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Author Topic: How stable/strong is this type of corner joinery for pavilion?  (Read 2023 times)

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Offline johnkim

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I want to build something similar and wonder if this type of corner is strong enough?

It seems easier to cut Than mortise and tenon so it will save some time...

Can someone show me how one would cut this type of corner?


What about the king post connection? Is it a simple through mortise on the king post and slot the tie beam through and peg it? Any downside of this?


I plan to design my pavilion to be 18' x 30' footprint(post to post) with 2' overhang with six 10"x10" posts using #1 & better Douglas Fir.

Local rules for dead load is 15psf, snow load 26 psf.

I'm stuck on choosing plates, ridge beam and tie beams sizes. What is the minimum I can get away with meeting the load requirement spanning 18'? 4x12? 4x14? 6x12? 6x14? 8x12? I will be self raising this frame and never done it before so don't want to add extra weight for no reason...

My plan:
1. Six 10"x10" posts
2. 8x8 king posts
3. 3x10 rafter
4. 3x8 knee braces


To join the top plates in order to span 30', can I use simple lap joint with structural nails or I need to use some fancy joinery? I don't mind using metal from places to places to simply my build...

Offline Don P

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Re: How stable/strong is this type of corner joinery for pavilion?
« Reply #1 on: August 11, 2021, 06:38:29 PM »
I'm not at all sure but it looks like this is not a true truss but is a post supporting a ridgebeam. I would first look at the tie beam supporting that post as a beam loaded with a concentrated load at midspan. Just as info, a midspan point load produces twice the bending moment in a beam compared to an equal load that is uniformly distributed along the length of a beam.

The ridgebeam carries half the roof load, the lower plates carry 1/4 of the roof load each(plus overhang). Those are all three uniformly loaded beams.

Then you mention 4x beam material and 6x. 2-4" thick wood is "dimensional lumber" and uses one set of design strength values in the calculations. 5x5 and larger uses the heavy timber design values, which are generally weaker. It can cause a hitch in your giddyup when you have to switch up to heavy timber.

There's the verbal instructions, you'll be in 3 different calcs in the toolbox, Midspan point load, the heavy timber simple beam calc and the dimensional lumber simple beam calc.

I've got 4 ICC codebooks and one NFPA book open and miles to go before I sleep. I'll check in on you when my brain goes numb  :D.

Oh, yes it will work, it's an eggcrate joint in a pair of crossed bridle joints in the post ends (if those aren't just applied corbels). The ends of those are in the weather, dumb! If you go that route make copper caps for the exposed wood and detail it to keep water from wicking in.
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Offline johnkim

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Re: How stable/strong is this type of corner joinery for pavilion?
« Reply #2 on: August 25, 2021, 08:21:19 PM »
Thank you so much Don P for the detailed information.

How feasible do you think it is to attempt to build a 16x30 footprint pavilion for someone who havent done timber frame before?

Im not too concerned with cutting the frame. Im worried about raising the frame...

These beams are heavy and have to lift them up 15 up in the air.

How much would it cost to get someone else to raise the frame?

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Re: How stable/strong is this type of corner joinery for pavilion?
« Reply #3 on: August 26, 2021, 07:40:33 AM »
Look at how folks are lifting things, simple machines "gin" poles (lifting engine), tripods, genie lift, look at @Jeff's pavilion build and the caution of what to avoid. The army rigging manual is a good read. Renting a lull or bringing in a boom truck are all options. Notching and cutting are just one aspect of building, there is a great deal of personal satisfaction in raising and outsmarting heavy objects, well, at least for my little pea brain. Just think through and plan how to do each step safely.
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Re: How stable/strong is this type of corner joinery for pavilion?
« Reply #4 on: August 26, 2021, 08:54:47 AM »
A Neanderthal brow is most helpful when raising a beam and things take a sudden turn.
Just call me the midget doctor.
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Offline johnkim

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Re: How stable/strong is this type of corner joinery for pavilion?
« Reply #5 on: August 26, 2021, 10:04:08 AM »
Thanks Don and Jeff for the encouragement!

I see some timber frame company bore holes in post to run electrical wire. How does one bore a hole through the post lengthwise? Do  you need some super long auger? I searched and couldn't find much information on this...

