I am currently building a shop with a small living quarters inside. I was going to frame up the living quarters and then have open cell foam sprayed behind that part and have closed cell foam sprayed in the rest of the shop.

But I had a contractor come out and he suggested spraying the whole shop with closed cell foam. Anyone every done it this way? If so how do you then insulate the living quarter walls? Regular batt insulation?

I would spray the whole thing with closed cell. It helps seal it up and adds strength. Then frame the living qtrs and either spray foam that or use batts.

I would think that is OK. Just make sure you don't leave the back side of the framed up part open in the back. I did a barn-do-minium at Fork once for some folks that was a temporary residence while they built a large home. They didn't see the need for the expense for any spray foam on the shop with living quarters.

Before we stood up the interior walls there was OSB on the back side before being stood up. Then the batt insulation was installed before the finished wall material went on the inside. That way there wasn't air leakage with the living quarters. Plus it keeps the insulation batts from falling out.

Open cell will allow water to pass through, so if you have a leak you can find it. Closed cell will divert a leak and you will never find it. Closed cell is also a much greater sound deadener.

I finally put the ac in my shop yesterday. I was told there was spray foam in the walls. What I found was 3” of closed cell when I ran the Freon lines through the wall. It was hotter in there when I turned it on than it was outside. It was comfortable in 15 minutes and 62 in there this morning. I turned up to something more reasonable, I’m going to leave it on and see what it does to the bill. It has its own meter so it will be easy to tell.

This may not be relevant to your question but I got tell my story.

Doesn't seem to be any one method that is preferred over the other. Are any of you installers by chance?

I’m building a barndominium right now and I am doing one inch of closed cell then 3-4 inches of open cell on top of it.

1 inch of closed cell will really be 2 inches once it expands. Closed cell is best for open area that won’t be covered on both sides, for example the inside of a metal building or the roof of a house. Open cell is used in the walls of a house, where it will be enclosed.

For your use, I would spray the entire shop in 1 inch of closed cell. Then , when you frame your walls run normal batt insulation between the studs. Spray foam, regardless of open or closed, is very tight and restricts the breathing of the house so additional air vents are required if you do a complete encapsulation. The added vents are necessary to allow the house to breathe, along with supplying enough air for your HVAC and fireplaces.

If you plan on building right up against an exterior wall, meaning attaching the studs of the living quarters to the exterior sheathing of the metal building, then I would elect for that area to be sprayed in open cell. But I wouldn’t build it that way if you don’t have too

We just did a barndo at our deer lease and went with about 1.5-2” of closed cell and then batt between that and the interior wall. Can’t remember the total R value it got us but it works very well.

That's what our builder did on our new office. 1" of closed topped with 4" of open cell

That is how it is supposed to be done. Alot of homes are all open cell and that is not the right way to do it at the end of the day.

This is Texas, not International Falls, MN. I've sat through energy seminars over the years of building. If you are here your emphasis is probably 75% attic vs. walls. If in MN somewhat swaying the other direction.

There are lots of builders, particularly south of here that put foam in the attics and batts in the walls. They are getting great energy bill feedback. The house has to breath!!!

If you build a house that is as air tight as a balloon how does your clothes dryer work the way it should? It doesn't. The typical clothes dryer is pumping 1,200 cubic feet of your bought and paid for conditioned air OUT of the house.

Think about it. The clothes dryer has an intake----where? --- under it or behind it. The exhaust is to the exterior. You have this huge "vacuum cleaner" pumping out your cool or warm air.

The energy debates can go on forever.

I will ask this question to someone I know who has a good grip on this and give you an honest answer as that is a very freaking good question Sir.

So what I gather from opinions here, this is what I should do.

Spray the shell of the shop with closed cell foam.
Frame up the living quarters inside the shop.
Add batt insulation to the framed up walls leaving a gap between the closed cell foam and the batt insulation in the walls. This does not seem like a good idea to me unless I am missing something. Doesn't seem like a good idea to have this empty void.

Correct me if I am misunderstanding anything.

Give me deminsions and I will talk to a builder. Yes you are on the right track.

