Michigan Insulation requirements

[lxrubin]

I just purchased a home and the previous owner was part way through insulating the garage. There's still about 20% of the walls and ceilings to go, but I'm not sure it's done to the best and latest standards. I'm in SE Michigan.

Right now there's R13 fiberglass batts in the sides with 1/4" (I think) drywall and R30 batts between the ceiling joists. There doesn't appear to be any vapor barriers. I know that in my climate, it's recommended to add a vapor barrier INSIDE the insulation behind the drywall.

How critical is this? Is it worth while to pull the drywall and add the vapor barrier? Since most heat loss happens through the ceiling, would my effort be best used by adding a vapor barrier under the joists?


Some theory questions....
I understand the theory of having the vapor barrier inside to catch condensation on the cold surface in the winter, but doesn't this work against me in the summer? I don't want condensation to build up on the other side of the barrier and soaking the insulation. Additionally, if the insulation is essentially in outdoor temperature without an air barrier, doesn't airflow move through the insulation and negate any actual insulation benefits? It's like wearing a sweater in the winter without a windblock material. Sure it helps as long as there not airflow.

 

[Moosefire]

I'm in the same area, Ive never heard of putting up any vapor barrier inside... I'm no carpenter either though....

Sent from my SM-N960U using Tapatalk

 

[foodie]

following this.....

 

[GRivera]

Are they faced batts, with the paper to the inside?

 

[lxrubin]

Are they faced batts, with the paper to the inside?

Yes they have paper on the inside.. I can't see how that's a barrier though since the edges are exposed.. I suppose it's helping, but not sealed.

 

[burleyfarm]

Yes they have paper on the inside.. I can't see how that's a barrier though since the edges are exposed.. I suppose it's helping, but not sealed.

That’s the correct way. Hopefully there’s house wrap under the siding too.


Sent from my iPhone using Tapatalk

 

[finn]

The paper has a black layer inside, facing the fiberglass. That’s the vapor barrier.

You should be good to go.

 

[mike93lx]

If it is 1/4" drywall and not 1/2", rip it all out anyway and start over because it is a hack job and you don't know what else is wrong.

You want a vapor barrier on the warm side to stop condensation from building in the wall cavity. That's the facing on the insulation. You can also do it with plastic sheeting.

If it is a 2x4 wall, r13 is about all you can get without doing foam

 

[finn]

Do they make 1/4” drywall? I know there is 3/8”, but 1/4”?

 

[mike93lx]

Do they make 1/4” drywall? I know there is 3/8”, but 1/4”?

Yes. Used for curves and covering old surfaces like lath or popcorn with asbestos

 

[ericm]

Vapor barrier requirements: https://www.iccsafe.org/wp-content/uploads/proclamations/TN06-Vapor-Retarders_pdf.pdf

 

[rerod]

This is a good discussion..

https://www.greenbuildingadvisor.co...?cid=170800&discussion=comment#comment-170800

 

[Randy in Maine]

I would rip out all of that **** and call up the spray foam guy for a good solid 3" of HD foam. Energy is not going to getting any cheaper in the future. At least then you will have a good solid foundation to build on.

 

[Jim greengo]

I would rip out all of that **** and call up the spray foam guy for a good solid 3" of HD foam. Energy is not going to getting any cheaper in the future. At least then you will have a good solid foundation to build on.

You're pretty limited on what youl be able to do inside of a wall once its spray foamed.

 

[homelessdespot]

Isn't drywall with latex paint on it considered a vapor barrier too?

 

[rerod]

Isn't drywall with latex paint on it considered a vapor barrier too?

If the drywall is sealed to the studs, a air barrier. Vapor will pass through unless you wall paper it.

 

[toyotadriver]

The reason for a vapor barrier in a cold environment is the house is warm inside. Warm air carries a lot of moisture. Houses have showering and cooking as key sources of moisture. Moisture condenses on cold surfaces. A vapor barrier helps keep moist air from getting to the cold surfaces to condense on. Your paper faced insulation is the vapor barrier. It's not as effective in extremely cold climates which is why you will usually see taped plastic in super cold environments for the vapor barrier.

 

[lxrubin]

Yes I understand this and agree with the reasoning. But, wouldn't the opposite happen in the summer? It gets quite hot and humid here, so wouldn't the air on the insulation side condense against the barrier since the inside temp will be so much lower? This is the reasoning to have vapor barriers on the outside in hot climates.

Or is it because the hot climate season is so short, the condensation is minimal and it has a long time to dry out in the winter season, which is quite dry?

A while ago, I read that if fiberglass insulation gets wet, it retains moisture so well that it essentially can never fully dry out in a typical wall environment. Is there any truth to this?