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Norm Bernstein
02-06-2005, 12:19 PM
Hi,

I'm doing a bit of planning ahead on my Ellipticat project, and am thinking about the deck. It is going to be a 'faux' teak deck, done in the style suggested by the Gougeon Bros... a subdeck of 6mm okume or AC fir marine plywood, a single layer of 10 oz. glass/epoxy on top of that, and a 1/4" top surface of teak strips, 1 3/4" wide, bonded to the sanded glass/epoxy surface with thickened epoxy. The seams will be filled with polysufide caulk.

I had the opportunity to talk with a professional boatbuilder at a wooden boat show in Portland, ME, last year, who was building an elegant (and expensive!) 22' daysailer. He did the deck in precisely the same fashion as I described above. One thing he told me was that he thickened his epoxy with a blend of fillers: one third colloidal silica, and two thirds microfibers.

I'm concerned about the strength of the bond, however. I've built a number of projects with glued teak, and have occasionally experienced failures, although not often. I'd like to absolutely insure that this project goes well, with no failures.

I was thinking that it might strengthen the bond appreciably if I built some sort of tool to add 'striations' (longitudinal grooves) to the bottom sides of the strips, thereby providing more surface area for the epoxy to grab.. another thing I might consider doing is to give the strip bottoms a rub-down with an acetone-soaked rag, to try to remove surface oils before I bond them. I've never done the acetone thing before, although I've seen it mentioned from time to time in boatbuilding literature.

Does anyone have any experience with doing the acetone thing? How about doing the bottom-groove thing? I was thinking that I could make a tool to do this... using a surplus table saw motor I have, and a ganged stack of small diameter saw blades, spaced by washers...

Any suggestions?

My project, by the way, is located at:

www.marisystems.com/ellipticat (http://www.marisystems.com/ellipticat)

RodB
02-06-2005, 01:53 PM
I also have been interested in this subject and I have read everything I could find... The concensus for modern epoxy laid decks seems to be keeping the teak strips thin enough so that expanson and swelling are not significant enough to cause bonding problems and graphite mixed in the epoxy is the adhesive of choice. Also, most writeups mention using acetone as a solvent wash on the teak surface to be glued down....also use a small torch to get rid of any remaining solvent before bonding.

See "Epoxy Works" (on the Gougeon stie) and you will find a great article where two guys laid a teak deck on a 40 foot sailboat....quite a job...

I also checked with the Gougeon Brothers tech dept recently to see if they were recommending any changes to the standard procedure in the aforementioned article. They said no...

Hope this helps.

RB

[ 02-06-2005, 01:56 PM: Message edited by: RodB ]

Norm Bernstein
02-06-2005, 02:17 PM
I think the point of the graphite in the epoxy was as a substitute for polysufide caulking of the seams. A number of forum participants have already suggested that this isn't a great idea, because the black sanding dust gets into the surface pores of the teak and is hard to remove... that's why I'm going to use polysilfide in the seams, instead.

JimD
02-06-2005, 02:21 PM
I've glued cedar strip to plywood sub deck and cabin, not quite the same, I realize, but as far as the bond is concerned, folks, I wager if you glue your strips to the plywood with epoxy thickened with just about anything except microballoons they ain't comin' off.

Paul Scheuer
02-06-2005, 02:24 PM
I would think that you could rough up the bottom of the deck strips enough to get a better mechanical connection without committing shop space to a motorized-faux-teak-deck-strip-striater.

For motivation, here's a glimps of a faux teak deck (in the background). I was focused on the castings. This is a Gozzard 44 at the boat show. The chock casting includes an integral cleat inboard.
http://www.imagestation.com/picture/sraid157/p648bb9bb8cb5939779957a71185e2058/f537f0bb.jpg

Frank Wentzel
02-06-2005, 02:27 PM
Norm

Note that the G-Bros. instructions say that you should leave the saw marks on the strips to aid in mechanical bonding. I think that would do the trick.

/// Frank ///

imported_Dutch
02-06-2005, 08:47 PM
screw em down bedded in 5200 and caulk the seams with Teak Decking Systems caulk. Ive redone the cockpits of a few sportsfishermen in that manner and havent had a failure ocur yet web page (http://www.teakdecking.com/caulking%20products.htm)

Magwitch
02-07-2005, 10:29 AM
I'm going to pretend I haven't seen this thread. My Doctor said I should avoid stress.
:(
IanW

Bruce Hooke
02-07-2005, 11:42 AM
Six years ago I helped my father redo the cockpit of his sailboat using teak strips glued down to a plywood base. So far that deck seems to be holding up just fine. Here are a couple of random thoughts:

1. We did do the acetone wipe. I don't know if it did any good but it does not seem to have done any harm. We did wait long enough to be certain the acetone had completely evaporated (15 to 30 minutes) before we started applying epoxy.

2. Our strips were pretty smooth and we did not do anything much to roughen them up. I'm not that convinced that roughing up really helps. It does not really add that much surface area and it does not seem like it creates enough of a keying effect to really matter.

