thought would be to do 1” by 6” finger joints, either hand cut or bandsaw and chisel. . Then I saw this ultimate finger and lock joint.
https://www.youtube.com/watch?v=0lY07rSSH6w

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John Smith

1879 posts in 581 days


#15 posted 06-02-2019 01:34 PM

I missed the edit cut-off time but here is an example of a scarfing jig and bits.
you can make a much simpler jig for a one-time use with regular lumber and plywood.



.

Edit: Heyoka’s post below is also a strong joint.

.

-- I am a painter. That's what I do. I paint things --

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