Old-School Foil Paper "Insulation"

[uberschall]

I'm about to undertake a top-secret project and I could use some guidance.

Let's say I'm looking to update a garage that has tatty foil/black paper on the walls. I honestly don't know how old it is or what it's trade name is.

Look like this:



Should I take this stuff down before air-sealing and putting up batt insulation?

Thanks!


Sent from my iPhone using Tapatalk

 

[The Cobbler]

I would remove the foil backing, yes.

 

[ard]

Hardly enough info to give ANY advice, IMO


Foil, even old, can be a very effective radiant barrier....

So let's do this.... On your new wall, what will the features be? ( and by 'new' I mean 'after you are done with whatever you will be doing to the old wall plus added improvements)

What is the water barrier? In other words, when it is raining and winds driving water at 50 mph, what stops the water and cause it to shed down to the ground?

What will be the air barrier?

There are a good many building science websites one can peruse to determine how not to piss away your remodeling $$$s.

 

[uberschall]

I don't know how much "building science" a 50 year old residential garage dictates, so I'll leave that to the brainy types.

Whether it was intended to be a vapor barrier or some kind of radiant insulation, it's torn up in a few areas so it's probably not much good either way.

While the garage is empty and I have easy access to the walls, I just want to establish whether I should remove it or not, as my goal is to ultimately insulate and drywall. I'll be pulling nails, sealing up any gaps/holes, and redoing some electrical no matter what.

 

[ard]

I don't know how much "building science" a 50 year old residential garage dictates, so I'll leave that to the brainy types.

Whether it was intended to be a vapor barrier or some kind of radiant insulation, it's torn up in a few areas so it's probably not much good either way.

While the garage is empty and I have easy access to the walls, I just want to establish whether I should remove it or not, as my goal is to ultimately insulate and drywall. I'll be pulling nails, sealing up any gaps/holes, and redoing some electrical no matter what.

Yeah, seems fashionable these days to kinda make fun of science, thoughtful consideration...that kind of stuff, eh?




Here is how much 'building science' a 50 year old structure dictates:

Right now, uninstalled. Wood on outside, somewhat permeable and worn radiant barrier. Wall is permeaable to water vapor, not much temp difference...

To upgrade you then stuff insulation in the bays, sheetrock, insultate.

Now you have moist warm air inside, as it permeates to the exterior sheathing (which is cold) it condenses on the wood. It cannot evaporate being trapped by that cellulose- under the sheetrock. That 50 year old structure begins to die

I dont purport to be an expert, nor even marginally qualified. But I do know that what I used to do 40 years ago with rehabs simply do not stand the test of time.

There are some really good sites that in an hour or two would let you understand and plan for a rehab that would be trouble free....

Good luck with the project!

 

[uberschall]

Yeah, seems fashionable these days to kinda make fun of science, thoughtful consideration...that kind of stuff, eh?

Ha, I get enough science at my day job! Only sort of kidding, but I know that it's unlikely I can make the garage very efficient without basically rebuilding it from the slab up. I'll save the real plans for a dedicated thread.

I guess the jury is still out on whether I should pull all the tatty foil stuff down in the meantime?

If you have a favorite link with rehab tips, I'd love to learn more.

 

[Marctrees]

You should end up w your vapor barrier facing into the room, being in Detroit, northern heating climate.

So like if you were to put sheetrock or something up, the poly barrier would be immediately behind the wall finish, hammer stapled to the studs, covering your newly insulated cavities.

So,if you were to you add insulation over whats there, that foil vapor barrier is in the wrong place.


Removing it would be a total needless mess.

All you have to do is slash through the foil, score it every few inches or so.

Sharp fresh razor knife.

That will effectively "remove" the barrier effect.

Google it - "Slash vapor barrier" - This is done all the time, when needed, to defeat barrier on any existing faced insulation.


Is your foil covering insulation, or just the foil?

If it's covering old insul, do as above.

If it's just a foil/paper barrier, just cut it out. Marc

 

[uberschall]

Good advice, thanks. I'm actually leaning toward removing it, as I want to inspect all the boards for damage/rot anyway. While it may be some extra work, now that I'm a little more convinced the foil isn't doing much good I'll sleep easier if it's gone.

