Ceiling Vapor Barrier / input

[NWOhioChevyGuy]

So I’m to the point of putting up my ceiling insulation in my build. The drywall will likely be a year or more out.

Will a standard poly 6 mil hold up that long before covering? Just stapling it up over craft faced R30 bats.
Or should I spend a little more and get this reinforced poly?

Polar Plastics 20' x 50' 6-mil Clear Reinforced Poly Plastic Sheeting at Menards
https://www.menards.com/main/p-1444451025809.htm

 

[brownbagg]

no vapor barrier on ceiling, vapor rise so moisture will not escape and will cause mold on ceiling

 

[dfiler2]

If you are in a cold climate you need the moisture barrier on the ceiling. I would go with the better stuff in case it turns into a couple of years.

 

[NWOhioChevyGuy]

YUP, Michigan

I’m leaning that way as well.

And there is no question there will be a VB, just if I should upgrade due to exposure.
The craft facing should support the insulation properly, but due to the potential long exposure want it protected.

 

[jkuro]

The craft facing is your vapor barrier.

 

[dfiler2]

The kraft face insulation is better than nothing but is always full of gaps and leaks.

 

[haveissues]

I think if it does not receive direct sunlight the 6 mil will survive.

 

[NWOhioChevyGuy]

Thanks for the input, there WILL be a VB.
And likely the reinforced version, just to be safe.

 

[kbs2244]

Do not confuse a vapor barrier with a moisture barrier
The no VB in a ceiling is the correct way
You need the vapor to vent
Moisture is actual water and you should not have a moisture problem in a ceiling
So, in a ceiling install, Kraft is O K but no poly

 

[Sumboodie]

The craft facing is your vapor barrier.

That's not rated as a vapor barrier in construction here.

 

[Sumboodie]

Do not confuse a vapor barrier with a moisture barrier
The no VB in a ceiling is the correct way
You need the vapor to vent
Moisture is actual water and you should not have a moisture problem in a ceiling
So, in a ceiling install, Kraft is O K but no poly

Not in cold climates. 6 mil poly on walls and ceiling between drywall and insulation.

 

[PoorUB]

Do not confuse a vapor barrier with a moisture barrier
The no VB in a ceiling is the correct way
You need the vapor to vent
Moisture is actual water and you should not have a moisture problem in a ceiling
So, in a ceiling install, Kraft is O K but no poly

Building code enforcement in our area would like to have a visit with you!

Here in ND walls and ceilings get a poly vapor barrier.

I was on a job site a few years ago and the rockers were about 1/2 way through hanging sheet rock when the inspector came in. He took one look and told then to take it back down and get a vabor barrier installed. They were not happy!

I remember the one guy arguing with him and he said if you want me to sign off on the job it will have vapor barrier, nobody moves in without an occupancy permit signed off on new construction around here!

 

[4x4Pete]

My trusses are 24" on center, I used 6 mil and then put drywall resilient channel perpendicular to the trusses. Held up the vapor barrier and insulation easily. I did r60 blow in and didn't want any issues it made the finished drywall ceiling super flat too.

 

[NWOhioChevyGuy]

My trusses are 24" on center, I used 6 mil and then put drywall resilient channel perpendicular to the trusses. Held up the vapor barrier and insulation easily. I did r60 blow in and didn't want any issues it made the finished drywall ceiling super flat too.

What is this Channel you speak of?? It’s a garage ceiling it don’t need to be perfectly flat.

 

[The Cobbler]

resilient channel is made for sound transmission deadening . no need for it in your application

 

[4x4Pete]

No need for it but it does give 1/2" drywall less sag when using it on 24" centers and keeps insulation from sagging the vapor barrier. I suppose you could rip plyood or use 1x3s to do the same thing. I chose to use the resilient channel.

 

[NWOhioChevyGuy]

5/8” here as bonus room above and need fire rated ceiling.

I did google it

 

[FredWanaker]

in a really cold climate interior vapors will go into the insulation and condense, then freeze near the exterior side of the insulation. In spring it will thaw and create a wet insulation and mold will follow. The vapor must be stopped from entering the insulation from the warm side. In hot humid climates the opposite holds. The outdoor humid air will work into the exterior side of the insulation and condense against the AC cooled drywall. In some climates like where I am, they argue all the time whether a vapor barrier is needed in the attic and which side it goes on if it is even used. Basically which ever side is warmer and more moist gets the barrier. The greater the difference the more it is needed. Poly will weaken if sun or UV gets to it long enough. That included lights that are heavy UV emitters like full spectrum bulbs. The length poly lasts depends on the quality of materials. There is no one size fits all answer. I have had some that lasted 3 - 4 years for solarization of lawn / garden in sunlight being used every summer, and other brands than barely made it a summer.

 

[rwreuter]

How about this situation.

-30x50 detached garage
-OSB on ceiling & wall
-Never cooled
-Heated (2 30k-80k BTU propane convection heaters) only when I am out there working in cold weather (live in southern Kansas), other than that, garage is always at ambient temperature
-Ceiling fans always run in the summer and run in the winter if I am working in it and heat it on
-Above the ceiling in the garage, full length is a subfloor (load barring trusses), basically another room) (Non heated area)


Vapor barrier in walls and ceilings or no?

 

[billconner]

How about this situation.

-30x50 detached garage
-OSB on ceiling & wall
-Never cooled
-Heated (2 30k-80k BTU propane convection heaters) only when I am out there working in cold weather (live in southern Kansas), other than that, garage is always at ambient temperature
-Ceiling fans always run in the summer and run in the winter if I am working in it and heat it on
-Above the ceiling in the garage, full length is a subfloor (load barring trusses), basically another room) (Non heated area)


Vapor barrier in walls and ceilings or no?

Yes if insulation (or planned). If no insulation, I don't think I'd add a vapor barrier.

 

[Sumboodie]

5/8” here as bonus room above and need fire rated ceiling.

I did google it

I thought 5/8" was normal for ceilings regardless?

The fire wall between my garage and house is 3/4" drywall.

In another place I lived, they did 2 layers of 1/2"

 

[NWOhioChevyGuy]

I thought 5/8" was normal for ceilings regardless?

The fire wall between my garage and house is 3/4" drywall.

In another place I lived, they did 2 layers of 1/2"

5/8” fire rated is all that is required here.

I wouldn’t know where to get 3/4” around here, never seen or used it.

 

[Sumboodie]

5/8” fire rated is all that is required here.

I wouldn’t know where to get 3/4” around here, never seen or used it.

Not sure. I do know pro places, and not home centers, carry 12-16ft long sheets as well as 4.5 and 5ft widths, among many other "non standards".

My house and garage has 9ft ceilings. 4.5ft wide sheetrock was used.

 

[NWOhioChevyGuy]

Picked up the insulation and VB today, went with he reinforced option.
Soon I will be able to at least heat while working out there.

The building drafts very well without insulation / ceiling. Aka heat don’t stay inside.

Looking forward to being able to work out there this winter.