To vapor barrier or not to vapor barrier...

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  #1  
Old 08-03-03, 08:40 PM
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Post To vapor barrier or not to vapor barrier...

First of all, I want to say thanks to all of the moderators on these boards. This is the first time I have posted, but have been using the information in this forum as a guide in my basement project and have found a lot of very valuable tips.

Here is some background on my project:

I am in the process of finishing 1/2 of my basement. My intention is to use this room as a home theater/family room. I am using 2x4 framing with pressure treated bottom plates. I have installed a 6 mil poly vapor barrier on the concrete block side of the framing. The framing is set tight against the wall (I have read that a 1" gap is recommended, but I got that info too late). I intend on using fiberglass bat insulation and 1/2 drywall. My home is only 6 years old and has had no water issues in the basement. I taped a few pieces of aluminum foil in various places on the walls and floor and had no evidence of moisture on either side of the foil. I live in Wisconsin (Milwaukee area) so we get our share of the 4 seasons. Here is my question:

While applying for and obtaining permits (thanks guys for talking me into doing this!!) I asked my building inspector what he recommended as far as how to do the vapor barrier. He said that if it were his project he would NOT put up any vapor barrier and use unfaced insulation between the concrete block and the drywall. He said that the vapor barrier would only trap moisture and could potentially cause mold/mildew problems(I assume this is what the 1" gap would be for). I decided to procede with my project and DID install a vapor barrier on the concrete block side of the wall with the thinking that I would get a few opinions on what to do when I got closer to closing up the walls. Well, the electrical is all run and will be inspected next week, so I need some thoughts on the vapor barrier.

Do I leave it as is and insulate and drywall?

Do I cut out the vapor barrier and go with what my building inspector suggests?

Do I cut slits in the vapor barrier and then insulate and drywall?

What are your thoughts on faced vs. unfaced insulation with/without a vapor barrier?

Your thoughts and maybe a little explanation as to why you suggest what you do would be greatly appreciated.

Keep up the great work guys!!
 
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  #2  
Old 08-03-03, 09:13 PM
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Vapor barrier

Everything I read about vapor retarders is that they are to stop water vapor in a home from passing through the drywall into the wall cavity and condensing on the inside of the sheathing. That means that vapor barriers always go on the warm side of the wall in cold climates. This means the warm side would be the heated area in your home.

Warm, moist air in heated areas is attracted to cooler surfaces and will pass through drywall and condensation is likely to form when it hits the cold wall cavity. Seal around electrical outlets and switches on exterior walls to prevent vapor transmission.
 
  #3  
Old 08-04-03, 06:12 AM
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vapor barrier

Thanks for the input!!

Would you then recommend that I remove the vapor barrier from the "cold" side of the wall before installing the barrier on the "warm" side? Would you recommend faced or unfaced insulation? Are there any potential pitfalls with installing a vapor barrier on the warm side as far as moisture that might seep through the concrete walls in the future? Would this moisture be trapped in the insulation? Could this be why my building inspector recommend that I do not install a vapor barrier at all?

I'm trying to get as much info as possible so I can make an informed decision on how to go about this. Thanks again!!
 
  #4  
Old 08-04-03, 07:14 AM
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Remove the vapor barrier against the basement wall.

Vapor barriers are only used with insulation. The purpose of it is to reduce and slow down the transmittance of water vapor to prevent condensation. All heat has moisture in it and insulation slows down heat flow but does not slow down the water vapor flow. If you install fiberglass insulation without a vapor barrier in an condition space, the probability of condensation occurring is high. In applying a vapor barrier you must understand the direction in which the heat will travel to apply the vapor barrier correctly. Another important factor is what accompanies condensation is temperature drop because as the temperature drops, the heat and/or air can can hold less moisture. This supports the rule that heat condenses on cooler surfaces.

If we apply this to your situation in your area, the vast majority of heat will come from inside the conditioned basement throughout the year. It is true that the heat during the summer is a factor in considering the placement of the vapor barrier, however, the majority of the basement walls are below grade, which is actually cooler than an air conditioned basement. And in most cases it creates a situation where you do not need to air condition the basement. So regardless of the season in your area, the direction of the heat transmittance will be from inside the conditioned basement to the outside. 70 degree Fahreheit air conditioned basement, 55 degree Fahrenheit masonry basement walls.

