I have an existing ranch house at 1285 sq. ft. A new 2nd floor addition is going on top for 1285 sq. ft. The R-13 will go in the walls at 8' high. The R-38 will go in the attic. This is all on REScheck. Then he added R-60 batt between the existing first and new 2nd floor in the 16" TJI @16" o.c. And he passes by .4%. Can he add insulation between conditioned spaces for an addition? What is he insulating himself from?
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uhm.... I've never seen this.
- Thread starter rktect 1
- Start date
vegas paul
Silver Member
Re: uhm.... I've never seen this.
He may have two different HVAC systems up and downstairs... if he anticipates only occupying one or the other at times, this might make sense, but I agreee it is unusual. Did the ResCheck take the R60 between floors into account? I don't recall how that is done in ResCheck.
He may have two different HVAC systems up and downstairs... if he anticipates only occupying one or the other at times, this might make sense, but I agreee it is unusual. Did the ResCheck take the R60 between floors into account? I don't recall how that is done in ResCheck.
TimNY
Platinum Member
Re: uhm.... I've never seen this.
Seems strange, but I see nothing prohibiting it.
The way I look a it, if the 1st floor wasn't insulated at all, it would not only make more sense to put the insulation between the floors, but by putting the insulation in the space below the first floor you would be creating a nonconformity.
Otherwise you would have to verify U-Factor and existing insulation values on the first floor to be able to use insulation installed below the first floor. They couldn't be required to bring them up to current code if they weren't compliant, yet the new addition must be.
Seems strange, but I see nothing prohibiting it.
The way I look a it, if the 1st floor wasn't insulated at all, it would not only make more sense to put the insulation between the floors, but by putting the insulation in the space below the first floor you would be creating a nonconformity.
Otherwise you would have to verify U-Factor and existing insulation values on the first floor to be able to use insulation installed below the first floor. They couldn't be required to bring them up to current code if they weren't compliant, yet the new addition must be.
mjesse
Registered User
Re: uhm.... I've never seen this.
I agree with what TimNY says.
Bringing the second floor into compliance with the floor batts is cheaper than bringing the Complete (including 1st floor walls and windows) into compliance.
mj
I agree with what TimNY says.
Bringing the second floor into compliance with the floor batts is cheaper than bringing the Complete (including 1st floor walls and windows) into compliance.
mj
JBI
Registered User
Re: uhm.... I've never seen this.
Sound attenuation?
Sound attenuation?
Re: uhm.... I've never seen this.
I suspect that he is gaming the program. The program will automatically assign that floor area to either floor over unconditioned space, or floor over outside air. In either case, the program will assume an enlarged exterior envelope. Since that floor is heavily insulated, the average insulation of the exterior envelope is increased, and so by comparing it to a reference standard of a larger envelope, he passes.
I suspect that he is gaming the program. The program will automatically assign that floor area to either floor over unconditioned space, or floor over outside air. In either case, the program will assume an enlarged exterior envelope. Since that floor is heavily insulated, the average insulation of the exterior envelope is increased, and so by comparing it to a reference standard of a larger envelope, he passes.
TimNY
Platinum Member
Re: uhm.... I've never seen this.
It is a good point, REScheck only has options for floors over unconditioned space or outdoor space.
However, I would think it is reasonable to accept. If somebody submitted a REScheck for a floor over a basement, but selected over outdoor space rather than unconditioned space, would you accept it? The insulation values would be higher.
Similarly, if he is selecting over unconditioned space and the space is conditioned, should it be accepted?
If they are adding a second floor to an uninsulated house, do they have to insulate the whole house? I know you say the house is already insulated, but the precedent you set today should be applied to the uninsulated home that comes across your desk tomorrow.
If they are adding an addition off the back of an uninsulated house, do they have to insulate the whole house?
I don't see anything in the definition of "BUILDING THERMAL ENVELOPE" that conflicts with what they propose.
Would it be better if they used prescriptive methods, R-21 in the wall and R-19 (assumed value) in the space between floors? Why would it be different?
Just asking the questions, I'm really not passionate about it one way or the other. I personally would allow it.
It is a good point, REScheck only has options for floors over unconditioned space or outdoor space.
However, I would think it is reasonable to accept. If somebody submitted a REScheck for a floor over a basement, but selected over outdoor space rather than unconditioned space, would you accept it? The insulation values would be higher.
Similarly, if he is selecting over unconditioned space and the space is conditioned, should it be accepted?
If they are adding a second floor to an uninsulated house, do they have to insulate the whole house? I know you say the house is already insulated, but the precedent you set today should be applied to the uninsulated home that comes across your desk tomorrow.
If they are adding an addition off the back of an uninsulated house, do they have to insulate the whole house?
I don't see anything in the definition of "BUILDING THERMAL ENVELOPE" that conflicts with what they propose.
Would it be better if they used prescriptive methods, R-21 in the wall and R-19 (assumed value) in the space between floors? Why would it be different?
Just asking the questions, I'm really not passionate about it one way or the other. I personally would allow it.
vegas paul
Silver Member
Re: uhm.... I've never seen this.
