Contractor Talk - Professional Construction and Remodeling Forum banner
1 - 20 of 25 Posts

·
Registered
Joined
·
9 Posts
Discussion Starter · #1 ·
Interested in your thoughts

Have 14 pieces of 16'x12"x6" fir that is heartwood for the most part and am wondering if I was to laminate 3 pieces together to create a beam would there be a difference whether the pieces are laminated to be 12" high and 18" wide or laid flat to be 12" wide and 18" high.
I may have enough to go 4 wide or 4 high, shooting for almost a 50' clear span.
Your thoughts would be welcome.

Thanks
 

·
Super Moderator
Joined
·
24,787 Posts
You need to consult an Engineer.

50' clear span is a ways out there. 18" tall probably steel.

Roof load?

I have a 20' clear span, sunshine & leaf load and mine is a glu-lam 15-1/2" tall & 5-1/2" wide.
 

·
stacker of sticks
Joined
·
8,502 Posts
You need to consult an Engineer.

50' clear span is a ways out there. 18" tall probably steel.

Roof load?

I have a 20' clear span, sunshine & leaf load and mine is a glu-lam 15-1/2" tall & 5-1/2" wide.
What does an 18" steel I beam cost a foot? Ballpark
 

·
General Contractor
Joined
·
8,081 Posts
Probably in the neighborhood of 4k give or take.
 

·
Super Moderator
Joined
·
24,787 Posts
Probably in the neighborhood of 4k give or take.
And that's just the beginning:

Add for:

Support columns
Anchors
Engineering & Design
Likely an oversize load. Permit & maybe a pilot car.
Crane
Traffic control
Method to attach rafters to beam.
If exposed in finished interior add for prep & Epoxy Paint, or wrap.

There will be more.....
 

·
Always Learning
Joined
·
8,721 Posts
griz said:
And that's just the beginning:

Add for:

Support columns
Anchors
Engineering & Design
Likely an oversize load. Permit & maybe a pilot car.
Crane
Traffic control
Method to attach rafters to beam.
If exposed in finished interior add for prep & Epoxy Paint, or wrap.

There will be more.....
What?! That's not included in the price?...
 

·
Registered
Joined
·
9 Posts
Discussion Starter · #9 ·
Yes and thanks folks for your input, I am aware of the need to know roof design, pitch, material to be used, live and dead loads, the importance of the supporting members and how they will transfer energy to the ground and a footing, the importance of the resin and bolt up of the beam and proper staggering but the real question was 4, 6" pieces wide (18") and a foot high or 4. 6" pieces piled to make it 18" high and a foot wide,
Of course I would only be doing this to meet code !!!
Just the kind of questions that keep me up at night :)

Thanks
 

·
General Contractor
Joined
·
8,081 Posts
Yes and thanks folks for your input, I am aware of the need to know roof design, pitch, material to be used, live and dead loads, the importance of the supporting members and how they will transfer energy to the ground and a footing, the importance of the resin and bolt up of the beam and proper staggering but the real question was 4, 6" pieces wide (18") and a foot high or 4. 6" pieces piled to make it 18" high and a foot wide,
Of course I would only be doing this to meet code !!!
Just the kind of questions that keep me up at night :)

Thanks
You should be sleeping at night... if anything, the structural Engineer should be up at night who is calculating the loads and the beam :thumbsup:
 

·
Registered
Remodel
Joined
·
31,114 Posts
would there be a difference whether the pieces are laminated to be 12" high and 18" wide or laid flat to be 12" wide and 18" high.
!2" wide 18" high would carry a higher load, if done correctly. I advise not doing this at all, or having an engineer work out what you need.
 

·
Registered
Joined
·
99 Posts
I'd get twice the material you have now and build it up both ways in my back yard and then load it up with bags of cement, that would far exceed your proposed load, and carefully document which one failed first and where. And then take that your engineer and see if it matches his calculations. But I wouldn't lose any sleep. I might glue and bolt and clamp until bedtime, but I wouldn't lose any sleep.
 

·
diplomat
Joined
·
5,292 Posts
Disclaimer: Not an engineer! I just like to see if I can predict what my engineer will say.

Just for kicks I opened BC calc and specced a double 5.5x18 BC GluLam 30F (highest spec I think) 50' glulam holding up 16' rafters as a ridge beam, with an Alberta snow load of 22psf. It fails by a good margin, but a 7x30" glulam passes, surprisingly. But these are manufactured and tested under specific conditions, with laminations that are stronger than the wood, many more staggered and finger jointed splices than you will have, carefully selected tension members, etc.

If not steel, look into a girder truss, 50' is easy for trusses as long as you can fit something 6' tall. Probably better is common free-span trusses for the entire structure.
 

·
Registered
Joined
·
818 Posts

·
General Contractor
Joined
·
8,081 Posts
hdavis said:
Simple math - he isn't going to get 50' with any kind of load off of an 18" deep beam 50' long.
I was talking about a 20' beam... If he need a 50' good luck with that, because they usually break the span at 20-25'.
 

·
Registered
Remodel
Joined
·
31,114 Posts
I was talking about a 20' beam... If he need a 50' good luck with that, because they usually break the span at 20-25'.
50' is just tough to do with a wood beam:thumbsup:

I know a building that was put together using site built nail lam beams on a half circle mold that ran right around 30' wall to wall, but that's easier to do than this one.
 

·
stacker of sticks
Joined
·
8,502 Posts
50' is just tough to do with a wood beam:thumbsup:

I know a building that was put together using site built nail lam beams on a half circle mold that ran right around 30' wall to wall, but that's easier to do than this one.
We did a 30' free span, 4 11.5" lvl. It was only a temp beam so we could jack the first floor back into place, but it had almost 2" of crown in it.
 

·
Registered
Joined
·
7,076 Posts
Addressing at least one of the original questions: a 12x18 beam and an 18x12 beam are not structural equivalents.

Ditto everyone else's comments about it not being your problem to figure out.
 

·
Super Moderator
Joined
·
24,787 Posts
Just remember that with a big enough checkbook & enough time many things are possible. Not always practical but possible....:thumbsup:
 
1 - 20 of 25 Posts
Top