Currently doing a complete renovation of the second floor bathroom in our 1908 home. A local flipper advised that code requires I insulate the 2 exterior walls with paper backed R13 and insulate the open joists above with paper backed R38 (only the area beyond the attic subfloor where roof is visible).
However, after doing some independent online research I have found many who say that this plan will actually retain moisture in the walls and that old houses last longer because the air flow works to dry any moisture that may enter the wall cavities. Some recommend dense, closed-cell spray foam insulation instead.
If I went with foam, would I have to install blocking to prevent it from going all the way down the framing into the basement? The room below is finished with plaster. I am planning to hang drywall in the bathroom that I am renovating.
Anybody have experience with this and can provide recommendations?
Thanks