The company I retired from was a maker of the foam. When we had this house built I had about as much technical advice as a fellow could hope for. The advice was to use open cell and encapsulate the house. The house itself needed to be built a bit different than one with old style insulation. We built it in 2009, and it has been great. Heating and cooling costs are half what on old style house would cost. The AC, for instance, is much smaller. Enough smaller that I was worried that they were drastically underestimating the size needed. But they were right.

A Honeywell air exchanger was added to the AC system, to warm or cool outside air as it was brought in as needed.

The house is very quiet. Seemed odd at first. And even though encapsulated, we still get dust in the house. It comes in through the small air gaps at the doors. Windows are all double pane and sealed.

I have to crack a window when we use the fireplace, or it can’t draw enough air. And the fireplace is a design for foamed houses, with its own draw of outside air, but still needs a bit more air.

So, my advice, for what it’s worth, is to not go for some sort of hybrid building with foam and old style batts. Not saying it won’t work, but you wouldn’t be taking full advantage of the benefits of foam insulation. Go with foam and encapsulate the house. Find a builder that understands the building of a foamed house, not one that builds ‘old style’ and isn’t fully versed in a foamed house. Same with the HVAC guy. And use open cell foam applied by folks with some history of using foam.

I had this house built with the technical advice of the makers of the foam. I did my research carefully and I am very happy with this house after about 12 years.

Open cell and a roof leak is a big problem. You put closed cell and the open. Not my house but ore my problem. My builder has a few in dallas and knows what she is doing. Insluation companies could screwed her and they still messed up on two custom homes.

If you have a roof leak with closed cell, the leak will be almost impossible to find. The water won’t penetrate at the point of the leak, like it would with open cell. That was a point strongly made by the technical and sales folks where I worked. It made sense to me then and still does now.

That said, ya’ll do what you want. I’m just sharing what I learned prior to having this house built, and the 12 years of living on it.

A clothes dryer is an exhaust fan. Seems like the CFM standard is closer to 800 CFM, but that is flexible number depending on manufacture. Example I use. A clothes dryer located inside the conditioned space will change the air 100% for each hour of operation. The areas nearest the laundry room will see quicker air changes quicker tha areas furthest away. But on average, 100 % air exchange per hour of operation.

Also, special care must be taken if you have any vented fossil fuel equipment. Combustion air must be provided or dryer can cause vented equipment to back draft. This is why fireplace must have outside air ducts.

I should have know this wouldn't have been a cut and dry and answer. I appreciate all the information and experiences from everyone. Real world experience is what really matters.

I will contact a couple more foam installers and see what they say about the whole thing as well.

OP, There are varying opinions that aren't on the same page. Encapsulating the entire home with foam is essentially what you are doing with your metal building if you use closed cell. Envelope is the term used, and your living space is an envelope within an envelope. That is why I said that a batted living space should be adequate.

As far as open cell vs. closed cell, there were several valid points. A water leak will find it's way through open cell and the leak can be found. We had one in this home this year and got a new roof due to an unknown hail storm and damage.

Closed cell has always seemed to be the norm for metal buildings. However, technology is always changing and I don't know what may be the best solution right now.

For years the company that I worked for did metal building maintenance for municipalities and state buildings.
At one time the state was convinced that spray foam was the latest and greatest thing since sliced bread.
I can’t tell you how many buildings that we pulled off and replaced all sheeting, roof, walls and all due to rust formation from the inside out.
My recommendation would be to use the reinforced vinyl backed insulation. You can do an R-19 in roof with another 6” unbacked in between the purlins for the roof and a R-19 for walls.
That way if you ever have to change out sheeting you don’t have to strip the building down to framing to allow re-sheeting.
Just something to think about.

Our house isn’t a metal bldg, so my personal experience possibly wouldn’t apply to metal bldgs. Still, the Polyurethane foam we are talking about shouldn’t, by itself, cause rust. It would seem that a moisture barrier would prevent rusting, and surely they used it.

My barn/workshop/apartment is a metal building, and I sure wish I had foam insulation in the workshop and apartment.

i think its 3-400 cfm for the dryer. but it has to come from somewhere in the house