Finishing Off Inside of Barn

Anonymous Poster · Jun 16, 2003

Going to be starting this project soon--need some advice.

We have a barn that is approximately 16 by 30. There's a loft above. I want to insulate, finish and paint the lower level so that it can be heated and cooled (as needed) throughout the year.

My questions mainly revolve around vapor barrier and insulation.

1. Is it correct to assume (since I have to put this on from the inside), that I have to cut the barrier to fit between the wall studs and simply staple it to the inside of the siding).

2. What material should I use?

3. Do I put the barrier on the ceiling as well? (I will be insulating the ceiling of the main level--the loft or second floor will not be insulated)

4. Since this barn is old, I don't think the wall studs were spaced in a manner that would allow me to use regular fiberglass insulation rolls. Should I buy the pink foam insulation so I can cut it to fit or is there still a way to use the rolls of fiberglass?

FYI--I am not going to be heating or cooling this space like a house. I am looking to insulate so that in the middle of summer, I can use a fairly large window AC to take down the moisture and temp to a relatively comfortable level. Likewise in winter, I will be heating the inside to a temp that is 20-25 degrees above the outside temp.

Thanks in advance for any help.

Bob

rancar · Jun 16, 2003

Bob...

The way you have described your project, this is what I would do.

I would use the pink fiberglass batts of insulation WITHOUT the attached vapor barrier. Carefully position these within your stud walls and in your ceiling. Do not compress this insulation as this will negate the insulation qualities it's designed to produce. If you need something to hold the insulation in place, use small metal or plastic restraining straps that home improvement centers sell just for this purpose. After all the insulation has been installed, cut and staple rolled plastic wrapping on the inside stud walls. The plastic vapor barrier should be installed facing the inside of the room that you want to keep cool and heated. After the inside is covered with the plastic wrapping, install your finished wall covering (eg, sheetrock)being careful not to puncture the plastic wrap except where you nail the sheetrock to the studs.

...Bob

Anonymous Poster · Jun 16, 2003

Bob,

Thanks--your response has triggered another question.

As you could probably tell, I was going to put the plastic on first, which I'm assuming would have been wrong. However, as you know, these older barns are not exactly 100% water tight and I was thinking that having the barrier on against the wall would stop water from getting at the insulation.

So--can I use something (like tar paper) to protect against water coming in and then put a layer of insulation followed by the plastic and finally the finished wall covering (wood in this case). Or--will that create a situation where I will have insulation between 2 vapor barriers and run the risk of trapping moisture where I want it least?

Thanks Again

Bob

rancar · Jun 16, 2003

"...these older barns are not exactly 100% water tight and I was thinking that having the barrier on against the wall would stop water from getting at the insulation...can I use something (like tar paper) to protect against water coming in and then put a layer of insulation followed by the plastic and finally the finished wall covering (wood in this case)..."

I wouldn't do this Bob. First off, as far as I know (based on my own experience in doing this type of work on my own 175 year old Greek Revival home) no building is ever 100% moisture proof. I don't think you want to make it 100% moisture proof. Buildings have to 'breathe' to let a certain amount of indoor moisture out. In most cases, this is done through air coming in through windows and entry doors. If you totally try to moisture proof this building, what may happen is moisture building up on the interior wall surfaces to the point it may cause mold to develop on interior surfaces.

Think of it this way. Imagine yourself in a rain storm where you try to totally waterproof yourself with a raincoat and other waterproof coverings. It doesn't take long before you start feeling just a bit sweaty as you perspire. There is no place your body moisture can go, so it condenses as sweat on your body and your body can't breathe. Well, it's the same with a building. You want a certain amount of air to come in to permit good air circulation but not too much that it negates the beneficial attributes that insulation is designed to produce.

"...will that create a situation where I will have insulation between 2 vapor barriers and run the risk of trapping moisture where I want it least?..."

Yes! That insulation, even it gets wet a bit from moisture hitting it on the outside, will dry out. If you have vapor barriers on both sides, any water moisture building up between the inside and outside walls will just stay there causing mildew and wood rot.

