Wall insulation question - barn

[Tractor_Jim_CT]

Hi Everyone and Happy 2007 New Year to all.

I have been converting a section of my barn to a heated work area. The outside of the barn has 1/2 inch plywood sheathing and is covered with Tyvek and 8 inch wide, ship-lapped cedar siding that is painted on both sides of the boards. I began insulating the inside barn outer walls with pink fiberglass insulation with a paper vapor barrier. I've noticed over time if I pull back the insulation, the inside plywood sheathing between the fiberglass and wall is damp/lightly wet.

I was wondering, am I better off cutting 2 inch foam board and insulating with a 1 inch gap between sheathing and the foam board. Also foam board will not absorb the water like fiberglass. Also, would I also benefit by closing in the walls with a thin 6 mil vapor barrier before siding inside.

I plan on closing the inside walls after they are insulated with cedar 12 in wide boards inside the work space. Heating system, propane gas heat has not been installed yet.

Thanks in advance.

 

[K7147]

Hi Everyone and Happy 2007 New Year to all.

I have been converting a section of my barn to a heated work area. The outside of the barn has 1/2 inch plywood sheathing and is covered with Tyvek and 8 inch wide, ship-lapped cedar siding that is painted on both sides of the boards. I began insulating the inside barn outer walls with pink fiberglass insulation with a paper vapor barrier. I've noticed over time if I pull back the insulation, the inside plywood sheathing between the fiberglass and wall is damp/lightly wet.

I was wondering, am I better off cutting 2 inch foam board and insulating with a 1 inch gap between sheathing and the foam board. Also foam board will not absorb the water like fiberglass. Also, would I also benefit by closing in the walls with a thin 6 mil vapor barrier before siding inside.

I plan on closing the inside walls after they are insulated with cedar 12 in wide boards inside the work space. Heating system, propane gas heat has not been installed yet.

Thanks in advance.

Hi!

Going under the assumption that the exterior siding has been properly applied as well as the Tyvek I’d suggest it’s possible that the moisture you are observing is actually coming from the one of two sources. The polymers in Tyvek should allow normal moisture to escape, however, it “resists” exterior moisture as opposed to being perfectly waterproof. Tyvek is also “breathable” in that it limits air leakage and does not stop it completely.

The two possible sources? Well, if one assumes that the combination of painted cedar siding, Tyvek, and ½” plywood siding was applied properly you now have a perfectly waterproof barrier. That means the moisture was there prior to installation of the exterior siding. This is doubtful as it appears you didn’t notice the moisture upon initial installation of the pink insulation….correct? The second possibility is that the moisture came from INSIDE the building. Once a water vapor barrier was in place (the siding) any water vapor inside the building couldn’t get out and collected on the interior side of the plywood. A propane heater, animals in the barn, or a good deal of human activity (breathing) will create a great deal more expelled water vapor than most people would imagine. This may well be the source of your observed moisture.

On a practical basis I'd live with the small amout of insulation quality you've lost due to the wetness and finish the pink stuff with an immediate 6 mil barrier applied over the pink. The small amount of trapped moisture will probably depart once the space is heated.

Had you installed the 6 mil vapor barrier immediately after installing the pink insulation you probably would not have had a wetness on the interior plywood walls. Don't feel alone...this is a very common situation! Happy new year to you too!

Hope this helps…………Ken

 

[Tractor_Jim_CT]

Ken, You would make a great chess player, covering all of the moves. Thank-you very much for your detail reply. I think the interior windows fog up, and I have to double check if it's the inside or outside.

Ken, would you use the foam board insulation that is a couple inches thick, but a couple notches lower in insulating properies with the 6 mil plastic vapor barrier, or would you use the batten pink fiberglass with paper vabor barrier, with the plastic 6 mil vapor barrier.

Thanks again for your help.

Jim

 

[K7147]

Hi Jim!

