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RES Check and Duct Insualtion

V

VIC1958

Member
Joined
Jan 7, 2015
Messages
7
Location
Chicago
Getting confused here, received RESCheck report and I noticed on the Inspectors Check List that the insulation for the duct work located outside the building envelope is suppose to be R8 for all supply and R6 for all others. It is not noted on the plans or any where else in the RESCheck report that the ducts need to be insulate. Can I assume that if it is noted on the inspection checklist that it must conform to those requirements? The confusion I see is that the 2012 IECC states insulating the duct work is listed as prescriptive and the RESCheck is a Total Building Trade-Off. Thanks in advance for the help
 
The insulation used in calcs over rides the prescriptive because of some other trade off in calcs. You can always go higher on duct insulation.
 
ResCheck is only requiring what the prescriptive minimums are in the IECC

Residential

403.2.1 Insulation (Prescriptive).

Supply ducts in attics shall be insulated to a minimum of R-8. All other ducts shall be insulated to a minimum of R-6.

Exception: Ducts or portions thereof located completely inside the building thermal envelope.

No trade off given that I can see
 
Exception: Ducts or portions thereof located completely inside the building thermal envelope......That is the only break you could get, but I agree with JDF, what the rescheck says is the min for the project due to the systems of tradeoffs and it could be made better. Also the printout that is to be posted near the electrical panel should be corrected to show what was actually done...
 
R403.2.1 lists the prescriptive duct outside the envelope insulation requirements of R-8 supply, R-6 all other.

If performance based method is used (i.e. ResCheck) then R405.2 states the mandatory requirement of all ducts outside the envelope to be minimum R-6.
 
It is my understanding that RESCheck is used for Total Building UA trade off and that Section 405 Simulated Performance Alternative would use software ie: REM/Rate. So 405.2 would not would not be addressed if REScheck was used.
 
So are you saying that the R6 and R8 are minimums that MUST be met, but they can go higher on the duct insulation and maybe go less somewhere else?
 
If RESCheck says R8 for supply, that is the min you must install on the supply ducts that are outside the conditioned envelope. If RESCheck says R6 for all other ducts, that is the min you must install on those ducts that are outside the conditioned envelope.
 
VIC1958 said:
It is my understanding that RESCheck is used for Total Building UA trade off and that Section 405 Simulated Performance Alternative would use software ie: REM/Rate. So 405.2 would not would not be addressed if REScheck was used.
Click to expand...
ResCheck, Rem Rate, HERS, et.al. are Simulated Performance Alternatives. If you are designing with one of these programs, R405 is applicable.

If you are not using a program, R402 and R403 are applicable.

If you are using ResCheck, and the design calls for R-8/R-6 duct insulation, that's what shall be used.
 
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