Is osb sheathing ok to use on the floor

[zlamb0002]

I have decided on a 5 ft teardrop and am trying to save a little money on the floor so I can spend more on other things. I saw that sheathing was really cheap compared to plywood so I was wondering if it would be fine and how thick does it need to be.

[bobhenry]

Hope so that's what I used.
Span specs say 1/2" at 2' on center supports and 3/4 at 3' o/c .
Some will tell you the osb will fall apart but the newer osb will NOT the old stuff was oxboard and WAS junk.
I have my small trailer coated with 2 heavy coats of polar seal (that rubberized mobile home coat) and it has sat out 2 1/2 years rain and sun and snow with absolutely no signs of swelling or flaking. Since there is no direct live load on the floor 1/2 would probably work just fine. If you are unaware there is 5/8 available also.

[kipnita]

Many camper manufacturers use osb as flooring with only the underside painted. We had a pop up and have a Shadow cruiser where osb is used.

I suspect that the water resistance of roofing material most use here is far superior to paint. If so, osb should be ok.

[halfdome, Danny]

Others may use it and be satisfied but... Just the way it's constructed vs real plywood I'll choose plywood every time. There is a reason plywood costs more, quality over price will always win. Were not talking like it will break the bank. Danny

[jimqpublic]

EDIT: Those with more knowledge than I have spoken. Listen to them.

My original response:
If that cost item is critical then I would say go ahead. Make sure you seal the edges well and paint the underside. Screws into the edge grain probably won't hold as well as plywood- use longer, thinner screws than you would for solid wood.

In my experience OSB is less likely to warp than plywood. It's also heavier due to the high percentage of resin.

[goldcoop]

NO!

Ask any 1990's Aliner owner! Almost all have had to replace the floor!

I did!

Cheers,

Coop

[mikeschn]

See my signature line!

Mike...

[rasp]

as one who works for an OSB maker I would not use it for a trailer.

[48Rob]

Will it work? Yes.
Should you use it? no.

It will work, if sealed well enough, and the seal is maintained regularly, but in the end, it will be a lot less expensive, and a lot less effort to just use good quality plywood.
(Heavy cardboard could be used too, if it is sealed perfectly. One little scratch though, and its finished).

Plywood also must be sealed, but in the event some moisture does make its way in, it won't require removing and replacing the flooring like OSB will. Plywood can withstand several major wettings before delamination causes any real concern.
One major wetting and OSB is done.

OSB was designed to be an inexpensive plywood/sheathing option for areas that are NOT exposed.
In areas that it is NOT exposed, it does a good job, not as good as plywood, but not bad.

Roof sheathing covered by shingles, flooring covered by other flooring, etc.

In the rental communities I look after, we have banned OSB for ANY exposed application. Most have been as shed siding.
Over the years, we've watched people paint, and paint, and paint some more to "protect" the OSB.
It still swells, separates, and rots.

No disrespect meant, use OSB if you wish, but if you can't afford to pay the difference between OSB and plywood, I would question the economic sense of building a teardrop in the first place?
Please don't take that statement as offense, for it is not meant to be.

It wouldn't make sense to buy a car if you couldn't afford the gas to operate it?

There is NOTHING wrong with building an inexpensive trailer.
Many of us have taken on the challenge to see how little we can spend, and some pretty neat examples have been the result.

However, it is important to understand the difference between saving money by using donated and low priced quality materials, and using cheap, low quality materials!

If you're on a tight budget, consider used materials.
Consider asking friends, family, co workers if they have some extra unused building material taking up space in their garage, basement, etc.
Once they hear about your cool project, you may have more material than you need...

Good luck with your build!
Check Craigs list, the local paper, recycling organizations, etc.
Good high quality building materials CAN be had for next to nothing if you just look for them!

Rob

[Elumia]

Don't always think in initial cost, think about long term cost of ownership.

How much does the material cost?
Is there a labor difference in installing it?
How much does it cost to protect it?
What if I have to repair it (or if I can't repair it replacement cost)?
How long will it last? Is that long enough? (you may see cheaper materials in commercial products because they only have to make it to the end of the warranty!)

