# OSB vs. Plywood for Interior Walls in So. Florida



## OBG65 (May 5, 2018)

Now that I'm retired and back from an Alaskan cruise, I've started to work on putting my 12x18 shed/shop together. Question is whether OSB (cheaper than PW) will work in the So. Florida humidity for interior walls and ceiling. The wall studs and trusses are 2x4 on 16" centers and will be insulated using R-15 faced insulation. It will also have a 1 ton ductless mini-split AC unit and I will also be painting the walls and ceiling.

Thanks in advance for your help.


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## Cherryville Chuck (Sep 28, 2010)

OSB has a coating on the outside to make it somewhat water resistant. I read that the makers had to do this because the first batches which didn't have it couldn't survive rain which might occur before roofing went on. It should be fine. I put it on the inside of my shop for the same reasons as you. I didn't want drywall because it's too easy to damage. Once painted white it reflects light fairly well. It's more desert like where I am and I have about R38 in top of it and my shop stays cool during the day and warm in winter.


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## OBG65 (May 5, 2018)

Thanks Chuck. How many coats of primer & paint did you use?


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## tomp913 (Mar 7, 2014)

I have OSB on the inside of my 24' x 24' garage/workshop - 2x4 studs, kraft face insulation, 14" blown insulation in the attic - and installed a mini-split about 3 years ago and have had no problems. It keeps the shop cool in the summer and warm in the winter and has been surprisingly inexpensive to operate. The OSB makes it easy to hang things on the wall, although I still looks for studs if it's something heavy.

I guess that I should paint the walls one of these days to brighten things up......................


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## OBG65 (May 5, 2018)

Thanks Tom. It may be that OSB is the way to go. It's about $350 for the 1/2" OSB and $515 15/32" PW. Saves me ~$150 that I can use for insulation, paint, or tools.


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## Cherryville Chuck (Sep 28, 2010)

I think I just used a paint that didn't need a primer and a medium or long nap roller and 2 coats. Like Tom said, you get the added benefit of being able to hang a lot of stuff. I still put in sections of pegboard and painted it white too. It's way easier to find a lot of tools that way. Good for things like small squares, saws, hammers, and with the right holders things like chisels and screwdrivers. For long stuff like levels and yardsticks it's finishing nails in the OSB.


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## hawkeye10 (Jul 28, 2015)

OBG65 said:


> Thanks Tom. It may be that OSB is the way to go. It's about $350 for the 1/2" OSB and $515 15/32" PW. Saves me ~$150 that I can use for insulation, paint, or tools.


Like Tom I used OSB and didn't paint it. Not painting it saved money and didn't hurt lighting much. I am talking about the shop I used to have and wish I had back. Oh well I guess that is life.


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## JOAT (Apr 9, 2010)

I say find the shiniest white you can find, and put on at least 2 coats. Paint it all, walls, ceiling, floor. Before you put any shelves, or whatever in, and I would paint them too. You will be amazed at how bright it makes the shop, but it will dim down as you put tools and all in, and sawdust gets on the walls.


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## RainMan 2.0 (May 6, 2014)

I’m going to use osb , but as I think Tom mentioned once, paint it prior to hanging it . Thought that was a great idea


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## DesertRatTom (Jul 3, 2012)

When I insulated by shed shop and office walls, I began by laying in that aluminized radiant barrier. The insulation went on top of that. I was surpirsed when we did the garage that the radiant barrier reduced roofing temperatlure by about 35 degrees. It only has an R rating of 4, but turning the infrared heat away is worth the effort to lay it in. I bought 4 ft wide rolls and cut them to fit between the studs. I also installed them between the ceiling joists, whice were not evenly spaced. Put R13 paper backed glass in next, then a 2 inch thick foam cut to fit precisely between the ceiling joists and held in place by finish nails hammered into the joists. No other covering on the ceiling. Walls are covered with a mix of ply and one whole 24 ft wall is covered in 1/4 inch pegboard. Never bothered with drywall in the shop. Stays warm in winter, but takes an hour to heat up when really cold. Small room AC cools nicely during summer here in the desert. I never painted the shops, just installed a lot of LED lighting


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## Knot2square (Jul 11, 2015)

Back in the day, my father in law used OSB on the outside of his shed. He painted it every two years and it lasted as long as I can remember. He lived in SW Georgia where the heat and humidity are terrible in the summer. I think you would be safe for inside use.


