Microllam Ridge Beam span size required

[jkingiv]

Hi,
I am designing a woodworking shop with dimensions of 20' x 30'. I would like to run a 30' long microllam ridge beam down the top of the 30' length and attach rafters to that.

I don't want ceiling joists or rafter ties or collar ties. I want the entire thing to be open from floor to rafters the whole length of the shop.

I tried using the span tables I found online and the load calculations, but I am not sure what I did is correct.

I realize it will be heavy and expensive, but I really want to go for the look.

Can anyone give any insight into the size of the microllam beam I'll need?

snow-load / live-load = 30 lbs/ft^2,
dead-load = 10 lbs/ft^2.
Shop size 30'x20',
with one ridge across the gable ends 30 feet in length,
and rafters hanging from that on 24" centers.
8/12 pitch roof.

Thank you!

 

[Homerr]

Assuming 2x6 end wall construction with 29'-1" clear span...bearing area is an issue...

(3) 1.75"x20" 2.0E Microllam LVL, deflection 1.072"
(4) 1.75"x20" 2.0E Microllam LVL, deflection 0.822"
(3) 1.75"x22" 2.0E Microllam LVL, deflection 0.819"
(4) 1.75"x22" 2.0E Microllam LVL, deflection 0.629"
(3) 1.75"x24" 2.0E Microllam LVL, deflection 0.642"
(4) 1.75"x24" 2.0E Microllam LVL, deflection 0.494"

For comparison, a single 5.125"x24" 24F-V4 Glulam beam has 0.674" deflection.

p.s. Is this to have a metal roof? If other, I'd up the DL a bit.

 

[tcianci]

First, welcome to GJ. Then, try going to the local municipality and tell them a guy in garage journal said I could do this...

I have said it a million times on here, the guys who sell LVL and other engineered lumber have the software supplied by the product manufacturer for the proper application of their products, and they supply those calculations for free and they're typically accepted in lieu of an engineers stamp by the municipality.

It doesn't get any simpler or more accurate than that.

Since you're new here, you probably haven't figured out that when it comes to accurate, technically important information, this ain't the place to hang out.

 

[maxpower_hd]

Diddo on the suppliers. They have engineers there that will be able to tell you what you need and they offer that service included in the price of the material. That being said, what you want can be done. My garage has a room over it and I have no beams or columns. It is 24x28 and they had me use 3 2x14s attached together for the ridge pole spanning the 24 feet. A little over kill possibly but we have snow load here to contend with as will as basic building structure. I did add collars because we opted for a vaulted finished ceiling but we didn't need to for structural reasons.

 

[Homerr]

I'll also add that the glulam will be cheaper than 3 or 4 LVLs. A lumber delivery truck may boom a single glulam in to place for you if everything is ready to go, but they won't hang around waiting for you to laminate 3 or 4 LVLs together.

A truss company may be able to make something with the 8/12 roof surface and 5/12 bottom chord (ceiling) where the interior vault ridge is about the same height as the bottom of the LVL's or glulam would be with the stick-built version. This assumes the height is important and the aesthetic of the interior pitch doesn't matter so much.

 

[Rock knocker]

The weight of an LVL is about 0.5 pounds per foot times the depth at 1.75" thickness. So a 10X3.5" LVL weighs about 10 pounds per foot (1/2pound X (1.75X2) X 10)

A 20X1.75" will also weigh about the same per foot.

So you may be able to get them in place without a crane, and laminate then in-situ

 

[kbs2244]

Once you get the wood beam info compare it to a steel beam.
It will be smaller and give you the option of hanging a hoist from it.

 

[maxpower_hd]

My LVL's we put in manually, no crane. The delivering trucks here will not put in place. They do not have the insurance if something happens. I would have had to hire a separate crane. The glue lam would have needed a crane. Same for the steel beam. So it was a cost saving measure for me to go with LVL.

 

[theoldwizard1]

Sizing the post underneath are just as important.

Seeing as your goal is a totally open building, you really should price out consytuction with Structured Insulated Panels (SIPS). The price should be similar once you realize that once the SIPS are install, they are completely insulated. For a non-inhabited building, you may be able to just prime and paint the OSB interior.

 

[tcianci]

Once again, a thread is skidding off track with half assed suggestions

1: Delivery trucks set things down not up, so you're not going to get a delivery truck to boom the beam into place.

2: A steel ridge beam creates a whole 'nother set of issues as far as attaching the rafters to the beam, and once you get through "stuffing" a steel beam so you can attach your rafters to it, there wont be anyplace for the trolley.

Does anyone think things through around here or do they derive some perverse satisfaction from firing off the first thing that comes to mind? Kind of makes me wonder what some of you do all day for a living where you can get paid for saying dumb stuff.

 

[gpflepsen]

My LVL's we put in manually, no crane. The delivering trucks here will not put in place. They do not have the insurance if something happens. I would have had to hire a separate crane. The glue lam would have needed a crane. Same for the steel beam. So it was a cost saving measure for me to go with LVL.

What was your LVL span?

My previous shop was 18x24 with 3 LVLs running 24' to act as the ridge beam. Heavy, but put up manually one at a time.

My current shop is going up now, 24x36. I wanted to run a 36' ridge beam but went with scissor trusses due to cost and the "that's a big span" factor. I never put the spec out for sizing though.

 

[Rock knocker]

Sizing the post underneath are just as important.

Seeing as your goal is a totally open building, you really should price out consytuction with Structured Insulated Panels (SIPS). The price should be similar once you realize that once the SIPS are install, they are completely insulated. For a non-inhabited building, you may be able to just prime and paint the OSB interior.

SIPs have nothing to do with clear and total span. That comes from the structure, be it truss, ridge beam with rafter or red iron.

 

[Homerr]

Once again, a thread is skidding off track with half assed suggestions

1: Delivery trucks set things down not up, so you're not going to get a delivery truck to boom the beam into place.

...

I've personally watched the lumber yard delivery truck set upper floor/roof beams on job sites with its boom. The crews were on the ball and ready to just have the beam "set down" up there.

 

[David C]

Mr Cianci,

It is refreshing to see that someone on the site has your insight and intelligence and is willing to state the truth in writing.

 

[tcianci]

Mr Cianci,

It is refreshing to see that someone on the site has your insight and intelligence and is willing to state the truth in writing.

I hope you meant that sarcastically

 

[cva1993]

Most pre-engineered joist/beam suppliers have software available for downloading to use. As a structural engineer I am comfortable in using it but most homeowners should contact the supplier and ask that the member be sized. They will do this at no cost usually.

 

[bczygan]

Not only will the supplier give you the correct size LVL for the span and loads, but also the cheapest and most available.

What contributing area did you use for your calculations? 10SF/LF?
So total load is #400/LF?
What limit on deflection? 1/240?

For 1.9E I can see 3 1 3/4x18" LVL's with 4x6 columns, but attention should be given to column length.

Each of the 3 plys are going to be about 195 pounds.

Is that what you came up with?