You may find that cheaper materials aren't always the cheapest way to go.

Mark

[jamesm]

mmm.lets see what a manufacturer has to say.... scroll down a bit to read what they say.
http://www.lpcorp.com/sheathing/productinformation/faqs.aspx

I would say yes it is fine if you use the correct exposure classification (just like plywood)....but that is what I used because that is what I had on hand and the manufacturer says it should be fine.

I have to disagree with Rob on this "OSB was designed to be an inexpensive plywood/sheathing option for areas that are NOT exposed.
In areas that it is NOT exposed, it does a good job, not as good as plywood, but not bad.

Roof sheathing covered by shingles, flooring covered by other flooring, etc. "

The plywood will swell and delaminate also if it is the incorrect type and or not protected from moisture. Plywood is made by shaving thin strips or plys of veneer from logs glued to each other at 90 degree angles.....OSB is made in the basically the exact same fashion. Instead of using large sheets of solid wood veneer, thousands of 3 and 4 inch long strands of solid wood are combined to make each sheet of OSB. High technology manufacturing equipment has the ability to orient the strands so they overlap and interlock at a 90 degree angle. Each strand of wood is completely coated with a high performance resin glue. After the OSB leaves the hot press, you have a structural engineered wood product that maximizes our natural resources and has superior high strength characteristics.

I also found "Why is OSB so popular?
Because it meets the same performance standards as plywood, yet is more cost-effective. OSB has excellent moisture tolerance and is much less susceptible to the stress related problems of plywood, such as warping and ply separation. Made from wood chips and resins, it has exceptional dimensional stability and consistent quality because it’s not dependent on the character of an individual log. LP OSB is easy to install, with pre-marked nailing lines and a skid-resistant surface, providing good traction on pitched surfaces"

So in conclusion...I would and did use OSB with exposure 1 rating for my floor. It will not be subject to long time exposure to the elements due to painting and undercoating. And from what I gather from the manufacturer it should do fine once protected from the weather.

But hey what do I know....Im just a sheetmetal worker with a cool tear!

[Franklin]

We had two pop-ups, one with OSB and one with plywood. No contest: plywood. I don't like the the feel, looks or smell of the OSB. Cathy

[48Rob]

Hi James,

You do have a cool tear!

I think we're both saying the same thing, just with a different perspective.

You're "for" OSB because the manufacturer’s studies have convinced you that if properly sealed, it is a good and suitable product.

And I wrote; it will work, if sealed well enough, and the seal is maintained regularly

I cautioned against using it for the floor of a trailer because of readily available research that shows it doesn't stand up to moisture as well as plywood, and on my 30+ years of personal experience in the construction industry, the housing industry, and as a housing maintenance inspector.

You noted that you chose, and used OSB with "exposure rating 1".
"Exposure 1" rated OSB is designed to temporarily withstand weather exposure during construction.
Just about any OSB a consumer can purchase at whatever store carries this rating.

Here is a basic fact sheet showing the 4 common grades of OSB;
Four grades of OSB are defined in terms of their mechanical performance and relative resistance to moisture. These are:

OSB/1 - General purpose boards and boards for interior fitments (including furniture) for use in dry conditions.

OSB/2 - Load-bearing boards for use in dry conditions.

OSB/3 - Load-bearing boards for use in humid conditions

OSB/4 - Heavy-duty load-bearing boards for use in humid conditions.

The exterior grades (3 & 4) of OSB are better suited to using in a potentially damp situation, but unfortunately, grade 1 is the "inexpensive" variety that most consumers are comparing to plywood at the big box stores.
The pricing on grade 3 and 4 OSB is considerably higher, one of the reasons it is special order only in many stores.

A few dollars cheaper...the store employee says; "it’s just as good as plywood".
So the deal is sealed, and the consumer takes home a product that may or may not be suitable, or the best choice for their particular project.

This is the seal found on exposure 1 rated OSB.