3. If I remember correctly*, the Gougeon Brothers STRONGLY recommend not using teak any thicker than 1/8". Thicker teak can overpower the glue as it shrinks and expands. IMOOP the single thing you could do to most improve your chances of a successful job would be to reduce the thickness of your planks. (*I wish I could find the old Gougeon article on epoxy-teak decks to be absolutely certain that I have the right maximum thickness recommendation in my head.)

4. We used epoxy (mixed with graphite to make it black) as our filler between the planks and it worked fine for us.

5. To hold the planks down while the glue under the planks cured we used the method of round-headed screws between the planks with washers under the screw head.

Frank Wentzel
02-07-2005, 02:15 PM
Bruce

I reread the article beore I posted. They say okay to go up to 1/4" strips but better at 1/8". They also go up to 3/4" but instead of black epoxy between the strips suggest using a flexible caulk.

/// Frank ///

Bruce Hooke
02-07-2005, 02:27 PM
Frank,

Did you find the article up on the web? If so where? I looked on the Gougeon Brothers' website and I couldn't find it...

- Bruce

imported_Dutch
02-07-2005, 04:04 PM
If I remember correctly*, the Gougeon Brothers STRONGLY recommend not using teak any thicker than 1/8". another good reason not to use epoxy to bed them in. are you kidding? 1/8 of an inch? by the time you sand theseam caulk flush your deck would be paper thin. do as i suggest above and you wont be sorry. or if you dont believe me do a test with 5200 and teak ahead of time and put it through some wet dry cycles after a full cure. you wont be able to get it off and coupled with the fastners youre bombprooof.

imported_Dutch
02-07-2005, 04:08 PM
4. We used epoxy (mixed with graphite to make it black) as our filler between the planks and it worked fine for us. i saw this done by a fellow i was sharing a shop with once. he was a professional as am i. he woulnd up with a sanding nightmare. stuff was like sanding concrete, dusted up like lampblack and stuck to everything in sight. to top it off the hardness of it compared to the teak makde it impossible to wind up with a flat deck. it wound up with undulations at every seam

imported_Dutch
02-07-2005, 04:09 PM
4. We used epoxy (mixed with graphite to make it black) as our filler between the planks and it worked fine for us. i saw this done by a fellow i was sharing a shop with once. he was a professional as am i. he woulnd up with a sanding nightmare. stuff was like sanding concrete, dusted up like lampblack and stuck to everything in sight. to top it off the hardness of it compared to the teak makde it impossible to wind up with a flat deck. it wound up with undulations at every seam

Nicholas Carey
02-07-2005, 04:12 PM
You should try the adhesive sold by Teak Decking Systems (http://www.teakdecking.com/), along with their caulk. TDS has manufactured and installed more teak decks of this type than anybody else. They've been doing this for more than 20 years.

They have two main products (outside of their decks). They make some sort of very thick proprietary epoxy specifically for bonding teak, as well as a proprietary caulk for caulking teak decks. If I remember from the MSDS when we did PIRATE's decks, it is, I believe, some sort of polyurethane.

The boatwrights around here swear by the stuff.

We did PIRATE's decks with it. Our subdeck is consisted of 3 layers of VG western red cedar (unused blanks for Pocock 8-man rowing shells). The grain runs 45 degrees to the centerline of the boat and each layer is laid perpindicular to the one below it. The whole assembly was laid out flat, laid up with epoxy and bagged on a [quite large] vacuum table.

The teak strips are about the dimensions you specify (3/8 x 1-3/4) with a 1/4 x 1/4 rebate on one side. The strips were laid on the subdeck, flush to each other. The rebate provided the seam and ensured uniform spacing) and were bedded in the TDS epoxy. The strips were pre-fit and dry-laid to ensure fit and uniformity without the time pressure involving in doing a large glue-up like this:

http://www.r-boat.org/html/restoration/rest14/rest14-02.jpg

As it happened, because we wanted the deck to look original to the boat (e.g., we needed plugged screw holes) we clamped the teak strips down by countersinking and screwing them down with bronze screws, with the intention of removing the screws afterwards). Unfortunately, the screw team, err, neglected to put release agent on the screws, so our deck is glued-and-screwed. Here's the deck partially plugged:

http://www.r-boat.org/html/restoration/rest14/rest14-11.jpg

After that it was time to caulk the newly laid decks. Each teak strip was masked off, leaving only the seams exposed (done because it greatly faciliates cleanup. A little labor now versus a lot later.) Here's a picture of PIRATE's deck in a semi-caulked state, with the caulkers at work:

http://www.r-boat.org/html/restoration/rest15/rest15-08.jpg

Each caulking crew has one guy driving the gun and another close behind with a squeegee, making sure the caulk filled the seam and had no air bubbles in it. With the TDS system, you don't need—so they say—a bondbreaker between the caulk and the bottom of the seam. Time will tell.

