Which is stronger: Laminated or solid hardwood?

[Bob Weisner]

Hi:

Which is stronger: Laminated hardwood veneer or soild hardwood ?

[Russ Massery]

In my opinion laminated because grains are going in different directions. But that's my opinion.

[Lee DeRaud]

In my opinion laminated because grains are going in different directions.

"Objection, assumes facts not in evidence."

Got (at least) three possibilities to consider here:
1. Solid wood
2. Plywood
3. "Glue-lam" (thin slices glued together, all grain running lengthwise)

Plywood is stiffer than solid of the same cross-section in every direction except along the solid's grain. Stronger? Define please: shear, tension, or compression? Given the quality of most of the plywood you get today, I suspect the answer is "none of the above".

The glue-lam is stronger than either, assuming it's done properly.

But that's just my opinion.

[Bob Weisner]

One more related question:

If you were using laminated wood and the top croose piece was also laminated and taking into account that all of the pieces would be weight bearing, what would be the best way to fasten the top to the sides? Dowels or mini biscuits?

Thanks,

[Lee DeRaud]

If you were using laminated wood and the top croose piece was also laminated and taking into account that all of the pieces would be weight bearing, what would be the best way to fasten the top to the sides? Dowels or mini biscuits?

No real evidence to back up the following but my gut feel is, if the joint is load-bearing, dowels (stronger/stiffer piece-to-piece interface), otherwise biscuits (less disruption to the cross-section of the pieces).

(Why yes, I am (or was) an engineer...why do you ask? )

[Mark Singer]

Laminated is stronger and more stable....I don't undersatnd the joinery question?

[Jim Becker]

I will be so bold as to suggest, "It depends on the application". Both can be very, very strong, depending on what you are doing with them. They both can also fail if not used appropriately.

[Rob Blaustein]

If the application is shelves for a bookcase, hardwood wins by a wide margin. In the Spring '05 issue of Woodworking Mag they tested deflection of different combinations of span, thickness, and depth of shelves by looking at the amount of weight needed to cause the boards to deflect by 1/4". For example, for a 12" wide board, 3/4" thick with a span of 36":
-solid maple, pecan or red oak will deflect 1/4" with 313 lbs
-birch faced plywood veneer core will take only 129 lbs.
Adding a 3/4" edge of solid wood will improve the strength of the plywood (or MDF or particleboard) considerably and make it almost as strong as solid wood, especially if it is 3/4" by 1 1/2", but hardwood is still stronger.

I remember seeing a test in Wood mag some time in the past few years and I think the results were similar.

That said, unless you have unusually heavy books and want to make a bookcase wider than 30", plywood is likely fine (I have lots of heavy textbooks in a 30" wide bookcase, 11" deep--birch veneer ply--with little deflection). If I were to make a wider bookcase I think I'd just edgeband the plywood with solid wood instead of thin stuff.

[Kelly C. Hanna]

I much prefer solid wood given the choice. After building a solid Red Oak Entertainment wall, I can safely say it's stronger than any Red Oak ply units I have ever built.

In construction of homes, the glue-lam rules...given it's dimensions, it can span greater distances than solid yellow or white Pine can. But then you think...hmmm...what would a similar sized slid Ipe beam do versus the glue-lam? I can tell you that viurtually nothing would be stronger unless you went to steel.

You can see that your question can be answered in many ways. Each type of wood could possibly have a different answer. If you specified which wood you were thinking of, you would get a definitive answer.