Beams for sawmill shed

[warren46]

I finally got around to sawing two beams for my new sawmill shed.  I had two red oak logs over 20' long that would make 6 X 12.  I want an opening of 20 feet on the two sides of the shed so I can get logs on the mill and slabs out of the back.

The larger log reached the limits of my mill and took about two hours to saw.  I got six 2X12's as side lumber.  A 20' green red oak 2X12 is a lot to take off of the mill.


  

  

 

[Bill Gaiche]

Yip, them suckers be heavy. bg

[hackberry jake]

The fun part is when you try to raise them in the air and set them on beams!

[ddcuning]

I don't mean to stir up trouble but according to my structural engineer, you cannot span 20' with conventional lumber 12" deep. Oak especially does not span well. Pine spans much better. When I built my sawmill shed, I put a 20' opening at the log deck and had to go with a laminated 14"x5-1/4" beam before the structural engineer would buy off on it. (don't quote me on the 5-1/4", that is going off of memory).

Just my experience.

Dave C

[SPD748]

I agree with Dave. I'd have an engineer look over and approve your span plans before committing. A few dollars now just may save your life later.

-lee

[Dave Shepard]

There is a beam that runs up the middle of my basement that supports the floor joists. One half is laminated hemlock lumber, which is straight as an arrow. The other end is some kind of oak. It has huge dips between the columns, with subsequent dips in the floors on both the first and second floor of the house. The house was built in '50 or '51. Maybe the beam should be stickered flat for a few decades before you put it up. :D

[warren46]

Looks like I should revise my plan. I'll check it out.  Thanks for the suggestion.

Warren

[acrosteve]

Maybe a little off topic, but where does poplar land as material for beams?  I have been contemplating doing something similar - Though maybe just 16' wide.


Thanks

[hackberry jake]

I used a hickory 6x10 for mine, but it is only 16'. I wouldn't be afraid of using the oak 6x12s to span 20' but I would give them substantial knee braces on each side to bring the actual spanned distance closer to 16'. You would still have a 20' wide opening towards the bottom where most logs and lumber pass through.
I just looked up Don-ps calcs in the tool box and it says a 20' #2 read oak beam should hold about 3,200 lbs.

[WoodenHead]

I'm not a structural engineer, but I have tried to calculate the size of beam required for a 20' span.  I had white pine to work with (which is not as good as some other choices).  In the end the beam had to be too large for my liking so I went with steel instead to handle our snow load.  Building code for my particular area requires me to use 45 pounds per square foot for roof load.  Here's a document from the American Wood Council that I found useful:

http://www.awc.org/pdf/wsdd/c2d.pdf

http://www.awc.org/pdf/wsdd/c2b.pdf contains some formulas I believe.

[drobertson]

We used three 2x12 with a 7/16 chip board as a laminate, straight as a sting for the last 7 years or so, laminating does help on free spans. not sure on engineering requirements.  Pretty sure the pitch has as much to do with it as does snow loads.  If it were me, I would use 2x12's laminated, switching the grain pattern with a plywood or chip board between them.  Codes are important, for many reasons.  Oak is very strong, as is pine, crown up,  watching for knots.  by the way, that is a mighty fine looking red oak! very nice 20' log.

[Dave Shepard]

3/8 or 1/2 steel plate would be a really good laminate for that application.

[drobertson]

3/8 or 1/2 steel plate would be a really good laminate for that application.

Agee on this, but maybe over kill. If going with steel, then why not just use an I-beam?  the stock is there, just laminate it with plywood or osb?

[hackberry jake]

I don't know about osb and being exposed to the humidity of outside. OSB scares me. I have a funny feeling that in 20 years or so, houses around the nation will just start collapsing because the OSB degraded... Maybe it's just me.

[scot wolf]

How 'bout resawing oak into 4/4 boards and selling.  Should be be plenty proceeds to buy some LVL for the beams.

[Peter Drouin]

I don't know about osb and being exposed to the humidity of outside. OSB scares me. I have a funny feeling that in 20 years or so, houses around the nation will just start collapsing because the OSB degraded... Maybe it's just me.

My oak is 10x12x24' looks ok to me.


 
see it at the far end . I used steel for the 45' door on the left

[drobertson]

Reading posts is sometimes difficult to read the exact intents to original questions, I understood the existing lumber was to be used for various reasons, such the reason I suggested OSB,
http://www.sishomes.com/components_benefits.html
It seems these new engineered systems are quite adequate for spanning lengths, safely,

[bandmiller2]

Warren, I would consider making your own trusses, there was a lot of talk of this here not long ago. My tractor shed and mill roof utilized oak timbers for many years no problems. Oak will sag but it won't break. Warren if you decide to use the oak timbers you can reduce the span with 45 degree braces they greatly reduce the span and are not in the way for loading logs. Frank C.

[warren46]

After reading all of the above suggestions I think I will use the beams with knee braces at the ends.  I can reduce the free span to an effective 14 feet if the knee braces are each 3 feet from the ends.

I can accept a little sag but want to avoid a catastrophic failure.

Warren

[kelLOGg]

The fun part is when you try to raise them in the air and set them on beams!

I agree - that is the fun part. On the sheds I have built I had much rather install the beams than set the posts. Once up, I rig the posts with hoists and up-up-up go the beams.

 


These chain clamps cinch the posts together very tightly.


