Adding more insulation to steel garrage.


Old 07-02-02, 05:42 PM
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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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Old 07-10-02, 08:35 AM
Join Date: Nov 2001
Location: USA
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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.
Old 07-29-02, 08:14 PM
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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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