Though there are many considerations here, in your situation you should try to visualize the heat with a percentage of moisture transmitting through the finished basement wall. Without a vapor barrier, the heat transmits through the sheet rock, then the insulation and then the masonry wall. As the heat transmits through the wall, the temperature begins to drop. Since the moisture content within the heat is not reduced or slowed down as it transmit through the wall, the probability of condensation occurring is high.

With the vapor barrier against the masonry wall, again the heat transmits the same way as it does above, except that when it get to the vapor barrier on the masonry wall, the vapor barrier prohibits and slows down the moisture in the heat from entering the masonry wall. In this situation the probability that condensation will occur is so high, you are almost assured that condensation will form on the vapor barrier.

The correct way of applying a vapor barrier in your situation is to reduce the moisture content or slow it down before the temperature of the heat drops to avoid condensation from occurring. The only way heat will form condensation is when the Relative Humidity (RH%) of the heat reaches 100%. The only way this can occur in your situation is by adding humidity to the heat or by temperature drop. The latter supports the installation of a vapor barrier, where the heat would transmit through the sheet rock, then the vapor barrier, before going into the insulation where the temperature drop will occur, then the insulation and finally through the masonry wall. This application dramatically reduces the probability of condensation from occurring inside the wall structure.

You should also heed TWELVEPOLE's advice. What my explaination discusses is heat transported moisture and Twelvepole's addresses air transported moisture. In the prevention of the growth of mold and mildew, air transported moisture is a much more important factor than heat transported moisture. DO NOT TAKE TWELVEPOLE's ADVICE LIGHTLY!!!
 
  #5  
Old 08-04-03, 09:43 AM
thevolcanogod
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I think I understand everything said. I have heard it recommended that you put slits in the vapor barrier at grade level - is that sound advice and why?

edit: nevermind - saw my answer half a page down.
 
  #6  
Old 08-04-03, 10:53 AM
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Site conditions dictate applications.

In the original post, "langer" pointed out that the building inspector recommended removal of the vapor barrier against the masonry wall. In other towns or States, they require moisture barriers against masonry walls. Though I do not know the exact reason for this, I can take an educated guess.

All applications concerning the prevention of condensation are based on Equilibrium Relative Humidity (ErH%). What this means is that air and/or materials that have a lower humidity level will absorb humidity from other air and/or materials that possess a higher humidity level until the humidity levels are equal. So when we look at particular applications, in most cases one particular application will not apply to every situation in every area of the world, no matter how good it sounds.

In areas where moisture barriers on masonry walls are mandated by building code, the most logical reasons for this are a high water table for the area and climatic conditions. And there could be other reasons that I might not be aware of, but I can assure you if building code requires it, there is more than sufficient data to support the building code.

The slits at the bottom of these moisture barriers are there to allow condensate to drain out from behind the moisture barrier. This indicates that this area experiences severe cold winters.
 
  #7  
Old 08-04-03, 11:14 AM
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thevolcanogod,

Just a word about what you may have read in the forum before may pertain to this that I wrote...

Vapor barrier should be placed directly under the drywall. The warm inside air containing water vapor can get past the wall finish and insulation and condense inside the colder wall cavity. If enough of this happens, and the water cannot escape, wood rot, mold, and other moisture-related problems are likely to occur. For this reason, building codes often require installing a vapor diffusion retarder on the warmest side of the wall cavity. This is what is required in Minnesota;

"A 4 mill poly vapor barrier must be placed against all concrete or block exterior foundation walls PRIOR TO APPLYING FURRING STRIPS for full height of the wall. Another 4 mill poly vapor barrier must be placed over furring strips and insulation prior to covering with finish materials. (State Energy Code Requirement)" - MINNESOTA CODE

***PLEASE NOTE THAT YOU MUST MAKE SMALL SLICES AT GRADE LEVEL ONLY (NOT AT FLOOR LEVEL) FOR WEEPING IN THE POLY IF POLY IS PLACED AGAINST THE BLOCK - ATTACH THE POLY WITH STAPLES TO YOUR JOISTS/FOUNDATION SILL PLATE***

Kraft Faced insulation is fine to use in the above scenario. No need for the poly and you can do everything easily. You may find this easier and I would do this versus unfaced and vapor barrier because I don't like to play with it any more than I have to.

