I have gotten a lot of good ideas from this site and they have help me formulate a plan for my dilemma. Just wanted to get some input and make sure that plan will work.
I built what is currently a Kodiak Steel home back in 2001. I am located 90 miles northwest of Houston, zone 2 high humidity. I really didn't know a whole lot about insulation back then so I kind of winged it. I used fiberglass in the walls between steel studs and cellulose blow in in the attic. Well I have been paying for the lack of knowledge since, in terms of high utility bills, sweating walls, dust and high humidity. I am doing something about it now.
Being that it is all metal, I know I need to move the thermal envelope outside all of the metal structures so I am going to use Rigid Foam board to cover the entire house. Right now, the roof is like a giant thermal antenna that gathers heat all day and radiates it through the I-Beams into the walls and into the house. The house heats up ridiculously fast. During the winter, it transfers the cold down into the the walls and it's unreal how fast the house cools down and sweats. I need to stop this and I believe that isolating the metal and keeping it all inside the conditioned space is the only way I can do this due the extreme thermal bridging qualities of the metal.
My thoughts on the roof are to take off the R-panel metal roof. Install Hat channel on the purlin 16" OC. Add OSB Sheathing. Cover with Tyvex. Use 3 layers of 2" Polyiso with staggered joints. Put the radiant blanket back on. Add furring strips and re-attach R panel metal.
On the walls, I was thinking removing steel lap siding. Removing fiberglass and going back with Roxul mostly for sound. Covering the metal studs with OSB. Covering with Tyvex. Adding 2-1" layers of Polyiso w/staggered joints. Furring and re-attaching metal lap siding.
I would take care to make sure that all the foam connects and is sealed. This will essentially make the entire house into a cooler. I already have a dehumidifier so I believe I could keep the temp and humidity in check. Being that I will have 6" of Polyiso with a radiant barrier and an air gap, I am thinking that the roof will have at least R-36 so I don't think I would have to insulate under the roof sheathing. I will remove all the dusty cellulose in the attic and have a sealed, conditioned attic as well. I know its a lot of work but it all bolts and screws together so not that troublesome.
Thoughts, concerns, suggestions. Not sure about the tyvex being proper so if anyone has any other alternatives, that would be welcomed.
Thanks.
PS. I tried to do this in paragraphs but it bunched it all together. |