INSULATION DEBATE....AGAIN

[Airforce_NavyDAD]

Hi all. New to the boards. We are going to start our Barndo built here very soon. My debate is over slab insulation. I've seen this talked about here along with other places so I figured I'd poke the bear once again.

No part of our build will have radiant heating. From what I've seen, EPX Insulation is the best bet @ 2" thick. We are in NW Indiana and our frost ranges from 48-60" depending on your proximity to the Toll Road. Regardless, is the 2" EPX still the best bet in my circumstances? Is 2" excessive?

What are the thoughts on the "magic" Prodex roll insulation?

Thank you all!

 

[egdede]

The magic stuff is fine, but hard to source. The regular kind is overhyped.

 

[Sumboodie]

Why not heat the floor? It's awesome to work on a warm floor vs freezing with insulated clothes on under a truck but dripping in sweat at the workbench.

I'm assuming Barndo means shop.

 

[Stuart in MN]

Barndo = barndominium.

I'm a little confused by your statement "No part of our build will not have radiant heating." It's sort of a double negative, do you mean there will be no radiant heating at all, or that the entire slab will have radiant heat?

When you say Prodex insulation, I assume you mean the thin bubble wrap kind of stuff with a foil face - the manufacturers tend to exaggerate on the R value of those kinds of products. They may provide some radiant protection, but they don't provide much insulation. It's mostly used in walls and ceilings, I'm not aware if it's suitable for use under a slab.

 

[bdbecker]

I kind of agree with what has already been posted... at the very least, why not insulate and run the tube in case you change your mind in the future? Even if you never hook it up, it would likely be a selling point to the next potential owner.

 

[billconner]

I think op is say all of slab will be radiant heated.

There are other insulation products for under slab but 2" EPS or XPS is common.

Are you going to extend the insulation and use it for a shallow frost protected foundation?

Post frame/pole barn or pre-emgineered steel frame or stick built? All of those and probably more have been used in barndominiums. It could impact foundation, slab or otherwise.

Likely to be permitted and inspected? You don't say where you are so can't take climate into account.

 

[LB-1911]

I think op is say all of slab will be radiant heated.

You don't say where you are so can't take climate into account.

Hi all. New to the boards. We are going to start our Barndo built here very soon. My debate is over slab insulation. We are in NW Indiana and our frost ranges from 48-60" depending on your proximity to the Toll Road. Regardless, is the 2" EPX still the best bet in my circumstances? Is 2" excessive?

 

[billconner]

Sorry. So used to clicking on name missed the statement.

 

[theoldwizard1]

There are other insulation products for under slab but 2" EPS or XPS is common.

Are you going to extend the insulation and use it for a shallow frost protected foundation?

Assuming there will be a footer around the perimeter It is EXTREMELY important that the footer should be insulated to the depth of the frost line.

 

[billconner]

Assuming there will be a footer around the perimeter It is EXTREMELY important that the footer should be insulated to the depth of the frost line.

Not sure what you're saying but even if insulation extends several feet past slab edge? And do you mean the frost line with or without the insulation? The insulation basically raises the frost line.

 

[theoldwizard1]

Not sure what you're saying but even if insulation extends several feet past slab edge? And do you mean the frost line with or without the insulation? The insulation basically raises the frost line.

Most garages have a "footer"/foundation that runs around the perimeter of the slab and goes as deep as the frost line (in some places this is call a "rat wall" because it prevents rodents from burrowing under the slab). This need to be insulated to the full depth.

The frost line under the slab doesn't matter. It is the frost line outside of the footer/foundation/rat wall. This is still the strongest way to build in areas that have a deep frost line.

 

[Airforce_NavyDAD]

Why not heat the floor? It's awesome to work on a warm floor vs freezing with insulated clothes on under a truck but dripping in sweat at the workbench.

I'm assuming Barndo means shop.

I don't want radiant heat. The cost to run it far outweighs the benefits. We are in propane country and utilizing a Geothermal Heat pump for our needs.

 

[LopezBart]

I don't want radiant heat. The cost to run it far outweighs the benefits. We are in propane country and utilizing a Geothermal Heat pump for our needs.

Our house has a heat pump and radiant heat... they do work together quite well.

