Vapor Barrier in Ceiling?

[central1ny]

I am working on insulating the ceiling of the covered connector between my house and the new garage and was wondering what the standard practice is for using vapor barrier in ceilings. The local codes enforcer tells me that I should not have a vapor barrier in the ceiling but this seems contrary to everything that I read on the internet. So what is the correct practice, should there be a vapor barrier on the ceiling or not? I live in NY.

I am installing R-30 unfaced insulation and was planning on putting a 6-MIL plastic over this. I realize that at the end of the day, I have to install per codes enforcer, but just wondering. Thanks!

 

[PsRumors]

IF you are using a vapor barrier it should go between the ceiling material (sheetrock, plywood, etc) and the insulation. Vapor barrier should NOT be placed on top of the insulation.

We don't use vapor barrier in the ceiling here in the south.

 

[Chevy Guy]

I'm wondering why you would want vapor barrier in the ceiling? Please elaborate on what you think this will accomplish.

 

[central1ny]

Mostly I was thinking the plastic would work as an air barrier. We are installing a pine ceiling and if the joints are not perfect, I can forsee that there is the potential for air infiltration. Maybe a solution would be to caulk all of the joints.

 

[50cal]

I am struggling with the same question only applies to cathedral cieling in our living room. From what I have read, http://www.garagejournal.com/forum/showthread.php?t=122613
no vapor barrire unless at climate zone 6 or above.

 

[50cal]

Rather than caulk all the joints, maybe a layer of drywall or osb just taped. It would be permeable.

 

[ForceFed70]

I would think that in NY you would be required to have a vapor barrier.

Perhaps the inspector thinks that the garage will be un-heated?

PsRumors is correct: The vapor barrier goes on the warm side of the insulation. Perhaps this is where the confusion is coming from?

 

[50cal]

I have had several insulation contractors look at my project. They have all said no vapor barrier in cieling. The moisture needs to get out. Not getting out is where mold comes from. Funny how things change in our old house remodel vapor barrier was all the rage. We put it everywhere.

 

[ForceFed70]

I have had several insulation contractors look at my project. They have all said no vapor barrier in cieling. The moisture needs to get out. Not getting out is where mold comes from. Funny how things change in our old house remodel vapor barrier was all the rage. We put it everywhere.

Your local building authority is who you should be talking to about whether vapor barrier is required.

Where are you located? In warmer climates, vapor barrier is not required.

In my location vapor barrier is a requirement for any heated space. They have a specific inspection just for vapor barrier. I just went through this last month.

Yes, moisture needs to escape. But in the proper way. Through the ceiling can result in excessive condensation leading to mold and rot.

 

[donnie m]

a good rule of thumb is you need a vapor barrier between the heated area and the insulation always...otherwise as the heat passes into the cool insulation in the unheated area moisture will accure then mold to follow. use plastic under your insulation or use kraft face insulation facing down towards the heated area.

 

[50cal]

Your local building authority is who you should be talking to about whether vapor barrier is required.

Where are you located? In warmer climates, vapor barrier is not required.

In my location vapor barrier is a requirement for any heated space. They have a specific inspection just for vapor barrier. I just went through this last month.

Yes, moisture needs to escape. But in the proper way. Through the ceiling can result in excessive condensation leading to mold and rot.

Like I siad its up in the air. I am about to go thru my rough in inspections and thinking about whats next. I will ask the inspector what he wants to see at that time. I am in zone 5. Attic ventilation plays a big part in this also as far as mold issues that is why I provided the link to another thread where this is disscused in depth.

 

[central1ny]

I would think that in NY you would be required to have a vapor barrier.

Perhaps the inspector thinks that the garage will be un-heated?

PsRumors is correct: The vapor barrier goes on the warm side of the insulation. Perhaps this is where the confusion is coming from?

I am in zone 5 in NY and as mentioned previously, the code inspector told me to not install vapor barrier. By the way, the ceiling that I am doing is for a new addition (or connector) between the house and the attached garage. The connector will be part of the living space and will therefore be heated. I read through the NYS residential building codes for 2010 and it does not specifically mention a vapor barrier for ceilings. The code is very explicit about the need for a vapor barrier on the walls though.

 

[jbs]

You are right about wanting an air barrier with t&g pine for sure. You don't want that warm moisture-laden air making it through into your insulation, especially air-permeable fiberglass.. I would either do a layer of drywall with the seams taped, or a layer of 1/2" rigid foam with the seams taped before the wood.

 

[trbomax]

They are going to allow wood directly against the joist without sheet rock as a fire barrior in a heated liveing space? Ive only built in ohio and michigan , and that wont fly in either place.

 

[brownbagg]

with favor barrier on ceiling, moisture will not go through the vapor barrier, and sit on the back side of your sheetrock, also your tools will rust

 

[wssix99]

I have had several insulation contractors look at my project. They have all said no vapor barrier in cieling. The moisture needs to get out. Not getting out is where mold comes from. Funny how things change in our old house remodel vapor barrier was all the rage. We put it everywhere.

^^^ This is correct.

For a practical demonstration, one could jump in a garbage bag tie it off at the neck. The inside of the bag will soon turn in to a smelly, humid sauna.

Typically, "normal" houses will not install a barrier in the ceiling to give vapor a passive pathway to escape. That being said, the wave of the future is to build "tight" houses for energy efficiency. (This includes more than vapor barriers on all walls.) These houses require an ERV to actively keep humidity and air quality in check.

 

[50cal]

^^^ This is correct.

For a practical demonstration, one could jump in a garbage bag tie it off at the neck. The inside of the bag will soon turn in to a smelly, humid sauna.

Typically, "normal" houses will not install a barrier in the ceiling to give vapor a passive pathway to escape. That being said, the wave of the future is to build "tight" houses for energy efficiency. (This includes more than vapor barriers on all walls.) These houses require an ERV to actively keep humidity and air quality in check.

[/QUOTE

I have an ERV installed, this is a tightly built home ICF, geothermal, and infloor heat in the basement slab.

 

[DickDeegan]

I live in Ontario, Canada and probably have similar weather to you. When I insulated my garage someone had dry walled the ceiling with no vapour barrier. I insulated on top of the drywall and then painted the drywall with two coats of oil based paint. The oil based paint is upposed to act as a vapour barrier.

**** Deegan

 

[innkeeper]

Very good comments by all..

 

[wssix99]

I have an ERV installed, this is a tightly built home ICF, geothermal, and infloor heat in the basement slab.

My wife (and general contractor) are about to break ground on an ICF house w/ ERV this spring. Generally, houses should "breathe" but we live by different rules because ICF is so air tight.

50 cal - I'd suggest you contact a passive house professional in your area for the answer to your particular situation. http://www.passivebuildings.ca/

While ICF houses with ERV's can be built air-tight, there are other barriers that hold back air but not moisture. I understand that employing these materials (and their physical location in the wall) varies regionally and is dependent on ambient temperatures and humidity conditions.

I just asked my "general contractor" about this situation absolutely got the wrong answer from her - regarding the ERV's ability to balance humidity. This has sparked some heated discussion. Fortunately, we're working with another builder who is passive house certified - so we'll be kicking the question up to him for arbitration regarding our house in Chicago.