Deck Construction and "Construction Adhesive"

[Paul Maselli]

http://pic17.picturetrail.com/VOL828/3186788/6508162/83727631.jpg The sloop "Elliot White's" :cool: new deck will be constructed as follows. Oak deck beams laminated to a camber of 4-3/4" in 10'-8". These will be laminated of 7 course of white oak bonded with TiteBond III.
The deck itself will be a first course of WhiteCedar T&G milled to 1/2" finished thickness. The T&G will be bedded with traditional boatyard bedding compound and secured with Bronze ringnails. (2")

Second Course: 12mm Meranti Plywood bonded to the cedar and also nailed with (2") bronze ringnails. All seams in the plywood will be scarfed and epoxied to eliminate but joints.

The deck will be finished with Dynel and West Epoxy trimmed with mahogany covering boards that will ship lap over the edges of the plywood and dynel.

Now heres the twist. I'm strongly considering bonding the plywood to the cedar with PL400 Waterproof Decking and Sub Floor Adhesive. It can be bought in 1 gallon or 5 gallon pails and applied with a notched trowel for each plywood section. The open time is enough to lay down the ply and set the nails. The bond is incredibly strong, I've never been able to seperate this glue joint in general construction applications. And the guarantee is for total water and weather proof cure.

Has anyone used the Construction grade adhesives in this type of application?

Thoughts?

[pjwalsh]

I tried PL premium as the primary adhesive/caulk for an el-cheapo plywood skiff last summer and have to say I was not that impressed. The PL Premium seems to me to be rather brittle once cured, and because it foamed slightly the bond line is full of holes. Also I do not think the bond it makes with wood substrates is all that strong - in sawhorses I have built using the PL Premium the glued surface between the legs and horizontal failed rather quicky. Granted this is probably a much higher loading situation than your decking application. For a deck rebuild such as you are considering I would stick with 3m 5200 which is not only a tenacious adhesive but also very flexible.

There seem to be dozens of PL adhesives available and you may be planning to use one with different characteristics, but why take a chance on such a major repair.

Good luck with your project.

cheers,

Peter

[ 03-03-2005, 08:59 AM: Message edited by: pjwalsh ]

[ssor]

Paul, First of all I question the use of meranti in any situation where wettin is a posibility. I am presently replacing some rot damaged meranti plywood in a dink that I built about five years ago. Beyond that I repair houses for a living and have seen many failures on ceramic tile floors where water got into the substrate and grew fungus. PL premiun construction adhesive is just that "construction adhesive". There are some very good adhesives for bonding underlayment panels, most are some form of acrylic but none are recomended for wet areas.

[Mike Vogdes]

Paul,
I have recently used Liquid Nails trowelable adhesive for repairing some paneling in my trawler with very good results, granted its nonstructural, however the bond was very good and I'm confident it will hold up in my case.

I did a few test panels to see how well it bonds and like you say, its tough stuff indeed, I couldn't break the bond without destroying the plywood.

In my application I used a laminate roller to ensure a good bond, being carefull not to do to big of an area to avoid skin over.

In your situation I would make up a couple test panels, one with PL400 and one with 5200 befor comitting to such a large project.

[Paul Maselli]

Thanks for your input so far guys. There are a few points I'd like to respond to.

Yes, I agree, any adhesive will be tested with a sample structural test. This will include West Epoxy, PL 400 Construction deck and subfloor adhesive, and Gorilla Glue to name a few.

PJWALSH points out that PL Premium created a brittle bond and sighted his saw horses as an example. These joints are almost always in shear and have severe racking forces applied to them. I agree that the PL would fail there. As for the adhesive being brittle, how different is that from our beloved epoxies, These adhesive create a bond that does not like any sort of movement. Cyclic swelling and shrinking of the wood is a big no no with epoxy, The most common applications include cold molding which requires the use of dimensional lumber that is milled to skantlings that can be locked into place and will not overcome the epoxy bond. I don't know if my 1/2" T&G cedar falls withing these parameters.

SSOR questions the use of Red Meranti. As I stated the entire deck will be a watertight skin with Dynel and Epoxy as the exposed surface. This will be finished with a 2 part polyurethane paint for longevity and UV resistance. I have used this stuff before and it is bullet proof. Finishes that last 8 years are not uncommon. Additionally the Meranti Plywood is certified for water proof bonding and full immersion. The Meranti itself may be slightly more prone to decay than say Okoume, but it will be encapsulated in a Glue / Epoxy substrate with all edge grain completely sealed with either epoxy alone or epoxy and Dynel. The Covering Boards will also ship lap over the dynel edges for a sealed caulkable seam. Second I understand his concerns about fungus. But a comparison between a house bathroom that is exsposed to steam, hot water and the lack of sunlight it can be expected for a Subfloor / Tile job to decay. The deck of a sailboat doesn't fairly compare.

