Glassing over teak deck. Bad idea?

I need to address the fact that my teak deck is leaking and in bad shape. I always thought I would remove all the teak and put a few layers of glass to add some stifness after sealing all the holes left from the screws.

But how about simply glassing over the teak? I have the feeling it's not the best way to do this project but I was curious to see if anybody had done it that way.

Greetings,
Mr. F. I have a friend who did that on his Island Gypsy. Cured the leaking problem. I haven't spoken to him in some time so I don't know of the long term effects.

According to the folks on the GB owners forum when this topic comes up, it is a VERY bad idea. The wood and seams will continue to "work" underneath the glass and the glass will start to separate from the wood, the glass will eventually then start to crack, and eventually moisture will start working down onto and then under the wood.

There are some folks who say glassing over a teak deck can be done safely. But I choose to believe the people who have had a ton of experience with this sort of thing, some on a professional basis as yard owners and shipwrights and who say that the only way to do the job properly for the maximum longevity is to remove the wood and then do the right job of prepping the subdeck, adding a couple of layers of glass, and then painting/non-skid.

Teak decks can also be brought up to snuff if enough wood remains to do this. The seams can be re-cut and re-sealed and the screws re-seated and re-plugged. We had this done to our 1973 deck some 15 years ago.

It''s time to redo many of the seams again and now there is a much better sealant on the market than was available when the work was done all those years ago. It's not rocket science to redo or repair seams, screws, and plugs but it does take time and the deck has to be dry when the work is done.

From a personal view when looking for a boat we found a nice GB that checked out OK at survey apart from the teak decks were glassed over the surveyors own words were it doesn't matter how well the glassing was done it has destroyed a good boat and will cost 3x more to rectifier its devalued the boat by 25% He added offer him less 40% this was a $170000 boat

The boat is still for sale 2 1/2 years on at 30% less

HOT roofing tar with a sprinkle of sand is the budget "cure".

Pull it up . plug all the screw holes , replace any rotten ply and Epoxy some GRP in place.

You'd be far better off coating it with something like Durabak. Glassing over would be a mess over the long term.

Durabak Truck Bed Liner Paint, Roll On Truck Bed Liner

You can do it, but don't apply the glass directly to the teak. The approach to take is to start by putting down a layer of 4-5mm marine plywood and then glassing over that. My cabin house top was done that way. The bottom layer is 5/8" fir t&g beadboard. I then epoxied down two layers of 5 mm marine plywood and finally put a layer of 10 oz glass over the top of it.

The plywood layer will give you a stable surface to work on.

Now the down side. If your deck is leaking and cored, the core is certainly wet. Glassing over the deck even with a layer of plywood between the teak and glass leaves the wet core in place. Furthermore, leaving the teak on the deck and glassing over it adds weight where you don't need it.

The best approach is to remove the teak, open up the deck and replace any wet core and then glass the deck. If you do that you don't need the layer of plywood. A well done job won't detract from the value of the boat.

Try "Top Secret coatings". I have used this over teak and it is GREAT. It is a 1 part flexible epoxy. You put down a primer, then paint ( with color chips if you want), Then clear coat.

Capt.Bill11 said:

You'd be far better off coating it with something like Durabak. Glassing over would be a mess over the long term.

Durabak Truck Bed Liner Paint, Roll On Truck Bed Liner

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I saw a teak deck that had been overlaid with Durabak. The owner swore it stopped all the leaks. You could see the teak planking where it had telegraphed through the Durabak though.

I replaced my teak deck. It was leaking bad and the teak actually had cracks in it that added to the leaking. My subdeck was rotted on places too. I've also seen a glass boat that had the teak removed and glassed over. That boat was two slips from me and I watched that project from start to finish.

Glass boats present different problems to fix and a cored glass boat the most problems. I've watched a cored boat repair as well.

If it were mine, I'd most certainly remove the teak first. That is a must do for several reasons but the main one is polyester resins won't stick to teak for very long. It will soon crack and delaminate. Once the teak is removed a good inspection will tell your next steps. One good way to dry out wet glass is to put denatured alcohol on it and that draws water out as it evaporates.

