Insulation, Radiant and Vapor Barriers - Vapor Barrier
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OPKER
05-19-02, 04:28 AM
I want to install vapor barrier from the inside of home. can I put housewrap inside before insulation goes in or after insulation before drywall goes on ? I live in Coastal Ga. A hot humid area.
OPKER
OPKER
resercon
05-19-02, 08:44 AM
You can go to http://www.eren.doe.gov/consumerinfo/refbriefs/bd4.html it is a brief on vapor barrier by the U.S. DOE and was actualy written by ASHREA. Now there are many issues concerning vapor barriers. It just so happens your situation is a big issue concerning house wraps and it affects on certain types of siding involving climates where cooling is dominant. It has always been the postion of the Building Performance Specialists of America (Architects) that vapor barriers should never be applied to the exterior of houses. Instead their position was 30 pound building paper, which has been done for years that way.
If you read the brief, it would appear that ASHREA has conceded to the Architects on this issue concerning your situation. It would except that the brief goes on to discuss air barriers, in which case there is no agreement between the two organizations. Though addressing air inflitration is a compelling arguement concerning moisture in climates as yours and is expressed well in the brief, when it comes to bringing the variety of components together to build a house that will sustain and prolong the integrity of the structure, the Architects are more apt. Because that is their primary function and desgning and decorating is secondary.
I will not side with either organization because their resources are far beyond my capabilities and the integrity of these two organizations are beyond reproach.
In your situation, as an Energy Conservationist that does not belong to either of the above mentioned organizations, I would recommend installing the 30 pound felt building paper only if wood siding is applied. If vynal siding is applied, I would recommend the house wrap, and/or a radiant barrier with a Perm rating of .1 or less.
If you read the brief, it would appear that ASHREA has conceded to the Architects on this issue concerning your situation. It would except that the brief goes on to discuss air barriers, in which case there is no agreement between the two organizations. Though addressing air inflitration is a compelling arguement concerning moisture in climates as yours and is expressed well in the brief, when it comes to bringing the variety of components together to build a house that will sustain and prolong the integrity of the structure, the Architects are more apt. Because that is their primary function and desgning and decorating is secondary.
I will not side with either organization because their resources are far beyond my capabilities and the integrity of these two organizations are beyond reproach.
In your situation, as an Energy Conservationist that does not belong to either of the above mentioned organizations, I would recommend installing the 30 pound felt building paper only if wood siding is applied. If vynal siding is applied, I would recommend the house wrap, and/or a radiant barrier with a Perm rating of .1 or less.
OPKER
05-19-02, 07:15 PM
What is a radiant barrier ? Remember the vinyl siding is installed already. The interior is not complete. Insulation has not been installed.
resercon
05-19-02, 09:35 PM
You can go to http://www.ornl.gov/roofs+walls/radiant/rb_02.html this is a fact sheet by the DOE on radiant barriers. It was written by Oak Ridge National Laboratory considered one of the best research facilities in the U.S. There are other fact sheets the DOE that may interest you, especially on insulation.
House wraps are only applied to the outside of houses and not the inside. I was assuming the siding was not installed yet by your description. If you read the brief it suggests that in climates such as yours, that the VDR or vapor barrier should be omitted. It goes further to imply the application of an Air/Vapor Barrier. Which is somewhat similar to what I said in the previous post. Since the house wrap and siding are already installed, the previous post does not apply to our situation. The radiant barrier will not apply also, though there are many that will disagree with me, the problem here is in your situation a dead air space is certainly warranted and that would prohibit you from installing adequate insulation to the wall that would meet local building codes.
Your situation makes is very difficult for me to answer. The reason for this is that I am very aware of the variety of organizations involved in this dispute over vapor barriers. And if you were to ask them, you would hear a different solution each time. There is one fact that none of us can ignore, that is fiberglass has a very low absorbancy rate to moisture. That installing fiberglass without a vapor has a very high probablitiy for moisture problem inside the insulation. With that said, the following is what I would recommend;
Install Manville's plastic wrap R-13 insulation. This is an insulation that has a vapor barrier surrounding the fiberglass insulation. One side has a higher Perm rating than the other side.
I strongly recommend you contact the manufacturer, get the person name to whom you speak to and ask for the proper application to their product. This is for warranty reasons.
I also recommend you ask an expert on either the brief or fact sheet, you will be in contact with either Oak Ridge, Tennessee Valley or ASHREA experts on this subject. These are dedicated professionals and I respect them. It does not mean I agree with them.
House wraps are only applied to the outside of houses and not the inside. I was assuming the siding was not installed yet by your description. If you read the brief it suggests that in climates such as yours, that the VDR or vapor barrier should be omitted. It goes further to imply the application of an Air/Vapor Barrier. Which is somewhat similar to what I said in the previous post. Since the house wrap and siding are already installed, the previous post does not apply to our situation. The radiant barrier will not apply also, though there are many that will disagree with me, the problem here is in your situation a dead air space is certainly warranted and that would prohibit you from installing adequate insulation to the wall that would meet local building codes.
Your situation makes is very difficult for me to answer. The reason for this is that I am very aware of the variety of organizations involved in this dispute over vapor barriers. And if you were to ask them, you would hear a different solution each time. There is one fact that none of us can ignore, that is fiberglass has a very low absorbancy rate to moisture. That installing fiberglass without a vapor has a very high probablitiy for moisture problem inside the insulation. With that said, the following is what I would recommend;
Install Manville's plastic wrap R-13 insulation. This is an insulation that has a vapor barrier surrounding the fiberglass insulation. One side has a higher Perm rating than the other side.
I strongly recommend you contact the manufacturer, get the person name to whom you speak to and ask for the proper application to their product. This is for warranty reasons.
I also recommend you ask an expert on either the brief or fact sheet, you will be in contact with either Oak Ridge, Tennessee Valley or ASHREA experts on this subject. These are dedicated professionals and I respect them. It does not mean I agree with them.