So I bought a house a few months back, been rehabbing it. Anyways, I took out all the dry wall in the house and I'm about to put in the new dry wall this week. I have a problem;

The walls have a vapor barrier, the ceiling did not. I kept the barrier on the walls, but I'm stuck on what to do with the ceiling.

My heating and air guy (who has been my fathers friend since before I was born), says not to put one on the ceiling, he says it will trap moisture and I think he said it will not be good for the dry wall.

My father in law swears up and down I have to have one or it will rot my trusses out if there is a lot of humidity in the house. He says it's been building code for 35 years (he is an electrician by trade and I'm sure been in a least a few new buildings ).

Obviously, they aren't both right, so which one is correct?

-Brandon

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The List;
1) 98 Jetta TDI (55+ MPG) 2) 95 BMW 325i 5 spd (Wife's car) 3) 82 Chevy Scottsdale 6.2 (tow duty)
4) 87 Fiero 3800 S1 S/C 5spd (almost road ready) 5) 85 S10 diesel 5spd (engine donor) 6) 84 S10 (receiver) 7) 84 S10 2.5 5spd (parts)
8) 87 GMC S15 2.8 5spd parts truck 9) 91 Mercedes 190E (diesel 5spd swap) 10) 84 Mercedes 190D (donor) 11) 85 Fiero (parts)
12) 85 Fiero SE (7730 ecm, 3500) 13) 87 GT (7730 ecm, hybrid 2800, izusu 5spd swap soon)

I would call your local county building inspector "anonymously" so you are not tipping them off if they have to inspect it when you are done.

this may help a little.

-Joe

There's no vapor barrier in my ceiling. The house was built in the 50's. There was just 1" or so thick insulation between the joists with the kraft paper facing down. I added 6" of pink on top of it. None of my exterior walls had insulation so I have removed all the drywall on the exterior walls, installed insulation with the kraft paper facing inwards and re-drywalled everything.

Larry

My house was built in 87, no vapor barrier either.

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Todd,
2008 Jeep Patriot Limited 4x2
2002 Ford Explorer Sport 2dr 4x2
2002 Ford Crown Victoria LX
1987 Pontiac Fiero SE / V6
1973 Volkswagen Type-2 Transporter

You do not want vapor barrier in the ceiling. The house needs to 'breathe'

yeah, that's what my research has been showing me, I have a ventilated attic so I should not need a barrier.

Thanks guys, I feel better already

My house was built late 2008-early2009--I moved in May 5-09.
No vapor barrier, and I live in a very wet climate. .

[This message has been edited by maryjane (edited 12-06-2009).]

The link that I posted earlier has some pretty good info on it, I was reading through it and learned some.

-Joe

YES, you do need to put vapour barrier on the ceiling! You want to keep all moisture contained on the "warm" side of the insulation. Without the barrier, moisture will condense in the insulation and/or attic space when the weather is cold. Over time, the roof structure will rot due to the condensation.

Contained in what--the sheetrock ceiling?
not a chance.

Absolutely you need a vapour barrier in the ceiling. If you need ventilation in the house, vapour through the ceiling is not the way to do it. Also, you want minimum R44 up there. Trust government guidelines on this one.

Arn

Yes you want vapor barrier everywhere. Warm air holds more moisture than cool air, when warm air hits cool air, the moisture condenses, EX. your windows on a very cold day. The purpose of the vapor barrier is to keep the moisure on the 'hot' side of the insulation, keeping it away from the cool air where it would condense. The vapor barier stops the moist air well below the cold zone, keeping the moisture in suspension.

With vapor barrier, you want the house to be a bubble, as air tight as possible, that means back wrapping all outlet boxed, then tuck-taping them to the barrier on the front, completely illiminates outlet drafts. Anywhere there is a hole or seam in the vapor barrier, you want to tuck tape, which is a special tape designed for use on vapor barriers, dont use just anything. You also want to glue the vapor barrier right to the base of the walls around the perimiter, or better yet, during construction lay the sills on vapor barrier and leave enough to wrap it around and tuck tape to the interior wall barrier.