Good luck. I tried rubber sealing products, all kinds of sealers, even waterproof deck sealers. Nothing works. It's only a band aid.

Greetings,
Mr. Cappie. Welcome aboard.

RT Firefly said:

Greetings,
Mr. Cappie. Welcome aboard.

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You must have a big boat RT.

With worldwide 1000th of owners of 70th and 80th build boats now facing the known problems with their teak decks, the internet would be overflowed if a "wonder" cure existed.

So go the old fashioned way by removing.....

I would also recommend removing the teak.
As an additional note, I have seen only 2 boats where the owners had used "Durabek" or equivalent coatings over the teak.
In my opinion it looked like crap in both cases.

In my opinion it looked like crap in both cases. __________________

Wait till ,you see roofing tar and sand!!

Glassing over teak deck. Bad idea?

YES

FF suggested a method a few years ago that I like the sounds of. Rip off the old teak, clean up the exposed fiberglass surface, lay down some of those hi-tech foam boards and glass over that.

Strong, light and watertight. True, it doesn't address the underlying wet core issues. But it sure sounds like a reasonable middle ground between a truck bed liner coating over the teak and taking everything apart and replacing the core.

If, a big if, I ever decide to address the deck, this is probably the course I'll take.

Well, looks like I'll put that idea to bed. Lol
I pretty much figured out it wasn't the best idea in the world but I wanted to have the rationale behind it. Makes a lot of sense.

However, by looking more carefully at my foredeck (which doesn't have teck) I realized that the PO laid down 3/4 ply over the teck and glassed over that. It feels very solid and stable (no cracks or any signs of delamination). I'll leave it like that and simply address the rest of the deck that needs attention.

Thanks for all your input.

A friend of mine just removed the teak from the cockpit and gunnells of his 63 ft Bertram sporty. It was a typicall laid teak deck, 3/4 inch planking. Had I been available I would have removed it just for the teak !!. What he found was that the decking added quite a bit to the structure of the deck, after removal it was a little "springy". the solution was to 'glass in a 3/4 inch thick layer of Coosa board (I think thats what it was) then a layer of 'glass on that. He's not done yet but it looks good and is just as stiff as original.

I realized that the PO laid down 3/4 ply over the teck and glassed over that

Did your surveyor warn you?

FF said:

I realized that the PO laid down 3/4 ply over the teck and glassed over that

Did your surveyor warn you?

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You're a funny man!

kulas44 said:

What he found was that the decking added quite a bit to the structure of the deck, after removal it was a little "springy".

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Yes, the teak planking adds a fair amount of stiffness. The typical practice when replacing a teak plank surface with fiberglass is to remove the teak, prep the top of the subdeck, then add two (or more if desired) layers of fiberglass on top of the subdeck and then put the non-skid surface on top of the final layer of fiberglass. The layers of fiberglass restore the stiffness that was lost when the teak planking was removed.

An acquaintance did this to his Island Gypsy. While two layers of glass on top of the exposed subdeck would most likely have been sufficient, he elected to add four layers. He did a beautiful job with his deck, probably better than the manufacturer would have done, and the result is a deck that is strong and stiff enough to land a plane on.

Surely there is an immediate problem with different levels of adhesion to teak and caulk of anything put over a deck.

One or two layers of glass will do little or nothing to restore the rigidity to a deck that has had teak removed from it. Glass just doesn't have that kind of structural rigidity to it. Especially in thin layers.

Capt.Bill11 said:

One or two layers of glass will do little or nothing to restore the rigidity to a deck that has had teak removed from it. .

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Yes it apparently does. This is the standard recommendation from the folks who know what they're talking about on the GB owners forum, and it was the recommendation to the fellow with the Island Gypsy I mentioned from the fellow who was advising him on the project, the former chief engineer of Uniflite. The four layers of glass that the IG owner put on was way overkill according to his advisor but it certainly didn't hurt anyting other than add unnecesary weight.

