What if Insulation is NOT glued?

[andrei_ca]

The main question: what if I just leave the insulation "floating" in between the fiberglass wall and the covering pannel/wood structure? Would that promote more moisture in the wall than if the foam was glued up to the wall? As far as I know, if I don't glue it, the material will seek to space a bit, creating cushions of air which increases isolation further. But if the air is humid this leads to condensation (so if I have dehumidifiers, that shouldn't be an issue?).

The interior design will be sorted out much later - tech is first. I'll probably use some horizontal wood shingles, or some planks of something to cover up the insulation foam, that will be screwed to vertical stringers (or whatever u call that), like most do it. I'll put threaded inserts in those and whatnot. I also plan to add some sort of venting along the corners so my walls could breather so moisture wouldn't get trapped. And of course, dehumidifiers to control moisture.

My choice so far is 1/2 Volara (closed cell foam, R 3.6, flexible, durable, water proof, mod reistant) costing 70c per sqft it's a long term investment. I would probably put it in two layers (I haven't found 1" volara rolls yet) in order to obtain a compunded R of 7.2. From my camping mat I know that is pretty badass for winter.

The second big question is: what if I buy a boat with a solid fiberglass lining sole? Should I take that apart? Keep it and insulate over it? Taking it apart seems more appealing frankly.

I was talking about Catalina 38 in another post, some design I like. I read somewhere that insulating over the lining sole is not the best thing. In that case an older run down model seems like a better option since I wanna do my own thing with it ( you can go ahead and suggest models too). Being able to get to the core of my boat would mean that I have quick access for repairs, just in case - I see it as a very convenient plus.

Andrei

[mike d.]

You should glue to hull, if that is your question, as this stops the condensation from forming on the inside hull surface. I don't see how a floating panel would be of much use. If you have air circulation, on both sides of the panel, that air would be able to get to the living space, no!?

[andrei_ca]

The air, you mean the cold? If yes. Not as far as I know. Having a bit of air between materials, insulates. Example: take a mitten get close to a hot iron, all ok, touch it and the temperature rises and only keeps increasing fast. Same for cold; I even remeber from wearing clothing like jeans, when it sticks to the body the cold becomes more apparent.

Here's another question: what is the R-value of the fiberglass hull+the sole? Still wondering if it's good to cover over the sole.

Andrei

[Adelie]

Originally Posted by andrei_ca

The main question: what if I just leave the insulation "floating" in between the fiberglass wall and the covering pannel/wood structure? Would that promote more moisture in the wall than if the foam was glued up to the wall? As far as I know, if I don't glue it, the material will seek to space a bit, creating cushions of air which increases isolation further. But if the air is humid this leads to condensation (so if I have dehumidifiers, that shouldn't be an issue?).

The interior design will be sorted out much later - tech is first. I'll probably use some horizontal wood shingles, or some planks of something to cover up the insulation foam, that will be screwed to vertical stringers (or whatever u call that), like most do it. I'll put threaded inserts in those and whatnot. I also plan to add some sort of venting along the corners so my walls could breather so moisture wouldn't get trapped. And of course, dehumidifiers to control moisture.

My choice so far is 1/2 Volara (closed cell foam, R 3.6, flexible, durable, water proof, mod reistant) costing 70c per sqft it's a long term investment. I would probably put it in two layers (I haven't found 1" volara rolls yet) in order to obtain a compunded R of 7.2. From my camping mat I know that is pretty badass for winter.

The second big question is: what if I buy a boat with a solid fiberglass lining sole? Should I take that apart? Keep it and insulate over it? Taking it apart seems more appealing frankly.

I was talking about Catalina 38 in another post, some design I like. I read somewhere that insulating over the lining sole is not the best thing. In that case an older run down model seems like a better option since I wanna do my own thing with it ( you can go ahead and suggest models too). Being able to get to the core of my boat would mean that I have quick access for repairs, just in case - I see it as a very convenient plus.

Andrei

The R-value is per inch, so you would need to get 2" to get an R-value of 7.6. The 1/2" foam will give you 1.8.

The reality is that 1/2" or at most 1" would be more than satisfactory for a boat. Because of the very small surface areas of a boat compared to a house you don't really need as high R-value.