Actually, I do like chess! My preference would be for the pink stuff due to the superior insulating qualities and it's abilities to better fill a given space.
Once this has been covered with an interior 6 mil plastic barrier you should no longer have worries about additional moisture build-up within the wall.

The paper barrier attached to the pink insulation is not a perfect barrier itself as there are too many opportunites for moisture infiltration around the edges.

In building our house here in Vermont I was a bit fanatical about insulation do to the occasional cold temperatures and potential cost of fuels.
We used from exterior to interior: Siding, Tyvek, R20 pink (Canadian product) within the six inch walls, and the interior vapor barrier was a foil/air bubble/foil moisture barrier of supposed R17 value, and finally 3/4" pine to the interior. I also plumbed a dedicated cold air intake for the wood stove so it wouldn't draft cold air in from elsewhere. The ceilings are of R60 value.

The primary heating system for both floors (basement) is radiant in the floors fired by propane, however, since one small wood stove heats the entire 1,700 sq ft of the first floor our propane bill for all of last year (to include appliances) was less than $400....and this is northern Vermont! I'm not a builder by trade, however, I sure know how to be cheap!

Ken

 

[SPIKER]

I didn't see anywhere where you stated if you had critters in there, or any source of moisture getting into the barn. SO where did the water build up come from? if it is concrete then you need to make sure that the moisture is not coming up through it. take a hunk of plastic bag will work. tape it down all way around out side of bad to the concrete if so equipped and wait 24 hrs remove and inspect to see if the Crete got damp. and or wet under the plastic. this will tell you if the moisture is coming up through it. one thing about plastic moisture barriers they usually trap IN more than they prevent. back in the 80's it was popular for people to wrap hole house in plastic most of those are now getting condemned for mold rot mildew problems. One builder my brother worked for was hired to attempt to repair a home done this way. (exterior plywood was so rotted you could push you're hand through it.! ) interior drywall was alive with mold about 1/2" thick nearly moss like. needless to say it wasn't worth fixing. was demoed about 3 weeks after insurance saw the shape it was in.


finding the moisture problem NOW is more important on north and east walls it may condense and the insulation you ave there now can hold this condensation there until it has proper ventilation and interior seals it may get worse.

mark m

 

[Tractor_Jim_CT]

Ken,

Thanks again. Is it better to do the bubble foil in the main house walls rather than stapling a 6 mil plastic vabor barrier, as the plastic holds the the potential for mold between the fiberglass and the exterior wall?

If the cement floor is wet after the taping a plastic square to the floor, what does one do to the cement floor? We had a lot of rain last night and the floor is dry in appearance and the inside sheating where I peeled back the fierglass insulation was dry, so I suspect the vapor barrier will solve the issue.

Your house sounds great. My mother was raised in Alberg Vermont, by the Canadian border. Not sure if I spelled it correctly.

 

[K7147]

Ken,

Thanks again. Is it better to do the bubble foil in the main house walls rather than stapling a 6 mil plastic vabor barrier, as the plastic holds the the potential for mold between the fiberglass and the exterior wall?

If the cement floor is wet after the taping a plastic square to the floor, what does one do to the cement floor? We had a lot of rain last night and the floor is dry in appearance and the inside sheating where I peeled back the fierglass insulation was dry, so I suspect the vapor barrier will solve the issue.

Your house sounds great. My mother was raised in Alberg Vermont, by the Canadian border. Not sure if I spelled it correctly.

Hi Again Jim!

If I understand your questions correctly….I guess these are my answers:

As far as retaining existing moisture within the wall the foil/bubble/foil barrier would act no differently than a typical 6 mill plastic barrier as neither are permeable to moisture. The foil/bubble/foil barrier does accomplish other tasks. It provides a double radiant barrier to prevent the escape of heat from the interior to the exterior. It provides an insulating barrier (air bubbles) that is very effective in preventing incursion of exterior cold air that has bypassed the pink outer layer of insulation. (Much like a double pane window) It adds to the overall “R factor” of the wall insulation. I suppose it could be argued that it has a positive effect with respect to being a fire barrier. This particular type of insulation is quite expensive when compared to the pink stuff, however, it’s made in Canada and was purchased when the exchange rate was favorable and Canadian taxes were rebated to U.S. purchasers.