Just thought this would help!
 
  #8  
Old 08-04-03, 11:52 AM
MusicField
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recommend NO vapor barrier

Building Science Corporation has done a wonderful job assembling the necessary and relevant information in a guidance document of basement insulation systems that can be found at the following link:

http://www.buildingscience.com/resou...on_systems.pdf

The guidance document does an excellent job at explaining the physics of the movement of water vapor in and around a basement. The guidance at times borders on the technically tedious, but for your application (the same as mine) pages 9 and 10 are especially helpful.

Based on the info in this document, and my understanding of the physics of the problem of moisture movement in a basement, I will be insulating my basement with between 1 and 1.5 inches of extruded polystyrene adhesively applied to the concrete wall, followed by studs with unfaced fiberglass insulation, followed by ½ inch drywall. I will also be running a dehumidifier in the basement during the summer to control humidity.

After digesting the Building Science Corporation info, I will NOT be use a vapor barrier in my basement finishing project, code requirements aside. The physics of water vapor moisture movement through basement walls systems makes the use of vapor barriers inadvisable.
 
  #9  
Old 08-04-03, 12:50 PM
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MusicField,

Although the applications and research that is done by the Building Science Corporation is good and informative, I for one am in agreement to some written material they have produced . I do however give caution to those that think this is the only way or best way. Some Building Officials, depending on the area of the country in which they enforce the codes, have incorporated some issues that the BSC has researched. Not all applications apply throughout United States.

Until such methods are approved by Building Officials and Manufacturers in changing the application of their products with vapor barriers, as an example, it is highly recommended by myself to not apply such methods unless this has been approved "across the board".

As you said, "After digesting the Building Science Corporation info, I will NOT be use a vapor barrier in my basement finishing project, code requirements aside", this is your opinion and your right to do as you will.

For the members of this Forum, I do not endorse the applications nor suggest using them without proper endorsements by those that regulate Building Codes. In addition, failure to abide by the Manufacturers installation methods will/may void warranties which would be a detrament to the members of this Forum and all homeowners alike.

I appreciate your input and suggestion but to all those reading this, caution should be taken. Check with your local Building Officials first before applying such methods, however sound they may appear.

Thanks for the input!
 
  #10  
Old 08-04-03, 01:57 PM
MusicField
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Doug, I appreciate your comments. I am not an expert, just a DIY’er who has a little understanding of how and why things work the way they do, and an insatiable curiosity for researching the "right" way to do what ever it is I am trying to do. In that sense, the Internet is a friend, because it makes researching topics of interest so much more efficient. I am certainly not recommending any particular way of doing anything. As DIY'ers, we are all individually responsible for doing our homework to ensure that we get satisfactory results with our projects.

Doug, I'm curious about something you wrote. You said "... failure to abide by the Manufacturers installation methods will/may void warranties which would be a detriment ..." In the basement finishing system proposed and recommended by Building Science Corporation for langer's (and my) basement (extruded polystyrene against concrete wall/unfaced fiberglass in stud cavity/drywall), what Manufacturer's installation methods where you referring to that would be in contradiction to this type of system?

langer noted that his building inspector recommended that he not use a vapor barrier in his project. ("He said that if it were his project he would NOT put up any vapor barrier and use unfaced insulation between the concrete block and the drywall. He said that the vapor barrier would only trap moisture and could potentially cause mold/mildew problems") Seems like an endorsement of Building Science Corp's findings, as they relate to langer's situation (and mine, too).

From the perspective of the physics of water vapor movement in basement finishing systems, building code requirements and manufacturer recommendations are irrelevant. In other words, the laws of nature (physics) dictate what will happen in a basement finishing system. It would appear that man's laws (building codes), break Nature's laws (at least Minnesota's building code breaks them in this situation).

