Ideal interior wall type?

[Dad Was A Racer]

My 30x50 engineered metal shop building is underway and I need some advice on what the best material/construction type is for interior walls in a shop.

Here's what I've considered thus far:

1. 7/16" OSB covered with FRP

2. 3/4" paint grade plywood painted white

3. 6" nickelgap Shiplap installed vertically then painted white.

My electrical conduit and black iron air pipe will be surface mounted either way, for ease of service, reconfiguration, etc. and the building will be insulated with 6" vinyl backed roll-in insulation.

I want something that will reflect light, be durable and easy to clean, and allow me to hang decorations, lightweight stuff directly to the walls without necessarily being right on the structural steel.

What's best?

 

[btdobie]

I've been known to worry too much, but I don't like combustable materials for walls especially in a shop. Ribed steel would work, and as long as the stuff is really light you can hang it with magnets instead of making holes.

If it has to be one of the choices you gave I would go with the shiplap. I think it would look the best.

Edit: when I say hang it with magnets, I mean the decorations not the ribbed steel

 

[NUTTSGT]

Welcome to the most debated subject on GJ.

No one answer is correct for everybody in every application.

Personally I have OSB painted white. However, I wouldn't care for the FRP though, to each his own. Out of your options, I'd go with the plywood painted white.

 

[Dad Was A Racer]

After doing the math on costs, time spent, etc. it sure looks like 7/16" OSB painted white will be the winner.

Any big advantage to using a primer like Kilz first, for those that have done this? I plan on painting it with high gloss enamel.

 

[astroracer]

After doing the math on costs, time spent, etc. it sure looks like 7/16" OSB painted white will be the winner.

Any big advantage to using a primer like Kilz first, for those that have done this? I plan on painting it with high gloss enamel.

OSB will look terrible painted with a high gloss... Gloss will show every nook bump and cranny in the OSB surface. Do a test patch before you buy a ton of paint.
Go with a satin finish. It will look better. I would also go with sheetrock, it will look much nicer, but that's just me.
Mark

 

[NUTTSGT]

After doing the math on costs, time spent, etc. it sure looks like 7/16" OSB painted white will be the winner.

Any big advantage to using a primer like Kilz first, for those that have done this? I plan on painting it with high gloss enamel.

I rolled two coats of Kilz oil based on my OSB before painting it.

 

[EVOLVO]

I just did my 30 X 22 with 1/2" plywood. Gathered up all the half used cans of white latex, some slight variation in shade, mixed it in a 5 gl bucket and applied two coats. Came out great, really lights the place up so much that I decided to skip the white enamel. Finger prints and palm smudges will fool folks into thinking I do things in there

 

[RivennHewn]

Painted OSB looks like ***.

FRP is clean and sanitary.

Drywall is easy to repair.

Wood burns.

 

[rburke65]

Key opinion....OSB will look bad....did I say opinion? I did Smart Siding panels and I'm satisfied. I screwed it onto the studs and that way I can remove it if necessary....and I have.

 

[James-W]

I have said this numerous times and nobody pays any attention. If you put OSB on the walls, smear a coat of drywall compound on the OSB before you paint it. The drywall compound will cover and hide the "wood chips" and it will look like drywall.

This is a challenge, if you don't believe me, take a piece of scrap OSB and put a coat of drywall compound on it. Then, when it is dry, put a coat of paint on it. If it doesn't look like drywall, then come back here and tell me I am full of ****. If it looks like drywall then come back here and tell me how nice it looks.

 

[RivennHewn]

I have said this numerous times and nobody pays any attention. If you put OSB on the walls, smear a coat of drywall compound on the OSB before you paint it. The drywall compound will cover and hide the "wood chips" and it will look like drywall.

This is a challenge, if you don't believe me, take a piece of scrap OSB and put a coat of drywall compound on it. Then, when it is dry, put a coat of paint on it. If it doesn't look like drywall, then come back here and tell me I am full of ****. If it looks like drywall then come back here and tell me how nice it looks.

Drywall is cheaper than OSB. What's the gain?

 

[James-W]

Drywall is cheaper than OSB. What's the gain?

