Strong enough ?????

[roger 4400]

 Hi everyone. Next spring I will build a sawmill for my new saw. I want to build a 24 X 40 ft building on a concrete foor ( 6 in.). For the mill I need an opening of  24 feet, so I will laminate a beam with 4   2X12 with 3 layers of 5/8 plywood in between the 2X12 ( spruce) , all glued and nailed and every 3 feet  I'll have 1/2 in bolt going true the whole beam like that    ...
          .           x                      x

          .            x                      x (bolts)                                                                                         beam

           ...
   
My beam will be supported with 8X10 (hemlock) posts, and will have angle braces  to help reduce the span ( if the braces are at 4 feet from the beam and locked to the post, the real span will be ± 16 feet. During winter, or when I'm not working in the mill, I'll have a removable post that I will put in the middle . Do you think this structure should be strong enough ???
I already have a 24X40 ft garage and will copy the trusses except I'll use my 2X4 that are stronger than the commercial 2X4 ( thinner). Trusses will be at every 2 ft like my garage.
The roof will be made of 1in. board and roofing shingles or thin metal ( a lot lighter) if the municipal by law accept this .
             

                                      40 ft:
       


            x         16 ft               x             16 ft       x     8 ft   x


           12 ft                                                                    12 ft

             x                                                                          x                  24 ft


           12 ft                                                                     12 ft


              x                  24 ft                       x           16 ft       x




   **** all the " X "  on the drawing are  the posts.         There will be braces in every post to beam connection.



x... beam
x                      #                                                                  #                   x
x                    #                                                                        #               x
x                  #                                                                              #           x
x                #                                                                                    #       x
x              #                                                                                           #  x             
x                                                                                                                x
x                                                                                                                x
x                                                                                                                x
x                                                                                                                x
x
x                                                          x  : are the posts
x                                                           .  : is the laminated beam
x                                                          #  : are the braces in every beam to post connection.


The beam will be laminated like this :

                                                         16 ft     +   8 ft
                                                            plywood
                                                          4 ft   + 16 ft  +  4 ft
                                                             plywood
                                                           8 ft    +    16 ft
                                                              plywood
                                                            4 ft   + 16 ft   + 4 ft
In the joint of the 4 ft and the 16 ft the brace will help the joint and the middle of the beam will be a full 2X12  16 ft.
So what is your opinion .
In Quebec there is snow but do not forget that during winter there will be removable posts  (maybe 3 X10 ) in the middle of every span over 8 ft.  Thank you for your help. Roger



         








         

[Jim_Rogers]

Without knowing the actual loads being put on this beam it's very hard to say.

Do you know the snow load for your area?

Jim Rogers

[thecfarm]

No idea about that. But good have a roof over you. I suppose you know when you do the beam to not to put it together the way it was in log form to get away from any defeats of the log.

[roger 4400]

I think the code say  a 4 ft load, but on my other garage (same size 24X40) the trusses were made by a truss manufacturer and I will build them the same way but with real 2X4 ( not 1 1/2  x 3 1/2)....so stronger. My other garage is 12 years old and we had 14 ft of snow in 2008 but there was never over a few feet on the roof ( wind). Remember that I will put another post in the middle during winter time to help the beam.
I will remember to mix the 2x12 to mix the grain....Yesterday I milled a small  white spruce :D 20 inches small butt and 24 in big butt 17 ft long almost clear ....a nice challenge for the mill and my son and I..Thank you for your experience and concern. Roger

[beenthere]

Roger
Just going to a larger dimension doesn't necessarily mean "stronger".

If the trusses were made from stress-rated lumber, then they went in the truss with known strength in the design.
Unless you are stress-rating your material too, then the larger dimension may not be stronger.

Doesn't mean a lot, but may mean something if you need to pass an inspection.