Building code officials can require a vapor barrier, and manufacturers can recommend that one be used, but that won't prevent water vapor present in summer in a humid basement (such as langers and mine) from penetrating an imperfect vapor barrier and causing condensation inside a wall, with all the subsequent nastiness that comes from having wet building components.

Building code requirements change over time, and typical of government, regulations are generally quite "behind the times" in taking information collected from research into account in new regulation sets. My guess is that sooner or later Minnesota will eventually get to a point where their building code will be re-written to eliminate the requirement for vapor barriers in basement finishing systems, in order to prevent some of the situations that were well-documented in the Building Science Corporation article.

I'm not trying to be disagreeable, just trying to help other DIY'ers out there by pointing out one very good source of information that, based on the laws of nature (physics), makes the most sense. It is up to each of us individually to decide how we will complete our DIY projects, based on the information that we have on-hand at the time we make our DIY project decisions.

Nature makes the laws. It's up to each of us to decide if we want to break them. If I were finishing a basement in Minnesota, I'd be requesting a variance.
 
  #11  
Old 08-04-03, 09:16 PM
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Building Codes

• Massachusetts' building codes are mandatory for all buildings statewide. Local jurisdictions may amend the codes only with state approval.
• For more information about statewide codes and enforcement issues, visit www.state.ma.us/bbrs/code.htm

Massachusetts Building Code
Vapor Diffusion
Molecules of water vapor will move through building materials, driven by differences in vapor pressure from one side of the material to the other; higher vapor pressure on one side will drive water vapor through the material to the lower pressure side. The vapor molecules move right through the molecular spaces in the building material in a process called diffusion, and different materials have different diffusion rates.

The code requires that certain materials be installed in the envelope assembly that will limit vapor diffusion to a slow enough rate that moisture does not accumulate within the system. Such materials are considered "vapor retarders" (sometimes called "vapor barriers") because they have an acceptably low vapor permeance. The Massachusetts Code generally requires that the material selected as the vapor retarder may have a "perm" rating no greater than 0.1. A material's permeability, for code compliance purposes, is determined using Table 9 in Chapter 24 of the 1997 ASHRAE Handbook of Fundamentals.

Generally speaking, in heating-dominated climates, such as Massachusetts, the vapor retarder should be placed on the warm-in-winter side of insulation so that it remains warm throughout the cold season. If a vapor retarder is allowed to get too cool, the water vapor that touches the retarder will condense into liquid water and damage the envelope. The proper location for the vapor retarder therefore depends on the location of the insulation in the envelope. It may go either inboard or outboard of the structural wall (framing, block, etc.), as long as it remains above the dew point of the water vapor.

No vapor retarder is absolutely perfect, so some water vapor will move through to the colder side. In order to avoid accumulation within a wall system, this limited amount of vapor must be allowed to dry out through the wall. Therefore, the building materials on the outboard side of the dedicated vapor retarder must be more permeable than the retarder itself. The code requires that all materials installed toward the cooler side of the vapor retarder must be at least ten times more permeable than the retarder.

Any seams, holes, tears, or other imperfections in the vapor retarder should be repaired during installation so that it is as complete as possible.

There are some exceptions to these requirements as long as it is demonstrated through calculations that the vapor passing through the envelope will not accumulate to a dangerous degree within the wall system.

Learn more about Air Movement, The Driving Forces of Air Movement, Stack Effect, Mechanical Pressurization, Leakage, Air Barriers, Compartmentalization, and the moisture issues associated with these issues within your home per the Massachusetts Building Code at

http://www.firstsourceonl.com/fsf/in.../bbrs/code.htm
 
  #12  
Old 08-04-03, 09:25 PM
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Building Science organization, who are they?

http://www.eia.doe.gov/emeu/efficien...gy_savings.htm This is a Dept. of Energy, Energy Information Adminstration website for "Energy Saver". It lists the most notable energy conservation organization inside and outside the U. S. This Building Science organization is not listed. For your information, my website is listed and is the only independant website listed.

