Plywood or sheathing on interior wall question - Bathroom remodel

   / Plywood or sheathing on interior wall question - Bathroom remodel #1  

Beltzington

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Appling, Georgia
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I'm using Hardy backer board on both the walls and floor of a walk-in shower. My "custom built" house apparently meant they were very creative at cutting corners and I found I have 24" OC framing in my interior walls. My thought was I will just install plywood over the studs to add more rigidity to the wall without having to work around the existing electrical and plumbing by adding additional studs.

Backer board installation instructions say it needs to be attached to studs at 16" OC max. There are no guidelines for mounting to wall sheathing, although mounting to a 20ga metal stud is "ok." If 20ga metal will hold the board there is no way a 5/8" thick wood panel will not. The additional advantage is in the future I can add grab bars, monkey bars or whatever anywhere in the shower without having to preplan there location. Also, the shower bay is huge so the loss of a couple inches on the wall is not a concern.

Why no specs for wood panel walls?
 
   / Plywood or sheathing on interior wall question - Bathroom remodel #2  
They do use it over sheathing for exterior application. I would guess as long as you hit your 24" studs and filled in the field as described it would hold. Just my opinion.

"HardieBacker 500 may be used up to a height not exceeding the lesser of: through the second-story above grade or 30 feet above grade. The HardieBacker 500 must be installed over sub-sheathing with a code approved water-resistive barrier, or in accordance with the applicable code. Install flashings, clearances, and other building practices per local code. James Hardie will assume no responsibility for water infiltration. Use a minimum No. 11 ga. 1¾” long roofing nails or No. 8-1¾” long (0.375” HD) or ribbed wafer head corrosion resistant screws spaced a maximum of 8" OC. "
 
   / Plywood or sheathing on interior wall question - Bathroom remodel #3  
I don't see a problem with it, just make sure you do hit your studs with the screws.
 
   / Plywood or sheathing on interior wall question - Bathroom remodel #4  
If you're planning to tile, I wouldn't skimp on the framing. If the wall isn't perfectly rigid your tile job may not last as long as it should. 24" OC, really? I'd hunt that guy down and give him a piece of my mind, or at least leave some bad reviews.

I'd be tempted to go ahead and replumb and reframe everything and "do it right." If you decide to add plywood to the main plumbing wall which contains the shower head and knobs, check to make sure your stubs are long enough for the extra thickness. You might get lucky here but I've always found that stripping out stuff done wrong and re-doing it right is generally the quickest and cheapest in the end. YMMV
 
   / Plywood or sheathing on interior wall question - Bathroom remodel #5  
   / Plywood or sheathing on interior wall question - Bathroom remodel #6  
Adding to a wall thickness always brings extra work and problems to be solved. I would fit in extra studs. They can be put in flat or notched out, and supplemented with blocking where needed. While you are doing it add studs in the corners for real good backing on the hardie backer edges.
 
   / Plywood or sheathing on interior wall question - Bathroom remodel #7  
To attain a 16" oc fastening schedule...one option would be to add horizontal blocking at 16"oc between the 24"oc studding... some offsets may be necessary to avoid plumbing etc...
 
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   / Plywood or sheathing on interior wall question - Bathroom remodel
  • Thread Starter
#8  
Appreciate the feedback - I bought the house 9-years after it was built so can only deal with the poor craftsmanship. Many, other issues have been uncovered over the last 20-years.

I did a very similar remodel of my parents master bath where I added studs at 16" OC and backing for all the grab-bars and shower door and from that experience I truly believe just spending a few extra dollars on sheathing would be much easier in this case.

With that in mind, my question would be is there a structural concern with adding the extra vertical weight, plywood, backer board, and tiles, to 24" OC studs?

JoeyD - I read those specs but incorrectly assumed HardiBacker 500 was an exterior product but I see it is for both interior and exterior. Thanks!
 
   / Plywood or sheathing on interior wall question - Bathroom remodel #9  
We do handicap remodels quite often. Personally I am a fan of sheathing over the studs and then your water proof barrier and hardi backer per the specs you already read. Mainly a fan because it seems the customer always wants a cabinet, mirror, towel or clothing holder, toilet paper, shower rods, or grab bars in some place that does not fit the existing studs. It just saves a incredible amount of work for the needed bracing backer boards. Also at some point and time someone handicapped or their helpers are likely to grab something that normally is not meant to be used for support and this way at least its not pulling out of the sheetrock.
Yes a spacer is needed to make the typical door jambs wider but its a minor deal for us. In reality tight spaces we have been known to put recessed blocks on the sides of the existing studs and then strips 16 or 24 inch wide in between the studs. Yes it more work but well worth it when the customer wants a change after the painting and tile work is done.
 
   / Plywood or sheathing on interior wall question - Bathroom remodel
  • Thread Starter
#10  
We do handicap remodels quite often. Personally I am a fan of sheathing over the studs and then your water proof barrier and hardi backer per the specs you already read. Mainly a fan because it seems the customer always wants a cabinet, mirror, towel or clothing holder, toilet paper, shower rods, or grab bars in some place that does not fit the existing studs. It just saves a incredible amount of work for the needed bracing backer boards. Also at some point and time someone handicapped or their helpers are likely to grab something that normally is not meant to be used for support and this way at least its not pulling out of the sheetrock.
Yes a spacer is needed to make the typical door jambs wider but its a minor deal for us. In reality tight spaces we have been known to put recessed blocks on the sides of the existing studs and then strips 16 or 24 inch wide in between the studs. Yes it more work but well worth it when the customer wants a change after the painting and tile work is done.

What do you use for sheathing and what thickness? Plywood or new grade of OSB like Advantech or ZIP? I was thinking about using RED ZIP sheathing as the moisture barrier is already applied and all I would need is to tape up the seams. I built a big pump-house using both these products and I am embarrassed to say they have been exposed to the weather for several years with no delamination even on the unprotected edges. My one concern would be I don't think they hold screws as well as plywood.
 
 
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