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Bugs Camp
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# Posted: 8 Mar 2015 11:27pm
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New to this awesome site. Have some definite questions as ou situation seems slightly different. We are in the western part of Va. Nat the edge of the George Washington forest. We have all four seasons. We have a 10' x20' wood structure with singled roof on a cement slab. The building is damp! We would like to do a low cost insulation and wood panel finish. I see lots of varying opinions on this and can only afford to do this once. Several questions:
1-the roll pink insulation appears to be the cheapest way to go? Is this correct?
2-I have seen suggestions of yes and no to using a plastic barrier as well-opinions?
3-if plastic rap is used would it be better to staple that to the inside of the exterior wall and then use the pink rolls?
4-in 3 years we have never had rodent visitors so would this be an invitation?
5-if pink r13 isn't used is there another low cost suggestion?
We want to use this for visitors to our camp and want the to be comfortable anytime of year.
All suggestions are much appreciated!
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RichInTheUSA
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# Posted: 8 Mar 2015 11:48pm
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I can't help you with the insulation question.... but I'm also west of the GW forest in VA. We're west of Strasburg on the N. end of the valley...
Welcome to the forum.
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Don_P
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# Posted: 9 Mar 2015 06:55am
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Welcome Bugs Camp,
First question is what is the source of the dampness. Is it simply a cold uninsulated slab meeting moist air and sweating?, a slab with no moisture barrier under it on damp ground rather than a gravel bed underneath? I'm guessing, can you define the source of the dampness? Identify and solve that issue before closing in. I'm suspecting a cold slab and warm moist air vs rising damp. An easy test is to tape a piece of plastic to the slab. After a few damp days look at it and see if there is moisture under the plastic, if so then the moisture the moisture is coming from below. If that square under the plastic is dry and the rest of the slab is damp then the moisture in the air is contacting a cool slab and is condensing on it. In the first case, seal the slab in the second, heat and vent, get the slab above dew point. This past weekend had the kind of conditions that would cause a slab in an unheated building to sweat like crazy. We came off of a period of very cold and the air temp and humidity quickly rose... a cold slab meeting warm moist air. If you open a door on a day like that you can see a trail of wet form on the slab in front of the door.
Generally heat will get the moisture into the air where it can be vented, cold will cause moist air to condense and wet the cold surface. You cannot heat and vent enough to get rid of water intrusion, a leak of some sort. Foam insulation is much more tolerant of dampness than fiberglass. Fiberglass R value plummets when it is damp as well as potentially harboring mold conditions.
Typically a vapor barrier is applied to the warm side of a wall because the moisture is moving with the air from the warm side to the cold side of an asembly, this is the "vapor drive". For most of us pick a season and define the warm side and you'll understand why using a vapor barrier is such a thorny problem. Most of us live in mixed climates. Generally the vapor barrier is applied to the warm in winter face, or for most of us the interior face is traditionally correct if you choose to use one. There is good reason to dry to either face in a mixed climate.
I hope all that helps a little in your sleuthing out the problem before you proceed.
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TheWildMan
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# Posted: 9 Mar 2015 12:54pm
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a building that small would always have damp conditions, there isn't a way to avoid it easily (i live full time in a similar building). fiberglass batts are the cheapest and easiest option, if your worried about speed this is your best bet. you could also use the mylar reflective insulation (alone or to improve fiberglass, mylar with R 13 batts becomes the eqivetant of R 20 when they are used together, 2 layers of mylar an inch apart will be about R10)
foam board could be cut and inserted instead of fiberglass then use cans of gap filler to fill gaps, this will be more expensive and time consuming.
spray foam will be better but cost the most.
I use a combo fiberglass and mylar myself
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Bugs Camp
Member
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# Posted: 9 Mar 2015 11:14pm
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You all are amazing! Will definitely try the plastic test! And the foam sounds like a safe bet either way! Hoping to make it there this weekend if the weather holds.
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MtnDon
Member
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# Posted: 9 Mar 2015 11:39pm
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you could also use the mylar reflective insulation (alone or to improve fiberglass,
Much of the hype about reflective insulation is just that; hype without any real scientific backing. Google "radiant barrier FTC" and read some of the results that come up before buying any of it.
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TheWildMan
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# Posted: 10 Mar 2015 09:46am
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MtnDon, its not really hype, but its not exactly insulation either. its a heat mirror, it bounces the heat back. its better than nothing but not as good as actual insulation.
in cold weather i put some of it next to my face, about 6 inches away, and my cheek did feel much warmer on that side. it wasn't creating heat or insulating, it was reflecting my own body heat back. its better than nothing but i would rather have regular insulation. when used in combination with fierglass it reflects some of the heat back, while insulation slows the rate of heat loss and keeps it in a contained area. the reflected insulation is the equivelant of R5 but with a single thin layer, if your limited to only 4 inches of insulation and use batts (R13) then a layer of mylar you get a little better performance.
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creeky
Member
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# Posted: 10 Mar 2015 12:19pm
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wildman. i put roxul in my joists and then put 1.5" polyiso foam board over the joists (R25 total). yes on the inside of the building. does not look pretty. but I heated my 12x20 studio through the coldest winter (my neighbor says) in 116 years (northeastern canada). mmmm. with 2 tanks of propane (100lbers, still on the second tank) and one face cord of wood.
i'll be up to 1 and a bit face cord by the end of the season.
bugs camp. a lot of us use roxul as it's hardier than the pink stuff. critters hate it. they'll tunnel thru but they will not nest. and it handles moisture way better. no mold issues. it can be a bit more expensive (depending on the sale). but if yer doing it once ...
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TheWildMan
Member
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# Posted: 10 Mar 2015 02:54pm
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I live in a 12 by 20 as well, i used 6 face cords of wood this year (no propane), Adirondack mountains, we get deep snow and deep cold. insulated with R13 batts and mylar, but the heat is mostly lost out the single pane windows (my storm windows and blankets over them only help so much).
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beachman
Member
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# Posted: 10 Mar 2015 05:49pm
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I am a fan of pink insulation with some ventilation to the outside wall. Then vapor barrier would be stapled on the inside studs to prevent moisture from getting into the insulation. Wallboard or whatever would be applied over this on the inside. This is what we used and with good results both in summer and winter.
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