Understood, I have drywall in my garage. BUT, some people prefer OSB because they can hang stuff anywhere on the walls and don't have to worry about hitting the studs. Then they paint the walls a light color, but you can still see the "wood chips" thru the paint. By putting drywall compound on the OSB you cover up all the "wood chips" and then when you paint the OSB the walls look like they are drywall. Also, you use a lot less paint because the paint won't soak in as much.

 

[Tduby]

Anyone have luck with metal that isn’t to lumpy or something that looks like half lap wood.

 

[fteufert]

My first garage has 3/4" plywood walls, and when it "caught fire" from weld spatter on a rag, the plywood didn't burn. The fire smoldered in the wall and literally cooked the 80 year old framing.



It made a chimney in the wall.

My new garage has OSB, and I have no fear of fire. With all the chemicals in thee, the walls are my last concern.

I'd do OSB, and in the future, you can always sheet rock over it.

My OSB looks fine painted, and is holding up great.

 

[seanc_mt]

I did OSB neighbor did sheetrock. He is very very good at sheetrock, he smoothwalled his entire shop 30x50x16. After one year of actual work ie: oxy/acetylene, welding, heavy equipment repairs the sheetrock is covered in black dust etc.

 

[HoosierBuddy]

I think I found the perfect solution when I did mine.

I had them finish the ceiling in steel sliding. They brought that down the walls 4-feet and then switched over to T1-11 exterior siding. I didn't finish the siding at all, so no painting or sealing was required. The white steel reflects light down. The T1-11 is very durable, looks great, and will take nails or screws without any problem.

Phil

 

[astroracer]

I did OSB neighbor did sheetrock. He is very very good at sheetrock, he smoothwalled his entire shop 30x50x16. After one year of actual work ie: oxy/acetylene, welding, heavy equipment repairs the sheetrock is covered in black dust etc.

Which means he works more then he cleans... Painted drywall will clean a lot easier then raw or painted OSB. Usually just wiping it down with a rag will get it clean. OSB will stay dirty until you paint it.
My shop is the same way, I work more then I worry about cleaning. The drywall may be a bit dirty but that doesn't worry me at all. If it was a showplace, maybe, but it isn't. It's dirty and gritty and I tell everyone don't walk in my shop without shoes unless you want to be picking steel and aluminum slivers out of your feet.
mark

 

[All]

My first garage had 3/4" plywood walls, and when it "caught fire" from weld spatter on a rag, the plywood didn't burn. The fire smoldered in the wall and literally cooked the 80 year old framing.

It made a chimney in the wall.

My new garage has OSB, and I have no fear of fire. With all the chemicals in thee, the walls are my last concern.

I'd do OSB

I need more help understanding this post, and the conclusions drawn from what had to have been a sobering experience.

Since fire propagation is a critical concern for the types of things we do in a shop, the choice of interior wall paneling inside a giant metal clad "oven" seems worthy of careful consideration of facts concerning the materials chosen.

A neighbor suffered a house fire recently, that blew over from a trailer parked on the side of the house. The house itself had concrete shiplap siding (HardiePlank) and a metal roof. One would think that the flames and embers from the burning trailer wouldn't effect the house as severely as they did.

But apparently, the heat from the burning trailer (likely from cooking "street" substances, judging by the activities of the occupant, using flammable gasses with the same explosive properties that we might use for brazing) was so intense and explosive that it burst open the windows to the otherwise flame impervious house.

As the interior burned, the concrete siding and the metal roof held the heat in like an oven, as the wood framing and lathing burned like charcoal inside. The crew of fire fighters had to chainsaw through the metal roof, (with chainsaw oil rooster tailing flames... those dudes were bad a**... if you never seen a fire fighter standing on top of a wildly burning house wielding a chainsaw that itself was also on fire... without even flinching... then you've missed a sight of amazing human courage). So much for the "fire protection" of a metal roof.

The entire structure had to be rebuilt. They are still working on it, a year later. Unfortunately, that metal roof was installed over a wood roof.

Which brings us back to putting wood interior walls inside of a metal building.

I spent a few minutes online trying to find some evidence of the implied assumption in the post quoted above, which I will paraphrase (or mischaracterize, so feel free to correct me) as that "OSB has more chemicals in it than plywood, and those chemicals contribute to greater fire resistance and/or reduced flame spread."

