Waterproofing plywood under carpet

bcollier9253

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Aug 24, 2013
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I'm getting close to being done with my stringer replacement, installing deck now. I resin coated the underneath side (poly), spread peanut butter on top of the stringers and bulkheads, layed plywood. I am using 2 layers of 1.5oz csm with poly resin. This deck will have carpet and I am wanting to give an extra ounce of prevention in waterproofing the deck. Will the glass and poly be good enough or should I coat it with some sort of roll on product?
 

Woodonglass

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The Poly and CSM will be more than adequate. If you want a bit more strength then you could lay one more layer of 6oz Fabric and go up the sides about 6"
 

bcollier9253

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I was just remembering what it looked like before I started this project... Wow!!! Don't want to be in that shape again! I reckon though it will take more years than what I have left to get there lol! Thanks Wood!
 

bcollier9253

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I am gonna fillet the deck to the hull sides and tab in with 8" 1708 and run my csm up past that.
 

ondarvr

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It wasn't completely clear, but it sounded like you just coated the bottom of the plywood with resin, is that correct?

​If you didn't use glass, then it will fail rather soon, resin alone will crack and peel off, leaving the underside exposed to the water.
 

jbcurt00

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Yep ^^^ as you said you used poly resin
I resin coated the underneath side (poly),
Its likely to crack and be of little value.

As long as you intend to store the boat well cover (or in a garage) w the bow high and the plug out, Poly resin and CSM are likely to be sufficient beneath the carpet.

Stored outside, uncovered, no, probably not.

If I wanted to put glue down carpet in a fiberglass boat, and didnt plan to put gelcoat on top of the glassed in deck, I'd consider following some of the tin boat builders deck sealing methods: Epoxy the deck, after poly resin and CSM are down.

Just have to remember after epoxy no poly resin products, incl gelcoat.

And still wouldnt leave it uncovered or bow down.
 

bcollier9253

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Correct, I just put resin on the underneath side, but as of yet I have only put one sheet down. The boat does have a full road cover and is parked under a lean to when not in use other than while at the lake camping for the weekend.
 

ondarvr

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Water will find its way below the plywood no mater how you build it or store it, and there is no good way for it to escape, so it sits in there and keeps everything wet at all times.

​Two CSM on top are enough, as long as you don't leave any unsealed screw holes, one unsealed hole trumps any resin, design or attention to detail effort.
 

bcollier9253

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Kinda why I wanted to roll something over the csm before I glued the carpet down. I tried to make previsions in that I drilled and sealed limber holes in the bulkheads to allow for drainage. I think Trooper on here had the idea of making channels when he poured his foam. I did as he did on that aspect.
 

ondarvr

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Rolling something over the CSM before laying down the carpet won't do anything to help.

​Everything still gets wet down there, makes no difference how it's done, limber holes and channels are great, but they don't make it dry.
 
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