Bathroom Wall Question

[mikester]

One more question for you folks.
I was planning on using PVC bead board on my 5x9 bathroom walls. A little over 40" high.
Back when I first bought the house I used regular 3/8" pine bead board that I glued to the MR board with PL and also used finish nails to hold it down. Two coats of oil based Minwax clear on top to seal it up. In less than 4 months it started to buckle. I wound up ripping it all out and had to replace all the MR board. A mess.

This time around I planned on using PVC. Its made by Royal siding. Again, 3/8" thick. The back isnt flat like typical pine it the thicker 1/2" products. It looks a bit like the budget composite decking that Lowes or HD sells. Im sure theres enough to use PL or another adhesive. Yesterday I went to order the stuff and the guy at the lumber yard told me theres no way that should be used in a bathroom. He said the steam will make it pop just like the pine. I was a little surprised. I figured PVC wouldnt do that. He said most people use the PVC beaded sheet material instead. AS he was explaining this the guy next to him said he used the sheet material and in a couple of years the **** seam opened up in his small bathroom and it now looks like ****.
Anyone have any suggestions as far as what works ?
This project starts Monday. I dont have a ton of time.

 

[mike93lx]

Moisture resistant drywall, a couple coats of good paint and a ventilation fan with a timer and/or humidity sensor.

 

[nadogail]

I used FRP panels from Home Depot in my garage workshop bathroom. If FRP works for fast food restaurants it is certainly good enough for my Workshop.

 

[mikester]

After some phone calls to Royal I was given the name of their area rep. After a short explanation of what I wanted to do he told me theres no way the PVC bead board will be an issue in a bathroom. Done have to seal it. Just glue it up.
Another thing he mentioned is some building codes limit the use of PVC being used for interior walls due to the toxic fumes given off during fires. His own state doesnt allow it for use in finished basements.

 

[mike93lx]

A sales guy for a product wants you to use their product? No way

 

[Fav Onefour]

The pine went down in four months? Did the MR fail because of moisture?
Must be dang high humidity for prolonged periods.
The PVC won't care about the moisture. Whatever it is attached to may be different. Do you have a plan to manage the moisture? That would help.

 

[Cougar67]

In 2015 I used PVC beadboard called Veranda from Home Depot from the top of the shower to the ceiling in my kids' bathroom. It was applied with Power Grab and only a few white brad nails. It put up with teenagers and still looks great. It's beadboard pattern but can be flipped to look like shiplap. It's over mold proof drywall.

 

[karoc]

I installed 1/4 bead board panels 3’x4’ wainscoting in my bathroom over 30 yrs ago. Still looks same way now as it did, but it’s real plywood type. Wallpaper kinda peeling off but not plywood bead board

 

[mike93lx]

I installed 1/4 bead board panels 3’x4’ wainscoting in my bathroom over 30 yrs ago. Still looks same way now as it did, but it’s real plywood type. Wallpaper kinda peeling off but not plywood bead board

What's underneath it?

 

[cgrutt]

I'm thinking issue you had with pine was caused by being glued down and natural changes in size of boards due to changes in humidity. Were the boards put down tight (no gap) when they were very dry (perhaps in winter with low humidity)? They probably absorbed humidity from bathroom, naturally expanded, had no room to move and popped. The reverse could have happened if glue prevented natural movement and they popped while shrinking due to drying out but I think first case is more likely.

PVC won't absorb steam but changes in temperature (from room temperature to higher with alot of steam) may still cause thermal expansion and you may have same problem if it's glued down tightly with no place to move. They nail vinyl siding loosely with large slots to allow for expansion because vinyl moves alot with changes in temp. I'm assuming you will be running the pvc vertically. I'd probably consider nailing strips between studs and nailing it instead of gluing. Leave some space to allow for expansion and contraction. Is it like a shiplap or T&G? They also make flexible glue for wood floors to concrete that goes on like a mastic (full coverage with grooves) I'm not sure if that would work or not for your application but it's probably better than construction adhesive.

Finally are you installing new sheetrock? If so I'd recommend using mold resistant and consider adding a waterproof membrane (similar to paint) such as Mapei Aquadefense or the red stuff from Home Depot. I'd also add a good exhaust fan vented to exterior if you don't already have one.

 

[mikester]

The pine went down in four months? Did the MR fail because of moisture?
Must be dang high humidity for prolonged periods.
The PVC won't care about the moisture. Whatever it is attached to may be different. Do you have a plan to manage the moisture? That would help.

Yeah, I was a little pissed that it buckled so fast. I did the original renovation in the Summer. By the Fall they started to pop. I really thought the oil based poly would be enough but it didnt make a difference. As far as managing the moisture its not as bad in the warmer months since we put in CAC. We have a 100 CFM Broan fan/light combo in the middle of the ceiling. I think the biggest issue is my wife and I take long showers back to back.