Keep in mind, that is a paraphrase of what the post implied. It may not be what the author meant to say, hence, I explained at the outset that I need help understanding the post.

I was not able to find any documentation, from the APA, or UL labs, or any other source that suggested that OSB was more fire resistant, or had a lower flame spread rating, than plywood. Most studies that I glanced through suggested that the performance of OSB and normal plywood in a fire were about equal, no advantage either way. However, other studies, including the UL lab test, demonstrated that fire retardant treated plywoods had vastly superior flame spread resistance over OSB.

While I was not looking to compare any other relevant property between OSB and plywood, invariably other properties would be mentioned in the comparison studies I was able to find. To summarize some of the properties compared:

Flame Spread Rating: OSB had the same as (non treated) Plywood
Flame Spread Rating: OSB had worse (a lot worse) than treated Plywood
(The higher the FSR number, the faster the fire will spread, which I consider "worse")
Nail Holding: OSB had less than Plywood
Planar Shear Strength: OSB had less than Plywood
Compression: OSB had less than Plywood
Tension: OSB had less than Plywood
Bending Strength: OSB had less than Plywood
Bending Stiffness: OSB had less than Plywood
Panel Weight: OSB had more than Plywood
Thickness Swell: OSB had more (a lot more) than Plywood

In fact, moisture was repeatedly cited as the worst enemy of OSB, not only due to the swelling, but due to the fact that the edges of OSB remain swollen long after the panel has dried out. The swollen edges are not only unsightly, but they are now weakened, and since the shear value of the paneling system relies in no small part on the nail scheduling around the edges of the panel, and having those edges weakened from the disassociation of the chips due to the swelling doesn't help.

From the overview I was able to gather in the short amount of time spent researching, it appeared that the principal benefit of OSB was material cost. It is cheaper. I was unable to verify any benefit in terms of fire resistance, nor was I able to see any other benefit to OSB compared to plywood, although I wasn't really looking to compare other attributes. On the other hand, I would welcome any links to resources that make a case for drawing a different conclusion.

As for the OP's question, if I had the budget, I would put 5/8" 1 hour fire resistant drywall over whatever substrate is used underneath for a "nailer".

 

[Lelandwelds]

I've been known to worry too much, but I don't like combustable materials for walls especially in a shop. Ribed steel would work, and as long as the stuff is really light you can hang it with magnets instead of making holes.

If it has to be one of the choices you gave I would go with the shiplap. I think it would look the best.

Edit: when I say hang it with magnets, I mean the decorations not the ribbed steel

If truly worried about fire, worry about wall cavities. Put in blocking and cellulose insulation.

Expensive choices. I think I would try my hand at drywall compound on OSB.

 

[BruceMc]

I spent a few minutes online trying to find some evidence of the implied assumption in the post quoted above, which I will paraphrase (or mischaracterize, so feel free to correct me) as that "OSB has more chemicals in it than plywood, and those chemicals contribute to greater fire resistance and/or reduced flame spread."

Keep in mind, that is a paraphrase of what the post implied. It may not be what the author meant to say, hence, I explained at the outset that I need help understanding the post.

Not even close to what they said. It seems pretty simple - with all the other chemicals (oil, thinners, paint, etc) inside the shop, the flammability of the walls is pretty low on the list of concerns.

 

[BruceMc]

Which means he works more then he cleans... Painted drywall will clean a lot easier then raw or painted OSB. Usually just wiping it down with a rag will get it clean. OSB will stay dirty until you paint it.

Painted OSB and sheetrock clean the same. You're cleaning the paint surface, not the material underneath.

There's a couple of reasons sheetrock gets textured. One is because, without a lot of cleaning, a super smooth surface starts looking like **** over time, even in a clean environment like a home. OSB has the advantage from the get go. It's a much better looking surface over time.

 

[btdobie]

My first garage has 3/4" plywood walls, and when it "caught fire" from weld spatter on a rag, the plywood didn't burn. The fire smoldered in the wall and literally cooked the 80 year old framing.



It made a chimney in the wall.

My new garage has OSB, and I have no fear of fire. With all the chemicals in thee, the walls are my last concern.

I'd do OSB, and in the future, you can always sheet rock over it.