I would not use adhesive for the reasons you'v given, access to the hull for repairs. I read of a low tack system that allows removal and replacement. What I would do is adhere velcro tape to the hull and the panels and hold them in place that way. Removable, but stay in place otherwise.

[andrei_ca]

How do you know that 1" will be more than enough? Experience?

Could you give me more info on that "per inch" fraction method for the R-value. A quick seach yields nothing.

Andrei

[J Clark H356]

You get condensation whenever the temperature reaches the dew point. In a boat without insulation in cool or cold water, it would typically be at the interior face of the fiberglass hull. If you insulate with foam, it must be closed cell or it will fill with,water and become saturated. You want full contact of the insulation with the hull, otherwise the air space just gives you a place for the dew point to occur and that is where the moisture will reside and you will get mold between the insulation and the fiberglass hull. Using Velcro with insulation gives you an airspace between the insulation and the hull, not good. You must also seal all the joints between the insulation. Your analogy of air and a mitten doesn't work in this envelope scenario. Mold growth takes a dark place and 70% relative humidity. Easy to obtain at the hull of a boat.

In comparison to a building with a brick cavity wall, we use the cavity air space to provide the space for the dew point to occur. The water in the cavity drains down the wall and flows out through weeps to the exterior. The wall is vented which helps keep it dryer. Think of that as your space between the insulation and the boat hull if you don't have full contact. You will run water down the space until you hit a stringer and then the water will infiltrate back into the boat materials, usually your wood inner liner. You will rot it from behind. You can't weep your condensate like the brick wall (hull) to the water except by having a continuous path to the bilge. Water vapor that has not condensed moves from warm to cold to the dew point. It can change direction during the daily cycle and depends on whether you have HVAC on inside the boat and keeping the interior at a relatively constant temperature and at a dryer level than the exterior environment. All of this is somewhat tricky if you don't understand insulation, dewpoints and water vapor pressure. You could easily screw up you boat interior if not careful.

The best closed cell foam insulation is polyisocyanurate. It has an R value of 5.6 per inch. If you use less than an inch you just take the decimal equivalent thickness and multiply it times the 5.6 to get your overall R value. Say you use half inch, then .5 x 5.6 = R of 2.8; 1/4 inch is .25 x 5.6 = R of 1.4. If you have more than an inch, say 1-1/2 inch it would be 1.5 x 5.6 = R of 8.4.

To get your heat loss you take the reciprocal of the R value which would be 1/R times the area in square feet times the (interior temperature-exterior temperature) to get your BTUH heat loss. You are basically replacing BTU's to stay at a constant temperature inside the boat. Heat gain is a reverse procedure but more variables are taken into account such as the humidity and reflectance value, color of the skin and some smaller variables.

Remember that if the joint is not tight and sealed, you have 0 R value at the joint and you will move the dew point location at that line. The technical bulletin below is for polyiso insulation and you can read about it there.

http://docserver.nrca.net/technical/8020.pdf

How much is enough depends on how much you can get installed with the other variables of your boat construction, drainage, heating and air conditioning system design and operation and where you plan to go and the temperature extremes you will encounter. One more complication in a boat is the fact that you can be in freezing conditions above the waterline and warmer conditions below the waterline. This makes for interesting dewpoint/condensation calculations as does the type of heating fuel used inside and it's relative moisture content along with cooking moisture and the number of people you are dealing with in the conditioned space.

Temperature and dew point calculations in walls of any kind are very complex and are not easily understood or calculated without fundamental engineering or physics knowledge. If you want to know more, look up WUFI on the Internet.

None of this is rocket science.

Good luck on your project.

[Adelie]

Where are you?

Where do you want to take the boat?

The R-value info was found here: Volara Foam

The last line of the testing info block says: "R value for 2#Volara: is 3.6 approx. The R value measurement is per inch."

I've been on a 27' boat in temps around 40F with no insulation at all. A very small heater kept us very toasty overnight.

I was on a 34' boat with no insulation, in snowy condition (we awoke with 2-3" snow on deck) and the small Wallas heater kept us toasty all night.

Fiber Reinforced Plastic has an R-value in the range of 2.0-2.5. Top-side thicknesses for a 30' boat are probably about 3/8" so the R would be about 0.75-.95. Adding 1/2 of Volara would triple or quadruple the R-value of the hull.

