# LVL Span question



## fred47 (Sep 5, 2014)

I am doing some remodeling that will require the installation of a LVL beam that will span 17 feet and support the second floor of the house. I was planning too bolt three 9-1/4" LVL's next to the existing 2x10 that is about 13 feet. I know that everyone will need more information in order to answer my question and I will provide that-however rather than posting too much info at this time I figured that I would just post the span question and add any info as needed.

So is the 17 foot span doable?


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## nealtw (Sep 5, 2014)

Welcome to the site. We install lvls and microlams all the time and have no idea about span loads as this is always figured out by an engineer. Evan if you can figure it out and you go for a permit the city will just circle that and ask for an engineers report. That being said the people who sell these things can make calls to the engineers that work for the people who make them and can be helpfull.
But you would be really lucky to get away with 14".


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## fred47 (Sep 5, 2014)

I assume that you meant 14 feet?






nealtw said:


> Welcome to the site. We install lvls and microlams all the time and have no idea about span loads as this is always figured out by an engineer. Evan if you can figure it out and you go for a permit the city will just circle that and ask for an engineers report. That being said the people who sell these things can make calls to the engineers that work for the people who make them and can be helpfull.
> But you would be really lucky to get away with 14".


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## JoeD (Sep 6, 2014)

No he probably meant a 14" wide beam. That's a long span and requires larger beam.


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## fred47 (Sep 6, 2014)

Ok then! 14" it is!

I have taken some pictures in hope that some things may be made a little clearer. They may change the outcome--maybe not--but I thought that I would give it a try!

My thought is that the joists that are supporting the second floor are 2x10's--10 feet long over the dinning room and 13.5 feet over the living room--16" OC --So an additional 3.5 feet requires a 14" wide LVL? (3-bolted to the existing 2x10?)






JoeD said:


> No he probably meant a 14" wide beam. That's a long span and requires larger beam.


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## Wuzzat? (Sep 6, 2014)

fred47 said:


> that will span 17 feet
> the existing 2x10 that is about 13 feet.


For a distributed load and the same deflection at midspan, a 17' beam has to be (17/13)^3 = 2.2x stronger than a 13' beam.

http://www.engineersedge.com/beam_bending/beam_bending1.htm

If you post a link to your candidate beam the specs can be compared to that of varying grades of 2x10s and wood types.  
These guys
http://en.wikipedia.org/wiki/Laminated_veneer_lumber
are whole different animals.

And a 14" (actual, not nominal) high joist is (14/10)^3 = 2.7x stronger than a 10" (actual, not nominal) high joist.


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## fred47 (Sep 7, 2014)

Please excuse my ignorance but are you saying that if I want to span 17 feet then I would need to go with a 14" wide LVL instead of three 9-1/4" LVL's bolted to the existing 2x10?  

 Another question---when you recommend the 14" LVL is that one 14" LVL or three 14" LVL's bolted to the existing 2x10?







Wuzzat? said:


> For a distributed load and the same deflection at midspan, a 17' beam has to be (17/13)^3 = 2.2x stronger than a 13' beam.
> 
> http://www.engineersedge.com/beam_bending/beam_bending1.htm
> 
> ...


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## Wuzzat? (Sep 7, 2014)

fred47 said:


> Please excuse my ignorance but are you saying that if I want to span 17 feet then I would need to go with a 14" wide LVL instead of three 9-1/4" LVL's bolted to the existing 2x10?
> 
> Another question---when you recommend the 14" LVL is that one 14" LVL or three 14" LVL's bolted to the existing 2x10?


I can just give general guidelines based on the formulas.  
A complete analysis is pretty tedious but the International Residential Code has tables if you use conventional lumber.
Bolting lumber together makes the analysis more difficult.

The LVL people will recommend the correct product for your application, but they of course will be biased into selling you slightly more strength than you need.  For whatever they recommend, ask what safety factor is built into their calculations.
A structural/civil/mechanical engineer can give you a size, either by hand or by using expert system software.  

