Refer Insulation

[Terra Nova]

Don't forget your garbage bags.

[crazyoldboatguy]

The vapor barrier is of minimal value if you have sufficient insulation. Properly sealing on the inside prevents moisture from penetrating the insulation from that direction. Proper insulation (4" for fridge, 6" for freezer using closed cell foam pink board) prevents the condensate from permeating the insulation from the outside. A vapor barrier on the outside may be of some use but it is unlikely to prevent saturation, long term, if your insulation is inadequate.

The polyiso is very interesting given the relatively low cost compared to the aerogels and VIPs. 5" insulation w/polyiso compared to 6" pink board is a significant size difference especially when you consider the cost differential with the aerogel or VIP.

[crazyoldboatguy]

Plastic garbage bags are quite impermeable to moisture and have quite the longevity while lying in a landfill or haven't you been paying attention to Earth Day?

[model 10]

Originally Posted by crazyoldboatguy

Plastic garbage bags are quite impermeable to moisture and have quite the longevity while lying in a landfill or haven't you been paying attention to Earth Day?

Trash compactor bags are much much better than garbage bags.

[crazyoldboatguy]

Any plastic with higher mils would be suitable, Thicker would help protect against vibration induced abrasion.

[Marpessa]

Hi folks,

I'm in the middle of this very same project right now (as I write this sitting on a bucket in the insulation isle of Home Depot).

I purchased sheets of the R-max because of the cost/r-value ratio. I have the 2" double layered on the flat walls and many many layers of the 1/2" on the radius. I'm now thinking of adding more now that I've read 6" for a freezer.

What about painting the panels as I jigsaw the puzzle together? Would you use spray rustoleum for this purpose? One friend recommended epoxy paint. Sounds expensive. He said eventually the foil sides break down too and you have to seal the foam on all surfaces, i.e. paint them. I feel I will be forced to use spray foam in some of the seams between jig saw pieces. I have staggered the seams between layers, but there still are gaps 1/16" or better in places where panels butt together. I know it takes on H2O but I have no choice.


He also said the Pinkboard will eventually take on water too, so don't be fooled. Time conquers all I guess...

Finally, there are rolls of Reflectix bubble-wrap silver stuff, looks like the real deal. Easy to fit down the hole and adhere, has a good r-value, but seems to handle heat and cold differently - like the label has a winter and summer r-value that depends on what type of heat radiation we are defending against (and in our case we want cold insulation anyway)...

Has anyone an opinion on these ideas?

Btw, my guy also recommended the same shopping list verbatim as SV. He's in the biz. Says if you can get it sealed, the foam will work for years.

So, to recap:

1) rustoleum paint or 2 part epoxy?
2) Reflectix?


Thanks all! I'll try to attach some pics now.





Sent from my iPod touch using Cruisers Sailing Forum

[Terra Nova]

Those air gaps will be a killer.

Should have a vapor barrier surrounding the whole thing.

[Marpessa]

I plan to fill the gaps with spray foam and build an inside layer of frp and I'll join it with west systems and fiberglass mesh.


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[Terra Nova]

Still, you will lack the important vapor barrier. And you will find that the spray foam will not travel to the bottom of your gaps. Better to seal the gaps as you go when installing the mating piece.

[SV THIRD DAY]

That's a good start.
Now, get a roll of foil tape and seal up all of those cut edges!
Also anywhere you nicked the foil over the RMax, slap on a piece of the foil tape to seal that up.

Paint....forget about it as it brings nothing to the table.

Epoxy paint, well lots of work for what?
The foil layer will work fine as long as you just vapor seal in the Rmax panels. On the top just use some fiberglass wall board, and cut to fit and then caulk the corners. On the inside...what was there before? If it was a fiberglass lined box, then you are done, you already have a vapor barrier. But if it open to air flow, then seal that up and you will be good.

[Terra Nova]

Originally Posted by SV THIRD DAY

...If it was a fiberglass lined box, then you are done, you already have a vapor barrier...

Fiberglass (polyester) is not a vapor barrier.

[SV THIRD DAY]

Originally Posted by Terra Nova

Fiberglass (polyester) is not a vapor barrier.

If you have the classic fiberglass/Gelcoat box that most boats have and are simply adding insulation to the inside of it my friend..that is as good a vapor barrier as you can get...it is a bathtub. How much vapor is flowing in/out of your fiberglass reefer icebox? Nada....except for the crappy seal and drain hole that needs be be plugged up.

[Terra Nova]

Originally Posted by SV THIRD DAY

If you have the classic fiberglass/Gelcoat box that most boats have and are simply adding insulation to the inside of it my friend..that is as good a vapor barrier as you can get...

Not so, unless you coat it in epoxy.

[SV THIRD DAY]

Originally Posted by Terra Nova

Not so, unless you coat it in epoxy.

Ha ha ha....funny indeed, but you have these guys in every techy thread that can't see the forest for the trees.

To say that the Figerglass Ice box liners on 99% of boats will not serve as a good vapor barrier is flat out crazy. It can be filled with water like a bathtub...but now we are told it will let air and moisture through? No...this is where practical real world experience trumps the "polyester isn't a vapor barrier" wikapedia smarts in my opinion. But what does 47yrs of refrigeration experience mean anyway....heck...we have just built and helped rebuild thousands of boxes...but na....rip it all out and spend the Big money, that's the only "right way"...

You can rip up your own box if it won't be a good enough vapor barrier for you...no problem. But counseling others with such info is just crazy. But that's the great thing about the internet, you get crazy Monday-Friday, the fun part is sorting through it with logic and common sense.

[Terra Nova]

As a professional, you might want to get your facts straight regarding vapor barriers. Polyester resin does not a vapor barrier make. That your liner can hold water is immaterial.