But two layers of glass is the typical recommendation. By which I mean put on one layer with resin and let it cure, then put on the next layer. Not just two layers of fabric and then resin. Also, I don't know what weight of glass fabric is recommended for this. So it may be pretty heavy stuff, I don't know.

Maybe being a bit more specific when saying two layers would be helpful. There is 6oz, 10oz, chop strand mat, biaxial 1708, woven roving and more. All have different strengths and absorb resin differently. Personally, I would use layers of 1708 and polyester resin.

What do you all think about assuming most of the core is wet, use a circular saw to cut at the outside edges of the core, lifting the teak and top layer of glass at once. This saves lots of labor. Remove/replace the core and glass over with 3-4 layers of 1708? Thoughts?

Greatlaker221 said:

Maybe being a bit more specific when saying two layers would be helpful. There is 6oz, 10oz, chop strand mat, biaxial 1708, woven roving and more. All have different strengths and absorb resin differently. Personally, I would use layers of 1708 and polyester resin.

What do you all think about assuming most of the core is wet, use a circular saw to cut at the outside edges of the core, lifting the teak and top layer of glass at once. This saves lots of labor. Remove/replace the core and glass over with 3-4 layers of 1708? Thoughts?

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Depends on core. In my case it was end grain balsa, well stuck to both top and bottom GRP skins. It had to be chiseled out. Although where damp it came out easier and where rotten it could be scooped out! Other core, ranging from plywood to offcuts of timber might be quite different to remove.

Remove the teak as a first step, then use a drill to test for wet core - just work your way outwards from known soft spots until the drill cuttings are dry. With a map of how much core has to be replaced you can then plan accordingly. I replaced all my foredeck core, about 92 sq ft. and nearly all of it was wet or rotten. But on the boat deck, the drill holes mapped out problem areas and I probably only did 25-30% of the total area as the rest was dry core.

I know I need to do some of my side decks, just haven't worked up enough enthusiasm yet. In part because I don't think the screws will come out easy enough for the teak to be able to be re-used. And I really like my teak side decks. Steps are straightforward: remove teak, map out wet/damp core, cut off top GRP layer and then remove the core. The fun starts as soon as the teak is lifted - the bedding compound is sticky and gets everywhere....

Greatlaker221 said:

What do you all think about assuming most of the core is wet, use a circular saw to cut at the outside edges of the core, lifting the teak and top layer of glass at once. This saves lots of labor. Remove/replace the core and glass over with 3-4 layers of 1708? Thoughts?

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I think that is certainly worth a try. Worst case you still need to chisel out the core or attaching screws.
I would replace the core with exterior plywood, then glass over it. Use mat as the first layer as it will stick to the plywood better. Then use roving or the biaxial stuff, followed by mat to make a nice surface. Then vinylester gelcoat tinting it to the color of your choice and add nonskid. It will roll right on and look great.

"But two layers of glass is the typical recommendation. By which I mean put on one layer with resin and let it cure, then put on the next layer."

BEWARE , any Polly resin that cures hard will have wax in it to achieve the cure.

This has to be sanded before the next coat/ layer of GRP is installed.

Resin is heavy with little strength , so laminating with NON wax resin will allow the most glass with just enough resin.When the first layer has gelled , the next can be laid up , that's how most hulls are built.

Then a layer of waxed resin can be laid on to cure , or just wait long enough with the sunshine to help cure it in a couple of days.

Epoxy would be first choice as repair resin, it will actually stick to wood or old GRP much better.

Epoxy works best too when it is not asked to stick to hardened epoxy .
Sanding to the glass works , but layer on layer after it begins to set is stronger and required no interlaminate sanding.

Epoxy will need a good scrub with strong soap after its hardened to remove the hardener.

Removed the teak from my back deck and then put two layers of biaxial cloth and polyester (fiberglass) resin down. The deck was a little too flexible before adding the fiberglass. The reason the two layers made such a difference is that the deck is not that large and it has a continuous curve from side to side and front to back. Had it been a flat surface, the 2 layers wouldn't have made as much of a difference.

Removing the teak

Ted