This building science organization along with many others primary purpose is to influence Federal, State and local Energy Codes. In fact they have influenced Minnesota's Energy Code. To be honest, I have serious concerns about accepting this code.

The difference between what these organizations propogate and local building codes is that the organizations based their positions on physics and the codes base it upon statistical data. There is a big difference between theory and practice. Where theory overlooks the variables and practice employs them.

There is a simple fact that as an Energy Conservationist that I am personally ashamed of, that is that more structures have been destroyed by Energy Conservationists than by any Architect, Engineer and/or building trade combined. I am appallled that my collegues have not learned from our mistakes. Their application clearly ignores other factors, such as the average basement has 2 negative Pascals, the absorption and expulsion rate towards moisture between the foam panels and masonry wall are different, and both negative and postive pressure are involved in the heating (expansion) and cooling (contraction) of that same air in the conditioned basement. Are we to ignore these factors and just take their word for it?

The men and women involved in determining building code for an area are entrusted the safety and well being of their residents. Their decisions are based on statistical data and not physics or theory. We expect no less from them and to insinuate that they are lagging is offensive.
 
  #13  
Old 08-04-03, 09:51 PM
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Why Building Codes?

Building codes establish minimal acceptable standards necessary for preserving public health, safety, and welfare and for protecting property. The purpose of building codes is to build safe buildings, thereby reducing death, injuries, and property damage.

Failure to follow codes in regard to protecting the structure from moisture related issues may result in health issues and property damage. For homeowner personal safety and health and that of his family, it is extremely important to build homes according to Building Codes.

Much has been written about mold, mildew, and decay and associated insect problems in residential structures secondary to moisture problems. If steps are not taken to prevent such problems and build the structure according to building codes, homeowner's insurance may not cover the structure when problems develop. Lending agencies and homeowner's insurance companies are becoming more and more cautious when dealing with homeowners and builders. They are requiring copies of permits and inspections. In some areas, documentation of permits and inspections is required at the time of the sale of the home.

Several months back we had a post in a forum by a realtor who had listed a house. Come to find out the homeowner finished out a basement. It was not done to code. The basement interior had to be ripped out before the house could be sold. Building codes are different in every city and county in every state. Only your local building inspector holds the key to what is allowed.

Last month I attended the WV State Homebuilders Association meeting where I attended the Codes Committee meeting. Codes and inspectors are getting tougher when it comes to moisture and ventilation issues within the home. The media has played a major role in focusing on health problems and deaths associated with poor air quality and mold and mildew problems. At October's convention our guest speaker will address these issues.
 
  #14  
Old 08-04-03, 10:23 PM
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Thumbs up A lot to digest

Thanks for all of the replies!! I seem to have sparked some spirited debate on this issue.

I am going to take a day or two to mull over all this info and to visit the websites that were listed before I ask any more questions.

Any other opinions out there?
 
  #15  
Old 08-04-03, 10:27 PM
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Physics of Water Vapor

A short lesson on the PHYSICS of water vapor! The air around us contains moisture. We hear how much every time the weather man says what the relative humidity is. He may say "35%" is the relative humidity. That means that at that temperature, the air is holding 35% of what it can hold of water. As the temperature of the air increases its ability to hold water also increases. The dew point is another term the weather man uses. This is closely related to relative humidity. If the air in the above example is cooled, it's relative humidity increases until it reaches 100%. The temperature at which this happens is the dew point temperature. If the air temperature falls any lower, some of the moisture that is in the air changes from vapor to either liquid or solid. This could be rain, snow, dew, frost, or even ice.

Before we go further, we need to talk a little about thermodynamics. That is the movement of heat energy. It is a LAW OF NATURE that heat energy travels toward a colder place. Also we need to know about vapor pressure. High temperature, high humidity air wants to go to low temperature, low humidity air. The greater this difference, the greater the vapor pressure. This vapor pressure is towards the low temperature or lower energy area.

We all know what insulation is, Right? It is the resistance to heat flow. It does not stop it. It only slows it down.