You want the house to be like a bubble, houses dont need to breathe, there is enough air exchange from uncrontrollable sources and door openings. As long as all your appliances are functioning and vented properly.

If you want to learn how to really insulate a house, watch some canadian home improvement shows, they take it seriously by golly dontcha know.

Oh, and all my refrences to vapor barrier is true plastic vapor barrier, im not too fond of the paper backed insulation bats, as you can imagine, there is a crack at every stud. Much easier and better to use roll plastic.

quote Originally posted by 86GT3.4DOHC: Yes you want vapor barrier everywhere. Warm air holds more moisture than cool air, when warm air hits cool air, the moisture condenses, EX. your windows on a very cold day. The purpose of the vapor barrier is to keep the moisure on the 'hot' side of the insulation, keeping it away from the cool air where it would condense. The vapor barier stops the moist air well below the cold zone, keeping the moisture in suspension. With vapor barrier, you want the house to be a bubble, as air tight as possible, that means back wrapping all outlet boxed, then tuck-taping them to the barrier on the front, completely illiminates outlet drafts. Anywhere there is a hole or seam in the vapor barrier, you want to tuck tape, which is a special tape designed for use on vapor barriers, dont use just anything. You also want to glue the vapor barrier right to the base of the walls around the perimiter, or better yet, during construction lay the sills on vapor barrier and leave enough to wrap it around and tuck tape to the interior wall barrier. You want the house to be like a bubble, houses dont need to breathe, there is enough air exchange from uncrontrollable sources and door openings. As long as all your appliances are functioning and vented properly. If you want to learn how to really insulate a house, watch some canadian home improvement shows, they take it seriously by golly dontcha know. Oh, and all my refrences to vapor barrier is true plastic vapor barrier, im not too fond of the paper backed insulation bats, as you can imagine, there is a crack at every stud. Much easier and better to use roll plastic.

Unlike certain Texans, you have it spot on.

When you live in a climate that has an average annual temperature under 40*F, you get an appreciation for controlling air infiltration, adding insulation and having a good vapour barrier. I can't wait to retire to a warmer climate.

quote Originally posted by TiredGXP: Unlike certain Texans, you have it spot on. When you live in a climate that has an average annual temperature under 40*F, you get an appreciation for controlling air infiltration, adding insulation and having a good vapour barrier. I can't wait to retire to a warmer climate.

maybe, just maybe, you're both correct, as it seems to depend greatly on climate.

Interesting. I have three turbine vents on my roof. I bought three designed covers for cold weather. I was told (by my neighbor) that indeed the home needed to breath, specifically the attic space. I also have three louvered attic vents at different ends of my home. I want to close them all up. They are there to let warm/hot air, which expands, get out. I want to keep cold air from entering especially on windy days.
I get no clear personal decision from reading this thread. The ...

quote Originally posted by 86GT3.4DOHC: Warm air holds more moisture than cool air, when warm air hits cool air, the moisture condenses, EX. your windows on a very cold day.

... above quote is fact but, the windows do eventually dry on their own.

The ATTIC needs to breathe. Ideally you should have louver vents in your soffit and ridge vents all across the peak of your roof.

The attic needs to breathe for 2 reasons. In the winter, the majority of the roof is above the attic space, which is slightly warmer due to heat from the house. Where the house ends and the soffits begin, the air is cooler, at this point you will develop ice dams, where the water that melted off the top off the roof hits the ice that has not melted because its above the cooler soffits. The watter will pool up and damage the roof. Having cooler circulating air helps mitigate this.

In the summer, the roof gets very hot, and having cooler air flowing past the back of the sheeting helps cool it and prevent the shingles from cooking. So yes the attic needs to breathe.

The condensation on your windows will evaporate, but condensation that forms inside of insulation and on rafters does not have free flowing air around it, or dry air from inside the house, so it will remain longer, and will cause rot mold and mildew while it is there.

1. I have no attic.
2. I am not concerned with ice dams.
3. I have no shingles to cook.
4. You didn't aswer my question regarding exactly where you envision trapping that moisture.

I have been in the attic of my house during the winter, when it has been wet and I can almost guarantee that my rafters don`t have any condensation on them. The ceiling joists may, as they are not easily seen.