Offline Don P

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Re: How stable/strong is this type of corner joinery for pavilion?
« Reply #6 on: August 26, 2021, 07:37:16 PM »
It's usually surface mounted but there is no reason you couldn't. I had a homeowner make me an 8' bit on a log home job when he changed his mind and wanted another outlet. It was a 1" ship auger with a section of pipe slipped over the 1/2" shank then a long piece of 1/2" rod. I was sweating bullets but stayed in the wall. Some years later a client did the same thing but just to kitchen counter level so I cut it down. You'll need to have your best zen-foo on. You need to back out to clear chips often to avoid them overtopping the bit and trapping it... heed my warning, that is no fun  :D.
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Re: How stable/strong is this type of corner joinery for pavilion?
« Reply #7 on: August 27, 2021, 09:38:04 AM »
Thanks DonP.

I have another question on corner joints like this


It doesnt look like it uses pegs. Do they use screws to hold down the tie beam and plate to the post from the top? Relying purely on gravity doesnt seem right...



Lastly, how is rafter typical attached? I dont see pegs on most timber frame plan so I assume you just nail it down?

Offline johnkim

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Re: How stable/strong is this type of corner joinery for pavilion?
« Reply #8 on: August 27, 2021, 04:56:43 PM »




Is this type of joint strong enough or it will fail like the photo said? 

How do you secure them together? Long screws?




Offline Don P

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Re: How stable/strong is this type of corner joinery for pavilion?
« Reply #9 on: August 27, 2021, 07:03:16 PM »
That is the joint I was envisioning, or an attached corbel on the outsides. The seasoning check they are calling a crack is from drying. A stress crack would more than likely start at an inside corner of the notch. I think I've been on that site, caveat emptor.

That is not to say that is a wonderful joint, without going back I think you were asking how it was done. Bringing the beams into the post at different elevations would remove less wood and be stronger.

Yes timber screws for that joint and the rafter connections. Maintain a continuous load path up,down and sideways.
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Offline johnkim

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Re: How stable/strong is this type of corner joinery for pavilion?
« Reply #10 on: September 01, 2021, 12:12:26 AM »
Thanks Don.

I designed a variation of the joint. What do you think of this version?


How Do I secure them together? Use a super long screw/bolt (20") from the top?



Regarding to clear span load calculation, does the use to knee brace reduce the clear span since there is some support?

 

 






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Re: How stable/strong is this type of corner joinery for pavilion?
« Reply #11 on: September 01, 2021, 07:25:52 AM »
It looks like you have notched the eave plate entirely over the post and tie? If so I'd back up and get the bottom edge up on the post. A long screw or a screw in the lower and then a screw from the upper beam into the lower would work. 

Do not reduce span and load counting on braces to pick up the slack, that would be optimistic thinking. Load goes to stiffness. The known load path is straight down the post.
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Re: How stable/strong is this type of corner joinery for pavilion?
« Reply #12 on: September 01, 2021, 07:55:12 PM »
Thanks Don.

Is this what you mean? I reduce the notch a bit to 3/4" just for alignment purpose and less material removal...

What do you think?

 

 

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Re: How stable/strong is this type of corner joinery for pavilion?
« Reply #13 on: September 02, 2021, 03:48:49 PM »
 

 

 

 

 

 


Here is my design:

1. 8x8 Posts
2. 8x8 King Posts
3. 12x4 Tie Beam
4. 12x4 Top Plate
5. 3x8  Knee Brace
6. 4x10 Rafter
7. 2x12 Long over hang fascia board for waterfall

Post to Post Dimension 14' x 10'
Rafter Spacing 26" OC

Snow load27 psf
Dead load15 psf
How is this design? How to I calculate if it can withstand the loads for my local rule?

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Re: How stable/strong is this type of corner joinery for pavilion?
« Reply #14 on: September 02, 2021, 07:48:01 PM »
What is the cantilever supporting and how. "Waterfall" isn't much to go on, are you hanging niagra off this thing  :D. Is there a plan for protecting those exposed timbers?