All of my exterior venting for appliances use this material. The Canadians know how to deal with cold and their product technology in this field leaves us far behind.

No matter how long it has cured concrete will retain a certain amount of moisture and will draw moisture from the soil underneath. Warm air rises and brings a certain amount of this moisture with the rise of the air. A piece of plastic on a concrete floor will provide a barrier to the rise of this moisture and it will collect under the plastic. There are many commercial cement floor products that will provide a surface barrier to stop the moisture from rising. Anything from a sealer to a full blown epoxy finish coating.

In my own situation I provided a complete insulating barrier to the entire foundation to include the floor in order to make the entire foundation a huge “heat sink” to aid in the operation of the “in floor” radiant heating.

Thanks for the kind comment on the house. The only difficulty was holding a nail gun in one hand and a book in the other! Oh yes, and obeying instructions from the distaff!! Did I ever tell you about my “free” house air conditioning in the summer?

Ok on your mom being from Vermont. It’s interesting to note that historically this area was developed by CT folks heading north. Evidently folks move back and forth between the two areas on a generational basis?

Have an excellent new year Jim,

Ken

 

[Buckeye_Jim]

Ken,

My son built a yurt where the only insulation was the bubble foil product. I am remembering that it wa only like .25" thick. Came in 4' high rolls with metal tape to seal the joints. Very easy to apply. Seemed to work ok for him, but he only lived in it for one winter here in the N. Calif. Mountains. Regarding your house, do have an air to air heat exchange to get fresh air into your home?

Jim, The vapor barrier inside is something I am now seeing recommended. Iuse to build houses, leaving the construction business in the early 80's. Back then the interior vapor barrier was never seen around these parts.

Jim

 

[K7147]

Ken,

My son built a yurt where the only insulation was the bubble foil product. I am remembering that it wa only like .25" thick. Came in 4' high rolls with metal tape to seal the joints. Very easy to apply. Seemed to work ok for him, but he only lived in it for one winter here in the N. Calif. Mountains. Regarding your house, do have an air to air heat exchange to get fresh air into your home?

Jim, The vapor barrier inside is something I am now seeing recommended. Iuse to build houses, leaving the construction business in the early 80's. Back then the interior vapor barrier was never seen around these parts.

Jim

Hi California Jim!

Ok on your son’s yurt. Yep, that’s the same material. It comes in many configurations although the foil/bubble/foil seems to be the most efficient. Yes, I do have an air-to-air exchange system to provide fresh air into the house. The house is extremely “tight” and without an exchange system an unhealthy house air environment would be a real possibility. My “back-up” air exchange system consists to two Brittany Spaniels who are afflicted with the “IN-OUT” syndrome with my wife and myself acting as door wardens!

Ken

 

[SPIKER]

"Moisture under the plastic" this is water coming up through ground contact and penetrates the concrete:" answered above is to SEAL the concrete with a good quality moisture barrier material, (epoxy surface coating is one such critter and many others too)

(quick note regarding there are 4 main variations of the bubble type insulation. listed in order of expense/insulation qualities with uses higher # more $ & insulation qualities)

1. "foil bubble poly" used for under slab the poly side contacts the concrete.
2. "foil bubble foil" used for insulation above ground (walls attic ect)
3."foil bubble bubble poly" under crete poly side against crete, added insulation mainly for radiant floors in cold areas.
4. "foil bubble bubble foil" above ground more insulation for higher radiation
areas (attics garages west walls under crawl spaces ect.)

end quick learning note...)


