So, I've been doing a lot of renovating of my house since I bought it, and I'm doing all of the work myself. Yesterday, I spent most of my day in the master bathroom ripping down tiles and existing drywall. The bathroom has two walls that connect to the exterior of the house (it's in a corner, and two of the walls need exterior to interior insulation). I'll be using batt insulation, the cotton candy-looking stuff, which has a vapor barrier made of kraftpaper on one side.

 

The insulation there now is in good shape, but is more than 30 years old. It's a faced insulation (fiberglass with a kraftpaper backing). I plan to add new insulation regardless, but my question is this.

 

As long as I'm careful not to compress the insulation, can I simply add another layer of faced insulation on top of the layer of faced insulation which is there now? I know this will bring greater protection against thermal transfer, and the wall cavity is large enough to receive two layers without compression, but my concern is specific to the faced layer already there.

 

I am not quite sure if creating a sandwich of exterior/fiberglass/kraftpaper/fiberglass/kraftpaper/interior will work or present unforeseen problems. Can you guys think of any reason not leave the existing faced layer in place, and just add another faced layer on top, as long as compression is not an issue?

 

I know it's okay to do when using unfaced insulation, but that vapor barrier in the middle has me apprehensive, since it's a bathroom project... Then again, an additional vapor barrier in the middle may be a good thing. I dunno.

 

Any ideas?

 

 

should be fine, the vapour barrier sandwiched in the middle will just sit there not doing much other than providing a tiny bit of insulating effect and the new vapour barrier will become the one that actually stops the moisture.

 

thats about it really. its all very inert so i don't think you'll suddenly cause a rift in the space time continuum or cause cats to chase dogs and hamsters to take over the world or anything.

thats about it really. its all very inert so i don't think you'll suddenly cause a rift in the space time continuum or cause cats to chase dogs and hamsters to take over the world or anything.

 

Phew... you knew EXACTLY what I was worried about. Thank FSM!

 

I didn't figure it would be a problem, it just seemed weird that I'd have a layer in there which effectively had a vapor barrier on each side. Thanks for the reassurance, IA.

In my grandfather's house (pre-civil war era) there was at least 5 different layers of insulation of various types including two layers of that kind. That house was at least 160years old when it was finally torn down.

You`d be crazy not to while you have this opportunity.

I don't see any reason there would be a problem either.

Beautiful. I'm also going to be using spray foam insulation in the cracks and crevices, and caulking around the window area. It seems obvious now that I have had responses from all of you, but for some reason after I'd spent hours inhaling dry wall dust and tile fragments I was not feeling overly confident and figured I'd check. Thanks each of you.