You cannot notch the cantilever timber as it passes over the post, the tension face is up on top of the beam there.
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Re: How stable/strong is this type of corner joinery for pavilion?
« Reply #15 on: September 02, 2021, 08:04:56 PM »
Start by checking the ridgebeam (I usually work from top down accumulating loads as I go)

In this design it supports half the rafter span on each side of it. The lower half of each rafter is supported on the plate. Which is another way of saying it supports half the roof.

 If the building is 14' wide half of that width is 7'. The span of the ridge is 10' . 7'x10'=70 square feet. Multiply that by your total load per square foot 42lbs per square foot=2940 lbs.
Go here and start plugging in your variables;
Design for Bending (forestryforum.com)

Duration is snow, repetitive member use is no, size factor is 4x12.
Give it a go.
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Re: How stable/strong is this type of corner joinery for pavilion?
« Reply #16 on: September 03, 2021, 11:22:12 AM »
What is the cantilever supporting and how. "Waterfall" isn't much to go on, are you hanging niagra off this thing  :D. Is there a plan for protecting those exposed timbers?

You cannot notch the cantilever timber as it passes over the post, the tension face is up on top of the beam there.
Hi Don,
The cantilever is supporting a 12’ pvc pipe with holes in it and a led strip to illuminate the water.
Something like this:



The heaviest element will be two 2x12” x14’ fascia board which is 50lbs each. The water fall component shouldn’t weigh more than 30lbs. Let's say 200lbs in total just to be safe?


When you say “you cannot notch cantilever as it passes over the post”, you mean the portion of the timber that extends beyond the post should not be notched?


I plan to use hidden metal hardware to attach the fascia board on the cantilever timber, this should be ok right? Should I add some knee braces to the cantilever portion to add extra support?






No plan to how to protect expose timber yet. I plan to use Douglas fir. Is there any special stain that offer extra protection for water exposure?

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Re: How stable/strong is this type of corner joinery for pavilion?
« Reply #17 on: September 05, 2021, 07:46:45 AM »
Quote
When you say you cannot notch cantilever as it passes over the post, you mean the portion of the timber that extends beyond the post should not be notched?
Basically I would try not notch the cantilever timber at all. One point of greatest bending stress is going to be along the upper edge over the post.

With that in mind I would run that beam through the posts unnotched, just pass it through at full dimension.

Then I would investigate the tie. Does that arrangement leave enough bearing surface to support the load of each end of the tie. It can be bed bolted or similar to the cantilever beam.

How did you do with the ridge calcs? Lets see what you've got, I'm trying to suss out your species and grade.

That connector or similar should work, Simpson also makes some concealed connectors that might be easier to source.

For protecting the cantilever typically a "roof" is used. Look at Japanese shrines or exposed beam ends on restored work here, typically a copper flashing cap.
The future is a foreign country, they will do things differently there - Simon Winchester

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Re: How stable/strong is this type of corner joinery for pavilion?
« Reply #18 on: September 09, 2021, 12:24:23 AM »
Hi Don,

Thank you.

The wood I plan to use is #1 structural Douglas Fir.

Here is the calculation:

Total Roof Width with 1' overhang: 16'
Total Roof Depth with 1' overhang: 12'
Surface Area of Ridge load = 8' * 12' = 96 sqft
Load: 42psf
Total Load on Ridge beam = 96 * 42 = 4032 lbs

Calculator Inputs:
Load: 4032lbs
Span: 105" (unsupported portion of ridge beam)
Width: 3.5"
Depth: 11.5"
Species: #1 Doug Fir-larch
Duration of Load: Snow
Repetitive Member: No
Size Factor (what does this mean?): 4x12
Wet Service (yes or no for my case?): no
Incised (what does this mean?): No


Result:



Max Moment (ft-lbs)
4410
Section Modulus Required
34.86
Section Modulus Input
77.15
Section Modulus Pass/Fail
Pass
Deflection (inches)
0.08
Max 1/360 (Floor)
0.29
Max 1/240 (Roof)
0.44
Deflection Pass/Fail
Pass
Shear (PSI)
75.13
Section Required
14.61
Section Input
40.25
Shear Pass/Fail
Pass


Looks like it passed.


