Insulation in pole barn help!?

[Catadj78]

I have ordered my materials for my shop with the exception of the upper wainscoating, doors, windows, insulation and they are set to be delivered once the trusses are made.

So I need to figure out a few more things before I go get the last set of materials and before roof metal goes on.

The metal company that is providing the materials has double bubble insulation I can order for the roof and walls for $550 total.

From what I have read double bubble is R1.

It is my understanding with this double bubble on both the walls and roof I will not have any condensation issues which is important however I do plan on at least heating the building. Maybe some kind of cooling down the road.

The building will be 40x40 10' eaves with a roughly 14x25 office that I plan on framing with 2x4s and roll insulation in this portion regardless as it will be heated and cooled right away.

Sorry for the long post but the questions is

I have an opportunity to purchase 1900 sq ft of r9 fanfold for $650 which is enough for the roof would this be better for the roof? Would I need a moisture barrier on top of the fanfold?

I also have found 1400 sq ft of unfaced r19 which is enough to do the exterior walls for $470. I would need a moisture barrier here I assume.

I will have to order a little more for the office but I am just worried about the building itself for now.

Is is worth the roughly $500 extra expense?

I am not insulating below the slab. I live in central Alabama

My main concerns is condensation in the building but I would like to be able to work in the building when it is 30 outside. We see very few days below this.

Advice? Suggestions?

I am worried about budget to an extent but that has been over since I registered here.

I plan on putting something on the interior walls but not entirely sure at this point. There will be no ceiling however.

thanks a lot for all of the ideas I have already stolen from you guys.

 

[justin1795]

price out what It would cost to stud up the walls on 24 centers and use roll insulation. might surprise you

 

[Catadj78]

price out what It would cost to stud up the walls on 24 centers and use roll insulation. might surprise you

My original plan was just use the double bubble and then come back later framing up a couple wall sections at a time and placing unfaced roll insulation.

I still may do it this way on the walls but seems like it is going to be much much easier to use the rigid insulation on the roof before the roof metal went on and then maybe another layer between the purlins.

Another thing, is house wrap worth messing with in a metal pole barn?

thanks

 

[squarles67]

I had the "double bubble" put on mine and I've had no issue with condensation. I'm in Southeast Texas with weather very similar to yours. Mine is a 42 x 50 pole barn with 14' walls. I considered putting sheet metal on the bottom of the trusses and blowing insulation on top to help protect from the heat in summer time but decided against it due to cost.

I'm also framing up a 12 x 30 section that will be insulated, heated and cooled.

 

[tmcelheny]

Id say go for it.. I spent about 600 additional adding 1/2" RBoard insulation between my metal and purlins.. nothing on the ceiling because eventually I will adding metal and blown in insulation later (it gets below 0 here in PA often) building is 30X40X12

 

[Catadj78]

I had the "double bubble" put on mine and I've had no issue with condensation. I'm in Southeast Texas with weather very similar to yours. Mine is a 42 x 50 pole barn with 14' walls. I considered putting sheet metal on the bottom of the trusses and blowing insulation on top to help protect from the heat in summer time but decided against it due to cost.

I'm also framing up a 12 x 30 section that will be insulated, heated and cooled.

Great looking shop.

How does it do in the winter? Get real cold?

 

[CA_Tallguy]

I'm in the process of putting up 2 layers of 3/4 polyiso rigid foam right now. Also taping the seams. This is going to cover the entire outer skin of my building, right under the metal (actually, I'm also going to put 1x4 lathing strips to create an extra air gap behind the metal).

Anyway, it's a LOT more work than I expected, especially since we're taping the seams. And we're doing it on the roof, over the framing, without any hard deck under it. So we have to be really careful up there not to fall through! LOL.

If I were in your shoes, I would do a LOT more R value when I put in the effort to insulate. Maybe wait to insulate if you are on a tight budget right now. I don't think a bit of condensation will kill you for a short time. I just don't know if it is worth the time to do R1.