I would not try to overdo it here. Your one inside vapor barrier should be sufficient. Anything more than this is overkill. Also, be sure to wear a protective face mask when installing the insulation. Without it, you'll be breathing in the fiberglass fibers. These fibers will stay within your throat and inner lung linings and may produce coughing spells and potential health problems in the future.

BTW, I insulated my entire house the way I've described it in the mid-1980s when it was undergoing renovation. So far, so good. No evident moisture problems exist on interior walls or surfaces. And the house is much warmer than it used to be prior to my installing this insulation. The first floor is also relatively cool in the summer (68-72F) compared to high ambient air temps that may exist on the outside (85-90F). I don't have air conditioning of any kind and may have a need for it only a handful of times each summer when outside temps exceed 95F. In these cases, we just dress down a bit. /forums/images/graemlins/smirk.gif

...Bob

CTyler · Jun 16, 2003

I don't claim to be an expert on this, just done some readin for my own shop.

Typicaly the vapor barrier is installed on the warm side of the wall. This depends on where your located. Pretty easy if you in Texas or North Dakota.

I don't think you want the insulation getting wet so you probably want plastic toward the outside. I say this because you gave the impression it will do so.

As far as plastic on both sides thats a no no unless it can breath, I.E. a permeable barrier. This is used in mixed climates.

CTyler · Jun 16, 2003

( I don't think you want the insulation getting wet so you probably want plastic toward the outside. I say this because you gave the impression it will do so. )

After thinking about this I would say fix your moisture problem if indeed there is one and put your retarder on the inside(warm side) of the wall.

They do make what is called a smart retarder that is semi permiable.

Anonymous Poster · Jun 16, 2003

Thanks for the replies guys

Bob--I think you are right about the "outside" vapor barrier. I may have painted an incorrect picture when I was talking about water getting in. It's not that water runs in when it rains, it's more of being able to see light through a very limited number of spots when inside the barn on a bright day. So your example of the insulation getting wet and drying out is exactly what I was looking for.

I've been looking for an excuse to use the new digital camera so I will take some before, during and after pictures.

Bob--thanks again for the insight.

Bob

rancar · Jun 16, 2003

"...I've been looking for an excuse to use the new digital camera so I will take some before, during and after pictures..." 

Great....I look forward to seeing the pics. This is also a good thing to do regardless for historical documentation purposes. You can also show the next potential property owner in the future what you've done. You can say something like, "See here, this is what the building looked like before....this is what it looks like now." /forums/images/graemlins/wink.gif This before/after photo documentation speaks volumes if and when you try to sell your place. It's so much easier to visualize and grasp what a project entails when one can see it than if one just 'hears' about it. What it really says is, "I care for this building so much, let me show you what I did." RESULT: Maybe a higher sales price. /forums/images/graemlins/laugh.gif

...Bob

Anonymous Poster · Jun 16, 2003

( Typicaly the vapor barrier is installed on the warm side of the wall. )

That's correct. A "double vapor barrier", with plastic inside and out typically results in the insulation holding water. In the winter, it holds ice.

You can use a permeable wrap, like Tyvek, on the outside. Cutting it to fit between the studs would be a major PITA. I suppose you could wrap it over the studs, then insulate, then vapor barrier over all that. I've never seen it done, but don't know why it would not work if you're halfway neat about it.

If you're using plastic vapor barrier, you can use the plain batts without the paper vapor barrier backing.

I'm looking at a material that Tek Supply lists in their catalog. It's a foil - plastic bubble - plastic stuff that comes in rolls. They say you can pressure wash it. I'm looking at that for the inside of a Quonset Hut type barn. I'll put 4-inch fiberglas bat wool under the plastic. The plastic stuff should serve as additional insulation, an inside surface, and a vapor barrier.

- Dennis

ikline · Jun 16, 2003

You might want to price out a professional doing it. I use to sell insulation for new construction and retro. Depending on the sq ft, you might actually break even having a professional doing as apposed to buying it and doing it yourself. If not, at least you will find out how they would do it.