A college student or professor may advise you for free, like in this movie
http://en.wikipedia.org/wiki/Erin_Brockovich_(film)
People are happy to talk about their work, even if you don't look like Julia Roberts. 

And, cantilevered beams are very complex to size.

It's one thing if only your life depends on your doing this correctly, but there are more lives at stake here.  
For this same reason I refused to provide a stock car driver with a circuit that would prevent wheelies.  BTW, vehicle dynamics are way more complex than beam sizing, not even taking into account driver reactions.

Thank you for asking.  Way too many OPs are not as curious as they should be.


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## fred47 (Sep 7, 2014)

I asked for info from the local lumber yard that I use and he didn't want to give advice and he told me that the place that makes the LVL's would not help either (he has tried asking them in the past). I have located an engineer the may be able to come up what something--I will post his recommendation. 






Wuzzat? said:


> I can just give general guidelines based on the formulas.
> A complete analysis is pretty tedious but the International Residential Code has tables if you use conventional lumber.
> Bolting lumber together makes the analysis more difficult.
> 
> ...


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## Wuzzat? (Sep 7, 2014)

I've asked for help online from makers of wood products, plywood, LVLs, etc. and they gave me links to assist me.  I'm kind of surprised at the way they are treating you.


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## nealtw (Sep 7, 2014)

The reason no one wants to give direction is liability. Because it is not just the beam, it is also the curb wall and footing that this will be sitting on.
Your work on the old beam is impressivefor the beam and bolting in the joists, but and engineer will never let you support that with 2 studs and I don't ever remmember seeing a cantilever that long on a beam, Those first 2 studs are carrying 2/3 of all the weight from above. An engineer will look at live and dead loads from the roof down and the the span and then the weight that the footing can carry. If your landing a big beam like that on a 8 ft high foundation wall the weight is spread sides from the top on a 45 angle in both direction but on a curb wall the footing depending on the load can be as big as 12" deep and 48 x 48. were your normal curb footing might be 18"
I did mean 14" high but could be as much as 19" high.


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## Wuzzat? (Sep 8, 2014)

The LVL people will probably give you span tables.  From there you can figure the modulus of elasticity and fiber strength.  Then you see if this fits your application.  
Not so easy and a lot rides on your getting it right.


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## nealtw (Sep 8, 2014)

Wuzzat? said:


> The LVL people will probably give you span tables.  From there you can figure the modulus of elasticity and fiber strength.  Then you see if this fits your application.
> Not so easy and a lot rides on your getting it right.



Not helpfull in figuring all the loads and bearing points and footing strength.


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## Wuzzat? (Sep 8, 2014)

nealtw said:


> Not helpfull in figuring all the loads and bearing points and footing strength.


That's in
"Then you see if this fits your application"

Another thing is that the formulas use beam loading per linear inch and the floor rating is in pounds per sq. ft. and so you need to know the joist spacing.  Maybe somebody has posted an alterable spreadsheet for doing this but I'd feel safer having someone qualified sign on to this.


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## nealtw (Sep 8, 2014)

That person is an engineer. When we do this kind of work, the engineer will size the beam and the bearing posts and the weight that footing has to take. A guess is made on footing size and we cut out the floor for that, then a geo- engineer checks the soil condition and may ask for bigger footings.


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## nealtw (Sep 9, 2014)

This week will be installing a beam, that will be carrying some pretty big loads. It is only 14 ft long but it is  but it will be 16" high and 7" wide. We get miuco lams but the strength is the same as bolted together lvls. BTW we have a crane drop it in place.


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## fred47 (Jan 2, 2015)

I bit the bullet and hired an engineer to plan out the beam. I will be installing 4 LVL 12" high. I need to wait until the weather warms up before starting again.


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## nealtw (Jan 4, 2015)

Did he give you a plan on how to get them there? What was the price range for that tid bit of info? I send people looking for an engineer all the time, it would be nice to have some idea of cost.


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