I have yet to put down my concrete this spring I HOPE: I have the "foil bubble bubble poly" already bought for my floor, but have lately been reading that this is great <bold><u>IF</u></bold> there is a air/dead space between the "foil,bubble,bubble,poly" and the dirt, otherwise the material is not all that great for under slab insulation. SO I'm adding at least 1" of the typical poly/Styrofoam hard boards under the floor/slab then the "foil bubble bubble poly" as the vapor barrier/insulation above the styro. Then small amount of sand, metal mesh and radiant PEX-AL-PEX attached to the mesh. Then concrete, with a wet applied concrete drying / hardening agent applied while the crete is wet during the final troweling/finishing stages of the concrete laying process. (product called Zypex" for this as a brand name I believe)

I would love to use the "foil bubble bubble foil" for wall insulation on the upstairs roof and the North & West walls but as mentioned it is expensive!.

What is now being said to do is if you live in a primarily HOT/DRY climate (down south of the Mason Dixon Line) then the Vapor Barrier needs to go between the outer wall/siding and the studs. If you live North of the line in primarily COLD/WET climate then the primary vapor barrier needs to go between the drywall and the stud wall (builders normally use craft backed pink stuff for this around here..) for along time the primary vapor barrier around here (Ohio is COLD and WET nearly year round) was put on the out side between the OSB & siding. which is where mold issues start to arise if it was a non-permeable vapor barrier such as plastic and or even this "foil bubble bubble foil/poly" stuff. this trapped the water vapor inside the walls in the pink stuff and against the OSB sheeting where the mold can thrive... the wisdom is changing I suppose...

anyhow hope this bit of info helped... this above is mainly what I've learned / gathered form reading books/mags on the subjects...

mark M

 

[Brad_Blazer]

Here is some no bs info on radiant barriers.
Radiant Barrier Fact Sheet

Brad

 

[Stampeder]

Tractor Jim:

I would wager a guess that if you pull off one of your cedar boards where you are seeing the moisture build up that you will also see that the inside of the cedar board is wet as well.
The reason is that you have an additional vapour barrier created between your exterior sheathing and the painted siding.
Wood siding should never be painted on the inside. Moisture gets trapped within the siding as well as preventing internal moisture from going through the siding to the outside.
I attended a building seminar given buy the building research people in Canada some years back that discussed this exact type of construction error. Moisture is a real problem in extreme cold.
In an ideal construction technique the siding would be spaced about 1/2 inch off your sheathing with gaps at the bottom and the top to create a chimney effect and the convection currents would carry any moisture coming through the walls up and out away from your building.
In this type of construction also rain that penetrates the outside paint barrier (which it does) would be driven through the cedar boards by the sun into the chimney space and go up and out as well.
I was told there is no reason that given this construction that siding shouldn't last 100 years.

Hope this helps.

 

[Tractor_Jim_CT]

Thanks everyone for your terrific feedback-

I primed and stained both sides of the exterior cedar to prevent water from seeping behind and into the board. I've experienced water behind one sided painted cedar shingles, and the peeling paint. It is recommended everywhere to paint both sides and it seems like a smart step.

Also, I have Tyvek on the plywood sheating, so moisture is not penetratring behind the cedar siding into the sheating.. I would think the fiberglass would be wet also, which has a paper vapor. It's rained very hard the last few days and the areas. I left the fiberglass pulled away from the sheathing in the problem areas to air out and I noticed this area stayed dry after several days if heavy rain.

I think I will place the vapor barrier on the inside walls before covering and see how this works.

 

[ELMO67]

Jim, what did you do to attach the cedar boards to the exterior of your building? If you used inside blocking for nailers, what spacing did you use and what size nails. This is probably the route I'm going when I side my 5 year old garage this year.

 

[ELMO67]

Hey Jim?

 

[EddieWalker]

... take a hunk of plastic bag will work. tape it down all way around out side of bad to the concrete if so equipped and wait 24 hrs remove and inspect to see if the Crete got damp. and or wet under the plastic. this will tell you if the moisture is coming up through it.

This test is actually to see if the slab is dry enough to put down wood and floating floors. The curing time for the concrete is several months depending on the climate your in. Until the concrete has sat for a certain amount of time, you will still have moisture in the slab. If you put down a wood floor, or a laminate floor over the concrete before it's done curing, the flooring will absorb that moisture and warp.