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## OBG65 (May 5, 2018)

Thanks for all the replies guys. Only issue with OSB I found in my searches was it's not water friendly as plywood is, so a undetected leak could be a major issue. Like DRTom I'm also using R-13 and will look at the radiant barrier as well. I have eight linked 4' 2 bulb LED lights being installed in the ceiling a four bulb 4' LED along one wall and three 3' LED along another wall so I may not need to paint the walls or ceiling if it will light it up. May be just seal it. But then again, I may end up painting it. Who knows.

Again, many thanks for the assist.


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## Cherryville Chuck (Sep 28, 2010)

My shop got a lot brighter with the white paint but it also made a nicer place to work in.


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## Stick486 (Jan 4, 2013)

using exterior gloss white is a big plus..
reflective and easier to broom down...


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## sreilly (May 22, 2018)

I can't offer much here as for the paneling but from what I used in the past in building I'd go OBS and save the money. Painting, well that's a personal choice. In my shop I hung all LED lights and they make any area bright. I took the fluorescent lights down and gave them away. I'll do the same in my garage before winter for sure. Now as far as the cooling units, here's where I'd pay close attention. Split, window, central all work the same. As a retired HVAC dude I can tell you many units were replaced when they only needed servicing, especially window and splits. I'm not a big fan of either but they do have their place. By splits I'm referring to units where the indoor unit is a wall hung fan and evaporator unit with the controls on it and the condenser (outdoor unit) sits outside with copper lines between them. Central units are similar except they have coils that are either sitting in a furnace or a boxed ducted air handler and the duct goes throughout the dwelling. The issue mostly is the return air. Regardless of system you have a fan and coil. The fan of course supplies air on the leaving side of the coil but also pulls room temperature air through the entering side into the cooled coil where the coil cools the air before supplying it back to the room. The coil is King and must be maintained (cleaned and filtered) properly or you will have declining performance resulting in higher operating cost, lower efficiency, and warmer air discharge. Installing the indoor unit where it is accessible for cleaning is extremely important. If used year round, a minimum of 1-2 times yearly depending on usage is best. 

But key is filtering the air. Most all split units (wall hung) have a mesh type thin filter in the indoor unit which is almost useless but better than nothing. It requires a lot of cleaning and very often. Unfortunately there's little way to use a better filter in the unit due to the thickness restriction of the unit. I would think constructing a box that can fit in front of the indoor unit would allow the use of a 1" pleated filter. This allows much better air filtration thus keeping the coil cleaner. When you do need to clean the coil use an approved evaporator coil cleaner for the indoor and an approved condenser cleaner for the outdoor unit coils. 

I use a 20x25x4" pleated filter in my central system at home. I installed this system 18 years ago and just replaced the indoor coil and outdoor unit (heat pump) but the gas furnace is still in great shape (dual fuel system with 5 zones). When we pulled the indoor coil off the furnace it was a clean and spotless as a new coil. That filter had stopped all the dirt from reaching the coil and kept the system very efficient over the years. It also prolonged the life of the system. I've replaced systems that were older but this one had developed a refrigerant leak that was proving very difficult to locate and we decided it was time to replace instead. 

I know this is a long post and I apologize but most people have no idea of what should be considered when installing a unit. That includes window units. You'll need to take them out at least yearly and thoroughly clean them,especially the coils, so make sure they are accessible when planning. They are sealed systems like your refrigerators so putting gauges on them is not possible without installing ports which often led to leaks so temperatures are the only way to easily diagnose them. I've seen a ton of good units tossed and all they had were dirty coils. You should see 18-20 degree difference between room temperature and discharge temperature when working properly.

Feels a little weird hitting the "Post Quick Reply" button


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## thomas1389 (Jan 4, 2012)

Sreilly (steve) A very good post on air. I continually learn from the guys on here. I'm grateful to be a member of this forum. Now if I could only figure out why I can't access "attached thumbnails" when they're posted.


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## OBG65 (May 5, 2018)

Thanks for the post Steve. I like the idea of adding a 1" pleated filter in front of the indoor unit and will be looking into making or possibly buying one, if available. I hope the WEN air filtration unit that I'm installing helps with the dust. To help with the temperature I'm installing a radiant barrier under the R-13 faced pink stuff. Should help with the sun issue here in So. Fla.I'll be talking to HVAC guy about that filter when he comes to install the unit. 

Funny how things go. Just when you think you've created the the best plan to get your shop up and running, you run into stuff that prolongs the process. I'll get progress pictures as I get really moving. 

The electrical should be done by the weekend by a licensed/certified electrician. I have a 60A breaker in the main panel in the house and had a 6/3 wire run through the attic to a junction box outside the house and in front of the shed. He's running 6g THWN wire underground in a schedule 40 conduit into the old 150A house panel I'm using in the shed, then 12/2 & 14/2 Romex to the outlets. The 110v/ & 220v circuits are going to be on 20A breakers with each of the 6 220v outlets on individual circuit breakers. The 110v outlets will be split into 5 circuits - main lights, supplemental lights, air filter, AC (the mini unit is 115v), and 6 outlets.


