# Insulation behind shower walls



## Nealtw (Jun 22, 2017)

If you run AC in the summer you might want it there.


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## ktownskier (Aug 22, 2018)

I would suggest checking your local building codes to see what they have. Just because they didn't do it in the 60's, doesn't mean it isn't required today. 

Regarding the new CBU from Hardie, you do have to seal the joints and any perforations. (Like screws and nails). 
Joints and Penetrations
• Seal fixture penetrations, plumbing penetrations and abutments to dissimilar
materials with flexible sealant (see “Materials Required”).
• Fill all joints with mortar (see “Materials Required”). While mortar is still
workable, embed minimum 2 in. wide high-strength alkali-resistant glass
fiber tape in the mortar and level.
• Do not use all-purpose joint compound or paper tape.
• When complete waterproofing is required, seal all joints, edges and fastener
penetrations with a liquid waterproofing membrane. Follow the liquid
waterproofing membrane manufacturer application instructions.

I am planning on using Redguard as half of my wall is greenboard and the rest is the new Kerdiboard. And for the joints, I plan on using Kerdi Band. Better to be safe than sorry. 

As for insulation, I was planning on using rockwool insulation as it is naturally moisture and mold resistant. Vermin also doesn't like it. Besides, why not insulate?

If you can, build a bigger shower, 36"x36" shower is kind of small. But if you can't, well, you were used to it before.


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## stardogFB (Feb 8, 2019)

Thanks for the quick replies from both of you. Since we live in the Houston area I can pretty much guarantee the A/C is often on in the summer.  I will go ahead an insulate, especially since its such a small area to cover anyway.

Regarding the Hydro Defense cement board, agree on covering all seams and penetrations before tiling, per manufacturer instructions. As far as the base, if I could go bigger I would. But I'm gaining a few more inches of floor space since I am replacing the current neo-angle configuration with 36" square base. You take what you can get.


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## chandler48 (Jun 5, 2017)

It's a good idea to insulate. Here, we gathered up 3 ea. 55 gallon drum liners of insulation that squirrels had pulled from the wall to make nests under the tub we removed 

Then we go back in with Roxul. Waterproof, fireproof, vermin proof, mold proof and needs no vapor barrier.


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