The plastic taped to the concrete is a test to see if it's dry enough. That's all. If you pull the plastic up and there is moisture there, then the concrete is still curing. If you pull the plastic and it's dry, then you can go ahead and install your flooring.

In most home construction, it's 3 to 4 or more months after the slab is poured before the flooring goes in, so the test is almost always dry. If you do an addition where you can put down the flooring a month after you poor the slab, the test will almost always come up wet.

It's just a matter of time until the slab cures and the plastic bag test will tell you when that is.

We've had the discussion of wether water travels upwards through concrete or not. I'm in the minority and don't believe this to be true, but allot of you disagree with me. I'd hate to get that started again since it's already been beaten to death in that other thread. This is totally different.

Sorry,
Eddie

 

[SPIKER]

eddie:

concrete is porous and will let water go in both directions, (how ever slowly) it will go through.. This is a fact. If you have water UNDER the slab it will show up by coming through, usually it is slow enough that the water does not pool up or puddle, it simply evaporates at or near the surface of the concrete. this is the reason for the plastic sheeting, when taped over the top of the concrete it will seal the moisture from evaporating into the air... This is also the reason i feels much cooler than most other types of flooring, it cools from the evaporation which cools the concrete.

You are right that this was beaten to death in many many other posts. I'm sure I can go into the basement of many homes built dozens of years ago that have concrete floors ( without a vapor barrier under them) tape down some plastic and after 24 hrs pull it up & have the surface wet... I can assure you it is not from the concrete still drying.

Mark M

 

[firefighter9208]

Why not just use a moisture meter. All flooring installers "should" have one. We built a new gym at the middle school where I used to work and it was 4 months before they could lay the hardwood. There was too much moisture in the concrete. They would come out every few days and use the meter to check the moisture level. This caused the contractor to miss the deadline on finishing the job. I don't think he lost any money though.

Chris

 

[EddieWalker]

Mark,

At no time would I compare a basement floor to a concrete pad on grade. Too many variables with a basement that will lead to water getting in. The worse is they hydrostatic preasure of being below teh surface. Any tiny crack is subject to the preasure of the surrounding walls to force water through those cracks.

A slab on grade has no hydrostatic preasure, so there is no force to force moisture upwards, against gravity through any cracks in concrete.

As for the porisity of concrete, I have yet been able to get water to soak into it, nor through it. This simple observation is where I put all my doubt in the theory that moisture will travel against gravity and work it's way up through solid concrete. Especially when the soil under a slab is dryer than the soil all around the home.

If you've ever done any bathroom remodels, you might have noticed places in the slab that are exposed to the soil underneath. This is common around some drain lines to allow positioning for the tub or shower. I've never seen these areas pluged or sealed, yet they remain dry. If water can travel up through concrete, how come it doesn't even make that soil slightly moist?

Pier and beam foundations are above grade, and the soil underneath a properly drained home, will dry out to the point of having no moisture. If they don't have any moisture, how does the soil under a slab get all this moisture to actualy travel against gravity and through a solid slab? If there was this force of water going upwards, wouldn't it travel out the side of the slab before actually going through it?

These are just my observations based on what I've seen personally. I don't have a degree, much of an education or any basis to support my opinion. It's just what I believe to be true.

Chris,

Your right about the moisture meters. They show that in time, the slab cures and the moisture levels decrease. At a certain point, there is no longer enough moisture in the slab to be a threat to the wood floors. This also proves that concrete floors are not pourus and do not bring water into them, nor do the hold water.

Another point on the vapor barrier and why it doesn't stop moisture from coming through a concrete slab. The moisture barrier is put done on the bottom of the slab. If water was able to travel through concrete, then it would be more likely at areas of more moisture. This would be along the edges of the slab. Has anybody ever heard of water coming through a slab around the edges where there is no moisture barrier and the ground around the building is sloping away?

Eddie