Caulking a teak deck

LostinFrance

LostinFrance

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Can anyone tell me if it is necesary to use the bond breaking tape between slats? The 6mm (square edge, not rebated) strips have been laid using epoxy. The problem fro me is that my suppliers don't sell the stuff (ok I can get around that) but there is loads of squeezed out epoxy left in the bottom of the groove, so to get the tape flat is going to be a nightmare. I know it's necessary if you're using rebated strips, but will the Sika caulking really stick to the epoxy enough to cause a problem? I seem to get conflicting replies, even from the professionals.
 
Sikaflex can't flex in two dimensions at the same time without failing.

So, if it is certain to be as rigid as a tiled floor on a concrete floor-slab then you should be OK.

If not, then it will fail, somewhere.

I really can't see how you got this far without considering the ramifications of your actions.

Your name isn't Tony Blair by any chance?

Steve cronin
 
As said in a slightly different way above, if the sika can't lift off the bottom of the groove, it can't stretch so much laterally as the planks expand and contract with heat, or with wet & dry. So, in time, bits will detach from the sides of the groove.

I found that scraping the old sealant neatly off the sides of the groove a far more time consuming activity than digging the poxy out from the bottom! I made a tool for the poxy, bending the tang of an old file through 120 degrees, grinding its tip to the right width chisel, then pulling this 'plough' through the groove. Worked well . . .
 
Real worry is whether water is going to find its way below. If there's a continguous bed of epoxy sealant over the whole deck (sounds like there might be if the teak strips have been bedded on/in epoxy) then any caulking is merely cosmetic. In which case, so what if a inch or two comes detached at some point in the future?

If that's the your situation than *uggering around with bond breaker is just wasted lifetime.
 
Thanks for the input, I have almost completed a 34' Van de Stadt and laid the teak deck all on me todd. I managed to get thus far so Tony Blair aint got nuthin on me /forums/images/graemlins/grin.gif All I wanted to know was if Sikaflex caulking sticks better to epoxy than it does to teak. Perhaps some advice on how to lay teak decking without getting epoxy squeeze out would be useful for the next one. In fact the teak is laid on a ply deck which has had two coats of epoxy plus the glue layer, but even so I don't want water trapped underneath. So it looks like its "get the router out" time. /forums/images/graemlins/frown.gif
 
I'd suggest you take care not to rout through the epoxy deck paint, otherwise you'll compromise the watertightness of the ply substrate. Either that, or you re-epoxy, post-routing, pre-caulking.

Having suffered from deck leaks with my old teak deck, they're not something I'd wish on anyone.
 
[ QUOTE ]
If there's a continguous bed of epoxy sealant over the whole deck (sounds like there might be if the teak strips have been bedded on/in epoxy) then any caulking is merely cosmetic. In which case, so what if a inch or two comes detached at some point in the future?


[/ QUOTE ] Not quite. The problem is winter freezing - a little water working its way down the crack freezes, opens the hole, then works its way under the teak plank, loosens off the plank . . .

I guess about six or seven of the deck planks on my boat had to be re-bedded when I bought it. Almost certainly loosened by that type of leakage. The caulking did not have a bond break under, and most of it had lifted off one or the other side of the teak leaving slots for the water to work into.

Poxy over ply sounds like another matter though - get the router out to ensure there's sufficient depth for the Sika to adhere to the planks?
 
[ QUOTE ]


I guess about six or seven of the deck planks on my boat had to be re-bedded when I bought it. Almost certainly loosened by that type of leakage. The caulking did not have a bond break under, and most of it had lifted off one or the other side of the teak leaving slots for the water to work into.


[/ QUOTE ]

That's interesting to hear, it may also be of course that the teak did not have the correct primer for the mastic applied.

6mm (5 after sanding) is plenty of depth for mastic. If the teak was thinner - 4mm or less - the epoxy will overcome the teaks ability to flex and therefore bond breaker tape is not necessary.

I only posted the question here because I have seen so many different opinions and I have seen sika (not their deck caulking admittedly) not bond very well to epoxy.
 
[ QUOTE ]
That's interesting to hear, it may also be of course that the teak did not have the correct primer for the mastic applied.

6mm (5 after sanding) is plenty of depth for mastic.