<img src="http://www.coxlumber.com/images/osb/apa_stam.gif">


We could each gather up factual information, and endless comments and stories about the virtues of both from the Internet, to support one view or the other, but in the end, the whole idea behind this debate is to offer up as much relevant information as we can so that the original poster can make up his own mind.

So with that in mind, I'll end with this quote from a major manufacturer of both plywood, and OSB products.

Rob

GOOD WOOD
“We don't ever say that OSB is not a good product,” says Chris H. Beyer, director of marketing services for Georgia-Pacific Building Products, which makes both products. “But plywood is better. [Plywood] has performance benefits that are important, and it is more versatile, especially when you talk about flooring options.”

In a 2003 technical paper, Georgia-Pacific stated that plywood holds up better under excessive wettings, has an all-wood surface that results in better glue adhesion, and is 15 percent lighter than OSB so it puts less stress on the floor framing system. Beyer further states that plywood is more forgiving than OSB and also helps create a quieter floor. “Tests indicate that it holds nails better, too,” Beyer adds.

[48Rob]

Hi James,

You do have a cool tear!

I think we're both saying the same thing, just with a different perspective.

You're "for" OSB because the manufacturer’s studies have convinced you that if properly sealed, it is a good and suitable product.

And I wrote; it will work, if sealed well enough, and the seal is maintained regularly

I cautioned against using it for the floor of a trailer because of readily available research that shows it doesn't stand up to moisture as well as plywood, and on my 30+ years of personal experience in the construction industry, the housing industry, and as a housing maintenance inspector.

You noted that you chose, and used OSB with "exposure rating 1".
"Exposure 1" rated OSB is designed to temporarily withstand weather exposure during construction.
Just about any OSB a consumer can purchase at whatever store carries this rating.

Here is a basic fact sheet showing the 4 common grades of OSB;
Four grades of OSB are defined in terms of their mechanical performance and relative resistance to moisture. These are:

OSB/1 - General purpose boards and boards for interior fitments (including furniture) for use in dry conditions.

OSB/2 - Load-bearing boards for use in dry conditions.

OSB/3 - Load-bearing boards for use in humid conditions

OSB/4 - Heavy-duty load-bearing boards for use in humid conditions.

The exterior grades (3 & 4) of OSB are better suited to using in a potentially damp situation, but unfortunately, grade 1 is the "inexpensive" variety that most consumers are comparing to plywood at the big box stores.
The pricing on grade 3 and 4 OSB is considerably higher, one of the reasons it is special order only in many stores.

A few dollars cheaper...the store employee says; "it’s just as good as plywood".
So the deal is sealed, and the consumer takes home a product that may or may not be suitable, or the best choice for their particular project.

This is the seal found on exposure 1 rated OSB.

<img src="http://www.coxlumber.com/images/osb/apa_stam.gif">


We could each gather up factual information, and endless comments and stories about the virtues of both from the Internet, to support one view or the other, but in the end, the whole idea behind this debate is to offer up as much relevant information as we can so that the original poster can make up hisor her own mind.

So with that in mind, I'll end with this quote from a major manufacturer of both plywood, and OSB products.

Rob

GOOD WOOD
“We don't ever say that OSB is not a good product,” says Chris H. Beyer, director of marketing services for Georgia-Pacific Building Products, which makes both products. “But plywood is better. [Plywood] has performance benefits that are important, and it is more versatile, especially when you talk about flooring options.”

In a 2003 technical paper, Georgia-Pacific stated that plywood holds up better under excessive wettings, has an all-wood surface that results in better glue adhesion, and is 15 percent lighter than OSB so it puts less stress on the floor framing system. Beyer further states that plywood is more forgiving than OSB and also helps create a quieter floor. “Tests indicate that it holds nails better, too,” Beyer adds.

[Elumia]

I think the key with either plywood or OSB is sealing cut edges. OSB and ply delaminate in different ways once wet. That's when trouble begins for either product!

In the floor of a teardrop we are really talking 1 or 2 sheets. Can it really be a budget buster? What's the cost difference $20?

Mark