iDRY Vacuum Kilns

Sponsors:

sawmill shed... beam span question

Started by sandsawmill14, October 13, 2016, 09:31:21 PM

Previous topic - Next topic

0 Members and 1 Guest are viewing this topic.

sandsawmill14

i am planning to start a mill shed in the next couple of weeks and need 18-20' of open to get logs into the mill  ??? i was planning to put braces from the post out 3' from the post on each side so it would be 12-14 feet between braces  :)  what size beam would i need  ??? it can bee out of almost any type of would but the rest of the building will be SYP and will use the same for beam unless yall think it wont hold up :)
hudson 228, lucky knuckleboom,stihl 038 064 441 magnum

JBS 181

Putting in knee braces? Sounds like that is what you are doing. I did the same thing with the same kind of span. Works very well. My shed has been in place for at least 5 years with no sagging. I used lodge pole pine because that is all I had available. I will second check tomorrow but I believe mine is 10" wide. I made mine out of 2" material and laminated them together mainly because I had no way to lift a solid piece up that high and get into place by myself. 3 pieces making a 6" x 10" beam.

sandsawmill14

i was thinking of using 3 2 x 12 syp for the beam but wasnt sure if that would be enough :) sounds like it would be though :) i have never spanned a beam that long before my shop is 24' clear span and i used sawmill 2 x 8s for rafters and its about 15 yrs old with no problem but rafters are different from beams  :) getting the beams up will be no problem as we  have a wheel loader there i can use to set it with :)
hudson 228, lucky knuckleboom,stihl 038 064 441 magnum

sandsawmill14

and yes knee braces is what i was talking about :)
hudson 228, lucky knuckleboom,stihl 038 064 441 magnum

LeeB

I recent researched for a 20 ft span and ended up using a laminated 3x12.  Snow load will be about the same as yours. total load may be a bit different as the span between beams was only 10 w/ 2x6 rafters on 2ft  centers. With the knee braces you should be fine I would think.
'98 LT40HDD/Lombardini, Case 580L, Cat D4C, JD 3032 tractor, JD 5410 tractor, Husky 346, 372 and 562XP's. Stihl MS180 and MS361, 1998 and 2006 3/4 Ton 5.9 Cummins 4x4's, 1989 Dodge D100 w/ 318, and a 1966 Chevy C60 w/ dump bed.

Ljohnsaw

Yes, knee braces help.  But, when doing the calculations, they are not to be taken into account (reducing the span).  If you want to do it right, you need to use the Tool Box and do your load calcs based on the full span and whatever roof loads it is supporting.  But only if you want to be absolutely sure. ;)
John Sawicky

Just North-East of Sacramento...

SkyTrak 9038, Ford 545D FEL, Davis Little Monster backhoe, Case 16+4 Trencher, Home Built 42" capacity/36" cut Bandmill up to 54' long - using it all to build a timber frame cabin.

Peter Drouin

Go with steel, Works well my door is 45'


  

  

 
A&P saw Mill LLC.
45' of Wood Mizer, cutting since 1987.
License NH softwood grader.

sandsawmill14

hudson 228, lucky knuckleboom,stihl 038 064 441 magnum

drobertson

We used 3 2 x 12' s. with OSB between two of them, on a 20 foot span, to date no issues since 07'.
only have a few chain saws I'm not suppose to use, but will at times, one dog Dolly, pretty good dog, just not sure what for yet,  working on getting the gardening back in order, and kinda thinking on maybe a small bbq bizz,  thinking about it,

kelLOGg

I used utility poles 30' long because I could get them free. I have about 21 -22 feet open and I used knee braces too.
Bob
Cook's MP-32, 20HP, 20' (modified w/ power feed, up/down, loader/turner)
DH kiln, CatClaw setter and sharpener, tandem trailer, log arch, tractor, thumb tacks

rjwoelk

It may not be convient, but if you run truss rafters 40 to 60 ft wide and how ever deep one needs it. Then you are clear span. If you need other doors come in on the side.  Saves making a large header, as your rafter does that for you. With a set up like this you can always extend it as you need to.
Lt15 palax wood processor,3020 JD 7120 CIH 36x72 hay shed for workshop coop tractor with a duetz for power plant

alanh

I did mine , 19  ft opening, with a 12" x 12" x20`hemlock, no sag. It was floating by in the Ct River and I winched it up, always wondered where it might have come from...

ChugiakTinkerer

I'm still pondering a shed design and haven't decided on whether to go with trusses and have a clear span throughout the building, or something like Peter's shed but with a more diminutive beam.  As mentioned above you should run through the beam calculator in the toolbox to get a design you know will work.

