Insulation help

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Forum topic by cruise posted 02-18-2009 06:10 PM 841 views 0 times favorited 2 replies Add to Favorites Watch
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2 posts in 3560 days

02-18-2009 06:10 PM

I have an old barn that was covered with metal due to the rotting wood. I now want to insulate the barn and line the inside of it with plywood. I have no construction experience but would like to do this on my own. So any help would be nice.

What type of insulatuion would work the best? Was thinking of using fiberglass.
How many mils should the vapor barrier be? And ithe barrier does go between the inulation and plywood right?

The barn is going to be used to shelter our horses and store things. At the time we do not plan on heating it.

Thanks for any info.

2 replies so far

View Waldschrat's profile


505 posts in 3611 days

#1 posted 02-18-2009 07:00 PM

Did you repair the rotted wood yet? Just make sure that the metal covering has fixed the leak. Once moisture has started rotting the wood, it would be wise to replace what ever was rotting… molding can or may still take place once it has started even if the wood has 12 percent moisture (depending on the humidity of where you live and the outside temps, and molds that can appear in your area, here I understand they are different and so I am speaking of what we have here). Normally for wood drying once it has reached the 20 % and below it is safe. So once it is dry it is out of the danger of getting rotted (sounds logical right?)

Insulation… The fibre glas insulation is good, I have also seen people here enclose their houses with styropor which I guess you guys call styrofoam. More economical fibreglas rolls are just that more economical, but they are generally open on one side so the fibres itch like crazy, but it is, in my opinion, a bit easier to work with because it stuffs easier and must not pass or cut as accurately as the foam. Foam is good too, i mean, just put your hand on a piece and see how much heat it reflects or holds in, it feel instantly warm. so it works well too… I have a chart in front of me with a ton of different building materials and looking at in general the styrofoam, or polystyrol, and different variations, all about average out a better per mm than the Fibreglas or Stonefibre roll insulation material.

If you are reall curious or anybody else, I have here formulas on how to calculate out the insulation values of your house walls, windows, doors, just about everything. Its not very hard to do just a little typing on the calculator and a little size measuring.

You are right, the moisture/vapor barrier should go between the insulation and the inside plywood that you will be installing to the inside. The reason for this is a rule we have here and that is “immer dichter innen wie aussen” which means “always sealed tighter (water/vapor tight) on the inside than on the outside, so moisture can come and go and the dew point is insidethe wall on the outside and so it does not occur underneath your sheetrock or plywood or on it, and start to mold, which is bad. But this only applies in winter when you have the inside heated. But since you are not heating at the moment it does not matter.

Now as far as many mills? Not sure what you have available there or what it costs, but making a estimate, I guess 4 or 5 mills ought to do the trick, not too thin or it is hard to work with and too thick is also not necessary, as moisture can not travel through plastic, no matter how thick it is… it is usually a cost factor.. the thicker it is the more it costs.

hoped this was helpful!

-- Nicholas, Cabinet/Furniture Maker, Blue Hill, Maine

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2 posts in 3560 days

#2 posted 02-19-2009 08:54 PM

Thanks for the info. I should have made myself more clear. The rotting wood from poor up keep over the years. The person we bought the farm from had placed metal on the roof, but did nothing to the sides. We replaced all the windows and resided the barn with metal. We were thinking of tearing it down. But a contractor came and looked at it and said with a solid foundation and a straight roof line it was worth fixing up. Which is what we did. Looks very nice on the outside, now it is time for the inside.

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