My house is on pier and beam and I would be more concerned about floor joists having condensation than rafters.

[This message has been edited by TXGOOD (edited 12-07-2009).]

Built in the '40s, renovated in the '70s and no vapor barrier here. And I have never seen a vapor barrier on the ceiling on any house I've installed A/V in (and that includes a few that top out at over $2M). YMMV, but it doesn't seem to be necessary in Oklahoma.

call the building inspector... what is code for your area?

BTW, put as much insulation into the ceiling as you can... go above the recommended amount. If you don't have the room, use spray foam insulation. If you want you can seal your attic with spray foam (hot attic theory). Check out http://www.masterhandyman.com

J.

You dont see condensation in a cold attic because there is no warm humid air. If you have actual air penetration into an attic, it has cooled and condensed long before it gets up into the air. There will be no condesnation on the visible surfaces because the moisture in the air is below the dewpoint. They do have it where moisure will condense in that situation, they call it rain. lol

You have no attic, no shingles (and thus im assuming a metal roof) and no worries about ice dams, congradulations, but as for the other 99.5% of homeowners who have a traditionally constructed house with traditional shingles all those things are very important to them. The signs of ice damns are pretty easy to spot, soft spongy sheeting above exterior walls, sagging of the roof surface just above the gutters, causing pooling, and water spots on the ceiling near exterior walls.

You are not 'trapping' any moisture, what vapor barrier does is prevent moisture from penetrating into the cold zone, in this conversation, the attic. If you want to get technical about it, the moisure stays in the warm zone, the living space. Warmth still escapes through heat transmission, but there is no movement of moisture.

A lot of older houses didnt have vapor barrier in the ceiling, drywall serves as a passible vapor barrier as long as you dont have too many penetrations, then again not too long before that a lot of houses didnt have insulation either. My motto is, if you're going to do it, do it right. Whats $20 for a roll of vapor barrier in the big picture. Build them however you want, but if you want to stay with the times, and increase your efficiency, you want to 'bubble' the house against all exterior surfaces. Like I said if you want to learn about insulation efficiency, watch some canadian home shows. They brag about being able to heat a room with a candle, whether thats an expression or actually possible, I dont know.

quote Originally posted by 86GT3.4DOHC: You dont see condensation in a cold attic because there is no warm humid air. If you have actual air penetration into an attic, it has cooled and condensed long before it gets up into the air. There will be no condesnation on the visible surfaces because the moisture in the air is below the dewpoint. They do have it where moisure will condense in that situation, they call it rain. lol You have no attic, no shingles (and thus im assuming a metal roof) and no worries about ice dams, congradulations, but as for the other 99.5% of homeowners who have a traditionally constructed house with traditional shingles all those things are very important to them. The signs of ice damns are pretty easy to spot, soft spongy sheeting above exterior walls, sagging of the roof surface just above the gutters, causing pooling, and water spots on the ceiling near exterior walls. You are not 'trapping' any moisture, what vapor barrier does is prevent moisture from penetrating into the cold zone, in this conversation, the attic. If you want to get technical about it, the moisure stays in the warm zone, the living space. Warmth still escapes through heat transmission, but there is no movement of moisture. A lot of older houses didnt have vapor barrier in the ceiling, drywall serves as a passible vapor barrier as long as you dont have too many penetrations, then again not too long before that a lot of houses didnt have insulation either. My motto is, if you're going to do it, do it right. Whats $20 for a roll of vapor barrier in the big picture. Build them however you want, but if you want to stay with the times, and increase your efficiency, you want to 'bubble' the house against all exterior surfaces. Like I said if you want to learn about insulation efficiency, watch some canadian home shows. They brag about being able to heat a room with a candle, whether thats an expression or actually possible, I dont know.

Are you a contractor, insulator, or work in the home building industry?

You missed my point... you seal the attic like a thermos. The underside of the attic is sprayed with foam... this creates a warm area that is sealed. No heat will rise, no heat will enter during the summer either. The shingles will not overheat.

