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
www.risingerhomes.com

[@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

[@seekfactsnotfiction9056]

Hey Matt, I'm trying to cover some vents that my parents can't stand the amount of air blowing downstairs. Which material would you recommend if we want to block all the air coming from those vents and at the same time get rid of the annoying noise or the blowing air pressure sound they make when vents are closed? I wanna get the right material to cover vents and have quiet or no sound from the covered vents! I have zero experience about this DIY stuff. Your help is appreciated.

[@patrickpenza5527]

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.

[@zefrum3]

thanks for this

[@hughgianni4713]

@Zaiden Mayson definitely, I have been using Flixzone} for since december myself :D

[@rickwilson478]

Thanks for your input...on the chance that you may see this comment so many years late... would you consider it appropriate to use between purlins under metal roof panels in a fire prone area of the Northern California Sierra Nevada foothills? Thank you, in advance, if you or anyone is able to respond 😊.

[@rickwilson478]

Also, is the poly iso the R- Max branded foil faced one side 1- 1/2" panels sold at Home Depot? Thanks again

[@user-rp5cn9vq5h]

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.

[@buildshow]

Tony, Great point! See this video I made on Borate treated insulation for foundations. kzbin.info/www/bejne/h4SmlnuDZsxparc Best, Matt

[@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.

[@josephmerritt1411]

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.

[@jeffdeluca1153]

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!

[@scottmohrman7789]

Matt, which foam would be best for my situation? I live in New Orleans and I will be rebuilding my home's exterior. I want to add exterior insulation and a rainscreen behind cement fiber siding. We have lots of water in Louisiana and I am leaning towards XPS because I have read that it is better with water.

[@stevenspainhower5493]

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.

[@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.

[@morehp1]

William Filer what kind of siding did the mobile home have that you went over?

[@deerhunter7482]

William make sure you install heavy poly on the ground under your home all the way from wall to wall and it will stop the ground moisture .

[@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?

[@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(?)

[@thelunglengshow]

Do you ship abroad?

[@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.

[@brentgrygar5227]

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!

[@buildshow]

Brent, Sounds like you are well underway to building a very efficient house! For the house wrap I'd recommend Tyvek Commercial D. That's the tougher and lower perm rated version of Drainwrap. It'll leave a drainage plane behind the foam so any bulk water can get out. For the foam you could go either way. The radiant barrier of the Polyiso is nice since you've got the air gap but if your house is one story then you won't have too much sun hitting those walls anyhow. It's probably a toss up between foil faced PolyIso and XPS. Be sure to use a "Morter Net" product at the base of your brick to ensure the weeps don't get clogged. Glad to help! Best, Matt

[@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?

[@PhotonHerald]

Use EPS. XPS off-gasses for a few years and you really don't want that in your house. Moreover, XPS, while offgassing, loses R-value until it's equal or slightly worse than EPS. You REALLY don't have to worry about it. 25 psi is QUITE rigid. If you're going to be anal about it though, you can get EPS in 40, 60 and 100PSI variants. They will cost significantly more though.

[@spkendrick]

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

[@outspokeninsider752]

Best for accoustic damping is RockWool or similar Mineral Wool. XPS doesn't do much, and I doubt PolyIso would help much either.

[@mickcollins5502]

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

[@kerryann2036]

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?

[@fabiangomez357]

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.

[@airhandler8304]

why does the polyiso have a foil face on it but not the other one?

[@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?

[@MrJCTECH]

good question, wish someone would answer that!

[@Chris_Porro_Land_o_Naps]

My contractor put down 1" Polyiso (Thermasheath 3) on my slab. we will pour 2-4" concrete topping slab on top of this. Radiant heat with Pex tube application. Any concerns?

[@onetwothree4148]

No

[@PhiLeo7973]

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.

[@Motoch3]

Has anyone done this detail. I am in Northern California. Typically I do 2" of close cell foam sprayed on the under side of roof sheathing and then fill the rest of the cavity with a batting insulation. The close cell allows for the due point to occur inside the 2" and since it is does not allow for moisture penetration we don't have to vent the roof. My question is if I go with 2-3 inches of Polyiso on the exterior of the roof deck will that substitute for my close cell spay foam allowing for the due point to occur on the outside of the roof deck?

[@MikeJones-vm2hn]

The surface temperature on the underside of the roof deck theoretically shouldn’t drop below dew point. And even times where it does it won’t be for a prolonged period of time. So a small amount of moisture should easily dissipate.

[@alanmajors9100]

Thanks for the comparison. Will be useful when I insulate a crawlspace. How about more comparisons on the products you use, like the commercial housewrap you prefer? Is the big box store a good place to shop, or do you have other recommendations on sourcing materials?

[@buildshow]

Alan, Great ideas for videos. I've got a house wrap comparison video in the works so hopefully that will be out soon. I'm generally not a big box fan as I buy mostly from local suppliers and lumberyards. The big boxes have some items that are a good but they have a lot of low performance stuff too. Appreciate the comments. Matt

[@terrymckann5594]

This is this and that is that and that one is better than this one and this one is better than that one i get it too

[@MetaView7]

This is better than this. OK O got it.

[@alexlindekugel8727]

poly iso will minimize fire damage and spead and poly iso a far sapirior product.

[@Harry-fu3eg]

Superior???

[@MrDave9111]

The current Dow spec sheets show that EPS has a much higher water absorption rate than Polyiso... - like 7 x. I know the processes used to make EPS has changed. Is that why? If so then this video should be changed as Polyiso is actually better at resisting moisture.

[@jt8025]

They are taking about XPS not EPS.

[@jesusisaliberal548]

Your captions say Expanded, but I'm pretty sure you mean Extruded Polystyrene (styrofoam). :-)

[@udmbfckx2916]

They don't talk about the "Problem" that has been plaguing Polyiso as of late and that is that below 50 F, the builders and clients are discovering that it starts losing its R-Value! This means that the board sitting inside the wall must be at 50 F or above to offer the material advantage. ...This video is 5 years old and a lot has happened ever since. In addition, XPS is the way to go if you want to walk on top of it.

[@onetwothree4148]

It gets down to - 20F around here and polyiso is still the go to product for roofs. Only the outermost part of the foam will drop to a cold enough temp to experience any reduction in r-value and that reduction is negligibly small.

[@CougarLand]

They all shrink...so there's that.

[@CougarLand]

OMG!, NEVER use foil-faced insulation on the wall sheathing. It's vapor-impermeable, thereby trapping moisture.

[@patrickpenza5527]

only if taping the joints

[@naturalhealing9970]

I wish he would have referred to each product by it's name rather than this or that.

[@BloominOnion1]

getting a little picky aren't we