I haven't noticed any problems with the TDS stuff bonding to the teak. And I'm not sure I'd spend the time 'grooving' the bottom of each strip to get a mechanical bond. The strips themselves are pretty much straight of the ripsaw. We acetoned the strips, but I'm not sure that really does much: some people claim that it aggravates any oil issues, since the acetone will draw fresh oil from the wood.

If I had my druthers, I'd omit the rebated for the caulking seam and clamp the strips down by fastening between strips with round- or pan-head screws with a big fender washer on top. The screws here not only clamp, but act as spacers to give you a uniform caulking seam. You also don't have the thousands of screw holes that need to be plugged.

Norm Bernstein
02-07-2005, 06:53 PM
Wow, that's quite a lot of additional information. I hadn't considered 5200 as an adhesive, as opposed to epoxy... but it might not be a bad idea. I DID consider the idea of using a notched spreader to spread the adhesive (whether it is thickened epoxy or 5200), in order to get an even thickness.

As I recall, the West System book did say that 1/4" was the maximum practical thickness, and also said that 1/8" was thick enough and durable enough to withstand years of sanding cycles.

As it turns out, I'm planning to buy the strips pre-cut to 1 3/4" x 1/4"... there's a mill in the south who advertises them at $0.67/lin ft, with a 750 lin ft minimum, just the right amount for my project. I really don't want to have to cut those strips myself, and based on a spreadsheet analysis, I wouldn't save more than a few percent if I did... so the dimensions I'm working with are fixed.

Once again, I've been warned against using graphite-filled epoxy as the faux 'caulk'... and I'm content to stick with ordinary black polysulfide. I'm sure the two part stuff sold by Teak Decking Systems is terrific, but I've done laid teak before, using polysulfide, and have always been satisfied with the results... and it's more reasonably priced.

I DO wish I could find one of those electric drill attachments for dispensing the caulk; doing it with a hand gun is pretty rough on the muscles of the hands. The only drill adaptor I've seen is kind of expensive, and I don't have any shop air, so pnuematic guns are out.

Paul Scheuer
02-07-2005, 08:13 PM
doing it with a hand gun is pretty rough on the muscles of the hands Stand By, Boys ! I just had an Idea !

I just looked at my super cheap Ace Hardware caulking gun. It's a "9 Inch, Smooth Rod" type, that plunges about 5/8 inch per squeeze. That's a lot, and a pretty tough squeeze, for most of the stuff I do. What if you improved the leverage by extending the handles and maybe add a limiter so that it takes hakf a stroke. A lot more strokes, but a lot easier on the hand. You might even get a little better control on the application rate, with a "low" gear.

JimConlin
02-07-2005, 11:13 PM
The TDS stuff is one-part and comparable in price with polysulfide. I found that it was easier to work with and sanded off more smoothly. An older job that I did with pulysulfide (3M 101) has not held up 100%.

imported_Dutch
02-07-2005, 11:46 PM
if you tape out each side of the seam and use the tds caulk filling the seam and then run a very flexible putty knife over the length of the seam pulling off the excess, it will put a nice little crown on the seam that when cured will make a nice little slightly concave area. very little if any sanding to do and it looks near perfection

imported_Dutch
02-07-2005, 11:48 PM
dont use polysulphide - give the tds caulk a try- youll never regret it

JimConlin
02-08-2005, 12:31 AM
What Dutch said

cbob
02-10-2005, 12:50 PM
Norm, I did a teak cockpit replacement, about 2.5'x 8'with with 2" x 1/2" resawn strips, no rabbit, over 1/2' fir ply. The ply was sealed with until coated thick with Smith's CPES, then each unsmoothed, pre measured, strip, fitted with fasrtening holes to line up, resawn strip was set and fastened down with Smith's Tropical Hardwood Epoxy, which squished up about 1/8'r so between the strips, which were spaced apart till fastened and the epoxy set with 1/8" Formica type old sail batten stock, pulled out before the epoxy cured. The fastenings were ss pan head (read thin heads for bunghole depth) screws, the bungs were set in the same Hardwood Epoxy. The bungs were rough clipped, and the grooves were paid with some black one part Sikaflex, which was recommended for this purpose, until a short while after it was in place, when Sika said they could no longer recommend this product for this application, as harsh teak cleaners were messing it up or some such, Put in the seam goop with the nozzle pointing at about a 45 degree angle FORWARD to watch it go in and avoid air entrapment, and tape before, I didnt and it was a real mess. After all is set the resawn roughness, the bungs and the black stuff were sanded smooth and clean. I don't use any cleaners other than salt water and a rust colored 3 M pad and this looks as good as it did when put in 20 years ago, which coulden't be said for the original 20 year old teak it replaced. The black Sikaflex still looks good and in the wetter times the teak expands and the black comes up a little proud, in dry times the opposite.
I know most of this isn't in your plans but a little food for thought might help, The pre fitting including fastenings, resawn roughness, the battens spacing, the epoxy squishing up, and the sanding afterwards ideas worked out fine, in my case. Good luck on this, cbob