ISOCAST R Polyisocyanurate Insulation

[Patrick_DeepPlaya]

Has anyone worked with Dow ISOCAST R Polyisocyanurate Insulation in building a refrigerator box?

The specs look pretty god if I'm reading them correctly.
http://products.construction.com/swt...414/290488.pdf

R 6.5 per inch
Water Absorption, ASTM C209, % by volume, max. 0.05

Seems perfect... any thoughts or first hand experience?

-patrick

[Woodchuck]

You might have to make the box pretty thick. A poorly insulated wall in a house is at least R20. I would think you would want to at least double that for refrigeration but thats just a guess. The best way to cut the stuff is on a table saw but be sure to wear a mask.

[skipmac]

No experience but certainly looks good on paper. Higher R value than Blue board and the specs for moisture absorption and permeability also look better. One phrase in the literature does concern me. From the product data sheet "the facer makes the board virtually moisture resistant". What? So this product is almost resistant to moisture?

To me this is a classic make a claim that sounds good but really says nothing phrase but could be a CYA wording required by the lawyers. Certainly the specs do indicate otherwise.

I went to the Dow website to compare specs to Styrofoam and saw a place to send a question Dow and did so. Will post their reply.

[witzgall]

I was under the impression the isocyanurate board was very water permeable. I would want to make sure that the absorption rate stated does not rely on the face material, installed in a wall, etc.

Chris

[Paul Lefebvre]

Patrick

I think this stuff would be fine if you were going to be using full sheets. However, once you cut it up and drill holes in it, you now have to worry about sealing all of those edges. Aluminum foil tape might work okay for the edges and foam for the holes, but then those are always going to be possible failure points.

Assuming you are going to use 4" of insulation, I don't think you are going to see a huge difference in box performance going from R20 to R26. Losses around lid seals and during lid openings is going to be a much bigger component of you heat losses at that stage than the R factor of your box. Now, if you only had enough room for a couple inches of insulation, it may be worth the risk to try it.

Paul

[janders]

Hey Pea, I'm using polyisocyanurate for my project but I'm only using it for the inboard sides of the box. On the side face the hull and all through the bottom, I'm installing polystyrene which supposedly has better moisture resistance properties. I assume those are the areas where I'm going to see the most moisture. I'm planning on coating the exposed edges of the polyiso with epoxy to keep water out. And I'll build a vapor barrier between the fridge box and the polyiso so condensation won't leak into the insulation.

[Patrick_DeepPlaya]

Woodchuck:
I'm generally following the guidance in the Kollman Books:
Selecting Equipment so the walls will be very thick indeed, 6"+ and yes, the goal is to get as high a rating as possible. I'm converting a large ice box to a refrigerator. This has sort of been done before but only by making a small Starboard box inside the larger void. The new box will be properly insulated. There's generally not any other material available than these rigid insulations. Vacuum panels have almost disappeared from the market completely.

Witzgall:
Based on what information do you say Polyisocyanurate is very water permeable? Looking at the spec sheets for Polyisocyanurate Water Absorpbtion rate os 0.05 and Styrofoam's is 0.1 according to the spec sheets (found here: Rigid Foam) Skipmac's point about it being the system of installation with two concrete walls that might be a problem, but I believe the ratings are for the material.

Skipmac:
I have asked Dow about this myself too and they basically said... we don't recommend that for use in a marine refrigerator. Which is the answer they will give for all of their products. They wouldn't engage in a more meaningful conversation. :-(

If they do answer you with regard to the water absorption rates being for the system or the material, I'd love to hear that.

Paul:
I am planning on 6"-10" of insulation so at 3R for every 2" it would definitely.

Jason:
Is that the big sheet in the workshop?
You have an interesting idea there too about mixing the types of insulation though... I should think about that.

(Disclaimer: /v Hello World and s/v Deep Playa share a workspace with two other boats in Ballard, WA)


Sounds like the basic answer though is only Jason is using this material and he's still in the design\construction phase... so no long-term users, at least not on this thread...