My OSB looks fine painted, and is holding up great.

But in OP's case the frame and exterior wall are metal so if he uses a none combustable interior finish then his whole building will be non combustable which will get him a discount from some insurance companies.

 

[All]

Not even close to what they said. It seems pretty simple - with all the other chemicals (oil, thinners, paint, etc) inside the shop, the flammability of the walls is pretty low on the list of concerns.

Thanks for the alternative interpretation.

The poster did not say "oils, thinners, paint, etc, inside the shop",
but instead said only "My new garage has OSB, and I have no fear of fire. With all the chemicals in thee, the walls are my last concern".


While your interpretation makes a lot of sense, it wasn't clear to me what the poster meant from his post, because the post topic was OSB and the thread title is interior wall type, not interior contents of a typical garage, the stuff of which we all have in our garages, regardless of wall type.

Thanks again for interpreting.

 

[tapered-pin]

why not just use FRT plywood if you're worried about fire? (or a few sprinkler heads off of a pvc domestic water line).

ideal would be plywood wall sheathing, assuming you're using wall mounted storage solutions,
less ideal would be 2X12 blocking in the walls and drywall sheathing
still less ideal would be a layer of 1/2" plywood covered by a layer of FRP or drywall for the finished look (as it's the most expensive)

 

[astroracer]

Painted OSB and sheetrock clean the same. You're cleaning the paint surface, not the material underneath.

I'm sorry but, no, they don't. Sheetrock is a smooth surface. OSB is Oriented Strand Board and is made of chipped wood fibers that is soaked in resin, heated, compressed and glued together. The OSB surface is like the surface of the moon. Nooks, crannies, pockets and anything but a smooth cleanable surface. Any dirt, dust and grit that gets driven into those pockets is not going to wipe off. Yes, you can clean the "paint" but you are not going to clean out all of the pockets and crannies... It will look dirty until it is repainted...
This is the voice of experience here. I did my machine shop floor with T&G OSB in 1992 and painted it gray. It sweeps and vacs but there is still tons of grit and dirt that will not come out of the voids that are inherent to the OSB...
Mark

 

[BruceMc]

This is the voice of experience here. I did my machine shop floor with T&G OSB in 1992 and painted it gray. It sweeps and vacs but there is still tons of grit and dirt that will not come out of the voids that are inherent to the OSB...
Mark

And you expect I'm talking from... ?

The subject is walls, not floors. Ground in dirt and grit on a heavy tread floor isn't really relevant to wiping down accumulated dust that has settled out on painted walls. I will agree, though - OSB isn't a very good choice for a floor surface, no matter how it's painted. A sub-floor maybe, but not the top surface. Out of curiosity, though - how well do you suppose drywall would clean up if you had used it for your floor instead?

 

[astroracer]

And you expect I'm talking from... ?

The subject is walls, not floors. Ground in dirt and grit on a heavy tread floor isn't really relevant to wiping down accumulated dust that has settled out on painted walls. I will agree, though - OSB isn't a very good choice for a floor surface, no matter how it's painted. A sub-floor maybe, but not the top surface. Out of curiosity, though - how well do you suppose drywall would clean up if you had used it for your floor instead?

Yea, the subject is walls and you take an example and turn it stupid... I used the OSB because it's what I could afford, yea drywall was cheaper but I learned my lesson after the first time...
Let's just drop it. We all know what OSB is and how it will look. The OP can do what he wants, it's his shop... He is probably scared shitless to post anything further with the amount of angst this thread has developed...
Mark

 

[Marctrees]

Dad was a racer - Regarding your insulation - Being near the hot humid Coast, I highly recommend you look into the below link.

It talks about how your fiberglass insulation facing showing in the building should be permeable.

