Closed Cell Foam + Rockwool- How To Flash & Batt 

Nice assembly Matt. It's coming along nicely.

Your Videos are really educational I’m an air-conditioned contractor in Louisiana I love the way you explain everything you’re a great contractor, I would love for you to build my home !

Matt, your knowledge and unselfish advice is gold to many of us. Thanks for sharing this incredible information. Priceless.

icredibly well informed. Rockwool is incredible for sound and batt. I have bought from IDI...Good company. You hit the spot with just enough for each application. Too many times the builder or homeowner is not interested in foam because they think they need an r-49 cavity foam filled....7" is overkill. 3" is max. You are spot on brother. And your exterior wall design is interesting. That wind blowing hard in the background was a great sales pitch on the foam too....Awesome video. I just came across it.

That is absolutely the very best application I've ever seen

This house is a case study in good practice

I love this stuff. That is a beautiful wall assembly.

I was a insulator (Residential) in the late 80's and early 90's & when I started the standard was R7 in the walls "with plastic" R19 floor & 30 in attic, when I left & went on to a different profession it was still the same orher than we were using R15 in the walls without plastic, I'm in N.C Raleigh area. It's amazing how far the industry has come. And I have to add I've been around construction & builders my whole adult life about 40 years & you my friend are a hell of a builder, I would love to have you build me or anyone in my family a home, I could rest knowing it was done with integrity.

I learn something useful on every video. Awesome video.

It would be nice to see insulation reviews start to show and include just how effective cork can be. Also, cork has many benefits to the environment. Is renewable, carbon sink, water resistant, vapor permeable, is almost perfect as insulation.

Great show.

Sound will go through electrical boxes. Here in Russia Acoustic group produce sound reducing electrical boxes for drywall. Sure they are for European DIN standard.

That foam is no joke. Used it to insulate around some old loose vinyl windows and the foam locked the windows in place better than the screws and blocking did.

OK, this answers my (and others) questions about the closed cell foam install. Now this brings us to the next question. What is the upcost of this wall (the 2x3 (5.5" wall thickness) heat break, Zip sheathing, foam, Rockwool) vs a "code" wall (for that area) and how does it compare (costwise) to, a comparable (R-value) ICF wall. If the ICF wall is cheaper, then how much more R-value can you add for the same cost? Love these shows! Please keep them coming!

What a well engineered wall system.

incredible didactic and important!! many thanks!!!

“I’m not in a high wind zone”, as the plastic door opening is blowing at a sustained 120mph! 😂 Great meeting you at JLC the other day Matt!

Just found this channel, REALLY like it over *other* spray foam (jones) videos ! He claims you can't do this!😮😂

I own 2 houses next door to each other, almost identical in layout, one built in 1908 & other 1910, both houses I redid the 3rd floor (complete gut). 1st house is ours & put in Rockwool with polyiso board on the inside (R-6 with drywall to go over it). This reduces thermal bridging through ceiling joists. Next house did closed cell foam between ceiling joists (both houses have roof above it). Considering the performance & price I would definitely do the Rockwool/polyiso combo. Probably half the price (with my labor) & I think it performed better. Again, exact same 3rd floors, next door to each other so a pretty good comparison. Close cell spray foam was about $6k for just the 3rd floor ceiling/walls.

Wow! LOVE the idea of using the "zip" boards to fix the thermal bridging from the studs!

We just foamed our home is Minnesota. 6" closed cell (R42) under the roof decking and 4" (R28) on the walls. It's incredible stuff!

hey matt I want you to talk about the final process of a build. what the contractor usually does before handing it off to the client. window cleaning! I am a window cleaner construction clean ups are a regular part of the job. id even love to clean your windows myself when the time comes.

Minnesota built home here. Cant stress enough put enough foam 2"+ and CONTROL THE MOISTURE through the entire build if its happening through the winter. I neglected to do so and had a lot of condensation occur between the flash and the batt when we had our extreme cold snap which occurs once if not twice a winter. Matt if you read this please look to mentioning it, because its still relatively new concept many aren't aware of, and it can be extremely scary situation. In my case all of it dried out as designed once it warmed up a bit and I dropped the moisture levels as much as possible.