Are you sure that R1 will prevent condensation? Or will the insulation just trap it so you don't know it is there? Now THAT would be a problem!

 

[Catadj78]

I'm in the process of putting up 2 layers of 3/4 polyiso rigid foam right now. Also taping the seams. This is going to cover the entire outer skin of my building, right under the metal (actually, I'm also going to put 1x4 lathing strips to create an extra air gap behind the metal).

Anyway, it's a LOT more work than I expected, especially since we're taping the seams. And we're doing it on the roof, over the framing, without any hard deck under it. So we have to be really careful up there not to fall through! LOL.

If I were in your shoes, I would do a LOT more R value when I put in the effort to insulate. Maybe wait to insulate if you are on a tight budget right now. I don't think a bit of condensation will kill you for a short time. I just don't know if it is worth the time to do R1.

Are you sure that R1 will prevent condensation? Or will the insulation just trap it so you don't know it is there? Now THAT would be a problem!

I believe the purpose of the double bubble is more for a radiant and moisture barrier that just so happens to have a little insulation value.

I am leaning towards just going with my original plan of the double bubble for now since I am not 100% on what will be covering the walls, electrical layout etc and just do the additional insulation at that time.

My trusses are steel and angles up towards the ridge to give me additional ceiling height. I do not plan on putting a ceiling so I will have to go with several layers of rigid insulation between the 2x6s and trusses

 

[CA_Tallguy]

As for your question about house wrap and since you also mentioned moisture barriers...

What you really need to be looking at is "permeability" of the different materials you are considering and the total "wall assembly" you plan with all the layers of different materials and how they are installed (venting, etc).

I've recently gone through a bunch of different options and it can start to make your head spin. There are charts for various materials out there to tell you what the perm rating is. From what I recall, there may even be separate perm ratings for moisture/liquid vs vapor. For instance, Tyvek brags about their vapor permeability while other competitors argue that Tyvek's vapor permeability is far too high.

I have no idea on who is right. Well, I do suspect that you have to look at the whole wall assembly and layers of materials to determine who is right. In some applications, you may want to retain some of that vapor permeability but in others you might want a complete barrier.

Now, keep in mind that certain materials may be VERY impermeable... so they are effectively a vapor and/or moisture barrier! Like the double bubble and vinyl faced fiberglass roll insulation! And there is some rule of thumb in building science, I believe, where you absolutely do not want to have dual vapor barriers (or materials that act like one) at different layers in your assembly. I guess that traps moisture between them an it has no place to go so you get rot or mold or something.

The other rule of thumb I read about is that your walls need to be able to dry outward or inward. Or I think they need to be able to dry both outward AND inward from wherever you have a moisture barrier.

What I decided to try to accomplish with my building is to have a secondary "drainage plane" and extra venting underneath my metal. So any condensation that accumulates has a way to dry out and/or drain out (you have to plan for the drainage and venting in your installation). I'm hoping that the extra venting will use convective action to exhaust the heat out from behind the metal siding/roofing during the very hot texas summers. Plus, I just like the idea of having secondary protection against any leaks and condensation that might get under my R-Panel.

One side note -- many metal roofing panel profiles like R-panel claim to be "self venting" so you don't absolutely need to do the extra venting space I am. I just want to see if it helps take the edge off the heat so my rigid foam underneath doesn't have to work so hard to keep it out.

In the end, with regards to house wrap, I decided to use the foil facing on my polyiso rigid foam insulation as my secondary drainage plane and moisture barrier. This foil facing is really impermeable so there didn't seem to be much point in using a house wrap as well. (Except it might be more durable... and if I did use one, I'd probably want a high permeability like Tyvek since my polyisio is so impermeable with the foil facing).

 

[CA_Tallguy]

I am leaning towards just going with my original plan of the double bubble for now since I am not 100% on what will be covering the walls, electrical layout etc and just do the additional insulation at that time.