Lets discuss two more items; house wrap and vapor barrier. House wrap slows air infiltration into the house. It is not a vapor barrier. It typically is placed on the outside of the house just under the siding. A vapor barrier is just what it says, a barrier to vapor transmission. Usually a 4 or 6 mil poly is used as a vapor barrier. This barrier needs to be placed in the WARM SIDE of the insulation. That is usually just under the sheetrock on the inside of the outside walls and ceiling.

O.K. With these items in mind, lets look at a home in the winter time. The inside conditions are 70F and 45F dew point. The outside conditions are 0F and -10F dew point. Because the inside air has more energy it wants to get to outside where the energy level is lower. The insulation tries to slow this movement. Keep in mind this movement is very slow. As the air moves, it carries with it the water that is in vapor form. As this air moves through the insulation its temperature drops. It continues to drop until it reaches the outside of the wall. At which time it is the same temperature as the outside air (0F).

If the insulation is not protected by a vapor barrier, on the warm side, here is what happens. As the air moves through the insulation it cools. When the air temperature inside the insulation reaches 45F or its dew point, the water begins to condense out and the insulation gets wet.. As the temperature continues to fall below freezing, the condensing moisture is now frost. When the insulation gets wet or frosted, its insulation value drops. Then the liquid water in the insulation turns to ice. The insulation value continues to drop and the cycle continues. This water and ice can cause lots of problems.

If the above insulation was protected by a vapor barrier, the water vapor and the air could not penetrate into the insulation. Heat would still transfer to the outside, but the moisture would remain inside. Therefore the insulation would remain dry and its value would remain the same.

Simons, Bob. Winters Up North. Simons Engineering Services. Retrieved 08 Aug 2003. http://www.chibardun.net/~ses1997/moist.htm
 
  #16  
Old 08-05-03, 07:06 AM
MusicField
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From my read of the Building Science Corp website, BSC isn't claiming to me an energy conservation organization, perhaps that's why it's not on the DOE website. BSC also doesn't seem to be in the business of developing building codes. My take on BSC is that it is an industry group, recognizing that improper construction techniques have resulted in monetary losses for the industry, that seeks to research these failures and correct them in a manner that is acceptable to all parties at the table: the builders providing housing and housing improvement services, the people buying housing and housing improvement services, and the government, which regulates both.

Resercon, I certainly didn't intend to offend ANYONE working in government developing and implementing building codes. I work for the state government here in Massachusetts as a regulator, so development of requirements and compliance with requirements is my line of work.

But to suggest that government has already figured out what is best for anyone in their particular situation, and then to hold to that position without looking at the state of research in any particular area, is not what the people who are served by their government, expect from their government. One of the reasons so many people dislike government so much is because some parts of it tend to have a cookie-cutter inflexible approach. Government (or the people running it/implementing its requirements) that believes that it has determined what is "right" for the people it serves, and government that is inflexible in the face of contradicting information, is offensive. Government that does not listen to the thoughtful concerns of the people it serves, is government that is doing a disservice to the people it represents.

In my experience, government generally doesn't spend the kind of money or commit the necessary resources to research and develop state-of-the-art anything. That is where private organizations, such as BSC, benefit everyone. In order to be most effective, government needs to be aware of this kind of research, and needs to be responsive to it in a timely manner.

In the case at hand, basement insulation systems in a combination cold/dry and hot/humid climate, it would seem that both statistical data (thoroughly documented in the BSC article linked above) AND physics would dictate AGAINST the use of a vapor barrier in a basement insulation system such as the one contemplated by langer in his project.

In my project, I proposed to my local building inspector the basement finishing system recommended by BSC for my climate. The inspector issued me a building permit for this method of construction.
 
  #17  
Old 08-05-03, 08:41 AM
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Over the years the thing that I have learned is that you cannot believe in something just because it is written down. The mistakes I have made in the past, in the present and probably in the future have made me to be cautious when giving advice. I happen to know many of the people involved in that organization by reputation. They are indeed dedicated and hard working individuals, however they could also be described as being over zealous. When we look at the differences between organizations like this verses local building code, several things stand out. For example, the decision for an application under a building code affects people lives, whereas, the decision to write a paper on a topic is merely a statement of opinion. Though many of us in this industry consider building code as a minimum standard which does not obtain the full potential of such applications, it goes without saying that each and everyone of us prefer to have the choice to pursue such goals, rather than having it imposed upon us through building codes. This exemplifies how complex the decision making process for building codes are. Where facts that are pertinent must be included and facts that are not be excluded. And at the same time be flexible enough to allow for freedom of choice. An aspect that people who write papers, like myself, do not have to consider when publishing such reports. This decision making process is apparently multifaceted and considering the amount of statistical data involved to describe this process as being formidable is putting it mildly.