Mike has the only application that is actually intended for the Liquid Nails. It is primarily used for paneling. I agree Testing needs to be done.

I have used Gorilla Glue both as an exterior adhesive as well as in the reconstruction of the Elliot White. The steamed frames in the stern of the boat were a very tight bend. We opted to kerf the 1-3/4" Oak and each Kerf was subsequently bonded with Gorilla Glue when we rivet these in place. The bond to White Oak is excellent.

All of this is a study in the alternative adhesives as well as the costs associated with them. I'm not looking to cut corners. I want to explore the alternatives that we have available to us and make prudent economical choices. Without these the best of materials won't see a project of this scale to completion if the moneys run out......

[Bob Smalser]

Originally posted by Paul Maselli:
....TiteBond III....PL400 Waterproof Decking and Sub Floor Adhesive....

Thoughts?Ok...yes.

I wouldn't be caught dead doing that level of irreversible work using unproven, non-marine products.

An interior panel or the odd interior shelf maybe...but the deck?

And the latest version of Elmer's GlueAll....a tarted-up interior aliphatic????? No aliphatic can be glued over in a repair...hence any of it is totally worthless to me.

No way.

Wait for my treatise on the effects of Bondo....non-marine, non-proven products generally require repair decades ahead of schedule and those repairs often take 3-fold as long (and cost 3-fold as much) as in a similar repair done with proven products.

[ 03-04-2005, 03:31 PM: Message edited by: Bob Smalser ]

[Cullen T.M. McGough]

1. Why?

2. Someday, someone, somewhere will have to replace the deck of your boat. I don't care how good it is. There are no 100-year old decks. If you bond the deck to the beams, they will also have to replace the beams.

-Cullen

"think of the children"

[Don Z.]

Originally posted by Paul Maselli:
Thanks for your input so far guys. There are a few points I'd like to respond to.

As for the adhesive being brittle, how different is that from our beloved epoxies, These adhesive create a bond that does not like any sort of movement. Cyclic swelling and shrinking of the wood is a big no no with epoxy, The most common applications include cold molding which requires the use of dimensional lumber that is milled to skantlings that can be locked into place and will not overcome the epoxy bond. I don't know if my 1/2" T&G cedar falls withing these parameters......Ummm... could that be why the recomendation is for 5200?

[pjwalsh]

I don't think you are going to tear the joint apart with the forces generated by 1/2" T&G, especially if it is kept relsatively dry by a plywood sheathing, but your deck may undergo some large deformation due to sea state and stress from the rig etc..., why not use an adhesive that can accomodate deformation without danger of failure. I still would say 5200 or another adhesive with good adhesive qualities and plenty of flexibility. Epoxy might be OK too - toughness is a combination of both strength and elongation at break. while epoxies may break at smaller elongations they are also much stronger than polyurethanes like PL premium and so are tougher (less brittle).

My earlier post was just to relate my own experience with PL premium as applied to boats, take it for what it is worth, after all your own experience is the one you will understand the most fully. I have slung a lot of these PL polyurethane adhesives while building houses and have never seen any failures in these applications in which the loads are relatively static. Of course this stuff has only been around for about 20 years.

Some forum posters have indicated the premium grade was very much like 5200 in being strong and flexible - not so in my experience. While PL premium and 3M5200 are both polyurethanes they are very different formulations and have much different qualities.

For the difference in cost I would use 5200, sikaflex or something similar between the T&G and the plywood

[ssor]

PL premium urethane caulk is a horse of a different color than the adhesive. While repairing a Payson "Nymph" that I built some time ago The black PL roofing caulk and sealant was still holding perfectly where the plywood was sound.
Typically bathroom floors are cold,steam rises, and the amount of water involved is not suffient to leave a damp floor. I have left red meranti plywood outside for months at a time with no signicant deterioration, but deprive it of air and the opportunity to dry out completely and it does go bad.

[Paul Maselli]

No, The deck will not be bonded to the deck beams. I stated it will be bedded with traditional boatyard bedding compound and nailed with bronze ring nails. The deck will be constructed of 1/2" T&G Cedar for the finished wood interior. Upon this I am laminating the 12mm plywood. This will be finished in Dynel.

As far as this deck being repairable and reversable it will outlast what was on the boat. I just removed that mahogony strip planked deck with my bare hands. Literally, it was all punk wood due to the iron nails used some 68 years ago and the effects of iron on oak. It should have been replaced 25 years ago. But it's in my hands now because the boat was neglected for the last 20 years.

Bob, It certainly is reversable. What repair Can be glued over down the road. Any adhesive left at that point will be removed and replaced with the new construction.

