[Screwlam]

For identical dimensions, are standard grade LVLs really stronger than a good cut of real hardwood SSL (White Oak, Locust, Ash etc.)

Run-of-the-mill LVLs are made of softwoods but get their strength from having many layers which eliminate imperfections in the woods such as knots, splitting and bad grain that reduce the nominal strength of SSL that goes by the bottom 5% strength rating. In addition LVLs get some bonus strength from the glue apparently.

In reality, are they really stronger than a high-grade knot-free true Hardwood beam, size for size? In terms of elasticiy within bending tolerance, but also actual break strength.

 

[carpdad]

There are also material's dead weight, how dry the product. Memory not good - "lvl is put together from many short fiber pieces which are more stable than natural fibers which are not under our control". Quotation is paraphrased. In real world, best grade lumbers aren't really available.

 

[Windows on Wash]

Short answer...yes. And cheaper in all likelihood than good wood.

 

[Bud9051]

The University of Maine has a very strong involvement in wood research and the link below can lead you to much of the information you seek.
https://composites.umaine.edu/key-services/wood-composites/

Bud

 

[Screwlam]

Menards sells 2.0E LVLs for much cheaper that I can get in the Northeast where they seem to all be sourced from blue Lynx engineering Oncenter LVL brand from Lowe's and other Regional Lumber stores. But also around here small Dimension hardwood can be locally sourced for rates barely exceeding lumber yard Pine. However, it seems that for larger Dimensions the price of choice hardwood goes up exponentially, to the point where it can match or exceed the cost of higher-end engineered products such as LVL or maybe even glulam. So price aside, a workable piece of 7x14 inch hickory seems like it would be stronger than four plies of 20 foot menards 14 inch LVL (1.9E) - on sale for under a hundred bucks each, about $2/ bd ft, but local hardwoods can be gotten for even less at this small size.

 

[House Designer]

For identical dimensions, are standard grade LVLs really stronger than a good cut of real hardwood SSL (White Oak, Locust, Ash etc.)

Run-of-the-mill LVLs are made of softwoods but get their strength from having many layers which eliminate imperfections in the woods such as knots, splitting and bad grain that reduce the nominal strength of SSL that goes by the bottom 5% strength rating. In addition LVLs get some bonus strength from the glue apparently.

In reality, are they really stronger than a high-grade knot-free true Hardwood beam, size for size? In terms of elasticiy within bending tolerance, but also actual break strength.

I ran a quick calculation to compare:
(2) 1.5 X 11.25 white oak beam (top grade- Select Structural)
with a medium grade
LVL (2) 1.5 x 11.25 Boise Cascade VersaLAM 2400 Fb .
My test case was a 10' span beam, loaded up to capacity.
The LVL was 101% stronger than the white oak beam, i.e. TWICE AS STRONG.

To put it another way, a single 10' long LVL was just as strong as a doubled 10' long White Oak beam.

(Note: My software allowed me to fudge the dimensions of the LVL to be 1.5 x 11.25, even though LVLs are typically 1.75" wide.)
Without fudging the LVL dimension, the (2) 1.75 x 11.25 LVL beam was 134% stronger than the (2) 1.5 x 11.25 white oak beam.

LVLs are amazing products.

 

[Screwlam]

Wow, so not 101% of the strength of the White Oak AKA 1% better, but twice as strong?
Are you sure it's not the latter? I thought they were about equivalent because lvls are rated 2.0E and the hardwoods are rated around 2 million MoE..

Can you run the same test for Shagbark Hickory and black locust?

Thank you for your reply.

 

[House Designer]

Screwlam, I ran the same calculation for Beech-Birch-Hickory, and it only improved 10% over White Oak. Sorry, my software doesn't have a selection for black locust.
I guess the wide disparity between design allowables for solid sawn lumber and LVL are due to the lack of defects in LVLs compared to even the highest grade of solid sawn lumber.