In all fairness there is the other side of the coin where the contributions given by such organizations to the field of energy conservation are unparallel. An example of this is the "Minneapolis Blower Door." Which is the standard for the measurement and verification of many of the applications for energy conservation today, not just in this country but around the world. More than 2 decades ago a similar organization introduced methods that formed the basis for programs on energy conservation in Minnesota. The innovativeness and creativeness of these programs raise more than just eyebrows considering there was no statistical data to support the implementation. Today Minnesota's Energy Code Standards far surpass all other States in the Union. The National surveys on energy consumption and environmental impact clearly support Minnesota's bold initiative. This country's National Policy on conservation and the environment is influenced if not modelled after the successes (plural) in Minnesota. Where improved building methods and applications produced lower energy consumption, increased comfort level for the occupants, improved indoor and outdoor environments. In the past few years, Minnesota brought forth a new concept known as "Sustainable Healthy Indoor Environments." This as I interpret it as being synonymous with Minnesota's conservation policy.

Though I stand in complete awe at Minnesota's accomplishments, I still take the side of caution in my opinions. I am reminded to often of the expression of this young woman's face when I told her that she had to take her children and leave this house immediately.
 
  #18  
Old 08-07-03, 07:17 AM
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ENERGY STAR HOMES

Kyoto Protocol main focus is the reduction of greenhouse emissions and the sharing of technology with other countries in order to obtain that goal. Though the political reasons for this global treaty may be self serving, some of the things that came about after the signing are considered to be historic.

An example of this is here in the U. S. where the Department of Energy and the EPA, who were long time adversaries, collaborated together to initiate several programs. One of several programs initiated by them is the Energy Star Homes. The main objective of this program is not to build an energy efficient home. Its primary purpose is market transformation. The definition of this is the changes made under the program persists long after the program initiative. In other words, the standards in the construction of Energy Star Homes become the standards in Building Codes or at least improve them.

ASHREA at first welcomed this initiative. However, soon afterwards health concerns arose and ASHREA unofficially withdrew its endorsement of the initiative. This resulted in a much heated debate that is known as "Sick Bulding Syndrome" (SBS), which is still being debated to this day.

In order to cause market transformation in building codes in this country, ASHREA must change their standards. This is because ASHREA's standards are the most acceptable in this industry and viewed by the majority as a bible in the construction industry. ASHREA will not adjust or change their standards unless the proposed changes are supported by statistical data that proves definitively that the proposed methods and/or applications poses more harm to people and/or property.

There are those who argrue that the goals in Kyoto Protocol and even Energy Star Programs include capturing lost opportunities. That ASHREA's inaction has resulted in these losses. While there are others that say it is better to be safe than sorry.
 
  #19  
Old 08-07-03, 01:10 PM
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vapor barrier

Alright. It took a while to digest all of that info and I think I have a fairly good idea of the logistics of how moisture travels in a basement. It sounds like I have 2 options:

1. Go with a vapor barrier on the "warm" side of the insulation (between insulation and drywall).

2. Go with NO vapor barrier at all and use unfaced insulation covered by the drywall.

(BTW--I have removed the 6mil poly from the concrete block side of my framing. It was in place for 2 months and there was one small spot, near the ceiling, about 3" in diameter where there was visible condensation on the concrete block side of the barrier. Otherwise the barrier was completely dry to the touch. We have had a fairly wet summer here.)

I guess I am leaning towards option #2 in addition to using a dehumidifier (which I currently have running down there). Hopefully this will cut down on the majority of the moisture that might travel through the drywall and condense inside the wall cavity. It seems that moisture weeping in from the concrete block won't be an issue, based on the paragraph above (knock on wood).