Matt, what are your thoughts on doing a spray in fiberglass over the foam, such as jm spider plus or knauf jetspray?

we're building a custom walk in cooler for a taproom in Philadelphia. Trying to figure out the climate zone and where I need the dew point to be/or if I even need to worry about one. It's a conditioned space inside of a conditioned space. That being said, very helpful video!

In South is enough open cell for walls and roof.We used to spray closed cell the sub floor /freezers. Closed cell is good for vapor barriers and R value, open cell - R value and sound . Cold states : roof - first closed cell ,then open , Sub floor - open cell first , then closed .

That's probably my favorite insulation system. Yes it's a little bit more expensive but really good... and more than enough for Canada too.

Hey Matt! I live just South of Houston and have a 25 yr old brick home that is an insulation nightmare.. meaning... I am freezing right now because the cold is just pouring though my walls. I can quite literally feel it. I also have been working to address less than adequate insulation in my attic and a poorly sealed attic that is allowing insulation to circulation in my home through the walls. Have been watching a lot of your videos on insulation.... So I have decided this is what I need in my attic. I have already paid good money for attic insulation replacement and sealing that was just not done right at all... my question is... can you recommend someone in Houston area that will come do this right!! There are a lot of insulation guys that just don't know what they are doing! Also, Any opinions on the foam fill for existing walls. I spoke to company called Retrofoam. Seems like a good deal. But no one services the Houston area. Although your Austin guy has offered to drive over if I go that route! Wondered if you could offer advice! Thanks for what you do!

Interesting video, thanks, the link to SPFA appears to require a membership to access, I am particularly interested in the applied thickness recommendation for for cold climates as I live in Fairbanks Alaska

I’ve seen it all, rockwool insulation, spray foam insulation, and now both

The thickness required for closed cell foam to become a vapor barrier varies depending on brand. No close cell spray foam becomes a vapor barrier at 1". You need to look at the TDS of the foam you are using. Most require at least 1.5", some required over 2". This system will work, it just super over kill. I have been a spray foam contractor for 15 years and studied at the Kansas Building Science Institute.

Hi Matt, great vid as always Just a question re the vapor barrier, if the closed cell is a VB and the ZIp system is a VB, then could this result in a vapor trap for the wood in the zip system?

@matt did you consider using the pre-insulated T-studs we've seen in your other videos?

We are purchasing a home built in the 80s in the north houston area. What are the rules when doing the attic with the closed or open cell foam? As far as AC equipment, venting, etc

Matt, You and Ken are another Dynamic Duo! Question: Considering Zip-R vs your InSoFast, would calculations be any different??? 😊 I am also planning to use the 2x6 T-Stud for my new home with 2" CCSF inside here in Coastal NC. Cheers, Eric

Basically a R32 in a wall in, what, Texas? That's going to perform so well. Wish I had that in my house...

Nice.

first time someone else besides Spray Jones has said how to do a proper flash and batt! good job. rule of thumb though without looking it up is over 2/3rds ratio. so R14 of closed cell means you should only do a max of R8 in batt form which of course isnt really a product anyone sells. youre better off just doing the 2-3" of closed cell and calling it a day.

Great job! 2' on center or 16" ?

good luck to anybody doing remodel down the road

In the south could you fill the bays all the way and then put up foam insolation panels across the wall and then put up the drywall?

Love his shows. Would LOVE to see his final cost as an actual house buyer not as the builder just to see the per square foot price. I can't imagine the regular home owner could ever come close to affording this type of build on a 2k sqft. home.

SPFA docs are not available for free. Shame. Still a very good video.

I'm building a bus to rv conversion and would love to know how thick my closed cell foam needs to be before putting rockwool over the top of it. A bus is basically a large metal box and I like the idea of sound deadening.

Interested in your personal studio wall assembly. What fabric did you use?

matt- have watched a lot of your videos and i tried to send and email to you and not sure if you got it or not, but have a question for you : we are in the process of moving to another house and thinking of going with a metal roof and the company offers adding a radiant barrier , which of course is extra. i would like to do the spray foam to the attic ( which we have done to the current house ) and in your opinion, would you do the metal roof and radiant barrier and no foam or add the foam or metal roof and foam with no radiant barrier. live in florida, so summers are much like texas.