If you really want to go with 1" then look at Ariflex (http://aps-sales.com/media/pdf/broch...es/ARIFLEX.pdf) is another possibility. Best of all it self-extinguishes in a fire.

I've looked at this in the past and found a number of options, key things to look for are flamability, R-value, closed cell, density and chemical resistance.

[DeepFrz]

++1 ^^ what J Clark has to say.

You might want to take a look at this stuff. It has an adhesive but it is removable. I understand that it is hypo allergenic and resists mold.

Armacell Product Selector - AP Armaflex SA, AP Armaflex FS SA - Self-Adhering Sheet and Roll Insulation

[andrei_ca]

J Clark you were crystal clear and you confirmed my "fears" . I surely understand what you say and I suspected it was more like that because there's unanimous understanding for gluing of isolation on boats.

Adelie, I'm around Toronto/Montreal Canada.

DeepFrz, I checked armaflex and saw a tutorial on the Frugal Mariner website on how he did it. I also read that that its better for heat than cold. Some studies show that Armaflex drops its effectiveness a lot in cold (or so they say). Frugal Mariner told me he was ok at 42F but not too warm either. I can get to -15F, with -40F exceptions (I could also travel south for the winter, it's so depressing anyway and not much work for my industry anyway: and that would solve a lot of this).

Volara is closed cell foam - the same as the home insulation foam foamular, that house spray thing and whatnot, just more flexible. It seems the R value is lower though. I must've been tired yesterday, because I noticed the per inch value for other products but for Volara I thought it was for the 1/2 thickness - now I get it 100%, thanks guys and gals.

I will delve further into the polyisocyanurate, and btw, some dude that built this super small shack in the woods advised me: "If you got the budget, I do spray foam.
There's stuff on amazon. Search green foam. Or diy spray foam. Comes in 2 looking propane tanks. Or the reflex hard foam is good to, foil on both sides. Then spray foam in Amy fracks. 7.2 isn't much. You'll spend a lot more on hearing it. I got R21 out of 2 inches." So yeah the reflex hard foam must be something like the poly u mention.

But there's one thing living covered in snow amidst dry air and another on water. Gluing all the way.

There is one more issue though: is the fiberglass sole stuck somehow to the hull? If I insulate the sole then that will surely create dew in between the sole and the hull if there's air in between.

Andrei

[DeepFrz]

There is one more issue. A well insulated boat has to be a well ventilated boat.

[Benz]

I have about 3/4" of insulation in my hull, not glued. The layer against the hull is 1/4" closed-cell packing wrap, very flexible, the next layer is styrofoam which I bought in 4x8 sheets. I made sure it stood a little proud of the "ribs" I had glassed to the hull, so that when I screwed my hull ceiling (which is redwood strips) to the ribs, the insulation would get squished down. I had all sorts of naysayers rage and storm and say that we would all die of mold poisoning within a couple of months. Well, we lived aboard, five of us, for five years, both in the tropics and in very snowy winters, with no mold-related deaths. It might have helped that a wood stove kept things good and dry, but we didn't use the stove in the tropics and still had no mold problem.
If there is a hull liner, I'd hesitate to cut it out--by the time you do all the work of cutting out structure, and peeling the interior back to the hull so you can insulate, you might be better served by building from a kit hull like I did. It's expensive, but a lot less work than removing everything from an existing boat before you can put it in again.
Lastly, even though I haven't died of mold, I think gluing insulation is still better, and my next build will have as much more insulation glued in and glassed over.
Ben
zartmancruising dot com

[DeepFrz]

Benz, ya but! You had your insulation trapped against the hull. Pretty much the same as gluing it, isn't it?

[andrei_ca]

Originally Posted by DeepFrz

There is one more issue. A well insulated boat has to be a well ventilated boat.

So that means dehumidifer and air vents leading outside right?

Andrei

[andrei_ca]

I got another info from this source on youtube that used 1/2 foamular (blue): he said water drips at the bottom and mops it once in a while. So case closed.

I might have been wrong about armacell - I confused it armaflex. Armacell seems to be close to volara, slightly warmer. Didn't compare prices anyway.

I'm going to research it too but if you could recommend how to find kit hulls that'd be nice . Thanks,

Andrei

[Scot McPherson]

I think it's not so much that it's glued, but that it is firmly pressed against the hull by whatever means