Don't take my word for it.. Google "Vapor barrier hot humid"

We ordered our 6" batts from Mueller..facing was made by Lamtec. Marc

https://www.lamtec.com/technical-bulletins/vapor-retarder-location/

 

[GrayFlattop]

Flame Spread Rating: OSB had the same as (non treated) Plywood
Flame Spread Rating: OSB had worse (a lot worse) than treated Plywood
(The higher the FSR number, the faster the fire will spread, which I consider "worse")
Nail Holding: OSB had less than Plywood
Planar Shear Strength: OSB had less than Plywood
Compression: OSB had less than Plywood
Tension: OSB had less than Plywood
Bending Strength: OSB had less than Plywood
Bending Stiffness: OSB had less than Plywood
Panel Weight: OSB had more than Plywood
Thickness Swell: OSB had more (a lot more) than Plywood

In fact, moisture was repeatedly cited as the worst enemy of OSB, not only due to the swelling, but due to the fact that the edges of OSB remain swollen long after the panel has dried out. The swollen edges are not only unsightly, but they are now weakened, and since the shear value of the paneling system relies in no small part on the nail scheduling around the edges of the panel, and having those edges weakened from the disassociation of the chips due to the swelling doesn't help.

From the overview I was able to gather in the short amount of time spent researching, it appeared that the principal benefit of OSB was material cost. It is cheaper. I was unable to verify any benefit in terms of fire resistance, nor was I able to see any other benefit to OSB compared to plywood, although I wasn't really looking to compare other attributes. On the other hand, I would welcome any links to resources that make a case for drawing a different conclusion.

As for the OP's question, if I had the budget, I would put 5/8" 1 hour fire resistant drywall over whatever substrate is used underneath for a "nailer".

Amen.

I struggle to understand the proliferation of OSB in recent years. It is simply not a good material based on properties and longevity, it is cheap - and that is the only positive attribute that OSB has.

Drywall is cheap - and fire retardant. I put up 5/8 drywall when I built my shop and I'd do it again unless I win the lottery - in which case I'd build using glazed concrete block, but that stuff is crazy expensive. Looking for a good compromise - painted concrete block. Spray on a coat of block filler and a couple of coats of high quality semi-gloss and you have a surface that is easy to maintain. But that takes the conversation more to the end of "ideal" rather than realistic.

If you really need a full surface "nailer", then sure - use a layer of 3/4 plywood underneath, but that too gets expensive and is overkill. If you want to hang stuff on the wall, install French cleats all the way around at multiple heights.

Just my $0.02

 

[lakeroadster]

If you put OSB on the walls, smear a coat of drywall compound on the OSB before you paint it.

Drywall is cheaper than OSB. What's the gain?

Take the handle of a floor broom and jab it into drywall...

Take the handle of a floor broom and jab it into OSB...

You'll see the gain.

 

[Tullugeon]

why not just use FRT plywood if you're worried about fire? (or a few sprinkler heads off of a pvc domestic water line).

ideal would be plywood wall sheathing, assuming you're using wall mounted storage solutions,
less ideal would be 2X12 blocking in the walls and drywall sheathing
still less ideal would be a layer of 1/2" plywood covered by a layer of FRP or drywall for the finished look (as it's the most expensive)

Sprinkler systems can become exhausting, depending on where you live. In an area I build a residential garage, when they saw my sprinkler system I was told it would have to meet code. It is not required but because I was putting it in, it would have to meet the fire code which for that area was based on commercial use.

So the price went from about $1,000 to more than 12k because I needed pressure tanks and inspections. I opted for powder instead.

 

[All]

Not even close to what they said. It seems pretty simple - with all the other chemicals (oil, thinners, paint, etc) inside the shop, the flammability of the walls is pretty low on the list of concerns.

The more I think about it, the more illogical this reasoning sounds, and the more I understand why I interpreted what they said in the original way that I did.

To assert that the flammability of the interior walls is least on the list of concerns when compared to all the other chemicals stored inside the building, such as oils, thinners, and other volatile and flammable liquids, aerosols, and compressed gasses...

... is like saying that what the walls of a chimney are made of is pretty low on the list of concerns, since whatever wood, newspaper, or natural gas plumbed into the chimney is far more flammable. Obviously, this does not make sense.

And the irony is, the poster that motivated this side bar related to interior wall discussion described the walls of his building... as a chimney!

We build chimneys to be flame resistant, so that whatever is burning inside the chimney won't also burn the chimney down.

Doesn't it make sense to use the same type of reasoning when building the interior of a shop that has a high concentration of flammables?

Isn't that why the UBC requires 5/8" drywall on the shared wall between a house and an attached garage?

 

[BruceMc]

We build chimneys to be flame resistant, so that whatever is burning inside the chimney won't also burn the chimney down.

