I am in the process of renovating my kitchen. I removed everything down to the studs. One of my bathrooms backs up to my kitchen. Once I opened up the wall behind my bathroom shower stall (a fiberglass one piece tub and surround), I see that there is no insulation, drywall, or cement board around my shower stall. It is just sitting in the open on the other side of my kitchen studs.

The bathroom is a small 3 fixture bathroom that has 1 exterior wall. This exterior wall is about 10’ long and the foot end of the tub is on the exterior wall. From what I can see, there is no insulation in this exterior wall. This bathroom was remodeled about 20 years ago and they added this stall. I think they removed the insulation only in this area--not the entire length of the wall.

This stall does not go all the way to the ceiling so it has drywall from around the top of the shower to the ceiling. Is it possible to put some type of insulation in this void around the stall? I have often said that this bathroom didn't feel as though is was insulated. It is always cold in this bathroom in the winter.

I do not want to tear out the shower stall at this point, but am hoping to be able to do something with the access that I have from my open kitchen walls. I do not know anything about vapor barriers or appropriate types of insulation for this situation.

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  • Hello, and welcome to Home Improvement. If you add a picture to your question we'll be more able to help you. And, please take our tour so you'll know how better to participate here. Jun 15, 2019 at 14:49
  • Thank you! I have now added the photo and taken the tour. I appreciate the advice.
    – tmdavis
    Jun 15, 2019 at 15:05
  • Is this a exterior wall or bath ,kitchen wall ? May need some edit her to help.
    – user101687
    Jun 15, 2019 at 15:59
  • This picture was taken while I was standing in my kitchen. The bathroom backs up to the kitchen. Where the red arrow is is an intersection where the house extends out and creates a corner water interior and exterior walls meet. The studs you see in the picture are an interior wall. The studded wall extend to the left of the tub surround about 10 feet. Starting at the red arrow to the left is an exterior wall and the wall where you see the PVC going through the wall on the left is an exterior wall. The wall where the PVC is running through the studs in an interior wall.
    – tmdavis
    Jun 15, 2019 at 17:00
  • Did you ever get this resolved? If so, please give a check-mark to the answer that helped you the most, or write up your own answer explaining what you did to get it fixed and give yourself a check mark. That will help others with this kind of problem know that this has a resolution and is a good place to look for their answer.
    – FreeMan
    Aug 10, 2020 at 21:47

3 Answers 3


There are two issues: 1) yes, you should add insulation, and 2) no, it should not have a vapor barrier.

1) Yes, insulation will help with the temperature comfort level you’re complaining about. It will help to maintain a constant temperature.

It will be difficult to install because it’s not very accessible.

2) A vapor barrier should not be installed.

Most people don’t understand that “vapor” moves both ways through a wall. That is to say, vapor moves from the warm side to the cool side. As the seasons change, vapor will move through the wall reaching its Dew Point, and turning from a vapor to a solid (water).

If this water is trapped in the wall, it could create dryrot or mold. With a vapor barrier, vapor will enter the wall but not be able to escape. In fact, poly sheeting can accelerate the problem and is no longer recommend, except in the coldest year-around climates.

Here’s an article that explains it better:


It’s very important to understand this concept for bathrooms with excessive moisture. That moisture needs a way to escape from the wall. (Even the best installed poly sheeting will allow vapor into the wall around outlets, joints in sheeting, top and bottom plates, etc. )


Yes any insulation is going to work .Do the whole bay top to bottom. Paper or foil faced. Vapor barriers face in to house. Foil may work better here little tougher, than paper.

  • No, vapor barriers are installed on the heated side...not necessarily the “house” side. Due to the potential amount of moisture and Dew Point, no vapor barrier may be appropriate so the cavity can dry out with change of seasons.
    – Lee Sam
    Jun 15, 2019 at 15:43
  • All vapor barriers are facing to the inside of a house, On a exterior wall. All. Poly would be better here in it goes in. That is why you have bath fans. If you have that much moisture mold on walls is going to happen.
    – user101687
    Jun 15, 2019 at 15:55
  • Vapor barriers go on the side that has heat most of the time. People in Texas, Florida, etc. would argue with you...
    – Lee Sam
    Jun 15, 2019 at 16:03
  • Do not have his home location. And both states have temp changes in the northern parts.
    – user101687
    Jun 15, 2019 at 16:06
  • Home is located in middle Georgia. High heat and humidity about 2/3 of the year. Predominantly mild cold winters.
    – tmdavis
    Jun 15, 2019 at 16:15

I suggest stuff Roxul in where you can. I would even open up the wall above the shower - a good 16" would be enough. You can feed insulation to the floor given there isn't any cross bracing.

I have written on here for tub installs that one of the main components of a good fiberglass shower install is to pack the cavities with insulation. I actually install it until it pushes the tub out and then taper off. This is for a tub install NOT on an exterior wall.

Given on an exterior wall the fact that you should have insulation for weather/wind the fiberglass also needs to be supported. With cheaper fiberglass you can easily tell if there is no insulation in the walls because it becomes wavy. The other big factor is sound. You will get a hollow echo without insulation.

Yes stuff the walls like a thanksgiving turkey. (and no vapor barrier - too late at this point to do it right)

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