What is the most common type of vapor barrier in commercial construction?

[sal]

In residential, I frequently see a polyethylene vapor barrier applied over fiberglass batt insulation (I’m in a heating climate)

I usually don’t see this in commercial construction but know that certain paints can function as vapor barriers. What are the most common types of vapor barriers in commercial construction in heating climates?

 

[TheCommish]

various plastics

 

[SCBO1]

CertainTeed has a vapor barrier called MemBrain, you might check that product out. I see polyethylene on the inside sometimes and I see kraft faced insulation quite a bit.

On the outside, I see zip panels and house wrap used here.

 

[Paul Sweet]

Zip panels and house wrap are air barriers, not vapor barriers.

Be careful not to provide vapor barriers on both inside and outside of a wall, otherwise vapor will get trapped in the wall, condense, and rust ferrous metals or rot wood and other organic products. A vapor barrier should generally go on the side of the wall that is warmer most of the year - inside in the north and outside in the south.

 

[SCBO1]

Agree with Paul, zip panels and house wraps are used as air barriers and should not be considered vapor barriers.

 

[RLGA]

Many fiberglass blankets are provided with vapor retarder facings. Once installed, the joints between the facings are sealed with the manufacturer's recommended tape. Electrical boxes and plumbing that penetrate the facing will need to be treated, just like a polyethylene sheet.

 

[RLGA]

There was a response by "duramaxpvcpanels" posted early this morning that is no longer shown. Is there a reason it was removed?

 

[cda]

There was a response by "duramaxpvcpanels" posted early this morning that is no longer shown. Is there a reason it was removed?

I think the new poster was scrubbed, due to looking like an ad???

 

[RLGA]

I think the new poster was scrubbed, due to looking like an ad???

Well, the user's name is a name of a product manufacturer for PVC panels, but none of the materials they listed were PVC panels. All items listed were generic descriptions of materials--many of which are considered vapor barriers in construction.

I did have one objection, though--"exterior grade plywood" can be a vapor retarder, but it does not meet the requirements for a vapor barrier, which requires a perm rating of 0.1 or less. According to the APA, plywood generally has a perm rating of 0.2 to 1.43 depending on the material and facings (https://www.performancepanels.com/permeability).