Regarding notching the tie and plate, the notch is only 3/4", does it make a big difference? I only added the notch for assembly alignment purpose during raising. I figure it will be easy to slot the heavy beam into a pre-cut slot and perfectly aligned than trying to adjust it on the fly to get the exact position.

Any other method for alignment of these pieces during raising?

What do you think of converting my project to post frame instead of cutting joinery? Would it be easier for a newbie to tackle than trying to learn joinery?

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Re: How stable/strong is this type of corner joinery for pavilion?
« Reply #19 on: September 09, 2021, 07:58:36 AM »
Quote
Size Factor (what does this mean?): 4x12
The base design values in the strength tables are multiplied by various adjustment factors, that is what those inputs are asking for in the calc.

Size factor in dimensional (2-4" thick lumber) came about after full scale testing of many samples. It recognizes that smaller dimensions are stronger in bending, tension and compression parallel to grain. The base design value for 12" wide material is multiplied by 1.0, no change. The size factor is multiplied by 1.1 for 10" wide up to 1.5 for 4" wide material.

For heavy timber the size factor is 1.0 up to 12" deep members and then derates the base design value when deeper. For round logs up to 13.5" 1.0, for larger round or diamond oriented square beams inscribe a rectangle within the section and use that size for calculations. We had an engineer on one log home job that said he inscribes that rectangle 1" inside the log just to be sure... and he did have some healthy logs in the design, rambling.

Incised, for dougfir mainly. To get treatment chemicals to penetrate refractory species it is incised with a knifed or spiked roller of specified penetration, cut size and incision density, good for treatment but it damages fiber, a 20% derate of bending, tension, compression parallel to grain, shear, 5% derate of stiffness.

Wet service, wet wood is weaker. On a treated deck, wet location, of incised timber... these factors become major. Dougfir would take a 35% strength hit.

Repetitive member, many members sharing the load distribute stress amongst themselves, a 1.15 increase in base design values.

Gotta roll, more later.
The future is a foreign country, they will do things differently there - Simon Winchester

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Re: How stable/strong is this type of corner joinery for pavilion?
« Reply #20 on: September 09, 2021, 07:31:05 PM »
See if this makes sense. The ridge is supporting half of the building width, less overhangs so 7' width x the unsupported span, 9' =63 sf x 42 psf= 2646 lbs.

Now when you get to the point load on the tie beam that overhang load is bearing on the ridge support post and then onto the tie beam, so half of 12' x 7' coming down on each ridge support post onto the tie.

In my work I don't get to say "It's only a 3/4" notch on the tension face". It crosses over the limitations published in the code reference, engineer country. I would avoid that cost by marking the reference point with a pencil and leave it full dimension.

There is a lot to be said for post frame, less "damage" to the timbers and if you buy something like Simpson connectors they come with published strength ratings and connection details. Pricing the correct steel for this might sway that too. If you can weld it might open up more possibilities if the inspector is agreeable. 
The future is a foreign country, they will do things differently there - Simon Winchester

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Re: How stable/strong is this type of corner joinery for pavilion?
« Reply #21 on: September 09, 2021, 08:26:07 PM »
This is what I've been playing with. The plate is passing through the post on the way to the cantilever. The tie beam is notched into the post and butts square to the plate. A bed bolt or cross bolt or there is a timberlinx connector to hold it all together. The bolt could pass through an outside decorative corbel in the bed bolt connection with a strap across the top to the tie. You've picked up the uplift connection of beams to post in that as well. Just one way that was bumping around.



 
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Re: How stable/strong is this type of corner joinery for pavilion?
« Reply #22 on: September 10, 2021, 12:51:13 PM »
Quote
Size Factor (what does this mean?): 4x12
The base design values in the strength tables are multiplied by various adjustment factors, that is what those inputs are asking for in the calc.

Size factor in dimensional (2-4" thick lumber) came about after full scale testing of many samples. It recognizes that smaller dimensions are stronger in bending, tension and compression parallel to grain. The base design value for 12" wide material is multiplied by 1.0, no change. The size factor is multiplied by 1.1 for 10" wide up to 1.5 for 4" wide material.

