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Adding more insulation to steel garrage.


waugh77's Avatar
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07-02-02, 05:42 PM   #1  
waugh77
Adding more insulation to steel garrage.

Just finnishing up an all steel garrage, have 4" of factory insulation between steel siding and beam's. Factory insulation is 6ft. wide, fiberglass, with a vynil type of vaper barrier. Beam's and purlins are 8 inches deep, would like to add extra insulation in ceiling and walls of shop and office area before finishing interior wall's.
Question? What or how much will I need to puncture existing vaper barrier? Can't slice it , it has support webbing in vaperbarrier.

 
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resercon's Avatar
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07-10-02, 08:35 AM   #2  
I would first check with the manufacturer of the garage on the procedure to add more insulation. To be honest, I would not recommend adding more to the garage. I base this on the law of diminishing return. Basically all that means is adding more insulation to a structure that already has insulation is considerably less effective than adding it to a structure that has no insulation. And this effectiveness diminishes as the insulation value increases.

For example, let's say there is no insualtion and you install R-13 verses R-19 in the ceiling. The difference in energy bills is $100./mo. with R-13 and $90./mo with R-19, but the difference in cost of installing the 2 is not that great. It's very cost effective to install the R-19.

But if R-13 already exists and you wish to add a R-6, the savings is $10./mo. the savings don't justify the costs. I'm only using these figures to illustrate the law of diminishing return. If you were to add R-12 instead of R-6, the savings would only be a dollar or a little bit more than that. You're doubling the insulation value but you're not doubling the savings. In fact it diminishes the more you add insulation.

 
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07-29-02, 08:14 PM   #3  
rbisys
Greetings,

Wish I could have talked to you before you installed the FG. It's going to be hotter than hell in there in the summer. How ever you can install a radiant barrier(RB) system under the existing FG.

NO DON"T PUNCTURE THE covering. This will allow moisture to enter the FG and you will a condensation disaster. Adding more FG to the existing could make it worse.

I sell an exclusive system of RB retofit for metal buildings. It is a patented system and will cost ABOUT $.60 / sf. It will dramatically reduce the heat gain during the summer and also help the winter bills.

If you are interested contact me at [email protected]

Thank you for considering my opinion.

 
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