Insulation

[Teo2006]

I have an older home that I am remodeling. The stud walls are actual 2 x 4's. Currently, the exterior walls have about 2 inches of insulation material consisting of blown in cellulose, wood slats(lathe) and then plaster type material,then aproximately a 2 inch cavity then the wood lathe and then the finish plaster. Apparently way back when the house was built (1900) that was the type of insulation they used in the stud cavities- a layer of lathe and plaster inside the stud cavities. I am removing the plaster and lathe on the finished side of the wall and will fill the 2 inch cavity with either fiberglass insulation or polystyrene foam board. Do I use a vapor barrier before I install the sheet rock ? Normally one would use vapor barrier but I am concerned that the plaster and lathe that are inside the cavities are already acting as a type of vapor barrier. If I install insulation in that 2 inch cavity and then a vapor barrier I may have a double vapor barrier which would hold moisture in the wall. What do you think ? The walls would end up like so....sheetrock,then 2 inches of insulation, then a layer of plaster, a layer of lathe, cellulose insulation,then the underlayment,then 2 layers of siding (wood covered by cement type tiles)

[marson]

I would definitely add a vapor barrier. I can't imagine that the lathe and"plaster" in your stud cavities is vapor impermeable. and even if it was, I think you still need a vapor barrier on the warm side. adding insulation to the setup will result in a colder stud cavity, potentially leading to condensation, so you want to keep the moisture out.

if it was mine, i'd gut everything out and insulate it properly.

[businessman]

I'd do the same and for the same reasons

E.L,

[buffalobill]

[Joe]

Most lathes are rather large machines to make round table legs and such. It must be very hard to stuff these into a wall cavity. OTOH, a wooden slat is what we call a lath, and yes, they were used to support plaster before the days of wallboard. After you remove all the woodworking machinery from inside your walls it would be good to use a vapor barrier. and keep it oriented to the warm side of the wall. Cheers,

Joe

[Goedjn]

I think you should call them wattles.