I'm remodeling a bathroom on the upper level of our house and have a couple of questions about attic insulation as it relates to (a) humidity from the bathroom and (b) the rain shower head pipe that will be installed in the attic such that the shower head protrudes from the bathroom ceiling.

I pulled the old drywall and cleaned out the old cellulose insulation that didn't fall when I dropped the ceiling and when done, I'll put greenboard up on the ceiling. I don't want the shower head piping in the attic to freeze in winter, so my plan was to put in a 3.5" layer of insulation between the rafters, then wrap the shower head pipe, then put another layer of (maybe 5.5" or more) unfaced insulation on top of the first.

The result would be that the shower head pipe would be wrapped and then sandwiched between the two layers insulation.

Faced insulation is readily available in the qty I need but unfaced insulation is not, so my intention is to pull the face off of my second layer.

So here are my questions:

  1. Should the first layer of 3.5" insulation between the studs, be faced or unfaced (ie: should I remove the face on my first layer)?

  2. If faced, should the paper be down against the drywall or up into the attic? I've found articles that say both (ie: the bathroom is conditioned vis a vis the attic and that the attic is conditioned vis a vis the outside).

Thanks! Rob

  • Green board is not rated to be used in a shower. Please find a wallboard product specifically rated for shower use such as densArmor.
    – Matthew
    Commented Jul 18, 2022 at 16:29

1 Answer 1


The first layer, the one between the studs should be faced with the face toward the bathroom. The second layer need not be faced.

Greenboard is OK on the ceiling but don't use it on the walls.

If you have a diverter valve for your shower, it should drain the pipe when the water's turned off. If just a straight shower, maybe not.

  • 2
    The "horizontal" run from the wall, across the ceiling and to the shower head should not be horizontal. It should have the standard 1/4" per foot slope to ensure that the pipe drains so that it doesn't freeze. If there's a diverter, it doesn't matter which way it slopes (it can drain through the shower head or the diverter), but without a diverter, it should slope towards the shower head so the water will drain out there.
    – FreeMan
    Commented Jul 18, 2022 at 13:46
  • @FreeMan Good point.
    – JACK
    Commented Jul 18, 2022 at 13:49
  • 1
    The op is planning to "put greenboard up on the ceiling". Why do you suggest cement backer board for a surface that is not going to be tiled?
    – brhans
    Commented Jul 18, 2022 at 14:21
  • @brhans you asked the question I was about to, the ceiling will be painted, hence the greenboard there.
    – rkb123
    Commented Jul 18, 2022 at 14:23
  • @rkb123 - yeah cement board for a painted surface doesn't make sense. You'd have to skim-coat it to make it look decent before you could paint it. Would be a complete PitA.
    – brhans
    Commented Jul 18, 2022 at 14:26

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