For heavy timber the size factor is 1.0 up to 12" deep members and then derates the base design value when deeper. For round logs up to 13.5" 1.0, for larger round or diamond oriented square beams inscribe a rectangle within the section and use that size for calculations. We had an engineer on one log home job that said he inscribes that rectangle 1" inside the log just to be sure... and he did have some healthy logs in the design, rambling.

Incised, for dougfir mainly. To get treatment chemicals to penetrate refractory species it is incised with a knifed or spiked roller of specified penetration, cut size and incision density, good for treatment but it damages fiber, a 20% derate of bending, tension, compression parallel to grain, shear, 5% derate of stiffness.

Wet service, wet wood is weaker. On a treated deck, wet location, of incised timber... these factors become major. Dougfir would take a 35% strength hit.

Repetitive member, many members sharing the load distribute stress amongst themselves, a 1.15 increase in base design values.

Gotta roll, more later.
Thank you for the explanation Don!

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Re: How stable/strong is this type of corner joinery for pavilion?
« Reply #23 on: September 10, 2021, 12:54:30 PM »
See if this makes sense. The ridge is supporting half of the building width, less overhangs so 7' width x the unsupported span, 9' =63 sf x 42 psf= 2646 lbs.

Now when you get to the point load on the tie beam that overhang load is bearing on the ridge support post and then onto the tie beam, so half of 12' x 7' coming down on each ridge support post onto the tie.

In my work I don't get to say "It's only a 3/4" notch on the tension face". It crosses over the limitations published in the code reference, engineer country. I would avoid that cost by marking the reference point with a pencil and leave it full dimension.

There is a lot to be said for post frame, less "damage" to the timbers and if you buy something like Simpson connectors they come with published strength ratings and connection details. Pricing the correct steel for this might sway that too. If you can weld it might open up more possibilities if the inspector is agreeable.

Thanks Don. I did some research on the forum about Post vs Timber frame. One cons of Post frame people said is that you need special engineering to figure out metal connector position, spacing of bolts and etc.

If we use Simpsons product, as you described with published connection detail, does this eliminate some of the engineering issues?

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Re: How stable/strong is this type of corner joinery for pavilion?
« Reply #24 on: September 10, 2021, 01:11:10 PM »
This is what I've been playing with. The plate is passing through the post on the way to the cantilever. The tie beam is notched into the post and butts square to the plate. A bed bolt or cross bolt or there is a timberlinx connector to hold it all together. The bolt could pass through an outside decorative corbel in the bed bolt connection with a strap across the top to the tie. You've picked up the uplift connection of beams to post in that as well. Just one way that was bumping around.


(Image hidden from quote, click to view.)
 
This is a great idea.
I recreated your idea using Timberlinx A475 with threadbolt and nuts. I'm thinking of recessing the nut into the post.
The last issue is how to attach the decorative corel to the post. Do you mean adding a metal strap tie on top of the corel to hold it like this? Since it at the top, I reckon it is barely visible and wouldn't take away the "timber frame" look?










Lastly, is it worth my investment to get a Makita chain mortiser? After this built, I will want to build a 16' x 30' pavillion with similar method. Since the design doesn't use a lot of mortise, I wonder if it is a good investment?
 

 

 
Timberlinx A475 with threadbolt

 


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Re: How stable/strong is this type of corner joinery for pavilion?
« Reply #25 on: September 10, 2021, 07:32:57 PM »
Take a look at the A155 further down in those Timberlinx drawings. I think that would work for the corbel and tie connection.

A heavy duty router would do a good job making housings for the braces, if you want to house them. I don't see a need for a mortiser if you go with these connectors.

On the engineering required. Timberframe joinery needs to be checked as well so I don't see a difference. With these proprietary connectors whether Simpson or Timberlinx, or whatever, if it has code approval there is a document with very good engineering for the connector and applications. Which, I'm not seeing US approval, if you have a building inspector involved. They are showing Canadian approval which most would probably be fine with but get the ok first.

And then I take issue with their installation manual ::). I would rather see the connector lower than midline, at most 4" or so off the post bearing surface. I would rather have the beam sitting on the seat rather than hanging from the connector when fully dry. If going with 2 connectors which isn't a bad idea, I'd space them no more than 5" between to avoid splitting during seasoning.
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Re: How stable/strong is this type of corner joinery for pavilion?
« Reply #26 on: September 12, 2021, 09:34:49 PM »
Thank you Don.

