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-   -   LVL beam spanning 30 feet? (http://www.diychatroom.com/f9/lvl-beam-spanning-30-feet-59656/)

Colorado Steve 12-20-2009 05:42 PM

LVL beam spanning 30 feet?
 
I'm having a breezeway built between my detached garage and house. Builder is going to use a 1 3/4" x 18" LVL beam to span this distance, no supports going to the ground.

The breezeway will be a roof only, no walls. Soffits and facia to match the house and asphalt shigles. Width is 8 feet.

This sound OK to you guys? It's over a concrete drive, so I'd rather not have upright supports if not needed since they'll be in the way of parking, etc.

Thanks for you thoughts on this one.

Steve

Bob Mariani 12-20-2009 06:19 PM

you need to consider the dead load (roof) and the snow load if you get snow. seems like you might. This beam would need to be twice the thickness.

Colorado Steve 12-20-2009 06:28 PM

We do get some snow, a couple of 4 to 8 inch storms per year.

Wouldn't the building dept. have to "sign off" on his plans for the beam?
Seems like there would be some fairly straightforward parameters that need to be met.

So you think this might need to be a 3" or so beam to account for occasional snow weight? Perhaps that's what he means by "double" in the specs below. I'd assumed he just meant two beams, period.

Wouldn't something like this have to be approved by an engineer?
Here are the specs of the builder's intent:

8-0 x 30-0 Breezeway

Double 1-3/4 x 18 LVL beams
Engineered design trusses 6/12 pitch Hip roof
7/16 OSB over roof
1-4 overhang
7/16 pre-primed maonite soffit
4/4x6 pre-primed masonite facsia
Felt paper and drip edge
30 yr asphalt shingles

tpolk 12-20-2009 06:34 PM

sounds like doubled beams. Ask him and ask how he calculated sizes, alot of times the lumber yards have span/load charts

kawendtco 12-20-2009 08:00 PM

2 18 inch 1-3/4 microlams fastened together as per there specs, one on each side of breezeway 8 feet apart will more than carry this. need to have triple cripples under the ends to support this though.

Colorado Steve 12-20-2009 08:38 PM

Thanks much for the input, guys.

Just wanted some corroboration on what's being planned. Seemed like an awfully long span without any ground support, but I feel better about it now. Should be pretty cool looking.

pyper 12-21-2009 11:42 AM

Ask him how much deflection there will be.

Decide if the sag will be enough to bother you.

Scuba_Dave 12-21-2009 11:45 AM

Wow, 30' is a good distance
I would have put maybe a 10' enclosed area near the house
Good place to get out of the weather, cuts the walk down before you are out of the wind

Post some pics once its done

Colorado Steve 12-21-2009 12:31 PM

Quote:

Originally Posted by pyper (Post 370202)
Ask him how much deflection there will be.

Decide if the sag will be enough to bother you.

Yeah, well, probably any sag is going to bother me if it's a perceptible sag.

MJW 12-21-2009 01:15 PM

Quote:

Originally Posted by tpolk (Post 369919)
sounds like doubled beams. Ask him and ask how he calculated sizes, alot of times the lumber yards have span/load charts

Yes. :thumbsup:

The inspector will probably want to see that. Also, LVL's/microlams are not to be exposed to weather, so make sure that is addressed.

30' is quite a distance.....is the driveway that wide? If not, what else are you spanning over, just curious.

pyper 12-21-2009 01:30 PM

Quote:

Originally Posted by Colorado Steve (Post 370238)
Yeah, well, probably any sag is going to bother me if it's a perceptible sag.

When they sized the beam to hold up my ceiling, they came up with two pieces, each 1.75 x 14" and 22 feet long. I think the deflection calculated was 3/4 inch. Since the beam was suspened above the rafters the deflection was irrelevant to me.

You can get the span charts off the manufacturer's website, too, if you know which one it is.

tpolk 12-21-2009 01:33 PM

you may find a steel I-beam for that span works better and is cheaper. you can have holes predrilled in the flanges for plates

Gary in WA 12-21-2009 01:35 PM

Probably a 1-1/2" of sag..... according to the chart.
BUT, they come with a camber (crown) so they load out flat.

Page #6--- deflection chart: http://www.parr.com/PDFs/LP%20LVL%201.9E.pdf

Be safe, Gary

firehawkmph 12-21-2009 05:41 PM

Quote:

Originally Posted by Colorado Steve (Post 369917)
Wouldn't the building dept. have to "sign off" on his plans for the beam?
Seems like there would be some fairly straightforward parameters that need to be met.

Wouldn't something like this have to be approved by an engineer?

Steve,
Here in Ohio, where I am, the many building dept's I have dealt with don't 'sign off' on the plan designs as far as the load calculations go. They mostly look for basic items in house prints to meet their codes. For instance, in our city, they require things like 12" block for basements, brick veneer on any exposed block, minimum square footages, etc. They do not check beam sizes, floor joist sizes, etc.

As for your second question, if you want it approved by an engineer, you have to hire one to take a look at what you have. In your case, it might not be a bad idea, shouldn't cost an arm and a leg. Especially if you are concerned with any percievable sag, which I agree you should be. The lumber salesman can look at a chart to size the beams, but I can almost bet they won't guarantee the sag factor.
Hope this helps,
Mike Hawkins:)

Colorado Steve 12-22-2009 02:25 AM

MJW - the 30' span is going over existing concrete drive. It's part of the apron on the existing 3 car attached garage that this detached garage will be adjacent to.

Hadn't thought about the weather exposure being an issue. I was actually hoping to leave the beams exposed for the asthetic look. Better rethink that.

Will look into steel I-beam, especially if that won't be more expensive. I guess the sag won't be much of an issue with the LVL beam, though, if it's designed to load out flat.

Here's a pretty poor looking mock up of the area. Taken last year from an R/C plane.


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