 

[ozarkgem]

After reading all of the above suggestions I think I will use the beams with knee braces at the ends.  I can reduce the free span to an effective 14 feet if the knee braces are each 3 feet from the ends.

I can accept a little sag but want to avoid a catastrophic failure.

Warren

'I used 2 2x12 nailed together to span a 20' opening for my mill. Shed is 28' wide 4/12 pitch. 15 yrs no problems. Depends on snow load is guess. I have a 25' span in my cabin I used 4- 2x8's glued and screwed for the ridge beam. 16' wide 4/12 pitch. My other cabin is 20' wide 8/12 pitch and I used 3 2x10's for the ridge beam spanning 20'. Now these are all for the ridge except for the sawmill shed opening. You get some support from the rafters on the ridge beams. I have a couple of books on wood engineering and it has span tables. IF I remember right solid beams have to be huge. My Amish neighbors built a 150' span wood bridge for Bass Pro and the timbers were huge. Forgot my camera that day. Pretty impressive.

[bandmiller2]

You'll be fine Warren your old enough to know what works. You can always bolt on  some steel plate on the in side of the 6x12 or even 2x12 oak planks. Show us when your done. Frank C.

[Alcranb]

Probably a foolish question but.....is there more strength, less chance of bowing in say 3, 2" x 6" x 20's nailed together than one 6" x 6" x 20' beam?

[thecfarm]

Seem like someone posted something about taking 3 diffeant 2x6 or using the same one but flipping one over and turning one end for end. That way any defeat would not be in the same place??

[tmarch]

Probably a foolish question but.....is there more strength, less chance of bowing in say 3, 2" x 6" x 20's nailed together than one 6" x 6" x 20' beam?

There is a lot more strength if the grain is opposing and of course the knots or defects in different places along the beam.

[beenthere]

And getting more depth to the beam is where additional strength can be gained.
i.e. sandwich three 2x10's with either plywood or steel in the laminations would increase strength considerably.

[barbender]

I would just use the Oak beams with knee braces and be done with it. If you know the loads the calculations are available, maybe in the forum toolbox, to figure the necessary size beam. I sized the ridge beam for our house, to free span 14' with our snow loads called for an 8"x12" with the Red Pine I was using.  It hasn't sagged at all.

[giant splinter]

I am trying to get started on my mill shed and cut an 8" X 14" X 27' header beam out of Douglas Fir for my 22' clear span log deck opening two years ago, it is moved over and resting on blocking right next to the foundation footings. Once I actually get rolling on this project I will add some photos. Mill sheds are very important to us and help a lot in all weather conditions to keep us dry and in the shade while allowing everyone to keep on sawing on the days when we just otherwise may not want to get snow down the back of jacket. Its always neat to see what everyone else is building for a mill shed and the FF has many very nice structures that we can look to for ideas when we plan out our own shack.

[tule peak timber]

What we did today..Expanding the existing shed for the new mill. Cheers Rob

  

 

[m wood]

always love to see your projects Rob.  You obviously don't believe in doing anything small.

[Tom L]

What we did today..Expanding the existing shed for the new mill. Cheers Rob

how did you anchor those posts? looks to be  a gap on the bottom.

[Andy White]

Warren46,
This was the same situation I was in when I framed my house. Needed to span 28' in three places for pony walls for hip roof to gable roof tieins. Engineers said 2x12 with plywood cores, glued and screwed. Figuring cost, I was able to buy factory Glulam beams to span that distance, and have more support than I would ever need. They shipped them to my site, and unloaded them while I was at work. Fabricated my own tie clips and bolted as recommended by mfgr. and all is well for six years now.


 


 


  

 
Most lumber yards can order them any length you need.         Andy

[tule peak timber]

The posts are anchored to a 1/2 yard of steel reinforced concrete with massive steel straps. I got to pick through the construction scraps of the winery we just finished the mill work package for and there was a lot of 1 inch rebar. I made good use of a lot of steel in the new mill slab and shed.  Cheers  Rob

[Mapleman]

There are a couple of things to keep in mind if you want to reduce some of the load on your cross beam by using knee braces.  First might be kind of obvious, but the braces need to be very well connected to both the beam and the post.  I've seen braces installed with just toe nails at each end and they will give under a heavy load.  Glue and screws would probably be best, you want a real rigid joint because if there's any flex in your fasteners you'll get a lot of deflection in the beam before the joints tighten up.

Also the knee braces will take some of the downward force from the beam and turn it into a sideways force on the posts so your posts need to be strong enough to take that sideways load and not bow out. 

In my sawmill shed I have two 24' openings spanned by solid 8X12 hemlock beams.  One snowy winter they started to sag a little (maybe 1" in the center of the span) but there was over 4 feet of snow on the roof above.  I shoveled the roof off and they straightened out.  I don't use the sawmill in the winter so what I do now in the fall as part of the winterizing routine is to put a temporary post under each span that I take out when I get ready to saw the next spring.  Seems to be working well so far.

Good luck with your project!

Dave

[venice]

Knee braces wont help that much in this situation. To prevent sagging you would have to move them far more to the centre of the beam than the desired headspace allows for.

I´d suggest I-Beam or Gluelam. Gluelam provides loadbearing tables for customers to figure out the needed dimensions. But you have to paint them for outside use.

Venice

[Klicker]

I did a  milling job for a 40 x60 barn. They used a double row of 6x8 for the beams to set the rafters on.