Here is the new design based on your inputs:

a. One Timberlinx A155 to connect tie beam, Plate, post and corbel
b. Two Simpson 15" Strong-Drive SDWS TIMBER Screw (Interior Grade) to reinforce the above joint

Strong-Drive SDWS TIMBER Screw (Interior Grade) | Simpson Strong-Tie

c. Four 15" SDWS on top of plate to secure plate to post. This should be ok for uplift?


Question:

1. Can interior grade screw used in this application when my pavilion will have roof and the screw will be protected from rain? There is no 15" screw for exterior grade...

2. at what stage do you stain the wood? After cutting all the joints?

3. When designing roof pitch, does the pitch has to be exact such as 6/12, 7/12 etc?  Do I start with a desired roof pitch such as 8/12 then derive king post length based on that?




 

 

 


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Re: How stable/strong is this type of corner joinery for pavilion?
« Reply #27 on: September 12, 2021, 11:30:46 PM »
The A155 is taking care of uplift with the shear connection at the post. I think I'd omit the other screws, they look like just more wood damage to the cantilever beam to me.

OK, check the tie beam. That will be the center point load calc, use the design values from previously. 7' trib width x (include the overhang this time) 6' x 42 psf

I usually draw it in sketchup and take the measures for kingpost, and everything else, directly from the sketch. The pitch can be anything. Usually it is called out in whole numbers but when there are intersecting roofs then pitches can be whatever makes it all work.
The future is a foreign country, they will do things differently there - Simon Winchester

Offline johnkim

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Re: How stable/strong is this type of corner joinery for pavilion?
« Reply #28 on: September 13, 2021, 01:53:16 PM »
The A155 is taking care of uplift with the shear connection at the post. I think I'd omit the other screws, they look like just more wood damage to the cantilever beam to me.

OK, check the tie beam. That will be the center point load calc, use the design values from previously. 7' trib width x (include the overhang this time) 6' x 42 psf

I usually draw it in sketchup and take the measures for kingpost, and everything else, directly from the sketch. The pitch can be anything. Usually it is called out in whole numbers but when there are intersecting roofs then pitches can be whatever makes it all work.
Thanks Don. I will take out the screws.


In rafter and ridge beam design, ridge beam always carries more load than tie beam and plate and should use heavier timber than tie and plate beam, correct?

Load:
Ridge Bean > Tie Beam > Plate , correct?


If I ever need to upsize the timber, it is always more economical to increase vertical depth of timber instead of lateral thickness, correct?

4x14 better than 6x12 when factoring wood cost, correct?



Tie Beam Calculation:

Two tie beams to transfer load from ridge beam, am I correct?

7' x 6' x 42 psf = 1764.

Passed.



 



For plates calculation, please correct if I'm wrong:

1. Each plate carries 1/4 of roof load : 12' x 16' x 1/4 x 42psf = 2016lbs



 



While we are here, I want to ask you about joining two plates for larger timber frame design (two bays).
Does something like this work? The red beam is another set of plate that will be supported by another post. This will be for a two bay design (6 posts total).
Red plate and non-red plate are seated at Post and connected by something like A155.
Tie beam and the non-red plate, and corbel are connected to the post via A155.


 


Offline Don P

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Re: How stable/strong is this type of corner joinery for pavilion?
« Reply #29 on: September 14, 2021, 09:36:21 PM »
You used the wrong calc to check the tie beam, this one is for a beam with a concentrated point load at midspan, it uses a different set of equations;
Midspan Point Loaded Simple Beam (forestryforum.com)

It depends on spans but I've usually ended up with the same sized tie beam as the ridge for those support conditions. Although the tie is only carrying half of the ridge load the ridge has a uniformly distributed load along its length, the tie is carrying half of the ridge load each but as a concentrated load at midspan... which, well let me show the equations for maximum bending moment for each beam condition.

Max moment for a simply supported uniformly loaded beam is
WL/8 (load W in lbs x span in feet/8 = bending force in the beam  foot-lbs)

Max bending moment for the same beam but with a concentrated load in the middle is;
PL/4 (point load P in lbs x span in ft/4= bending moment in ft-lbs)

A point load produces twice the bending force in a beam as a concentrated center point load.