[/ QUOTE ] Teak was 7mm to 9mm thick, laid 10 years earlier. Depth to the epoxy was variable, never less than 5mm. Bonding to both the epoxy and the wood was fierce, excepting in some parts where the epoxy was a little soft - poorly cured? I say bonding was fierce, since where the sealant had parted from the wood, it was usually surfaced with a veneer of teak! And almost all the sealant had to be chiselled out, cm by cm. Ugh, what a job. [ QUOTE ]
If the teak was thinner - 4mm or less - the epoxy will overcome the teaks ability to flex and therefore bond breaker tape is not necessary.


[/ QUOTE ] Good point. I didn't think of that.
 
Can I answer that?

Because you are sealing in a soft non-durable substrate which once wet will never dry out and therefore rot, under a multi-strip framework tenuously held together by a mastic compound who's integrity cannot be totally relied upon and all this in a hostile marine environment subject to severe temperature and humidity changes not to mention, stretching, twisting and shock deformation.

Then we have the holes: who needs a lot of holes through their previously competent GRP deck?

Steve cronin
 
Holes

With a totally flat deck maybe and lots of bags of sand to hold it down until the glue is cured but with the twist on most modern boats' decks I wouldn't put any faith in just epoxy & anyway, the (part) encapsulated rot zone makes it a no-no for me plus the uncertainty of getting absolutely every square inch of the ply and every square inch of the strips to be bonded down. Otherwise, you get voids and what do voids mean?
Voids means water ingress.

Water ingress means rot.

Then there are the edges. How do you seal them especially when any sort of moulded-in gunwale will hold water against the edge of the ply.


Steve Cronin
 
Re: Holes

The glue (something from Sika, dunno what) is squeegeed over the deck before the strip goes down. The strip is then laid and clamped into the curve using cramps running from the toeail and temporary screws driven in the 'seam' and fitted with packing pieces. The strip is weighted with anything the yard can get onto it including assorted bits of ironmongery, sand bags and water bags. Because the gunk goes onto the deck (and, incidentally fills the old and previous planks temp screwholes) there are no voids under the gunk, although just conceivably, there may be some between the plank and the gunk.

As practiced by Yarmouth Marine Services on my boat.
 
Re: Can I answer that?

[ QUOTE ]
Because you are sealing in a soft non-durable substrate which once wet will never dry out and therefore rot, under a multi-strip framework tenuously held together by a mastic compound who's integrity cannot be totally relied upon and all this in a hostile marine environment subject to severe temperature and humidity changes not to mention, stretching, twisting and shock deformation.

Then we have the holes: who needs a lot of holes through their previously competent GRP deck?

Steve cronin

[/ QUOTE ]

Steve I think you are responding to my question to mirelles attempt at wit. So let me put you and mirelle right on a little point.
I have built this boat almost single handedly from red cedar laminated strips with epoxy soaked glassfibre each side. Apart from the deck which is made from marine grade structural hardwood ply over yellow pine deckbeams. The ply ( as I have already mentioned) has had 2 heavy coats of epoxy resin each side and a further coat of epoxy glue to bed in the teak strips. This is, in fact, industry standard practice. The plywood is as waterproof as the proverbial ducks bum. The teak is bedded down well enough for me to be happy. Do you really think that I am going to take a bodgers short cut after all that?? Soft non durable substrate is total bollocks, but then you didn't know; but if you and muriel didn't know why do you pretend to? YOU may not know much about working with wood, but it is my profession and although I may be an amateur boatbuilder I reckon I can cut the ice with most people on this forum. I was only unsure about sika's ability to stick to epoxy, I didn't need sarky comments from prats that know less than me.

The teak is NOT a multi strip framework tenuously held by a mastic compound, it is a practical non slip and decorative FINISH to my deck. Firstly it is bonded with epoxy not mastic, and why the hell do you call it a framework???? explain that one for me please.

Stretching twisting and shock. Lets move on to that eh? Plywood? what does it do real good? well, it twists, and you can hit it real hard with a hammer and the hammer doesn't damge it. Stretching? hmm, well I must admit I have never stretched a bit, but if you curve it, the outside layers stretch and the inside layers compress. Eh voila! looks like it passes that test too.
Shall we move onto teak? Surely I don't have to.

GRP? I have no GRP on my boat in the sense you mean.

Steve, if I have maligned you mistakenly I apologise, but I am reacting to perceived sarcasm, which I find quite prevalent in this forum.

Oh and a note to Twister Ken, you MIGHT get by with weights, but I wouldn't dare. I couldn't anyway with my hull, too much curve. Screws, then pellets to fill the holes are the answer. Even with a straight plank you would need lots of weights.

Well, I await to be flamed.
 
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