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Thad Opat
Posted: Oct 14, 2014 03:45 PM
new construction zone 4
1)Would like to know correct amount of closed cell spray foam to use in 2x6 walls and (underside of roof sheathing) vaulted ceiling for Zone 4 being southern kansas?
2)Should one leave gap in wall or fill with other insulation to fill cavity since wall is 2x6? Ceiling as well?
3)How would one know if hvac's load calculation is done correctly for spray foam? Is there a website to go to where you can do a load calc on your house?

mark moyer
Posted: Oct 17, 2014 09:06 PM
1) depends on what code you are building too..
2009? 2012?? 2015?? (yep,,,screw 2012,,lets waste more time enacting real energy efficient building mandates and wait for the next "cycle"...and the beat goes on..oh yes,,and thanx SPFA..your in the bed with the wrong govt agency..help me make more money,,i pay you dues)

the book will tell you what to do...its pretty much black and white..REMEMBER THOSE SPECS ARE MINIMUMS...if your contractor "aint sure" HIRE A
"FOAM FRIENDLY BUILDER" that knows his P's&Q's

2) dead air space has R value...most cc foams air impermeable ~3/4",,,most open cells 3"..this cavity will be the same temp or +/-1 degree in the 2x6 wall..
Think of the ceiling airspace as only there because you had to hang drywall to meet the fire rating of the assembly...(NOT THE BECAUSE OF THE FOAM...CLASS 1 FOR INTERIOR FOAM,,BUT THE CLASS 3 FOR THE FRAMING MEMBERS AND SHEETING AND OTHER WOOD COMPONENTS)thank you SPFA!!!!

3) you hire a real H VAC tech just like you hire a real SPF contractor,,,they understand manual J...(wattzaa j?) and what the crap means...pay the fee its worth it..for SPF to be cost effective it has to be integrated at the design level,,not as an afterthought..
manual j its out there,,and even you can do the calculations if you understand the technology,,

foam-it! however????

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