Doesn't it make sense to use the same type of reasoning when building the interior of a shop that has a high concentration of flammables?

Isn't that why the UBC requires 5/8" drywall on the shared wall between a house and an attached garage?

Chimneys are built to be fireproof, not flame resistant.

Flame resistant means it takes a little longer to burn, giving you and your family time to escape or firefighters a little additional time to try to save the rest of the structure. In an unoccupied space, that extra bit of time doesn't make that much difference when it comes to losing the structure, unless there is some kind of remote fire monitoring. By the time someone outside the building notices, it's usually pretty far gone.

I'm honestly no more concerned about the fire risk of the OSB in my shop than I am about the fire risk of the knotty pine T&G inside my residence.

 

[n20junkie]

Ever try to light the face of plywood?

Try it some time. Take a torch to the face and it will laugh at you. What causes building fires is electrical, a fuel fire or an errant spark.

The first two are going to burn the building flat. The last one can usually be protected for by sealing the edges of whatever wall surface you choose.

I personally choose to have the stem walls come up 12 inches above the floor so sparks that bounced would almost certainly land on concrete and not sneak under the wall surface and contact the bottom plate.

 

[sierradmax]

1/4" PVC over 7/16" OSB?
https://www.amazon.com/dp/B00JPHPK5E/?tag=atomicindus08-20

 

[Marctrees]

There's also the textured white fiberglass "milkhouse" panels, 4x8.

https://www.menards.com/main/paint/...stic-frp-wall-panel-4-x-8/p-1444450799332.htm

Marc

 

[tapered-pin]

Ever try to light the face of plywood?

Try it some time. Take a torch to the face and it will laugh at you. What causes building fires is electrical, a fuel fire or an errant spark.

plywood isn't hard to light when it's been in a conditioned environment for 10 years. (AC units drain the moisture out of a dwelling)

 

[Jackfre]

After doing the math on costs, time spent, etc. it sure looks like 7/16" OSB painted white will be the winner.

Any big advantage to using a primer like Kilz first, for those that have done this? I plan on painting it with high gloss enamel.

I think the high gloss will be annoying. I have semi-gloss off white on my 1/2" plywood set vertically. Due to cost I used 8' sheets vs the 10's. A two foot strip at the top with a 1x4 band covering the seam handles the appearance. Four years in I find the 1/2" to be sufficient for hanging about anything. If it is heavy, I am spanning studs anyway so it is secured. Set vertically, I can access any part of the wall interior for modifications. I think rather than using conduit all over the place, I would downfeed the wires to localize and ease access for alteration(s). As far as using the primer first, paint is 90% preparation and 10% application. You will have a better surface if you prime it first. I would spend the extra dough to get a good grade of plywood over the OSB. I think you will be happier with it.

 

[Lelandwelds]

My grandfather once mentioned that plywood was despised when it became commonly used in home building. I think OSB is getting the same treatment.

A little blocking and sheetrock becomes almost impossible to punch through. The drywall mud on OSB idea is intriguing. My dream building funded by Lotto winnings would be tilt wall with 4" of XPS on the outside and metal skinned commercial freezer panels for a roof.

It is pretty easy to tour the aftermath of a fire if you are reasonable. There is a bit of info on the internet too. Fires are often electrical in origin and it is the contents that ignite the structure. Metal buildings are not considered fireproof btw.

Fires are usually the result of some dumb action or neglect. Untended grease on stove. Deep frying turkey on wood deck. Rotten wood failing under leaking gas waterheater. Sparks into wood shavings. BLO soaked rags in the corner. Cleaning concrete with gasoline. Don't be stupid.

 

[Simplytodd]

Just finished the interior walls in my 30 x 50 shop and started painting last week. Went with 3/4” A-C plywood. I like that I can hang just about anything anywhere.

I had drywall in my last garage not having that again. Patching drywall and painting it *****. If you don’t want your wall to look splotched it means painting the whole wall. It means retapping, pulling everything off the walls.

I am using a semi gloss oil based paint. First coat surprisingly didn’t soak up as much as I thought. Second coat completely covered and looks nice. The 1 1/8” tongue and groove I used for decking in the loft took three coats before it looked as good.