Hello Matt! Can you tell us viewers if dark exterior paint colors affect the efficiency of a home and if so, by what kind of approx margin? We are building a home and wanting to paint it navy but we are afraid the dark color will make cooling it difficult. For reference, we are in NC and we NEVER run the heat, even in the winter. If its only 5-10% power consumption increase then we may go ahead and do it. But if its something significant, it would be interesting to know. Maybe this would be a cool science video for you guys :)

What advice would you have on dealing with full dimension 2x4 walls in zone 6? I considered using .5" of rigid foam or 1" comfort board or and firring out .5" on the inside with R-15 Rockwool. I am also considering firring out either the inside or outside walls 1.5" and going the flash & batt route or R-19 Rockwool. I am from the south but this house is in the north and I don't want to get this detail wrong... Any ideas would be much appreciated!

Can you show how you would put in a fire place in a netzero home?

Can this also be done to attic floor? Thanks

At about 8:55, Matt discusses MW printing the R-value on the batt. During the install R15 was placed on the lower section and R13 was placed in the upper section. Was that a specific design decision or a quality control issue?

Would this be a smart, efficient move for a Vented attic space? Long Island, NY area. Current attic insulation is lacking & a lot of poorly installed batts. Crushed, no vapor barrier…etc….

If I need to pull my siding off my house, and there is currently no sheathing or vapor barrier beneath, can I use closed cell spray foam against the sheetrock before installing new sheathing, vapor barrier, and siding over it?

what is that green spray on the first 32" of the t studs"

love the back and forth complete (yet layman-friendly) explanation of the closed cell. wasn't quite sure why the rockwool was even needed, since you already got to an R14 in TX with the closed cell -- if 14 wasn't enough why not just another inch of spray?

Matt we are in the middle of a remodel and can’t find a straight answer. Our house is 105yr old in a dry California climate. It was built with wood siding, a felt layer, and 1/2” wood sheathing. It doesn’t have a vapor barrier do I need to add one or use hard foam insulation before putting in Rockwool? What would be the best way.

Can you recommend a good builder for middle Georgia?

A bit off topic, but was is the green coating on the bottom portions of the studs ?

One thing I most definitely like about RU-vid, sort of like the books or magazines of old (of which I do not buy or have any more), is that I can refer back to them (haha... if I remember where they might be, but so to was the case with books and magazines, but at least now I have an intelligent(?) search engine). Currently I do not know what is in my house's walls, but I know there is nothing in my floors for I having a house with a crawl space and having inspected that visually. (Sigh)... Really, builders need to [censored] so that 120 years down the road things do not need to be fixed only because it was done inadequately the first time.

My question is how does the vapor get out of the wood?

In this particular hybrid method, why the closed cell foam and not an open cell foam?

Can you flash & bat these products in a roof insulation job?..would be phenomenal.

Are t studs cheaper than a 2 x 6 in today prices?

On a flat roof 18’ tall in front, back is 10’ tall framing out 4” metal studs 14 ga on top putting plywood and metal roof. Is it ok to spray foam for condensation ? 1200 sq ft home.

Can you please post the link to the document you eluded to? SPFA-147 Spray Polyurethane Foam for Hybrid Insulation Systems - Part 2: Climate Zones 4-7:

Something I've been wondering about with sprayfoam since I started seeing it, is how much of a P.I.T.A. is it if you need to do some rewiring/renovating ? To me it seems like it would be a lot as you have to dig the wires out of the foam, and dig new channels for the wire if you are re routing it.

What about the top of studs need to be sealed.

I'm doing 3" of closed cell in my attached heated / cooled garage / shop. Zone 5. I will have 2.5" of space left in the wall that I could fill with rockwool. Will it be a problem to use this in a space that I might not always want to condition? If I am going out of town for the week I plan on not conditioning the shop.

I hate doing flash and batt but I really hate doing it with mineral wool lol. If I am doing flash and batt i prefer to use Knauf batts (fiberglass and mineral wool blend acoustic batts)

We need min r40 walls in Canada...r60 roof. Spray spray spray

What about putting open cell foam on top of the closed cell foam?