 

[Airforce_NavyDAD]

Our house has a heat pump and radiant heat... they do work together quite well.

Again, it would be cost prohibitive with propane.

 

[LopezBart]

The heat pump supplies the hot water for the radiant heat. We only use propane for cooking.

 

[Airforce_NavyDAD]

Still don't want radiant. You need an auxiliary so yours must be electric. No thanks. You cannot have forced air heat and generate heating water at the same time. No thanks.

 

[Airforce_NavyDAD]

I kind of agree with what has already been posted... at the very least, why not insulate and run the tube in case you change your mind in the future? Even if you never hook it up, it would likely be a selling point to the next potential owner.

No radiant for us.

 

[Airforce_NavyDAD]

Barndo = barndominium.

I'm a little confused by your statement "No part of our build will not have radiant heating." It's sort of a double negative, do you mean there will be no radiant heating at all, or that the entire slab will have radiant heat?

When you say Prodex insulation, I assume you mean the thin bubble wrap kind of stuff with a foil face - the manufacturers tend to exaggerate on the R value of those kinds of products. They may provide some radiant protection, but they don't provide much insulation. It's mostly used in walls and ceilings, I'm not aware if it's suitable for use under a slab.

Yes, no radiant. Thank you.

 

[Airforce_NavyDAD]

I think op is say all of slab will be radiant heated.

There are other insulation products for under slab but 2" EPS or XPS is common.

Are you going to extend the insulation and use it for a shallow frost protected foundation?

Post frame/pole barn or pre-emgineered steel frame or stick built? All of those and probably more have been used in barndominiums. It could impact foundation, slab or otherwise.

Likely to be permitted and inspected? You don't say where you are so can't take climate into account.

I am not extended insulation to frost. There will be a rodent wall extending 24" below the slab that will be insulated. The soil is well drained sand /gravel mix. I don't know what I would insulate below the rodent wall since the slab is "floating". Unless I'm missing something.

 

[pcmeiners]

As you can see some really like slab heating

"Yes, no radiant. Thank you." .......I believe it is sinking in, slowly


2" of XPS is better the EPS, less heat and moisture conduction, thicker the better as long as you can afford it.

"EPS has a water vapour diffusion resistance of 30-70, whereas XPS reaches 80-250. Slightly more permeable to air and moisture, EPS is less resistant to water vapour than XPS. If you’re looking to insulate a space prone to humidity (e.g. floors, cellars, and foundation walls), XPS is your best option. "

Moisture/air movement through insulation moves heat along with them. You can be sure EPS R-value does not include the effect of ground moisture.

Blog

www.soprema.co.uk

Notice in this image the exterior buried insulation, horizontal wing insulation is a good idea


"We are in propane country and utilizing a Geothermal Heat pump for our needs."

Your using electric for the heat pump, correct? Just checking as some commercial installs use propane in the adsorption process

 

[Airforce_NavyDAD]

Thank you for the excellent explanation of the differences. And the detail dwg. Very clear now. I've not be presented with this by the A/E we utilized so this has me wondering and and I will certainly be posing some questions tomorrow.

"Your using electric for the heat pump, correct?"
Yes of course it is electric. My auxiliary will be an HW coil in the duct tied into a small boiler system for DHW and Backup heat. The electric consumed by the DX cycle is far less than that used to run resistance toasters compared to the amount of energy created. I'm not sure where you were going with this one.

 

[Sumboodie]

Assuming there will be a footer around the perimeter It is EXTREMELY important that the footer should be insulated to the depth of the frost line.

It normal in the L48 to have footers that deep?

 

[Sumboodie]

As you can see some really like slab heating

"Yes, no radiant. Thank you." .......I believe it is sinking in, slowly


2" of XPS is better the EPS, less heat and moisture conduction, thicker the better as long as you can afford it.

"EPS has a water vapour diffusion resistance of 30-70, whereas XPS reaches 80-250. Slightly more permeable to air and moisture, EPS is less resistant to water vapour than XPS. If you’re looking to insulate a space prone to humidity (e.g. floors, cellars, and foundation walls), XPS is your best option. "

Moisture/air movement through insulation moves heat along with them. You can be sure EPS R-value does not include the effect of ground moisture.

