Rockwool Wicking Insulation

[LarkCayeRes]

I would like to insulate my aluminium boat, I will skin the interior of the boat with Aluminium. Except for the bilge, I have a nearly impermeable
barrier for moisture. I would to use a non-flammable insulation, like rock-wool. (All other foams, and rubber foam do burn very nicely with a little heat) The problem is humidity / condensation.

I have been considering a "new" concept (not mine) of using a wicking material to suck the humidity/condensation out of the insulation, to a dry area to be evaporated. It is being used successfully to insulate cold pipes, and seems like the concept could be applied to boats. Any opinions/ideas?

http://docserver.nrca.net/pdfs/technical/339.pdf

http://www.insulation.or...article.cfm?id=IO040802

http://www.pharmaceutica...cts-Cold-Pipes-From-0002

[GordMay]

Greetings and welcome aboard the CF, LarkCayeRes.

[DougM]

Can you tell us what you are trying to insulate against: a hot outdoor environment (ie you're in the tropics) or a cold outdoor environment (northern climate)?

[LarkCayeRes]

Sadly I would like to insulate against both. If I could only pick one, I would insulate against the Heat. Ie hot humid summer.

[DougM]

A little on moisture transport (i like to talk about it but can never find anyone to listen )

The principle to follow when insulating is to use a warm side vapour barrier, and avoid cold side vapour barriers.

If insulating against tropical heat, all is well. The aluminum hull is the warm side, and for practical purposes, it is a perfect vapour barrier. You can use any insulation, include those that allow moisture wicking (diffusion) like rockwool, fiberglass, or celluslose. As long as you use a moisture permeable wall panel, all is well. You could have moisture introduced in your insulation, and it will simply wick/diffuse through your insulation and wallboard into your cooler interior.

If you use this system in a cold climate, you'll get a serious problem, of course, because moisture will diffuse from the warmer, higher-humidity interior to the cooler hull. If the wall is cold enough to be below the dew point of the air in the interior, condensation will occur. This moisture cannot go farther because the hull is a perfect vapour barrier, and you've got a 'condensation trap', where moisture will continue to build up until the temperature and humidity conditions change. The result is moisture problems (mold, wet insulation, corrosion etc).

You can alleviate this condition by adding a warm side vapour barrier to slow down the rate of inbound moisture diffusion. But in the boat situation you'll still end up with moisture because none of it can get out through your perfect vapour barrier (metal hull).

If you wanted to wick it away, you'd need a path which would have be be laterally along the inside of the hull (because you don't want to make holes to let it out obviously). And you'd need low humidity (typically cold) area at the end of that path. I'm sure someone could figure out how to build something, but i can't see anything that would be easy.

Probably it would be much easier to use an insulation with very low moisture permeability, like a spray-on closed cell foam. But check its specs to make sure it is closed cell and low permeability - typical foam that you get at a hardware store in a spray can is open cell and would be no better than fiber insulations.

[LarkCayeRes]

I was thinking that a separate wicking layer could be added to each side of the rockwool. I am assuming the wicking layer is better at transporting water than the insulation. This wicking material could then be dryed, either passively or actively. From the roxul "advertisements" rockwool looks like it would be a poor wick. I assume we are talking about a minor amount of water, if it is removed continuously. I`m just not sure where to run the wick, and how to do the drying. Or how much water there could be. Or if this is all overkill. From what I have read Fiberglass matt like used to make boats is a good wick.

[LarkCayeRes]

I would prefer not using foam, if it can be done without creating a wet mess.

[familycruisers]

Bubble wrap applied properly can give up to r-8. thats what i plan to use.

[LarkCayeRes]

Any details on that bubble wrap? Thats equal to about an inch and a half or more of good foam. How much bubble wrap are you using?

[familycruisers]

If you apply strips, then apply a full layer, making a sealed air gap, and they say you go from r6 to r8. (claimed)

[familycruisers]

Reflective Bubble Reflective Insulation : Foil Bubble Foil Insulation

something like this

[LarkCayeRes]

I don't mean to be difficult, but i would really look into the bubble stuff. Even with air gap. It looks way too good to be true.

http://www.healthyheatin.../Page_55_o_bldg_sys.htm

[familycruisers]

I use it in the hvac trade. The cheap stuff at lowes works. I use stuff i get at Lyon & Conklin and that's what ill be using on the boat. I think it will make a great insulated/vapor barrier. I'll post my tesults, but they make take awhile to become tested.

[familycruisers]

That site I randomly Googled is claiming higher still. I'm just quoting what we see performance wise when used the insulate duct.

[familycruisers]

I took some time and reread the article you posted. I would have to agree with all the findings about using it as a radiant barrier under concrete. The air gap is critical, using it under concrete, vapor barrier, yes, radiant barrier, no. i dont see how they get the claimed r15. I would say r6 would be close to accurate from the material ive used. Plus for $100 bucks it'll make the quarter berths nice and cushy for my little girls.