As per my post on vapor/moisture barriers - just keep in mind that I believe your double bubble will function as one, which will necessitate your planning on allowing a way for all layers of insulation and other materials underneath it to dry inwards. For example, it might be a bad idea to use that vinyl faced insulation in conjunction with the double bubble as the material sandwiched in the middle would have no way for moisture to escape.

So you are kind of locking yourself in as to future possibilities by going with the double bubble. I told my contractor that I didn't want the vinyl faced fiberglass insulation for that reason.

 

[Catadj78]

As for your question about house wrap and since you also mentioned moisture barriers...

What you really need to be looking at is "permeability" of the different materials you are considering and the total "wall assembly" you plan with all the layers of different materials and how they are installed (venting, etc).

I've recently gone through a bunch of different options and it can start to make your head spin. There are charts for various materials out there to tell you what the perm rating is. From what I recall, there may even be separate perm ratings for moisture/liquid vs vapor. For instance, Tyvek brags about their vapor permeability while other competitors argue that Tyvek's vapor permeability is far too high.

I have no idea on who is right. Well, I do suspect that you have to look at the whole wall assembly and layers of materials to determine who is right. In some applications, you may want to retain some of that vapor permeability but in others you might want a complete barrier.

Now, keep in mind that certain materials may be VERY impermeable... so they are effectively a vapor and/or moisture barrier! Like the double bubble and vinyl faced fiberglass roll insulation! And there is some rule of thumb in building science, I believe, where you absolutely do not want to have dual vapor barriers (or materials that act like one) at different layers in your assembly. I guess that traps moisture between them an it has no place to go so you get rot or mold or something.

The other rule of thumb I read about is that your walls need to be able to dry outward or inward. Or I think they need to be able to dry both outward AND inward from wherever you have a moisture barrier.

What I decided to try to accomplish with my building is to have a secondary "drainage plane" and extra venting underneath my metal. So any condensation that accumulates has a way to dry out and/or drain out (you have to plan for the drainage and venting in your installation). I'm hoping that the extra venting will use convective action to exhaust the heat out from behind the metal siding/roofing during the very hot texas summers. Plus, I just like the idea of having secondary protection against any leaks and condensation that might get under my R-Panel.

One side note -- many metal roofing panel profiles like R-panel claim to be "self venting" so you don't absolutely need to do the extra venting space I am. I just want to see if it helps take the edge off the heat so my rigid foam underneath doesn't have to work so hard to keep it out.

In the end, with regards to house wrap, I decided to use the foil facing on my polyiso rigid foam insulation as my secondary drainage plane and moisture barrier. This foil facing is really impermeable so there didn't seem to be much point in using a house wrap as well. (Except it might be more durable... and if I did use one, I'd probably want a high permeability like Tyvek since my polyisio is so impermeable with the foil facing).

I will have R panel for the exterior. It seems to me the R panel would not be air tight so you would feel the wind blowing inside the building. I was planning on boxing the corners in completely with 2x6s and use some kind of spray foam to fill in any voids in the walls. I will have 1' overhang with vented soffit as well as a ridge vent.

As per my post on vapor/moisture barriers - just keep in mind that I believe your double bubble will function as one, which will necessitate your planning on allowing a way for all layers of insulation and other materials underneath it to dry inwards. For example, it might be a bad idea to use that vinyl faced insulation in conjunction with the double bubble as the material sandwiched in the middle would have no way for moisture to escape.

So you are kind of locking yourself in as to future possibilities by going with the double bubble. I told my contractor that I didn't want the vinyl faced fiberglass insulation for that reason.

I was planning on insulating with unfaced batt on the walls to stay away from having multiple vapor barriers

 

[CA_Tallguy]

I will have R panel for the exterior. It seems to me the R panel would not be air tight so you would feel the wind blowing inside the building. I was planning on boxing the corners in completely with 2x6s and use some kind of spray foam to fill in any voids in the walls. I will have 1' overhang with vented soffit as well as a ridge vent.

The profile of the R-panel is what makes it "self-venting" but yes that means it isn't air-tight. That's where your secondary house wrap, vapor barrier, rigid foam or even just sheathing like OSB comes in... if you want to make use of that venting. They make screens to go in there and they also have blocking fillers for people who want to just block it. Or you can fashion your own screens to allow air to circulate but keep the bugs out.