Blog

www.soprema.co.uk

Notice in this image the exterior buried insulation, horizontal wing insulation is a good idea


"We are in propane country and utilizing a Geothermal Heat pump for our needs."

Your using electric for the heat pump, correct? Just checking as some commercial installs use propane in the adsorption process

Like it because it's awesome for a shop. Granted I heat 9-10 months a year. Heating season is about September to May. Not uncommon to kick the heat on atleast several times every month.

. Even better is a "dual system" with some type of forced air for quick recovery.

As far as slan insulation, 2" is the minimum.

 

[Airforce_NavyDAD]

It normal in the L48 to have footers that deep?

In our area frost is between 48-60". This is very generalized and no two Engineers will agree. Oxymoron I know...
We are in very good drainage so that benefits us in some regards.

 

[Airforce_NavyDAD]

I think op is say all of slab will be radiant heated.

There are other insulation products for under slab but 2" EPS or XPS is common.

Are you going to extend the insulation and use it for a shallow frost protected foundation?

Post frame/pole barn or pre-emgineered steel frame or stick built? All of those and probably more have been used in barndominiums. It could impact foundation, slab or otherwise.

Likely to be permitted and inspected? You don't say where you are so can't take climate into account.

This will be Post Frame/ Pole style construction for both the home and shop/garage area. This will all be done legally.

 

[LB-1911]

This will be Post Frame/ Pole style construction for both the home and shop/garage area. This will all be done legally.

Thank you for the excellent explanation of the differences. And the detail dwg. Very clear now. I've not be presented with this by the A/E we utilized so this has me wondering and and I will certainly be posing some questions tomorrow.

Have you checked what info the county building / permitting office in which your project is located has available?

The code in effect for the construction of one-and two-family dwellings and townhouses is the 2020 Indiana Residential Code (effective December 26, 2019). The 2020 IRC is based on the 2018 International Residential Code with Indiana amendments.

View the free, digital version of the 2020 IRC here

Digital Codes

ICC Digital Codes is the largest provider of model codes, custom codes and standards used worldwide to construct safe, sustainable, affordable and resilient structures.

codes.iccsafe.org

Good Luck w/your project.

 

[pcmeiners]

Yes of course it is electric. My auxiliary will be an HW coil in the duct tied into a small boiler system for DHW and Backup heat. The electric consumed by the DX cycle is far less than that used to run resistance toasters compared to the amount of energy created. I'm not sure where you were going with this one."

Where was I going ... though not common propane could be used, not efficient at 150% vs a COP of 4++ for electric geo, and expensive, some people/companies would actually go for it. Wish I had the resources for geo, I had to go multiple single zone standard heat pumps to gain efficiency close to geo ( a little over COP4)

Even with the foam boards I would use a vapor barrier below the boards. Make sure they compact the ground and gravel properly, rarely done properly.

 

[luvtheheat]

In our area frost is between 48-60".

Ask me again why I live in southern AZ.....

 

[pcmeiners]

"Ask me again why I live in southern AZ....."

I won't..., I was in Flagstaff for one day in 1979?, it was 119° at 3pm. I could not live there with the possibility of that temperature.

 

[Airforce_NavyDAD]

Yes of course it is electric. My auxiliary will be an HW coil in the duct tied into a small boiler system for DHW and Backup heat. The electric consumed by the DX cycle is far less than that used to run resistance toasters compared to the amount of energy created. I'm not sure where you were going with this one."

Where was I going ... though not common propane could be used, not efficient at 150% vs a COP of 4++ for electric geo, and expensive, some people/companies would actually go for it. Wish I had the resources for geo, I had to go multiple single zone standard heat pumps to gain efficiency close to geo ( a little over COP4)

Even with the foam boards I would use a vapor barrier below the boards. Make sure they compact the ground and gravel properly, rarely done properly.

Thank you!

 

[Airforce_NavyDAD]

Ask me again why I live in southern AZ.....

My oldest is stationed at Davis. He says it's a toss-up between Syria and Davis with regards to desert heat. One more deployment then my boy comes home finally...

I'm not built for heat like that. I have the wrong body type...