That then quantifies the stress, the calc is comparing the allowable stresses in the beam size you plug in to see if it is below the allowable stress for that species and grade.

In factoring cost there is more going on than just the volume in the timber. Bending resistance is based on the shape of the beam. Depth is squared in that equation. Adding the same amount of volume to 2 beams, one of square cross section and the other being rectangular, the rectangular one with an equal number of board feet will be far stronger and stiffer.

That is referred to as the section modulus of the beam in the bending calculations, the equation is bd2/6 (breadth x depth squared/6)
Going deeper builds strength fastest. Deeper is usually cheaper. That said stepping to a 14" deep might be crossing an availability line that carries a heavier cost than going thicker.

Now for the plates, tributary width is half a rafter span + the overhang- 3.5'+1' x 42psf=189 lbs per foot of beam. We have another situation here. The plate is a beam that is overhanging the support at one end and there is a 200# load out on the end of that overhang. I'm going to cheat and check it the easy way first. It would be very conservative to check this as a beam overhanging one support with a uniform load of 189 lbs per foot. That is this calc;
Beam Overhanging One Support-Uniformly Distributed Load (forestryforum.com)

For the joinery question look through the timberlinx standard detail manual, They show several post and splice details. Near the end they show a 4 way connection to a post, in several places they show a stub tenon into a post. Your 4x12 inserted a bit into an 8x post is pretty much the same detail as the stub tenon in their drawings.

The future is a foreign country, they will do things differently there - Simon Winchester

Offline johnkim

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Re: How stable/strong is this type of corner joinery for pavilion?
« Reply #30 on: September 27, 2021, 11:49:03 PM »
Thank you Don for the detailed explanation.

I did the overhang cal and it seems to be ok.



 
My next question is related to how to secure King Post to tie beam and Ridge Beam.

I plan to use two 3/4 pegs as the connection. Would this work without tenon and mortise? Or I should add timberlinx?



 

 



Finally, for rafters, I was going to go with 30" OC for aesthetic reason but it looks like I can't use 1x6 T&G pine on 30" OC. 2x6 is going to be significantly more costly.

As result, I'm going with 24" OC with 1x6 T&G. I plan to add a sheathing on top of the T&G to avoid roofing nail from piercing. Should I use OSB or plywood? What thickness?

Offline Don P

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Re: How stable/strong is this type of corner joinery for pavilion?
« Reply #31 on: September 28, 2021, 07:24:56 AM »
That brought back a memory. Everyone says the Amish are wonderful builders, and the workmanship is usually good. When we step outside and isolate ourselves it can cause some thinking problems. We stopped in to visit a log home they were building, the 1x6 T&G roof sheathing was spanning from purlin to purlin. I asked what the spacing was on the purlins, 7'.

Wander the sheet goods aisles looking at the APA stamp on the sheets. There will be a span rating stamped on each sheet, the shorter number is allowable floor span, the larger span rating is for roof sheathing. Check, but 19/32" osb or ply should be rated for the desired 30" span. then what is the T&G, wallpaper, the ply is the sheathing. Load goes to stiffness.

The unique inspector we had last wouldn't let someone use home milled, ungraded, walnut stair treads. Adjust riser height and put graded SPF lumber sub-treads down first, the walnut is carpet on the structural tread.

The pegged ridge post is fine, I would us a single peg about 3" from the inside pocket at each end. Think through shrinkage whan making connections. widely spaced cross grain pegs set up splitting potential. pegging closer to bearing seats keeps the shrinking beam bearing on the seat rather than lofting up and hanging on a more distant peg.
The future is a foreign country, they will do things differently there - Simon Winchester

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Re: How stable/strong is this type of corner joinery for pavilion?
« Reply #32 on: September 29, 2021, 11:45:53 PM »
That brought back a memory. Everyone says the Amish are wonderful builders, and the workmanship is usually good. When we step outside and isolate ourselves it can cause some thinking problems. We stopped in to visit a log home they were building, the 1x6 T&G roof sheathing was spanning from purlin to purlin. I asked what the spacing was on the purlins, 7'.

