Wood Glue for Plywood Beams

[phamENG]

Looking for a glue that conforms to ASTM D3930, Standard Specification for Adhesives for Wood-Based Materials for Construction of Manufactured Homes. Anyone know of any that fit this? Google has failed me, and according to forum search "D3930" has never been typed on this website before. So I'm not optimistic.

This is the recommended spec from APA for use in all plywood beams. I have some fancy, curved rafters that the contractor thinks he can build cheaper by laminating plywood rather than cutting it from an LVL. Want to make sure a suitable adhesive is readily available before I spec a generic standard.

 

[ChorasDen]

I am not familiar with this standard, falls outside of what we usually use for installation in the engineered wood product business. What's specific about this standard for manufactured holes that differs from other adhesive standards? Manufactured home construction has a lot of interesting and unique qualities to it, so I'm curious if there is something special about this ASTM.

 

[phamENG]

Looks like a lot of it is in the scope of the standard - most standards cover a particular installation, strength category, etc. This one has sub categories for structural/semistructural, interior vs exterior, etc. It measures performance under high temp and low temp, deformation and creep, gap filling, and a few other things.

I think about the shallow, curved beams used in RV roofs and similar structures that are subject to a wide variety of temperatures as well as structural demands.

 

[EdStainless]

This standard covers two groups and three types of adhesive, presumably with numerous specific versions under each.
What is real troubling is that when you do a search you find places to buy the spec, but no adhesive supplier web sites pop up.
Makes me wonder ...

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P.E. Metallurgy, consulting work welcomed

 

[BridgeSmith]

This is a little off the topic, but will the laminated plywood have adequate strength to replace an LVL? My understanding is that the allowable bending stress for plywood is typically half or less that of LVL.

Rod Smith, P.E., The artist formerly known as HotRod10

 

[dik]

My favourite is Lepage PL Premium... conforms to ASTM D3498... I don't know what D3930 is.

I've often used it for gluing steel strap to wood joists for reinforcing.

So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[dik]

I think LVLs are a lot stronger... but, my wood guy is away right now...

https://wesbeam.com/getattachment/7...EWPAA-Design-Guide-Structural-Plywood-and-LVL

So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[phamENG]

Rod - a 2x4 would do the job for the loads and span, but the profile to be cut requires a member 17" deep. So it's more about lumber availability.

dik, that's what I usually specify (it's a Loctite product south of the border), but it's a non structural standard and APA is pretty specific in what they think should be used.

Ed, that's where I wound up, too. This thread was a last ditch effort to find something.

 

[phamENG]

And bending stress for plywood used in a beam is comparable to an LVL. The issue is that the net thickness of each ply for bending is less than half of the gross thickness (veneer grain direction). So martial wise it's up there - bending capacity for the same section, however, is much less.

 

[dik]

thanks, pham... I've used it for decades, reinforcing wood joists/beams, and they still haven't delaminated. One of my favourite adhesives... that and Hit-Hy 200 V3...

ASTM D3498 Standard Specification for Adhesives for Field-Gluing Wood Structural Panels (Plywood or Oriented Strand Board) to Wood Based Floor System Framing...

[URL unfurl="true"]https://res.cloudinary.com/engineering-com/image/upload/v1661553921/tips/TD---LOC-PL-Premium-3X---2019.12.12_rsy1oy.pdf[/url]

So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[dhengr]