Making use of the venting in the panel profile, going up to your ridge vent on the roof and just exhausting at the top of outside walls, will give you a higher performance building.

I suspect a lot of people just try to seal up the R-panel not understanding the venting. That was my first idea before I did a lot of research over the last few months.

 

[CA_Tallguy]

Here are some good diagrams of various ways to build an envelope. These are for residential construction so of course it isn't necessary to go this far on an outbuilding. But it is good to help understand some of the concepts.

Note where they have furring strips in the assembly for a ventilation cavity. That is kind of built in to the R-panel to some limited degree, but to make use of it, that's where it is best to have a continuous layer of another material under the siding, forming the inside wall of the ventilation cavity.

http://web.ornl.gov/sci/buildingsfoundations/handbook/section4-2.shtml

 

[Catadj78]

Here are some good diagrams of various ways to build an envelope. These are for residential construction so of course it isn't necessary to go this far on an outbuilding. But it is good to help understand some of the concepts.

Note where they have furring strips in the assembly for a ventilation cavity. That is kind of built in to the R-panel to some limited degree, but to make use of it, that's where it is best to have a continuous layer of another material under the siding, forming the inside wall of the ventilation cavity.

http://web.ornl.gov/sci/buildingsfoundations/handbook/section4-2.shtml

thanks a lot.

My main concern is condensation in the building. One of my FILs barns/shops floor stays wet when it rains and drips from the ceiling on occasions which makes for working in it miserable. I believe the double bubble and moisture barrier under the concrete will solve this. When I frame up for my office it will be totally insulated however since the shop will be an ongoing project anyways Ill wait for the batt insulation.

I added another roll of double bubble to my order so that I will have enough to wrap the corners well enough. thanks for the help!!

 

[squarles67]

Great looking shop.

How does it do in the winter? Get real cold?

This will be it's first winter. So far it does pretty good with big temperature swings but if it stays cold it gets pretty chilly inside.

 

[Catadj78]

This will be it's first winter. So far it does pretty good with big temperature swings but if it stays cold it gets pretty chilly inside.

Do you heat it? If so how?

thanks

 

[kluckfab]

You can always build a false wall then insulate the false wall then you could leave a void so the air can breath behind the insulation, this is a bad photo but that is what I did.

 

[Catadj78]

This is what I was planning on doing something similar to this when I start on the walls.

 

[kluckfab]

Yeah figure with drywall, framing, and insulation it is about $30 for a 8' section. I use r13 but that is fine since the tin acts a barrier. I am cheap and I am doing 24" on center studs.

 

[Catadj78]

Yeah figure with drywall, framing, and insulation it is about $30 for a 8' section. I use r13 but that is fine since the tin acts a barrier. I am cheap and I am doing 24" on center studs.

I was thinking about running the framing the other way on the exterior walls. I may go ahead and put them in as I am framing before I put the metal up. Seems like it will make the building stronger this way.

$30 a section doesn't seem bad though

 

[kluckfab]

Yeah I am cheap I would like to do spray foam but I can justify that cost. I will be posting finally pictures soon.

 

[Catadj78]

Yeah I am cheap I would like to do spray foam but I can justify that cost. I will be posting finally pictures soon.

I am cheap too. Unless I get a killer deal on someone spraying it I dont see my building getting any either.

 

[maynard9089]

If you are concerned about moisture ask your metal supplier if they offer Dripstop. I have it on my roof and have zero condensation issues. It didn't add much cost to the material.

 

[squarles67]

I haven't used any heat. I have a torpedo kerosene heater but haven't fired it up yet.

 

[Autiger1892]

Any chance the OP is still around and could give an update?

Sent from my Pixel 3 XL using Tapatalk

 

[trbomax]

This is what I was planning on doing something similar to this when I start on the walls.

t

This is what I did except that bottom sill shoul;d be treated.