The Titebond III is not Ehlmers Glue. Ehlmers is a Cross-linking polyvinyl acetate, these have very low bond strength and are water soluble.. Titebond III is an Advanced Polymer designed for full exposure and exterior applications. It has a 4000 psi shear strength and fully water proof for above the waterline. Decks are usually above the water line. If not the glue is not your biggest problem. I will go thoroughly test this glue as well.

But epoxy is not the adhesive of choice when working with white oak. The Gorilla Glue does bond well. It may be the better choice. It is not inexpensive though. In comparison it is nearly the cost of epoxy.

Thanks again, These discussions are what makes the WBF uniquely intellectual.

BONDO has no place on a boat. Period. Even on a frozen snot chlorox bottle. There are better polyester fillers. But that's not what this is about!

[Bob Smalser]

Epoxies can be glued over easily. Urea resins can be glued over easily. Polyurethanes appear to glue over easily....etc, et al.

Titebond III is brand spanking new and is not a polyurethane...merely a higher-speed "crosslinked polymer" PVA with a lot of hype attached. They wouldn't label it "Titebond" if it wasn't an extension of the other Titebond aliphatic glue they sell.

Heck...polyurethanes haven't stood the test of time to risk in any important structure in a boat, let alone Titebond III.

You asked for an opinion....and you got it from somebody with a bit of experience fixing other people's messes: Not using proven marine adhesives is a needless invite to a potential horror story...Bondo was hyped as the cat's meow for plywood builders 20 years ago (and still is in some circles), but we've learned a thing or two since them...and all for what? A hundred bucks saved in a 5 grand project? 5 minutes per mixing bowl of glue?

I simply don't understand.

[ 03-04-2005, 10:22 PM: Message edited by: Bob Smalser ]

[Paul Maselli]

Well you know what they say about opinions. Yes I did ask for them and I do appreciate the range of knowledge that they bring to the table.

I too am a proffesional in this trade. I too fix other peoples messes.

I started this thread to discuss adhesives like PL construction mastics. This has turned towards the use of non traditional adhesives and there irreversability. If you read the content of my original post I am considering "LAMINATING" the oak deck beams with TITEBOND III. This is an application that the reversability of which really doesn't come into play. First off we know Epoxy does NOT work well with Oak. I have a Snipe Tiller that was laminated with epoxy and each course is seperating at the glue line creeping inward.

What don't you understand Bob, the intellegent discussion of options available to us inthis day of chemestry?

OTOH, tell me where you can buy polysulfide or polyurethane caulk in economical qtys larger than the 10 oz caulk tube? You're paying more for the packaging than the contents. That is not a wise use of funds.

Resourcenol would most likey be the best grade adhesive. The problem with this is that it requires very high clamping forces and a very well controlled temperature range to have consistant results. In addtion to this these deck beams will be bright and dark purple glue lines aren't attractive.

Initial tests of the TiteBond III show good adhesion to oak. These are being weathered and will be steamed as well. Both conditions far more extreme than the atmosphere that a dry deck beam lives in under a dynel deck. In addition to these beams being glued they are being nailed with bronze ring nails. Glue line failure seams unlikely. Reversability is not applicable. If these beams need work 40 years down the road the entire deck will probably be replaced. Even if htis turns out to be 25 years, that is a pretty darn good return on the initial investment.

[Bob Smalser]

I don't understand why for 10 minutes or two dollars more, any builder...professional or amateur....won't use products that have been proven for decades in marine use and insist on experimenting instead.

"Irreversibility" in my mind includes having to tear off that new deck to get at a failed beam.

[ssor]

Gonna drive bronze ringshank 2" long nails into seasoned white oak? Okaaaaay

[Elco's]

ssor :D

[Paul Maselli]

SSOR, Would you drive anything into oak without a pilot hole? :rolleyes: Ring nails or screws, each will need to be predrilled. Each will need to be c/bored. I've placed over $6,000.00 in bronze fasteners into the hull ato this point. Bronze ring nails are over a 50% savings compared to screws. My Boat, My Budget, My dollars well spent. Anyone who doesn't consider their budget and materials is not doing any project small or large ( Elliot White is a large project) any justice.

[ssor]

If you're going to drill pilot holes then driving nails seems a bit "penny wise and pound foolish". The first time you have a need to pull one of those nails you will wish it had a slot in the head. The best of us bend a nail once in a while and pulling ring shank nails is not a picnic. Also fastening 1/2" cedar to oak, do you need 1 1/2" of nail in the oak?
Actually, I suppose that you really only wanted approval of your plan to use construction adhesive for lamenating the plywood to the cedar. You never did ask about the use of nails to fasten the deck. I'm sorry that I brought it up.

[Roger Cumming]

I am with Smalser on this one. Experimenting on a project as major as deck replacement seems ill advised. The boat will be left out in the rain. Use a waterproof glue with a record of success in boatbuilding. Bulletproof decks are like leakproof boats. I've read about them but never seen one.