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## sreilly (May 22, 2018)

OBG65 said:


> 12/2 & 14/2 Romex to the outlets. The 110v/ & 220v circuits are going to be on 20A breakers with each of the 6 220v outlets on individual circuit breakers. The 110v outlets will be split into 5 circuits - main lights, supplemental lights, air filter, AC (the mini unit is 115v), and 6 outlets.


One issue here, 14/2 is only rated 15 amps. Your electrician can guide you on breaker sizes. How long a run is it between panels? Distance will have some affect on voltage drop if too far but again your electrician can make sure you're OK. Most of my work was design build computerized zoning systems. I did commercial and residential systems but what I enjoyed the most was control work. I cut my teeth on Carrier's VVT (variable volume, variable temperature) zoning systems and then their home controls (Comfort Zone). From there I learned Trane's zoning systems, Omni Zone, and Carriers fully modular system (name escapes me) that required a 6 week school to learn the basics for programing and designing. That was installed at a radar site with dual packaged systems, one duct system, alternating equipment runs, emergency backup starts in case one failed, and a ton of federal government requirements per the FCC. It was a nightmare and when finished, inspected, and passed they had us dumb down the system so their maintenance people could work on it. Basically went to T87 T-stats, relays and contactors while all those upto date and sophisticated controls went in a box never to be used again. All at an extra charge of course. The monetary fines for down radar site, not to mention the danger from lost coverage, is something no one wants to be dealing with. I saw the same with the telephone company and it's switch rooms, another big customer of ours. Redundancy is key and still there are times you can't cover everything. But that's another story. 

Did I mention I'm glad to be retired......far less stress.


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## Knothead47 (Feb 10, 2010)

I used OSB since it was cheap....like me. Need to get ambitious and paint it.


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## Cherryville Chuck (Sep 28, 2010)

Steve is correct about wire size. If the panel has a 20 amp breaker then you must use 12 gauge wire. It's a good idea to mix some plugs and some lights together in circuits or use dedicated lighting circuits. The last thing you want is for all the lights to go out if you overload a circuit.


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## radios (Sep 30, 2009)

painting the entire interior of it is a good idea to prevent MOLD.. without paint, it could seep into the wood fibers.. I don't remember what months it was in Florida, but it is the time that you get very cool temperatures, but the humidity at night is so bad, that it's unbearable outside, and the moisture just makes everything sweat water, in the day, the sun dries everything up, and is actually much more comfortable, even though the temperature is much higher..:grin:


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## Stick486 (Jan 4, 2013)

and just because I like kicking over the can of worms...

nobody mentioned fire rocking over the OSB to satisfy local codes (if any) and to avoid headaches/stress/losses come insurance claim time...
VOE on the insurance dodge...


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## OBG65 (May 5, 2018)

I've decided to go with 3/8" plywood. I found it to be the best option for me. I'm going to prime and and paint it. 

Now for attaching the ply to the studs I've been debating whether to use 2" deck screws or getting the Hitachi NT 65MA4 DA 15g finish nailer. The nailer would be faster than the screws but then would I need a nailer if I'm not going to do base boards, trim, or crown molding work. I already own an 18g brad nailer and a 23g pin nailer. Is there a benefit from having a 15g nail gun in addition to the other two I already own.

Thanks for the advice.

BTW, I'll post pics of the shop build when I get most of it done. I'm taking pics as I go along.


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## Evied1983 (Jan 25, 2021)

OBG65 said:


> I've decided to go with 3/8" plywood, which I bought here Sheet Materials Wholesale | Hardwood Chinese External Grade Plywood . I found it to be the best option for me. I'm going to prime and and paint it.
> 
> Now for attaching the ply to the studs I've been debating whether to use 2" deck screws or getting the Hitachi NT 65MA4 DA 15g finish nailer. The nailer would be faster than the screws but then would I need a nailer if I'm not going to do base boards, trim, or crown molding work. I already own an 18g brad nailer and a 23g pin nailer. Is there a benefit from having a 15g nail gun in addition to the other two I already own.
> 
> ...


*OSB* has a smoother and more consistent finished surface, and a painted *OSB wall* will have a smoother look than a painted *plywood wall*. *Plywood* is more moisture-resistant than *OSB*, and can be a better choice if you live in a humid climate *or* if your garage is underground and prone to retain moisture and humidity.


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