[Red Clay Hound]

I'm pretty rusty on my structural engineering, but I think 24 ft. would be stretching the capacity for a laminated wood beam - you are getting into steel I-beam territory.  Based on a quick internet search it looks like design snow loads in Quebec are going to be in the 50 psf range.  With a trussed roof design you really don't need posts on the end of the building to support the roof - the trusses are designed to span the building.  Can you orient your building such that you can set your sawmill on one end of the building?  This gives you the added advantage of having more overhead clearance.  I built a sawmill shed the exact same size (24'x40') and my mill is sitting on one end.  Here is a photo of my shed (this is my first time uploading photos, so hopefully it works):



 

I built my own trusses.  Mine are spaced 4' apart with 2x4 purlins supporting the metal roof, but I'm in Georgia - not much snow load here.  If you copy commercial trusses and use lumber that is fairly clear (no large knots), you should be ok.  Using rough cut oversized lumber will provide some extra safety factor.  One of the most important aspects of building your own trusses is connecting the truss members properly.  Commercial trusses usually use metal gusset plates that are installed by a large hydraulic press.  You won't be able to duplicate that yourself, but you can make it just as strong using half inch plywood gussets on each side.  Use a construction adhesive such as liquid nails and plenty of 10d nails.  Here is a good publication on building your own trusses:

http://www.public.iastate.edu/~mwps_dis/mwps_web/plans/truss_24.pdf

Good luck!

[beenthere]

In addition to Red Clay Hound's suggestion, that snow and water from the roof will slide down the sides, not in front of the entry to the mill. 

Thanks for that link. Am considering making 8 24' trusses and your link saves me doing a search for a plan.

[thecfarm]

I myself would try to build it like Red Clay Hound building. In my other house the eves was on the garage door end. Was a bother when the snow would melt off the roof and turn to ice when it hit the ground. Made it kinda slick,walking and getting the car in there more times than I liked. I did not make the mistake on this house.

[roger 4400]

Thank you Red Clay Hound, Techfarm and Beenthere. I am considering every of your experience and suggestion.....BUT my problem is that My mill is 30 feet long, so I think the only solution is the way I draw my shed. The shed will also ""connect to my existing 24X40 garage and will make a 24X80 building. I might have to look for a I steel beam as suggested. A stupid question ...how do you fasten the trusses to a steel beam???? Do we have to put a flat piece of wood bolted to the beam with bolts drilled true the beam ???What would be the size (6X10, 6X12 or more ) of such a beam? Is the weight over 1000 pounds???? ( need to put it on with my tractor 43 Hp ). Thank you. Roger

[thecfarm]

A 30 footor does change things. I suppose it's the Baker? That is a long one. Why the long lenght? What's the use for the long lumber?

[Red Clay Hound]

Like I said, I am rusty on my stuctural engineering, so I would not want to risk giving you bad information on the beam size.  You might be able to get a large building supply store to help you with that or check out this link:

http://www.justanswer.com/sip/structural-engineering/beams?r=ppc|ga|3|HI+%2D+Fling+%2D+Structural|Beam+Size&JPKW=beam%20size&JPDC=S&JPST=&JPAD=11744007528&JPRC=1&JPAF=txt&JPCD=20120419&jclt=Beam+Size&JPMT=p&JPNW=g&JPOP=Colin_AnsweredYourTime_Control&gclid=CIPX2-3_-bECFcKc7QodVzcAhg

I haven't used them, but it sounds like they might be able to give you the information you need.

As for connecting the trusses to the steel beam - there are several different ways to skin that cat.  You could do as you suggested - bolt a flat board to the top of the beam to connect your trusses to.  Or, you could make some brackets out of angle iron and bolt one side to the beam and the other side to the truss.  Or you could drill holes through the flange on the I-beam and insert lag screws into the bottom of the truss.

Good luck!

[roger 4400]

I want a ± 24 ft opening because when I cut 16 footers ( ± 16 ft 8 in) I like it when I have a few feet either side if I did not centered the log perfectly on my run way, and when I'm behind the engine , ready to cut my 16 footer, I'm ± 4 feet behind ( so 20 ft)and I do not like having a post right beside me, I want as muchh light as possible,maybe I'm stupid :D but I like to see wide, I'm made this way. YES you are right, you know your mills, it is a Baker, the deck is at least 24 ft  or 26 ft long ( must add the tong) to a total of 30 ft.
During the last weeks I milled some 2X4 16 ft long to build my trusses. I even cut some 2X12 , 17 ft long for the beam. Made 9  2X12 out of a nice white spruce log, and truly when I fit the log on the mill, I needed a lot of space :D. it was so heavy ( manual mill) but working slowly and wisely helped a lot. ( many tricks learned on this site with good people sharing their experience) Thanks. Roger