The Forestry Forum is sponsored in part by:

iDRY Vacuum Kilns


Forestry Forum
Sponsored by:


TimberKing Sawmills



Toll Free 1-800-582-0470

LogRite Tools



Norwood Industries Inc.




Your source for Portable Sawmills, Edgers, Resaws, Sharpeners, Setters, Bandsaw Blades and Sawmill Parts

EZ Boardwalk Sawmills. More Saw For Less Money!

STIHLDealers.com sponsored by Northeast STIHL


Woodland Sawmills

Peterson Swingmills

 KASCO SharpTech WoodMaxx Blades

Turbosawmill

Sawmill Exchange

Michigan Firewood, your BRUTE FORCE Authorized Dealer

Baker Products

ECHO-Bearcat

iDRY Wood Lumber Vacuum Drying for everyon

Nyle Kiln Dry Systems

Chainsawr, The Worlds Largest Inventory of Chainsaw Parts

Smith Sawmill Service



Author Topic: How stable/strong is this type of corner joinery for pavilion?  (Read 2037 times)

0 Members and 1 Guest are viewing this topic.

Offline johnkim

  • member
  • *
  • Posts: 18
  • I'm new!
    • Share Post
 

 

 


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

  • Senior Member x2
  • *****
  • Posts: 8776
  • Location: Southwestern VA
  • Gender: Male
    • Share Post
    • Calculator Index
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.
The future is a foreign country, they will do things differently there - Simon Winchester

Offline johnkim

  • member
  • *
  • Posts: 18
  • I'm new!
    • Share Post
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?

Offline Don P

  • Senior Member x2
  • *****
  • Posts: 8776
  • Location: Southwestern VA
  • Gender: Male
    • Share Post
    • Calculator Index
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.
The future is a foreign country, they will do things differently there - Simon Winchester

Offline Jeff

  • Fearless Leader
  • Administrator
  • *****
  • Posts: 51562
  • Age: 60
  • Location: Harrison MI
  • Gender: Male
  • Oh la di oh la da
    • Share Post
    • Behind the  Forestry Forum YouTube channel
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.
Forestry Forum Founder and Chief Cook and Bottle Washer.

Commercial circle sawmill sawyer in a past life.
Ezekiel 22:30

Offline johnkim

  • member
  • *
  • Posts: 18
  • I'm new!
    • Share Post
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

  • Senior Member x2
  • *****
  • Posts: 8776
  • Location: Southwestern VA
  • Gender: Male
    • Share Post
    • Calculator Index
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.
The future is a foreign country, they will do things differently there - Simon Winchester

Offline johnkim

  • member
  • *
  • Posts: 18
  • I'm new!
    • Share Post
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

  • member
  • *
  • Posts: 18
  • I'm new!
    • Share Post
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

  • Senior Member x2
  • *****
  • Posts: 8776
  • Location: Southwestern VA
  • Gender: Male
    • Share Post
    • Calculator Index
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.
The future is a foreign country, they will do things differently there - Simon Winchester

Offline johnkim

  • member
  • *
  • Posts: 18
  • I'm new!
    • Share Post
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?

 

 






Offline Don P

  • Senior Member x2
  • *****
  • Posts: 8776
  • Location: Southwestern VA
  • Gender: Male
    • Share Post
    • Calculator Index
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.
The future is a foreign country, they will do things differently there - Simon Winchester

Offline johnkim

  • member
  • *
  • Posts: 18
  • I'm new!
    • Share Post
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?

 

 

Offline johnkim

  • member
  • *
  • Posts: 18
  • I'm new!
    • Share Post
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?

Offline Don P

  • Senior Member x2
  • *****
  • Posts: 8776
  • Location: Southwestern VA
  • Gender: Male
    • Share Post
    • Calculator Index
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.
The future is a foreign country, they will do things differently there - Simon Winchester

Offline Don P

  • Senior Member x2
  • *****
  • Posts: 8776
  • Location: Southwestern VA
  • Gender: Male
    • Share Post
    • Calculator Index
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.
The future is a foreign country, they will do things differently there - Simon Winchester

Offline johnkim

  • member
  • *
  • Posts: 18
  • I'm new!
    • Share Post
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?

Offline Don P

  • Senior Member x2
  • *****
  • Posts: 8776
  • Location: Southwestern VA
  • Gender: Male
    • Share Post
    • Calculator Index
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

Offline johnkim

  • member
  • *
  • Posts: 18
  • I'm new!
    • Share Post
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?

Offline Don P

  • Senior Member x2
  • *****
  • Posts: 8776
  • Location: Southwestern VA
  • Gender: Male
    • Share Post
    • Calculator Index
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


Share via delicious Share via digg Share via facebook Share via linkedin Share via pinterest Share via reddit Share via stumble Share via tumblr Share via twitter

xx
Spline joinery at building corner

Started by Griffon on Timber Framing/Log construction

3 Replies
2121 Views
Last post February 19, 2007, 08:49:10 AM
by Don P
xx
Winch-line Hook, ring type vs. sleeve type

Started by CuddleBugFirewood on Forestry and Logging

7 Replies
2544 Views
Last post March 23, 2013, 12:25:58 PM
by lumberjack48
xx
Two new additions to the stable

Started by scsmith42 on Chainsaws

11 Replies
1369 Views
Last post November 08, 2017, 02:59:59 PM
by JJinAK
xx
'Nother Logrite in the Stable

Started by Magicman on Sawmills and Milling

45 Replies
4368 Views
Last post December 30, 2017, 05:43:45 PM
by Jeff
 


Powered by EzPortal