Wander the sheet goods aisles looking at the APA stamp on the sheets. There will be a span rating stamped on each sheet, the shorter number is allowable floor span, the larger span rating is for roof sheathing. Check, but 19/32" osb or ply should be rated for the desired 30" span. then what is the T&G, wallpaper, the ply is the sheathing. Load goes to stiffness.

The unique inspector we had last wouldn't let someone use home milled, ungraded, walnut stair treads. Adjust riser height and put graded SPF lumber sub-treads down first, the walnut is carpet on the structural tread.

The pegged ridge post is fine, I would us a single peg about 3" from the inside pocket at each end. Think through shrinkage whan making connections. widely spaced cross grain pegs set up splitting potential. pegging closer to bearing seats keeps the shrinking beam bearing on the seat rather than lofting up and hanging on a more distant peg.
Thanks for the Amish story. I agree that a lot of the redtapes is due to local regulation...

Your inspector reminds me of a movie that was brought up on this forum called Still Mine: Still Mine (2012) - IMDb . The antagonist is building a retirement house using lumbers he milled without stamps. Inspector wants to torn it down despite it being engineered...


I will modify the peg based on your suggestion.

Thank you again DonP for your patience and taught me a lot about calculation. I just found out you are the one that created all those useful calculator as well. Great job!


If you don't mind, I want to confirm how to calculate load on another design I'm playing with.

This is a shed roof design. Outside post to post 14' x 12' . 12" roof overhang on all side except front which is 66" overhang.

Few questions:

1. On Shed roof design like this, is the only load-bearing beam the front and rear beam where the rafter will be resting on? What is the purpose of the side beam? Just to increase stiffness of the structure?

2. Total roof print dimension is approximately 16' x 19' = 304 sqft. Assume total load 41psf. Total roof load = 41 * 304 = 12464lbs .
If only the front and rear beams are carrying the load, the the uniform load on each beam is 12464/2 = 6232lbs . Is this correct? Given same dimension, we have to use beefier front and rear beam shed roof design compare to gable roof?

3. My biggest question is 66" of roof overhang. Is this possible? How do I go about calculating what rafter size to use with such a big overhang?


My idea:
a. Total Loads / # of rafters = uniform load per rafter
b. Find out load per ft and use your calculator here to test overhang : https://forestryforum.com/members/donp/oerhangbm.htm
Is this correct?

4. Can I omit the side beam or just use it for decorative purpose?

5. Since total load is 12464lbs with 4 posts, each foundation will need to carry 3116lbs of load. Assume 1500psf soil capacity , a 12" sonotube pier would not be sufficient for this structure (1178 lbs). Is it better to consider helical pier for this building? Maybe more economical than a 22" concrete footer? Is this calculation in the right direction?


 


Offline Don P

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Re: How stable/strong is this type of corner joinery for pavilion?
« Reply #33 on: October 02, 2021, 09:19:21 PM »
You really don't need the side tie on a shed roofed structure, bracing would be the main concern.

The outputs for R1 and R2 in the calc are giving the appropriate load at each rafter support, it is not evenly divided, the overhanging end has more beam and post load.

The future is a foreign country, they will do things differently there - Simon Winchester

Offline kantuckid

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Re: How stable/strong is this type of corner joinery for pavilion?
« Reply #34 on: October 03, 2021, 09:06:18 AM »
On the how to hide electrical wires-I got real good at long auger bits when I built my house. In my new timber frame great room I had the walls as hollow and covered with a skin of log siding in and out to play inside but for elevated wiring I made simple, homemade "U"-channel wooden strips that are hardly noticed unless you try to find them. Easily made on a tablesaw from same wood as the structure.
I find the Amish an interesting bunch. I've used them foir previous shingle roofs and more recently for home meat standing seam roof and screwdown shop metal roof. This last crew one kid smoked, one was a dipper and both were talking to GF's at breaks on flip phones.  ;D
Times a changing, huh? The general notion we see in many ads now days that all of them are a breed of master craftsmen is not true-if it ever was? Like the rest of us, I find them variable in skill sets and knowledge in construction. One constant theme is they DO! have a strong work ethic.
Kan=Kansas;tuck=Kentucky;kid=what I'm not


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