Insulation 1 1/2 story

[Tazz]

I have a 1 1/2 story home. The upstairs bedrooms get pretty warm in the summer. I recently bought double paned vinyl windows, This helped SOMEWHAT last year. Since it is a 1 1/2 story I do have access to all the outside walls other than the window walls. There is old insualtion in between the studs that are exposed. I have access to all that. Easy to work on. The insulation has PAPER on the one side that faces into the attic. This insulation is old and worn. What I want to do it to get some insulation boards 4'x8' x 3/4" with the foil on one side. Really like to cocoon both rooms. Questions

1. If I am installing the insulation board do I still need insulation in between the studs on the wall?
2. If I need the insulation in between the studs on the wall does it need to be with OUT the paper if I install the insulation board over it...?
3. If I install the insulation board over the existing insulation thats in the wall can there be moisture build up in between the new insulation board and the inusaltion with paper on the outside of it.?

Everything I have seen says to encapsulate the uptairs. Even plug off the pathway on the kneewalls that are from the front of the house to the back inbetween the floors. No insualtion in between the floors but plug iff so no air can travel in between the floor.

Any help would be greatly appreciated.

Marty

[hallerb]

The BEST INSULATION is expanding foam about R6 per inch, plus as it expands it seals air leaks cracks etc,

yes and encapsulate the entire iving area

[Paul M. Eldridge]

Hi Marty,

With respect to question #1, it would seem foolish not to insulate the wall cavity prior to installing the insulation board. I take it the foam board you have in mind is rated at R6 or R7? If that's the case,

3.5 inches of fiberglass will provide you with another R12 or R13, effectively tripling the thermal performance of this wall, at a very nominal cost.

#2: I'll defer to others on this one, but my sense is that you should forego a paper facing if you plan to install a foil backed product on top.

#3: Again, as with #2 I'm not the best qualified to answer this, but you could slice or remove the paper backing if this is a concern. Is the R-value marked on this insulation? If it's old, it may be only R7 which means it should be replaced with R12 or R13. I'd also caulk and seal all cracks and joints while the wall cavity is accessible.

Cheers, Paul