The simple beam with uniform load is at https://forestryforum.com/members/donp/beamclc06b.htm
If you are looking at a shed 20' deep and say 36' wide, you'll be supporting the rafters with your 36' walls.  Each of the long walls has to support one half of the weight of the roof.  A 20' wide opening in the long wall will need a header capable of supporting half the depth of the roof (10' in this example) by the length of the beam.  That comes out to 200 square feet of roof.  The total weight will be the live load and dead load values multiplied by 200.  This is where a snow load makes or breaks a roof.  Dead loads are typically under 10 lbs per s.f., and live loads may be 10 or 20 lbs.  If you have a lot of snow though it adds a lot of weight.

Assuming there is no snow to speak of, let's look at 10 psf live load and 10 psf dead load.  That makes 4000 lbs total load on the beam, of which half is dead load.  Going to the calculator page linked above, put in the following values:
  Total Load on Beam(pounds)  4000
  Dead Load on Beam (pounds)  2000
  Span of Beam (inches)  240
  Width of Beam  9
  Depth of Beam  11.25

This will be for a built-up beam made of 6 plies of 2x12.  For wood species, I would start with the weakest wood available and see how it works.  I usually pick SPF #2 B+S.  If you select that then click on Show Result you'll see that this beam fails.  If however you select a stronger species or grade you will find that it passes.  This would be the case even if SPF #2 was used, because built-up beams are stronger than the same size of sawn timber.  The calculator page assumes sawn timber, but engineering calculations using a built-up beam should have a 15% increase in the bending strength of the beam.

The quality of the wood makes a huge difference.  If you can get your hands on select grade doug fir, you could do a built-up beam using 3.5 x 12 rough-sawn or a built-up beam of three 2x12 dimensional.

Edit: caught the typo in my last sentence, hope it makes more sense now.

Woodland Mills HM130

clintnelms

I used a steel truss on the end of my shed where I load my logs at. It's 30 foot.


fishfighter

Quote from: clintnelms on October 15, 2016, 10:13:38 AM
I used a steel truss on the end of my shed where I load my logs at. It's 30 foot.



That is what I am planning on doing. ;D

sandsawmill14

that bar joist would be great  :) i might check around and see what one would cost but i will probably use wood because it will be free and i gotta do it cheap or not do it  :-\  i have no money  :D :D :D
hudson 228, lucky knuckleboom,stihl 038 064 441 magnum

Kbeitz

Quote from: sandsawmill14 on October 15, 2016, 07:32:17 PM
that bar joist would be great  :) i might check around and see what one would cost but i will probably use wood because it will be free and i gotta do it cheap or not do it  :-\  i have no money  :D :D :D

If you can weld they are easy to make. Just angle iron and round stock...
Collector and builder of many things.
Love machine shop work
and Wood work shop work
And now a saw mill work

clintnelms

Quote from: sandsawmill14 on October 15, 2016, 07:32:17 PM
that bar joist would be great  :) i might check around and see what one would cost but i will probably use wood because it will be free and i gotta do it cheap or not do it  :-\  i have no money  :D :D :D

I believe mine was somewhere between $250 and $300.I can't quite remember. Well worth it to me.

ncsawyer

Quote from: Peter Drouin on October 14, 2016, 06:18:04 AM
Go with steel, Works well my door is 45'

I agree with Peter.  I had a piece of 8x8 by 1/2 inch thick angle from a big power line tower that I used for mine. Its a 24ft clear span.



  

  

  

Those are 16 foot logs stacked in the opening at the mill. 
2015 Wood-Mizer LT40DD35
Woodmaster 718 planer
Ford 445 Skip Loader

Peter Drouin

A&P saw Mill LLC.
45' of Wood Mizer, cutting since 1987.
License NH softwood grader.

ozarkgem

I used 2  2x12s 20' long. one on each side of the 6x6 post. 12 yrs and no sag.
Mighty Mite Band Mill, Case Backhoe, 763 Bobcat, Ford 3400 w/FEL , 1962 Ford 4000, Int dump truck, Clark forklift, lots of trailers. Stihl 046 Magnum, 029 Stihl. complete machine shop to keep everything going.

Jesper Jepsen

Well the only place I've seen any calculations on beam span is in the "Log span Tables" book from the International Log builders Association.  They deal in round logs but the span tables are here.


ChugiakTinkerer

There is this table from Southern Pine: http://www.southernpine.com/app/uploads/SS_1-6L.pdf

Treating the beam like a garage door header would certainly be adequate from a code perspective, if that is a concern.  Can't recall from OP at this point.  Web page leading to that PDF is here: http://www.southernpine.com/span-tables/headers-beams-size-selection-tables/

Edit to add: Huh, waddayaknow?  there's a Wikipedia entry on flitch beams: https://en.wikipedia.org/wiki/Flitch_beam
Woodland Mills HM130

Thank You Sponsors!