PhamENG:
Look up Resorcinol resins and Phenolic resins mostly used for plywoods and GlueLams. Google isn’t real much help since on the first 7 trillion listings they are mostly selling 7oz. bottles of stuff at Home Depot and the like. Maybe talk with a GlueLam beam manuf’er. or a plywood manuf’er. about what glue they use. Clamping pressure and temp. are important for a good joint. Probably Titebond II or III would be o.k., and resonably priced, in this application, they are good woodworking glues. Maybe Titebond would be helpful with some info., probably no ICC-ESR reports though. The side by side joints of plywood making up a width of a curved beam may not be real critical, since they are primarily holding pieces (standing plys) together in shear, with each ply acting individually and summing for a total cap’y. Thus, not much shear flow btwn. the plys. Plywood standing edge bending is not as good as the in-plane bending which stresses the outer skin plys, in plane. You can only really count the plys which are in line (in plane) with the bending stress, not the edge cross plys. I would rough-cut the beam (shaped) plywood pieces on a band saw, oversize by .2-.25" each edge, first. I can examine the edges for large voids and flaws, and reject any bad pieces. Then, I can glue the pieces together, with good butt joints, maybe some nails each side of the joint line, staggered joints of course, and finally use a straight trim router bit run against a final shape template to get the final beam shape. The bearing on the bit is right at the chuck and runs in a template nailed to the faces of the rough shape beam.

 

[hokie66]

LVL has all the wood fibres parallel. Not so with plywood. And the manufacturing of both LVL and plywood depends on applied pressure. Not practical for DIY work.

 

[phamENG]

Dhengr- thanks as always. You make a good point about the non critical nature of the joint. The APA guide looks at plywood laminated flanges as well, and those would be critical for shear flow. Using PL premium would likely suffice here.

Hokie- are you saying making lvls is not practical for DIY? If so, I agree...

 

[BridgeSmith]

bending capacity for the same section, however, is much less.

That's what I was getting at. I was assuming a structural beam where the size of the plywood beam would need to be the same as the LVL it was replacing.

Rod Smith, P.E., The artist formerly known as HotRod10

 

[kipfoot]

phamENG: I can't seem to trace how you determined that you need ASTM D3930. Why wouldn't you be okay with APA's "Design and Fabrication of Glued Plywood-Lumber Beams"?

An older (1995) version of "Design and Fabrication of All-Plywood Beams" only mentions California's Mobile Home spec in the glossary, but also includes D4689 and D2559 in the section on materials.

You probably found the contact information on the Henkel-adhesives site for Loctite products.

 

[Brad805]

Searching for a glue that a contractor can use in their shop that meets all the specs of a glue intended to be used by a professional manufacturer is not an easy task. When you look at the specs the vast majority of these glues require far more clamping pressure than most framer types will have access to. Resorcinol is the go to adhesive for glulam manufacturers as dhengr mentioned. I pasted a sample glueup of how many clamp they use. Your contractor will not have that many clamps. Resorcinol is also not for your everyday user. That requires special safety precautions. I have used it in my own shop and when I bought it the safety precautions made me think twice about it. Presumably this is a lightly loaded element, so I think this will be an engineering decision. I think either PL Premium or West Epoxy options would be the best for a small fabricator. West Epoxy is used all the time in boat repairs and the Six10 product is awesome. Your contractor will not like the price of it. Last tubes I bought were something like $30 (CAD) per tube.

 

[phamENG]

kipfoot - it's the 2008 version of the all plywood beams document.

Brad - not trying to tell them to make a glulam in the field. I'm well aware of the futility of such things. It's two sheets of plywood 5 feet long getting glued together and cut to a curved profile for a structural application. Just looking to see if there's actually a glue available that meets the standard recommended by APA for field or shop fabricating all plywood beams. If I find one, maybe I'll discover that it's not feasible for similar reasons. But for now, it seems there are no such glues on the market.

I'm spec'ing PL Premium as I usually do, since as dhengr reminded me it's not a critical joint (as a horizontal glulam joint or a vertical plywood 'flange' to web joint would be), and specifying adequate bracing/blocking and nailing surfaces to be affixed to the side of the plywood. And I'll just avoid the plywood beam business for anything that might have one of those "critical" glue joints in it in the future.

 

[kipfoot]

from the 2016 version:

 

[phamENG]

kipfoot - thanks for that. I didn't know there was a newer version. D2559 strays into the realm of industrial press equipment that Brad brought up. Not very user friendly here.

Though searching for it did lead me to another thread on the same topic from not too long ago. Guess I should have broadened my search - I would have discovered the newer APA document! thread507-472596