Which Foam Board? Polyiso vs XPS Insulation

I think there are two good choices for Exterior Rigid Foam Insulation. In this video Dow Chemical Rep Kevin and I will tell you about the differences between XPS and Polyiso insulation.
-Matt Risinger
Risinger Homes in Austin, TX

[DonTruman]

Appreciate the talk. Sounds like the applications for polyiso are few, if at all. A slight improvement in R-value, a slightly lower price, but the downsides of water absorbency and easier to damage probably counters the benefits.

[buildshow]

Garry Barnett,  I do think that Neopor is an interesting product.  It's not readily available but I would expect that to change.  Dow is a huge company and they make some great products, of course there are other manufacturers of exterior rigid foam.  This video is intended to educate on the differences so that builders can make informed decisions, and buyers can know what's on their house.  Best, Matt

[patrickpenza]

You could use a 25psi polyiso instead of the 20psi you are holding and eliminate the furring...
Also, foil-faced iso is closer to 6.5/inch once you get past 1" in thickness.
Lastly, the water absorption rate of foil-faced iso is less than .04%. They both work perfectly well in any wall configuration. Iso has a far better performance than xps in high-temp and fire situations as XPS is only applicable in mass walls to meet NFPA 285 standards and that also has to be detailed properly according to the test reports. Polyiso has shown to be NFPA 285 compliant in over 85 different assemblies due to its great fire-retardant characteristics.

[rpcnvqh]

Matt, you do a great job and your customers are lucky to have you as a resource.  We could use more builders like you at our development in Georgia.  In the future you should touch upon foam board being an interstate expressway for termites.  Termites love to tunnel through this stuff and it gives them limitless access to the building envelope if you are using exterior foam board as insulation.  Hopefully the manufacturers will figure out how to add a product to the foam board to mitigate this issue.

[josephmerritt]

Viewers should check out the new products that have come on the market since this video was made many years ago. Check out Logix Halo products Graphite Polystyrene
(GPS) Rigid Foam Insulation with foil skins. The GPS foam is a graphite fiber-filled XPS foam: .013 Perms, R=5/inch, and flame spread index less than 25. There are versions to use in contact with soil, on interior walls, and on exterior walls.

[WilliamFiler]

I added 1" POLY ISO foil backed over a manufactured home siding, then cedar shingles with ring shank framing nailer through each shingle, through the foam, into the existing siding/sheer. I hope I have no moisture problems.

[brentgrygar]

My initial thoughts for insulating my new house are 2x6 walls with cavity filled open cell foam wrapped with plywood sheathing.  I then want to use a house wrap of some kind(any suggestions of type and if multiple layers are used would be appreciated) then wrapped with 3/4 in thick foil backed polyiso.  There would be 1 in of airgap followed by acme brick exterior. After watching this video about the moisture concerns,  would use of the XPS be better even though I lose the radiant barrier qualities of the polyiso?  I live in Waco, Tx so my climate is the same as yours.  Thanks Matt for the videos, as they are super informative as I try to design my energy efficient new home!

[JolieGaronne]

I'm curious about the toxicity between the two? I read and heard people say that the XPS is much more toxic than the polyisol(?)

[LATINOSTRADERZ]

Good morning Matt, I have a question. You know, I want to insulate my Master Cool 7000 series evaporative unit with some foam board that will help me insulate the unit as much as possible to get its best R-value efficiency and thus be able to insulate the unit and give it better performance inside the unit so that it has a better temperature than how the unit comes from the factory, which itself does not have any sun protection on the sheet. I don't know if I made myself clear, what I'm looking for is which foam board is best for me that won't get damaged by the sun, water, etc. because it would be directly exposed to high temperatures.

[CougarLand]

Wow, seriously...how could you forget to mention the difference between the one (polyiso) being a Class I vapor retarder of .1 perm vs. the the other being Class II of .8 ? That besides the water issue of polyiso determines how and where the product can be used correctly.

[stevenspainhower]

Confusing because the speaker keeps shaking both binders/signs, and the hand-held signs don't indicate which product it is. For example, this one (which one?) can get wet and This one . . . . Maddening. Would have been much better to hold up the name of the product so we can clearly see what he's talking about.

[mariomatejka]

Great video Matt! I have successfully used Dow's XPS for insulating foundation walls.
Now I want to insulate a concrete slab by laying the XPS on top of the slab and covering it up with plywood to act as a subfloor. The only thing I am worried about is the compression strength of the XPS. Would the XPS under the plywood compress under foot traffic?

[mickcollins]

Hi, what is best product for roof of a slideon camper? What product is the best for the side walls? What Aliminium profiles do you use on the outside of both these applications for camper? Is there a site where all this information can be found, specific to what your caravan/ slideon/motor campers? Cheers Mick, I intend to build my own slideon truck camper, so being water tight/ strong/ and light weight are very important to me. Who is your wholesaler in Victoria (Australia), where I can go and talk about the materials that I need to build this project. Cheers Mick

[kerryann]

I'm looking to Insulate a Trailer.
It's just a trailer up in the woods so I'm not looking to spend a lot of money. What type can get wet?

[PhiLeo]

Having Kevin hold up & shake each board on camera to explain the characteristics of each board is confusing when watching on a smartphone rather than saying iso or xps is better at.... I didnt know what each sample was. Patrick Penza's concise comment below was more concise, and has more pragmatic value, imo, than the entirety of the rep's presentation. Do enjoy your channel.

[fabiangomez]

Which is best, or what would be best to use on top of RV walls, not inside the walls, to keep the cold out in winter and heat out during summer. It will cover windows and walls inside.

[techstermb]

Matt, thanks for the video. We have a 1/12 roof ... the current roof is a rock roof with tar paper. We want to replace with TPO. We are taking bids from roofers ... we are hoping to add insulation to the new roof. One of the bidders is suggesting 4" polyiso insulation, than over that, a fire retardant of some sort, and then the TPO. We currently have no insulation in the ceiling. We live near the ocean... I'm in central coastal California. What roofing insulation would you suggest we use?

[BrentDunnaway]

Matt, I'm concerned about the quality of my cellular phone signal with the foil backed boards and metal siding. Can anyone report their experiences with this?

[jeffdeluca]

Hey Matt... you impress me as the go-to guy for construction answers... I need to insulate the attic loft area of my 16x20' shop. I plan to insulate the 2x4 rafters with a ventilated ridge. How would you do it? Foil faced foam on the rafter surface to create an airspace or ??? Thank you much! Enjoy your vids!

[spkendrick]

So you would recommend an xps polystyrene for insulating a metal roof inside a metal building? Would that help with sound dampening also?