CSM only for a top layer of a new deck?

[lvl]

Hey guys I got the answer for the underside of the deck I will use 3/4 oz CSM. Now would a single layer of 1 1/2 oz CSM be good for a top layer? The plywood that is there is 3/4 and that is what I will be putting back. Do I need a layer of 1708 biaxial or would the CSM be good enough? My understanding from the last question I had was all the strength comes from the plywood so I would assume 1 layer of heavier CSM would be good. We all know what happens when we assume.

What would be the best thing to do first tape the edges then mat over the whole deck or deck first then tape?

Thx

 

[Woodonglass]

Re: CSM only for a top layer of a new deck?

Are you using Poly or Epoxy. I am going to assume myself and say poly. If so then the 1 1/2 will be fine but I prefer using 6 oz cloth. I will totally disappear and give you a Much better looking and stronger surface for Less than 10 bucks more in costs.

I'm just sayin...

 

[Yacht Dr.]

Re: CSM only for a top layer of a new deck?

What finish are you looking for ?

Top glass is only dependant on your top coat .

YD.

 

[drewpster]

Re: CSM only for a top layer of a new deck?

YD please advise on this, but I remember reading somewhere that CSM is also good to help with water tightness of the top layer when using Polyester resins. Is this true as well? I'm guess the random pattern of the CSM helps hold the resin and keep it from wicking water. I use 6 oz. over a CSM layer to give a smooth surface and to help keep it water tight.

 

[erikgreen]

Re: CSM only for a top layer of a new deck?

CSM adds to waterproofing when used as a top layer, it also avoids patterning where the cloth grid shows through. It goes well as a layer right underneath gelcoat in polyester layups.

 

[ondarvr]

Re: CSM only for a top layer of a new deck?

1 layer of 1.5oz CSM would be the absolute minimum thickness for the topside, the reason is the top will take a beating and 1 layer won't take a great deal of abuse. Adding a cloth or another layer of CSM makes it far more durable. I used 1708 on one of my boats, but only because the core was a honeycomb product that needed some support, it actually made a very good nonskid finish with no additional grit needed. The fiber bundles made very uniform ridges that looked pretty good after it was gel coated with zero slip.

 

[oops!]

Re: CSM only for a top layer of a new deck?

the deck needs to be glassed for waterproofing...you you will need fiberglass on it,,,,not just resin coating....(resin coating by itself does nothing...it just gets brittle and will crack...it needs the glass)


one single layer of csm WILL work.....but IMHO....inadequate.
you will go thru that layer with heavy traffic.

my suggestion for decks (poly based) is 2 layers of csm and a 6 oz finishing cloth.

this will give you a smooth finish on the deck to either gellcoat or carpet....

you do need a minimum of 8 oz on a deck.

however....the big 1708 is overkill.....you would also need a finishing layer as the 1708 will cure with ridges on it.
so if you used a csm over the 1708....you would have 26.5 oz on your deck.....that is just added weight and not necessary.

 

[oops!]

Re: CSM only for a top layer of a new deck?

lol....jody we were typing at the same time.

 

[cajun_1]

Re: CSM only for a top layer of a new deck?

Here comes a dumb question ... what is csm ???

 

[JAFO1]

Re: CSM only for a top layer of a new deck?

Here comes a dumb question ... what is csm ???

Howdy! The only dumb question is the one not asked. CSM = Chopped Strand Mat.

 

[Yacht Dr.]

Re: CSM only for a top layer of a new deck?

YD please advise on this, but I remember reading somewhere that CSM is also good to help with water tightness of the top layer when using Polyester resins. Is this true as well? I'm guess the random pattern of the CSM helps hold the resin and keep it from wicking water. I use 6 oz. over a CSM layer to give a smooth surface and to help keep it water tight.

I was just saying that some use paint over there last coat of glass for a texture thing ( like finish cloth ).

Or if your going for a smooth finish..or griptex finish..then you would end your lam with mat. Then sand/prep and paint or gel/finish.

No .. 1 layer of 1.5 oz mat is not good enough ( and you will have a hard time wetting it out without drowning it in resin ).

YD.

 

[cajun_1]

Re: CSM only for a top layer of a new deck?

Howdy! The only dumb question is the one not asked. CSM = Chopped Strand Mat.

Thank you very much ...