Wall insulation question - barn
- Thread starter Tractor_Jim_CT
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Stampeder
Gold Member
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- Montana 4940C, FEL, Quick change 3 point factory hitch, pallet forks, grapple, 50 gal tank sprayer, Bush Hog PHD
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.
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.
OP
Tractor_Jim_CT
Silver Member
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.
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.
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.
EddieWalker
Epic Contributor
SPIKER said:
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
Elite Member
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
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
Platinum Member
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
Chris
EddieWalker
Epic Contributor
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
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