You should not install drywall, but instead install plexiglass.

Where do I find the studs used in this video?

How can this be done when redoing the siding from the outside of the house? Put bat's down and spray foam over it?

Matt’s got the only house on the planet that you have to wear a jacket on the inside in the summer!

I would like to do this process on a barndominium

Can you flash and batt the attic? Cuz that’s where the sapping heat comes from. 🔥

When they spray the stuff on the roof Rafters and underlayment of a roof, if the roof leaks how can they tell where it's coming from? Doesn't it hold the moisture against the wood and then cause more damage instead of draining?

Does the spray insulation “gas-off”?

Isn't the vapor barrier on the outside?. Tyvek or zip coating?

The problem with flash and batt is the majority of insulation companies only install 1/2” or less of closed cell foam. After putting installing foam below manufacturer recommendations, they cram a fiberglass batt into the cavity. The fiberglass batts are designed to completely fill the cavity for maximum effectiveness. They aren’t made to be crushed down. The methods used in this video are overkill, but installed correctly with enough cavity space for all materials.

Where is the warm in winter side vapor barrier?

@Matt Can you do a video on selective spectrum blocking films? I rent so I can't make drastic changes to the house (if I could even afford them) and it's frickin hot right now. I've heard UVA/UVB/IR blocking films can help with that. Though there are also downsides with them, like accidentally melting your neighbor's siding and not being able to put them on the inside of double/triple paned windows. Also it'd be cool if you could experiment with putting them on a plexiglass sheet for quicker install/takedown. Just slide that up against the glass between the screen and the window. Maybe some double sided tape or tacky putty to hold it there over the summer so you can still open the windows in the evening.

I have seen horror stories on flash and batt. Would you suggest a blower door test and aerobarrier before the bat? to triple check to make sure there is no holes/ air leaks missed during the spray foam part?

Total embodied carbon is 10x higher than fiberglass and the r value is 4.2 per inch. Unless you are using Rockwood for sound, it’s not worth the cost. Foam and fiberglass is good, exceeds code, and good air barrier. Fire resistance won’t matter when the entire structure is wood.

Won't the closed cell foam shrink over time??

These videos will spoil future home builders. I talked to several builders who had no clue what Zip r sheathing was let alone T-studs. They were reluctant to try anything new. Building my house like this would have cost me a little more in material cost but made finding a builder much more costly and complicated in itself.

Any concerns that the moisture in the wood encased in urethane will rot the wood and create mold? Also, sheathing fasteners could create a cold spot in the wood causing a potential for condensation.

If around r30 you have demishing returns on insulation why would you insulate higher?

Why not just cap it with open cell foam instead of rockwool? Is it purely the cost ?

Matt “Overkill” Risinger

Why don’t you use spray in rock wool?

Where do the soffets go if you spray foamed where the rafters meet the wall?

but the zip-r takes care of thermal bridging...so why have the t-studs?

Cover it with Aluminum double bubble across the studs and tape it off. The ceilings too, Reflects heat out reflects heat in. Cut my heating and a/c bill by 80%. You couldn't pay me to put batt insulation in my walls. You Guys complaining about the cost, I get it, but if you do that with foam and then cover it across the studs every day of every year you will be paying yourself back. By My rough calculations it took 3 years to pay off the entire insulation job. Been money in the bank ever since..

Matt, Would you consider putting open cell on top of the closed cell? What would be the good and bad about that?

Got a price of 125 dollars a sheet of ZIP R 3. How can someone afford to cover a whole house in it?

Can anyone touch on the batt filling the cavities completely (I’m specifically wondering about the warm side). In the vid it says batts have to touch all 6 sides. To help describe what I’m confused about: if you were to use a 2x4 sized batt in a 2x6 wall (FYI I’m not saying this) would it not perform as 2x4 batts would with 2x4 studs?? Thanks

Aero barrier and bat much more environmentally friendly Aero barrier and Rock Wool is hard to beat on Price and performance that’s why Owens Corning dropped the pink foam to flash with their fiberglass batts

Off topic but, Matt, got your email on the OSB prices...more like 3x... seeing $80 sheet of OSB here. Crazy. 12/2 wiring is up too!