Although if it proves to be too much extra effort, I'll score it as you suggested and move along.

Thanks!

 

[ard]

You should end up w your vapor barrier facing into the room, being in Detroit, northern heating climate.

So like if you were to put sheetrock or something up, the poly barrier would be immediately behind the wall finish, hammer stapled to the studs, covering your newly insulated cavities.

So,if you were to you add insulation over whats there, that foil vapor barrier is in the wrong place.


Removing it would be a total needless mess.

All you have to do is slash through the foil, score it every few inches or so.

Sharp fresh razor knife.

That will effectively "remove" the barrier effect.

Google it - "Slash vapor barrier" - This is done all the time, when needed, to defeat barrier on any existing faced insulation.


Is your foil covering insulation, or just the foil?

If it's covering old insul, do as above.

If it's just a foil/paper barrier, just cut it out. Marc

you are assuming a lot about that being a "vapor" barrier, no?

Where should his WRB (water resistive barrier) be? You know, the thing that stops rainwater- and wind driven rain- from entering the wall cavity??? (Not a vapor barrier, different thing.)

IMO you cant just whach out components, add in insulation, plastic sheeting, sheetrock and think the wall will work.

If the outside of that structure is not WATER SHEDDING, then water may be passing into the interior...once you seal up the wall cavities, you have a real mess.

 

[uberschall]

I promise I'll eventually install vinyl siding over the whole garage, and I pinky swear I'll put up Tyvek or similar first.

Whatever the foil stuff is, it's 50 years old and torn up...so as I said, it's probably not doing much either way. Assuming it was a precursor to a more modern home wrap like Tyvek, I still can't figure why it's between the studs and sheathing and not under the siding.

I'm not trying to get my garage LEED certified, I just hoped someone would know it was called Johnsons' Weather-Blok or something and it's got asbestos in it, or that it's permeable enough I could leave it, etc.

I appreciate the lively discussion and thank everyone for stopping by.

 

[dandan111]

I'd leave it in there. Tape the torn spots.

 

[Marctrees]

Ard - I never commented about anything other than the foil paper currently in place.

You are TOTALLY correct other than that.

dandan - Being "north of Detroit" he does not want an impermeable barrier on the outside, so no point in taping it.

The opposite, it should be slashed all over, at least, or removed.


Actually, if it is just a single layer, not facing on any insulation that would make it messy, he should take one hour and just cut it all out w a fresh razor.

First - That existing barrier is in the wrong place in the scheme of the layers for THAT climate.

(Opposite, in a "cooling climate"

STUDY.)

Second - Then he can do his inspection for damage.

Also, all above is Not what my Grandmother's Aunt told me, Google it, READ and learn.

I am NOT directing the last comment to YOU personally at ALL, but everyone.

I CONSTANTLY see people on forums that are like phobic or something to research themselves.

People (not so much this post, but slightly) ask questions they could have been answered very quickly w a few selected search terms, like everyday.

Most folks, maybe not most, but MANY, are too lazy, or maybe legitamately busy, to search on their own. Marc

 

[uberschall]

Searching Google for "foil paper insulation/barrier" doesn't yield much - mostly that foil bubble ****.

The scenarios outlined here don't include timber framing with wood sheathing and wood or vinyl siding. The closest is probably Figure 12, up to the stucco, anyway.

As I mentioned a couple posts up, the location of the foil sheet is hard to justify. If water is effectively driven into the siding, it wets the sheathing and then the paper side of the foil sheet, effectively trapping moisture between the foil on the inside and paint on the outside.

Modern timber-frame houses built in the area are generally wrapped with Tyvek outside the sheathing and under siding/brick. In theory, properly installed home wrap keeps exterior moisture from ever reaching the wood.

Because I won't have plumbing or cooking equipment in the garage, it's unlikely I'll be introducing much moisture to the air inside - heck, I heat with a wood stove, which seems to dry everything out.

I think the consensus is to remove the foil ****, while it was probably well intended at the time, it's not doing much now.