ResCheck is designed to measure the thermal envelope of the home - the floor joist fill area described above is not part of the thermal envelope, therefore it should not be included in the calculation. Perhaps there is a more sophisticated tool, other than ResCheck, that could assign some value to this insulation, but ResCheck always treats it as thermal envelope, so using this insulation in the calc skews the result.
ResCheck is designed to measure the thermal envelope of the home - the floor joist fill area described above is not part of the thermal envelope, therefore it should not be included in the calculation. Perhaps there is a more sophisticated tool, other than ResCheck, that could assign some value to this insulation, but ResCheck always treats it as thermal envelope, so using this insulation in the calc skews the result.
TimNY
Platinum Member
Re: uhm.... I've never seen this.
Indeed the proposed insulation is in a floor and encloses conditioned space.
The only problem I see (not a problem for me, but I could understand if other AHJs went the other way) is that REScheck does not have a floor option "over conditioned space".
That being said, I do not see how you could prevent the prescriptive values from being used.
By definition, it is part of the thermal envelope. The definition of building thermal envelope includes "floors" (as opposed to "exterior walls" as specified in the definition) that enclose conditioned space.vegas paul said:
Indeed the proposed insulation is in a floor and encloses conditioned space.
The only problem I see (not a problem for me, but I could understand if other AHJs went the other way) is that REScheck does not have a floor option "over conditioned space".
That being said, I do not see how you could prevent the prescriptive values from being used.
Re: uhm.... I've never seen this.
He isn't using prescriptive values. Here he would need R-20 or R-13/R-5 in the walls. He only has R-13 in the walls.
Could he change this? Sure, but that isn't my call. I have to accept or deny his REScheck at this point. But I don't see how adding insulation into the floors does any good at all. All it does is waste money on insulation without adding one single benifit to the thermal envelope. I could place a pallet of insulation in the center of this room on the floor and it would have the same effect as he is getting.
He isn't using prescriptive values. Here he would need R-20 or R-13/R-5 in the walls. He only has R-13 in the walls.
Could he change this? Sure, but that isn't my call. I have to accept or deny his REScheck at this point. But I don't see how adding insulation into the floors does any good at all. All it does is waste money on insulation without adding one single benifit to the thermal envelope. I could place a pallet of insulation in the center of this room on the floor and it would have the same effect as he is getting.
Re: uhm.... I've never seen this.
I've been emailing REScheck DOE about this. So far I have been told to change on the project tab from new construction to addition/alteration. Once you do this go to the envelope tab and a new section called alteration details will appear. Where the new addition attaches to the existing building, in my case the floor, that componenet would change to one of the options available. Again in my case it was "alteration exposes a framing cavity but is filled with insulation". He doesn't get to pick his R-value for this. I am still trying to get more confirmation regarding this issue, but it seems more correct now.
And now this project fails by 13.5%.
I've been emailing REScheck DOE about this. So far I have been told to change on the project tab from new construction to addition/alteration. Once you do this go to the envelope tab and a new section called alteration details will appear. Where the new addition attaches to the existing building, in my case the floor, that componenet would change to one of the options available. Again in my case it was "alteration exposes a framing cavity but is filled with insulation". He doesn't get to pick his R-value for this. I am still trying to get more confirmation regarding this issue, but it seems more correct now.
And now this project fails by 13.5%.
FredK
Gold Member
Re: uhm.... I've never seen this.
Putting on my dummy hat as I didn't even know that was an option. Thank for the heads up.rktect 1 said:
TimNY
Platinum Member
Re: uhm.... I've never seen this.
I will respectfully disagree on insulation between the floors not doing any good at all, but I respect your position on having to accept or deny the REScheck.
Both the 4.2.0 and 4.3.0 versions of REScheck for NYS don't have this option (or I can't find it).rktect 1 said:
I will respectfully disagree on insulation between the floors not doing any good at all, but I respect your position on having to accept or deny the REScheck.
Re: uhm.... I've never seen this.
DOE REScheck personel called me up. They now explained that REScheck is not a performance based software program but instead is a tradeoff program. They told me that the floor has to be removed from the list. So what I had said in my previous post was incorrect. I still am not 100% certain what the alterations details does but they are specific about exemptions which they told me for my project I had none.
I was also informed that when a person wants to use spray foam insulation to be sure they are giving you the "installed" R-value and not the "effective" R-value. Just FYI. These should both be listed in the product specs.
DOE REScheck personel called me up. They now explained that REScheck is not a performance based software program but instead is a tradeoff program. They told me that the floor has to be removed from the list. So what I had said in my previous post was incorrect. I still am not 100% certain what the alterations details does but they are specific about exemptions which they told me for my project I had none.
I was also informed that when a person wants to use spray foam insulation to be sure they are giving you the "installed" R-value and not the "effective" R-value. Just FYI. These should both be listed in the product specs.
Re: uhm.... I've never seen this.
You're never going to get the entire structure to comply when you add an addition to an existing, under-insulated home.... and it's not the intent to require it.. people will stop doing additions and renovations if they are required to replace all windows and insulate every existing wall. Renovations are a significant revenue source for most building departments.
You're never going to get the entire structure to comply when you add an addition to an existing, under-insulated home.... and it's not the intent to require it.. people will stop doing additions and renovations if they are required to replace all windows and insulate every existing wall. Renovations are a significant revenue source for most building departments.