Bathroom remodel - insulation questions

[TresK3]

We are remodeling the bathroom in a house built in 1961. The exterior walls are block, with furring strips and drywall/tile over that. The tile came up about 3.5 feet . I removed the lower part completely, down to the furring strips. The upper portion still has the original drywall. Before I cover the lower part back over with greenboard, I'm thinking about pushing some foam insulation boards up between the block and the drywall. The furring strips give me about 3/4 inch. Any thoughts, ideas, or opinions? Will I have any moisture issues because I'm insulating a space that wasn't insulated before?

Also, I pulled out a bulkhead over the old tub (we're putting in a new, tiled walk in shower). This part faces an unfinished attic space and there is old "rock wool" insulation between the studs. Also rock wool along the ceiling, where the roof rafters cut the upper corner of the room. The insulation seems to be in fine shape, just old (and the paper backing is brittle). Should I leave that in place when I install the cement board, or replace it with "the pink stuff"?

Thanks!
(I'll probably be posting some electrical and plumbing questions in a bit.

 

[fbelec]

hi tresk3 your bath must be cold in the winter. if you can afford the space stud the wall of block so you can insulate the wall with r13. if you use the 1/2 inch foam board the best you'll get i think is r5 in that wall. if you don't have to move that rock wool leave it. it's nasty stuff. what are you using for heat?

frank

 

[TresK3]

hi tresk3 your bath must be cold in the winter. if you can afford the space stud the wall of block so you can insulate the wall with r13. if you use the 1/2 inch foam board the best you'll get i think is r5 in that wall. if you don't have to move that rock wool leave it. it's nasty stuff. what are you using for heat?

frank

Heat is from baseboard hot-water radiators. It's actually pretty comfortable in the winter, but could be more energy efficient. Taking off the entire wall, down to the block, to build it out with studs is a lot of work. (Plus... I just realized would interfere with placement of the baseboard heaters. For all intents and purposes, those are immovable.)

 

[fbelec]

i can understand that. so foam boards it is. better than nothing at all

 

[moey]

The foamboard has to go tight up against a surface or the edges have to be sealed. You just cant stuff it loosely up a opening and expect it to provide insulation.

 

[TresK3]

The foamboard has to go tight up against a surface or the edges have to be sealed. You just cant stuff it loosely up a opening and expect it to provide insulation.

Moey- Good to know. I should be able to cut it pretty tight and wedge it in. I may also get some "liquid foam" stuff in a spray can, in case there are areas that need a little more sealing.

Thanks to both of you,
Tres

 

[vinny11950]

FYI on foam board insulation is that ant colonies can settle in there. Supposedly the foam boards make a good home for them. I only say this because my yard has lots of different ant colonies all around the house, and they are constantly probing to get in, so I decided against using foam board insulation because I don't want to give them another reason to get in.

 

[sportbikerider78]

You you'd like some insulation in there, I'd just take the rest of the sheetrock out, insulate and re-sheet rock. I had my entire (big) master bath sheetrocked for $500.

Sheet rock is basically, the cheapest thing you can remove and have done...it also can have the biggest impact.