I'm thinking issue you had with pine was caused by being glued down and natural changes in size of boards due to changes in humidity. Were the boards put down tight (no gap) when they were very dry (perhaps in winter with low humidity)? They probably absorbed humidity from bathroom, naturally expanded, had no room to move and popped. The reverse could have happened if glue prevented natural movement and they popped while shrinking due to drying out but I think first case is more likely.

PVC won't absorb steam but changes in temperature (from room temperature to higher with alot of steam) may still cause thermal expansion and you may have same problem if it's glued down tightly with no place to move. They nail vinyl siding loosely with large slots to allow for expansion because vinyl moves alot with changes in temp. I'm assuming you will be running the pvc vertically. I'd probably consider nailing strips between studs and nailing it instead of gluing. Leave some space to allow for expansion and contraction. Is it like a shiplap or T&G? They also make flexible glue for wood floors to concrete that goes on like a mastic (full coverage with grooves) I'm not sure if that would work or not for your application but it's probably better than construction adhesive.

Finally are you installing new sheetrock? If so I'd recommend using mold resistant and consider adding a waterproof membrane (similar to paint) such as Mapei Aquadefense or the red stuff from Home Depot. I'd also add a good exhaust fan vented to exterior if you don't already have one.

At this point I think Im going to just leave the walls painted. No bead board. The 3/8 PVC products arent flat on the back. They remind me of the lower end composite deck boards sold at the big box stores. Im sure gluing them to the MR board will be a pain in the ****. Not full contact. If I went to 1/2" I'd have to kick out the slant fin baseboard on the one wall and I dont know how it would meet up to the tile for the shower walls.
The second time I did the room over I used a paint designed for bathroom ceilings made by Zinsser. They discontinued that but I see theyre making a mold resistant primer now so I'll probably do the whole room with that before I final coat everything. Hopefully that will help keep it nice.

 

[karoc]

Mike, I installed the green Sheetrock first and still tape joints as if was just going to paint. Yes I know it’s time to refresh our bathroom

 

[Fav Onefour]

Yeah, I was a little pissed that it buckled so fast. I did the original renovation in the Summer. By the Fall they started to pop. I really thought the oil based poly would be enough but it didnt make a difference. As far as managing the moisture its not as bad in the warmer months since we put in CAC. We have a 100 CFM Broan fan/light combo in the middle of the ceiling. I think the biggest issue is my wife and I take long showers back to back.

At this point I think Im going to just leave the walls painted. No bead board. The 3/8 PVC products arent flat on the back. They remind me of the lower end composite deck boards sold at the big box stores. Im sure gluing them to the MR board will be a pain in the ****. Not full contact. If I went to 1/2" I'd have to kick out the slant fin baseboard on the one wall and I dont know how it would meet up to the tile for the shower walls.
The second time I did the room over I used a paint designed for bathroom ceilings made by Zinsser. They discontinued that but I see theyre making a mold resistant primer now so I'll probably do the whole room with that before I final coat everything. Hopefully that will help keep it nice.

It sounds like you did the right thing with oil poly and bath paint. I wonder if the wood was getting moisture on backside with prolonged high moisture environment.

It would be worth checking humidity levels in the bath vs. the home. Those cheapo digital units work great. I use them in quite a few places. No need to mount the things. I just set them on a flat surface and wait for them to acclimate.
Your fan should have plenty of capacity if you're using double time rule. With AC, I would think it should be drawing drier air into the bath too. It would be good to verify the fan is doing what it should.

We also like a good shower. That doesn't mean the bathroom needs to be a steam bath. I go with the mirror indicator. If the air is managed correctly, the mirror shouldn't fog.

 

[PoorUB]

As for bathroom ventilation, IMO, people do not run the fan long enough. You should have a fan with a humidity sensor, or put in a push button timer.

We have push button timers in both baths. 10, 20, 30, and 60 minutes. It might take me 10 minutes to shower, but the timer is left on for an hour. We also have forced air heat and I have the fan running constantly during "awake" hours. Not economical, but I don't have moisture issues in either bath.

An air exchanger puling air out of the bath would be more economical.

 

[Fav Onefour]

@PoorUB , So incredibly true.
People do not use the fans long enough.
My wife, bless her soul is very budget minded. We typically get ready in two different bathrooms.
She was under the impression that saving money by not running the fan was a good thing.
I was polite when I said.
"I'll teach you how to redo the bathroom when water damage and mold is a problem."
I'm patient as all get out and I waited. It took about a year before her lesson.
Don't go thinking that I made her tackle the project solo. But, she was elbows deep into refinishing the bath.

Wet bathroom environments are one of those things that do a slow creep on damage. People don't realize it's happening until a specific point and it's usually too late by then.
I use sensor switches in quite a few rental places. They help. The disadvantage is the location with most wiring. Fan switches are often by the entry door which means the whole room is humid before the sensor switch kicks the fan on. Run times are much, much, longer in that situation. If they are manually started along with the shower, run times are good. Those lessons are a little harder to teach. Some folks just have a hard time understanding the benefits of being proactive.