Here is the information:

http://www.masterhandyman.c...cfm?pubdate=20010714


Homeowners have new insulation option in the Hot Roof Theory

By Glenn Haege / Special to The Detroit News

I have been preaching the attic insulation gospel according to the Cold Roof Theory for 18 years. The trouble is that it doesn’t always work.

The Cold Roof Theory calls for insulation and ventilation to protect houses from heat loss and prevent ice dam roof damage. The insulation provides a thermal barrier, while a continuous stream of air, coming in through the soffit vents and exfiltrating through roof or ridge vents, keeps the roof deck cool.

Mike Kearns, Kearns Brothers Insulation, (313) 277-8000, called to tell me that a product called the Cobra Soft Edge by GAF is no longer available for homes whose soffits are too narrow for traditional venting. Obviously, the theory can’t work if a key ventilation element is missing.

In addition to houses with narrow soffits, many older homes have floored storage attics. Other homes have essential equipment located in the attic. In both cases, covering attic floors with a 12- or 14-inch-deep layer of insulation is not an option.

When I asked the top people at Owens Corning Insulation what was the best way to insulate storage attics, their technical expert told me that there is no good way to do the job. If you can’t insulate the attic using the cold roof insulation theory, there has to be another option.

There is. It’s called the Hot Roof Theory.

A few years ago, the scientists at the Oakridge National Laboratory in Tennessee tested properly vented and totally sealed attics. They found that proper venting only reduced the roof deck temperature by 3 to 5 degrees Fahrenheit.

Further testing determined that not venting an attic might reduce the service life of organic asphalt or fiberglass shingles by a maximum of five years. The temperature differential did not seem to have any effect on homes with higher quality tile or metal roofing systems.

In practical terms, this means that if you throw out the Cold Roof Theory, you have to resign yourself to shortening the service life of your shingles or upgrading to a higher quality roofing system. Most organic shingle manufacturers also void their warranties if there is not sufficient ventilation.

Using the Hot Roof Theory, the attic is completely sealed. The soffit areas are packed with insulation, and the attic walls and ceiling (the roof deck) are coated with insulation. The best type of insulation for this type of a project is sprayed foam.

Icynene, a Canadian spray foam manufactured by Icynene Inc., (800) 758-7325, has been making major inroads in insulation projects using the Hot Roof Theory. By using Icynene, the attic roof deck and walls can be insulated and sealed from wind infiltration in one application.

The product is an expanding, totally benign, water-based foam with exceptional adhesion qualities and virtually no off-gassing. Unlike cellulose or fiberglass insulation, Icynene is not damaged by water, and the original R-value is restored as soon as the product dries.

When an attic is insulated using the Hot Roof Theory, the attic temperature adjusts to within 10 degrees of the ambient temperature of the house. Because the attic is heated or cooled by air that would normally escape from the house, it does not raise the load on the heating and cooling system.

If a new house is totally foam insulated, it has most, if not all, of the benefits of foam insulated concrete block construction. It is quieter than traditional wood frame construction. The heating and cooling equipment can be safely downsized, and a 30 to 50 percent reduction in total heating and cooling costs is often realized. The need for artificial humidification is also greatly reduced. Reducing humidity levels cuts mold spores and other microbials, creating a healthier home.

Because foam insulation seals the building envelope, mechanical ventilation is required. This is usually accomplished by adding vents and a small, continuously operating, whole-house fan. An Energy Recovery Ventilator installed by heating and cooling contractor will also take care of the problem.

In Southern Michigan, Icynene insulation is installed by Seal Tech Insulation, (734) 649-8584. The Icynene web site, www.icynene.com, lists installation contractors for every part of the country.

Closed-cell polyurethanes, such as Comfort Foam, produced by the Comfort Foam Division of Foam Enterprises of Minneapolis, (800) 888-3342, also can be used, according to Bill Amend, the division manager.

"When it comes to insulation, I think that P-value is even more important than the R-value. A closed-cell polyurethane foam stops air penetration. Fiberglass can’t make that claim," Amend said. If you want to learn more about his views on insulation, see the company’s web site, www.comfortfoam.com.

Gabe Farkas, the technical director of Icynene Inc., says that while foam insulation is about three times more expensive than cellulose or fiberglass insulation, it is also about six times more effective.

