That's the same I was told, open cell on the roof and closed on the walls. And I had a roof leak, it was easy to find and repair.

I have not heard about spraying open cell on the ceiling. Everything I have read is to use closed cell on the ceiling. But it makes sense for finding a leak.

Wrong. That first layer of closed cell in the walls is creating too tight of a house. Again, houses have to breathe. Open cell in the walls, closed cell where the foam will be exposed. I’d worry less about a water leak and more about the house breathing as it needs to or you will be dealing with mold and other issues.

Well, I’ll say it one more time. I discussed the advantages of open cell vs closed cell with the technical and sales guys where I worked. The Polyurethane Foam was made at our PU plant in Geismar, Louisiana. I knew we had both open and closed to offer, and I had a house about to be built, and foam was going to be the chosen insulation. What I didn’t know was which one to choose. The R value on closed was higher, so I was leaning that way, but the PU guys pushed me to open cell. There were quite a few reasons why, all of which I can’t remember.

Think of closed cell as a hard foam. Open cell is more like a firmer version of Angel Food Cake. It’s easier to get to a problem in or behind open cell.

The thing that surprised me the most was that the foam goes on the underside of the roof, and not on the ceiling. The thought of having no insulation on the ceiling just seemed wrong. The thought of having no soffits also seemed wrong. No roof vents seemed wrong. I had to cross my fingers and hope these folks knew their business, and thankfully, they did.

What now interests me is why any of you really really want closed cell. What will it do for you that open cell won’t? Do you see a real advantage from closed cell? What is it? There is a minor R Value increase in closed cell, but it isn’t significant.

One thing I keep being told about the closed cell is that it is good for the shop area because it is not as flammable as open cell foam when exposed on the walls. May or may not be an advantage.

If you have open cell in your attic, go take a temp reading in there tomorrow around 3pm, I have closed cell in mine, we will see if there is any significant difference.

There’s truth to that.

A house or barndaminion has been to breath. Spray foam contractors want you in spray everything as it’s easier, faster and more money for them. Even when you spray from ventilate the attic. If no air flow you have to put in special ac to bring outside air in. Not rocket science, if not ventilated it will sweat just like an ice chest and condensation will rot interior framing and mildew. Good way is close cell roof and walls. Then frame outside walls, cover with 1/4” double foiled insulation (comes in 4’x100’ rolls) as vapor barrier. Sheetrock over that. You’ll be amazed at your small electric bill. House will breath, you can use conventional ac unit and dead air space in wall is additional insulation. Win win situation. I see metal homes, framed out barns everyday that it’s almost 🌧 raining inside and rots wood framing quick. It’s amazing how quick. Most foam contractors only care about quick money and doing as many as possible. I do think some contractors just don’t care or really know?

You know I love calling you a DF and this is just another prime example. If you engineer it the right way and no it is not cheap but yes, I am correct but thank you for trying to look smart Zima boy. We appreciate you thinking you have outsmarted me yet again lol.

Just like ^ ^ sleeping in a sealed up tent. The moisture vapor has to go somewhere

So you have closed cell on the roof decking of a stick framed home? So far all I've seen in traditional stick framed homes is open cell.

A roof leak will drip through with open cell. We experienced this in the past year and got a new roof. With closed cell I suppose sooner or later a drip will happen. It will soak up a LOT of water and the OSB will turn to mush before the leak.

One of these days you may have a roofer fall from the very top all the way to your living room floor if the decking had been soaking up water for a while. That is if he gets past or breaks through the ceiling joists.

And as far as your temp challenge, do you really expect much difference between close vs. open cell? My open cell attic is in the 80's when it is over 100 outside. A traditional attic can run from 130's to over 150. If your closed cell is five degrees cooler than the open cell is that some kind of chest beating win?

Tell us about that when EMS comes to get a roofer out of your house.

Not worried about anybody falling through as long as I’ll live here.

I’m just honestly curious about the difference, if any.

Oh please, so tell me what your house is insulated with and how many homes you’ve lived in with foam. How many have been present for the design and installation? Your information is nothing more than hearsay. Nice try though

Open cell is porous. Closed cell is some very strong glue like insulation. They each have their place.

I don't claim to be an engineer. I just know what I have observed in over thirty years of building.

If I was building a metal building tomorrow it would get closed cell and call it a day.

And as far as the OP, he could probably have a cardboard box inside of that "envelope" and be reasonably efficient.

Insulation and air tight can be an overkill problem.

This is Texas. Focus on the attic, windows, and you are most of the way there. Spend as much as you want on that road to diminishing returns.

Take a picture of your attic tomorrow and post it. My house was built in 96 focker so it is crap and you know that lol. Seriously take a pic and send it either to me or this thread.

Have you had foam done as a retrofit? I would really like to know your experience.

Honestly, this isn't some smart [censored] reply here. I've heard everything and don't know what to think anymore.

I've had one insulator tell me that they go in and vacuum out the previous blown in insulation and then do the foam. I'm subject to doing another flip home and would like to know if you did do a retro and if you are happy with your energy bills.

I have not and did not see that as a smart arse post at all Sir. On my house it would not be cost effective and many flips it just isnt. You need in the bones to do that and this house is not a POS so that is not feasible. I could blow more in but spray foaming is just not the right call. Tuesday we will have a ground breaking post on this I hope.

Too many experts for me. I should have known better. I just know what doesn’t and doesn’t work. Just trying to help. That’s why you see so many mistakes. LOL MAGA

Im not an expert but I think your last post was correct. If it is engeneered right it works but insulatiors are idiots for the most part and they do not do it right 95% of the time so you have to stay on top of them.