Any thoughts? Will the combination of the dehumidifier with no vapor barrier keep me dry?

One other question. If I did install a vapor barrier on the "warm" side of my framing, what happens to the moisture that the barrier stops? Does it get absorbed into the drywall? Do the properties of the drywall keep the moisture in the room?

BTW--The electrical inspector left my house an hour ago and gave me a thumbs up on my rough electrical inspection. This was my first attempt at doing anything of this magnitude. There is a certain sense of accomplishment in doing a job on your own. There is an even greater sense of accomplishment when someone who has been doing inspections for 45 years says that my job was better than most he's seen from a DIY'er. It is worth the price of addmission ($50 permit fee) to hear that from him.
 
  #20  
Old 08-08-03, 07:17 AM
MusicField
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Run the dehumidifier during July & August and in June & Septemeber whenever the weather is humid. Make sure the dehumidifer is appropriately sized for the space, and monitor & keep the relative humidity below 50%, and you will be fine. If you have central AC upstairs, this also helps alot at removing humidity from the house during humid weather.

Congrats passing your electrical inspection. Feels great, eh? Keep up the good work.
 
  #21  
Old 08-10-03, 10:04 PM
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Vapor barrier

A vapor barrier is recommended. Please reread the information posted in this thread. It explains very well why a vapor retarder/barrier is recommended. Controlling humidity levels the the basement area with a dehumidifier will help control humidity and minimize problems associated with high humidity. Yet, a vapor barrier is recommended to prevent humidity from collecting on cold walls inside the wall cavity and resulting in moisture problems.
 
  #22  
Old 08-11-03, 08:16 AM
MusicField
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Whether a vapor barrier is recommended or not, I guess is a function of who is doing the recommending.

In langer's case, then building inspector recommended NO vapor barrier.

FWIW, I agree with langer's building inspector, and recommend that he NOT use one in his project.
 
  #23  
Old 11-08-03, 12:00 PM
cleon1983
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Twelvepole, what is recommended in our part of the country? I'm up the road in Ashland preparing to build my frame in the basement. Originally, they had a poly against the block with paneling nailed to furring strips. I'm building a frame to hang drywall. Best I can tell, I should build the frame an inch away, use fiberglass insulation in the frame, and put the poly on the drywall side of frame. A question above asked what happens to the moisture when it hits the poly? Does it soak into the sheet rock or is it minimal?
 
  #24  
Old 11-10-03, 08:08 AM
MusicField
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cleon,

i recommend a continuous layer of extruded polystyrene 1 inch think adhesively applied to the concrete wall, followed by framing, with unfaced fiberglass (3.5 inch think) between the the walls studs, followed by drywall. No vapor barrier.

The rational for no vapor barrier is based on the physics of water vapor movement in below grade masonay assemblages, which is described in great detail in a research article on this vay suject at this link:

http://www.buildingscience.com/resou...on_systems.pdf
 
  #25  
Old 11-11-03, 11:12 AM
loco
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No one mentioned the use of dri-loc on the walls.
 
  #26  
Old 11-12-03, 12:12 PM
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V/B

Just guess its where your at. We put poly over the cement walls .2X4 studs R 13 2 mil poly then the dry wall. been like that for over 25 years now. ED
 
  #27  
Old 11-17-03, 08:58 AM
cleon1983
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Where can I find the extruded polystyrene 1 inch thick? Lowes didn't have it, or maybe I was talking to somebody there that didn't know his butt from a hole in the ground. There is a home depot about 20 miles away. What does it usually cost?
 
  #28  
Old 11-17-03, 10:23 AM
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Lightbulb poly

You got hold of a" DUD-"---------- they have it ,also Home depot ED
 
  #29  
Old 06-06-05, 07:16 PM
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Musicfield...

What is the purpose of glueing the polystyrene blocks to the cement walls? If there are any spaces left without adhesive wouldn't mold grow there?

Did this advice come from the 'Building Science' PDF?

I am also thinking that any vapor barrier may be slightly porous to water vapor and that is why BS does not recommend it.

Dan
 
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