Although both Icynene and Comfort Foam have earned the Energy Star rating, not all building inspectors have accepted or even know about the hot roof insulation theory. To learn more, contact the manufacturers, then check with your local building officials. If you get way ahead of the curve, you can earn bragging rights big time.

Note: This article was accurate at the date of publication. However, information contained in it may have changed. If you plan to use the information contained herein for any purpose, verification of its continued accuracy is your responsibility.

quote Originally posted by 86GT3.4DOHC: Like I said, a bad idea, without cool air flowing under the sheeting, you will cook the shingles, especially if there is insulation touching the sheeting holding the heat in. If you were going to do that (like in a cathedral ceiling installation), they make baffles that create air passages against the sheeting, but allow you to directly insulate the back side. Also I believe there are some codes regulating hot zones \ cold zones. For example in some areas its against code to insulate your crawl space and make it a warm zone. I dunno about attics.

personally, i would not barriewr the cieling---just for air quality, ya need some flow and circultion, otherwise you are gonna wake up every morning spitting out a lung.......

and, if you are screwing around in an older attick, make sure the insulation is not vermiculite (the stuff is gold in colour)........most of it is safe, but there is an ammount around that came out of one mine and is contaminated with asbestos.........and that stuff WILL make ya deaded breathing it in.

quote Originally posted by jaskispyder: You missed my point... you seal the attic like a thermos. The underside of the attic is sprayed with foam... this creates a warm area that is sealed. No heat will rise, no heat will enter during the summer either. The shingles will not overheat. Here is the information: Icynene, a Canadian spray foam manufactured by Icynene Inc., (800) 758-7325, has been making major inroads in insulation projects using the Hot Roof Theory. By using Icynene, the attic roof deck and walls can be insulated and sealed from wind infiltration in one application. The product is an expanding, totally benign, water-based foam with exceptional adhesion qualities and virtually no off-gassing. Unlike cellulose or fiberglass insulation, Icynene is not damaged by water, and the original R-value is restored as soon as the product dries.

My house is insulated with Icynene. I'll never use a fiberglass batting insulation again, after seeing the benefits of Icynene. It's that good. I had it applied when we renovated our 1850's house. I had thought about the fiberglass batting type, as it was about 1/3 the price of Icynene, but I realized that in this old of a house, there is no house-wrap, thus, lots of air infiltration. Plus, I live on a fairly busy road, and was concerned about noise. After seeing a 'This Old House' which featured the product, I found a local company that sprays it. I did all the prep work, which saves a considerable amount of $. Since the product is sprayed in, and expands, any outlet not taped/sealed or window opening WILL get filled. Based on my heating oil usage, I figure that the added cost of the insulation has already been paid for. I went from 5 or 6 tanks of oil a year down to 2. It's a fantastic product.

quote Originally posted by dsnover: My house is insulated with Icynene. . I went from 5 or 6 tanks of oil a year down to 2. It's a fantastic product.

Global warming.

Yup, sounds like great stuff (ha ha)... I am thinking about having my crawlspace sprayed. I hate fiberglass also. I had cellulose used in the ceiling this past winter. The cost would have been too high to have them spray that. I don't think I will be staying at this house in the long run, but if I do, I will look into using spray insulation (icynene).

quote Originally posted by dsnover: My house is insulated with Icynene. I'll never use a fiberglass batting insulation again, after seeing the benefits of Icynene. It's that good. I had it applied when we renovated our 1850's house. I had thought about the fiberglass batting type, as it was about 1/3 the price of Icynene, but I realized that in this old of a house, there is no house-wrap, thus, lots of air infiltration. Plus, I live on a fairly busy road, and was concerned about noise. After seeing a 'This Old House' which featured the product, I found a local company that sprays it. I did all the prep work, which saves a considerable amount of $. Since the product is sprayed in, and expands, any outlet not taped/sealed or window opening WILL get filled. Based on my heating oil usage, I figure that the added cost of the insulation has already been paid for. I went from 5 or 6 tanks of oil a year down to 2. It's a fantastic product.

We had Icynene put in the front half of our turn-of-the-century house and it made a huge difference in not only wall insulation, but eliminating drafts.