-p

[janders]

Yep, the shiny foil sheet stack up against the wall is polyisocyanurate. The pink stuff (which I think I've since dragged back to the boat) is polystyrene.

[rourkeh]

I redid my ice box recently on my Cheoy Lee. Had no refrigeration previously. Box was huge, big enough to climb in and sit down and I am 6'1" 200 lbs. My problem was the existing box was within 2" of the hull sides and a bulkhead and there was only 2" of original spray foam insulation which was useless. I ended up building a box within the box by using 1" and 2" polyiso board 4" all the way around, and heavy plastic sheeting as vapor barrier in between each board. I used contact cement to adhere the plastic to the board sections with overlap at the corners and shot insulating foam into the layers to fill the voids. When I got all the board done I built interior walls and a spillover barrier with a fan to control the air flow from fridge to freezer. I am using a danfoss 50 system from Fridgeboat and it runs very little given the size of the finished box. Polyiso is the only real option unless you want to work with vacu panels. I am extemely happy with the results. The board is very easy to work with and requires only a razor knife for cutting and shaping the panels. Buy the panels with the foil covering. Good luck

[skipmac]

Originally Posted by rourkeh

Polyiso is the only real option unless you want to work with vacu panels.

Hi,

Can you clarify why you say polyiso is the only real option? Better R value rating, easier to work with or other? What about concerns expressed about long term moisture absorption? Were you able to find data to confirm that is not a problem?

Thanks
Skip

[rourkeh]

Best option because. Highest R value per inch. Closed cell foam excellent resistance to water/moisture intrusion. Easy to work with, not fragile. Availability. Cost. Go to manufacturers web site and read about product.

[Mark Johnson]

Looks good, but consider that ALL foams will perform better for longer, it it is 100% encapsulated with glass or glassed/ply walls "all" around. This totally eliminates the water absorbtion issue! Mark

[skipmac]

Originally Posted by rourkeh

Best option because. Highest R value per inch. Closed cell foam excellent resistance to water/moisture intrusion. Easy to work with, not fragile. Availability. Cost. Go to manufacturers web site and read about product.

Did go to the Dow web site and look (see post number 3 in the thread). Cursory reading of the specs of the polyisocyanurate vs the polystyrene the PI looked a little better than the PS but if you read some of the statements more closely the specs or claims in regard to moisture absorption are a bit ambiguous.

I think the concerns expressed in this thread are that the polystyrene has been used and proved to work but seems to be no one giving information based on long term use of the polyisocyanurate.

[skipmac]

Got a reply back from the Dow tech support line. I asked the following question.

" Dow Styrofoam extruded polystyrene vs ISOCAST R Polyisocyanurate Insulation.

Comparing these two products for insulation in a marine environment with high humidity and potential for moisture absorption with corresponding loss of R value over long time period. Can you recommend which product offers the best performance in regards to maintaining dryness and insulating characteristics over long term in this situation?"

And the reply from Dow.


"Thank you for contacting The Dow Chemical Company.

ISOCAST(TM) R is designed for insulating a concrete sandwich panels. STYROFOAM(TM) products are what we recommend for high humidity."


Skip

[SV Demeter]

So I guess Im still confused here. I was reading and thought Polyisocyanurate was more moisture resistant than polystyrene? Im looking at using this for my isulation:

TUFF-R? Insulation (U.S. Residential Only)

Looks like an R value of 6.5 per inch which with 4.5" would get me to almost 30 which Im thinking is a pretty good number for a fridge no?

If Im using blue board or styrofoam Im only seeing R value of 5 per inch based on this:

STYROFOAM? Brand CAVITYMATE? Insulation

Is it in fact the case that polystyrene is better in a moisture rich environment? In which case I will need to go to 6"? Is a R value of 30 overkill for a fridge only application? Need to get back into that Kollmann book.