 

[pcmeiners]

Yes, my body was not designed for heat, more toward -40°. If I were station in the Davis area, I would shrivel up, and mummify.

 

[hh76]

Most garages have a "footer"/foundation that runs around the perimeter of the slab and goes as deep as the frost line (in some places this is call a "rat wall" because it prevents rodents from burrowing under the slab). This need to be insulated to the full depth.

The frost line under the slab doesn't matter. It is the frost line outside of the footer/foundation/rat wall. This is still the strongest way to build in areas that have a deep frost line.

I just poured with a "frost protected shallow foundation". The idea is to insulate out far enough from the foundation that frost never forms under.

 

[Airforce_NavyDAD]

I just poured with a "frost protected shallow foundation". The idea is to insulate out far enough from the foundation that frost never forms under.

That is the way I understand it. How far out from the rodent wall did you insulate?

 

[Firebrick43]

Hi all. New to the boards. We are going to start our Barndo built here very soon. My debate is over slab insulation. I've seen this talked about here along with other places so I figured I'd poke the bear once again.

No part of our build will have radiant heating. From what I've seen, EPX Insulation is the best bet @ 2" thick. We are in NW Indiana and our frost ranges from 48-60" depending on your proximity to the Toll Road. Regardless, is the 2" EPX still the best bet in my circumstances? Is 2" excessive?

What are the thoughts on the "magic" Prodex roll insulation?

Thank you all!

Prodex is snake oil except as a condensation blanket under a metal roof.

It’s especially bad to use it under a slab. The air filled cells will in no way survive any length of time meaning the only good it would do is a very expensive vapor barrier which stegowrap will perform much better and cheaper in that regard

 

[hh76]

That is the way I understand it. How far out from the rodent wall did you insulate?

7', which was what is what's called for in my location.

No frost wall, just thickened edge slab.

 

[MadScientist3019]

Assuming there will be a footer around the perimeter It is EXTREMELY important that the footer should be insulated to the depth of the frost line.

This is very important as noted.

I am not extended insulation to frost. There will be a rodent wall extending 24" below the slab that will be insulated. The soil is well drained sand /gravel mix. I don't know what I would insulate below the rodent wall since the slab is "floating". Unless I'm missing something.

I will say that if you're looking for bang for your buck insulating vertically and depending on location some wing insulation will actually be the best bet. The only reason to insulate all of the horizontal sq footage is when you do in floor heat but you don't want to do that (I don't disagree). I will say that with my build I went with 2" of foam panel down to my frost line vertically and no wings. What this does is allow the ground to be a heat sink that works in both summer and winter. The ground temperatures don't vary much below frost line.

In the end I'm keeping my 40x60 post frame building at 70 degrees with only 2x 12k btu heat pumps and the cost is minimal. The other thing to consider is a thermal barrier at the outer wall. I ran 1" of foam continuous outside my framing members and the underground insulation is just a continuation of this. Check out some research of this as well, there's lots out there like this one:

DOE Building Foundations Section 4-1 Insulation Location

This resource helps identify amount of insulation by your location in the US as well:

https://www.homeinnovation.com/~/media/Files/Reports/Revised-Builders-Guide-to-Frost-Protected-Shallow-Foundations.pdf

 

[Airforce_NavyDAD]

There will be no footer around the perimeter except for the cookies that support the perma-columns. Are you saying I should wrap those and out horizontally outside of the building?

 

[MadScientist3019]

There will be no footer around the perimeter except for the cookies that support the perma-columns. Are you saying I should wrap those and out horizontally outside of the building?

It sounds like a typical post frame like I did so you'll have a grade board that goes from post to post at ground level. I attached my foam to that and excavated between the posts like a trench between them and inserted my foam vertically and backfilled with gravel and some perforated pipe so i've got very good moisture control as well while I was in there. I did it all by hand as i did it after initial construction and I built the whole thing myself by hand but you could do this with a trencher or backhoe style equipment too if done before the posts are set.

 

[Sumboodie]

In our area frost is between 48-60". This is very generalized and no two Engineers will agree. Oxymoron I know...
We are in very good drainage so that benefits us in some regards.

It's around 120" here, allegedly. But I've seen water lines only buried 4-5ft and be ok, and ones buried 10-12ft that freeze.