Is OSB Bad?! (Oriented Strand Board--What It's For / When To Use It...House Sheathing/Subfloor)

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Many people don't know what to make of this strange-looking sheet/panel lumber that you see on houses everywhere. In this short video, The Honest Carpenter discusses what OSB is for, and why it still has a crucial place in the construction market!

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Is OSB Bad?! (Oriented Strand Board--What It's For / When To Use It...House Sheathing/Subfloor)

OSB is short for ORIENTED STRAND BOARD.

It first showed up in the 1970s, when the APA approved it as a multi-purpose construction panel.

OSB is typically used as sheathing for floors, roofs and walls in residential construction. Many builders turned to it in the 80s because of its low price point.

OSB is made up of small wood strands mixed with various waxes, resins and adhesives and pressed into mats and panels.

Despite its ugly appearance, OSB actually has better shear strength than plywood--this is, essentially, the property that prevents houses from collapsing sideways

If OSB has a serious weakness, it has always been with MOISTURE PENETRATION.

When OSB sits out in inclement weather, it absorbs moisture. This causes EDGE SWELLING--pronounced swelling at the edges.

Edge swelling can cause problems in construction if it pushes up shingles and thin flooring. This is known as "Expressing" or "Telegraphing."

OSB has a lot of competition in the market these days. The ZIP WALL SYSTEM is sort of like a house sheathing and house wrap in one, which is getting used a lot. And ADVANTECH is a very stable subfloor material that many builders prefer over OSB these days.

Thanks for watching!

The Honest Carpenter

[dannypullen]

I’ve been framing since 1975 and i have been using OSB since it was invented and I have no complaints, about it or plywood. You just have to know what to use here and there.

[joeyager]

I used 7/16 OSB to finish the walls in my shop instead of drywall 20 years ago. I put it up with the more textured side out. Painted white it gives an interesting texture wall finish. And being in a shop, you can attach anything anywhere without needing to attach to find a stud or girt.

[johnhansen]

I was taught to prime the wood after cutting to size with a white lead oil paint, then let it dry before installing the wooden pieces. Today, I will prim large pieces like flooring on both sides and the edges with a decent primer before installing them, now I use water based primer. I was trained as a carpenter by my father, but became an electrician. (The Carpenters were not taking any apprentices when I was ready.) So I only do the carpentry work on my home. I have never found anyone else who believed in priming the cut boards before installing them. I still do, although I only work on my home.

[louislandi]

Another great lesson. Men of your caliber do not just pop up.
You had to have had outstanding
parents. It really shows. And you never waste our time. Always direct and to the point. Looking
forward to the next time.

[joeolejar]

The first horse stalls I built was done with 3/4 plywood. Learned that a horse could dent and even break through with a swift kick. Last ones I used OSB. In 10 years, the OSB has remained undamaged. I'm sold on its durability and structural integrity.

[feathermerchant]

When contemplating OSB, I am somehow reminded of the line from the Christmas Story movie: "My old man's spare tires were only actually tires in the academic sense. They were round and had once been made of rubber."

[gneiss]

OSB is made from trembling aspen up here in eastern Canada (which is the source of most of your eastern US wood) Aspen is a hardwood that is not suitable for dimensioned lumber so it is abundant and cheap. That is why it out competes plywood.

[flagmichael]

That explains a lot! A couple weeks ago I replaced much of the carpet and other flooring in our house with LVP. The last room was the master bath, but there I noticed the plywood subfloor was overlaid with 1/4 inch OSB. It was glued down as well, so I was stuck with a transition. When I pulled up the existing vinyl flooring I saw vinyl tile, and around the toilet it was not adhered at all. Under the vinyl tile was the OSB that had apparently been receiving water (my guess, from the pattern, was a neglected tank leak) for many months at some point before we bought the house 20 years ago. It was rather thoroughly rotted - fortunately I had recently bought an N100 respirator - but the remains were still glued to the subfloor. I used an entire 50 lb bag of leveling cement to get it and the affected surroundings filled.
I understand it has its place, but in the vicinity of water it seems out of place.

[DanKoning]

My buddy worked for "Heartland" a big shed/storage building co. During that time they did a: OSB vs plywood test. They repeatedly parked a 1/2 ton pickup truck on a 10' x 16' mock sub-floor using 1/2" and 5/8" flooring, and treated 2 x 4's [4' on center so the flooring would bear most of the load]. In the end the OSB out performed the plywood with regards to sagging, and damage; *but* like you said, just don't get it wet. ;)

[forestranger]

In the uk oriented strand board comes in different grades and level OSB 3 is passed by buildings control as structural
timber for building with. It can be left out in the rain without treatment for many months. You often see building sites use
it as shuttering around the external fencing of a site to keep the public away. OSB 2 is furniture grade for carcasses and
areas that don’t get seen. It’s brilliant stuff and in my opinion superior to ply. You can screw the edge on wider boards
using special course threaded screws, but for sheathing it’s the only option.

[laurareese]

Perfect timing on this video! I just bought a sheet for my workbench I'm building. Now I know I need to put a coat of finish on it but it's not exposed so I'm going for it.
Thanks for the very interesting videos. As a female just getting into DIY you make accessible videos without being condescending. Thank you for that.

[emiebex]

I've used OSB on a few floors & walls, & for the most part it holds up pretty good. Tip: If you absolutely have to use OSB externally use a can of Flex Seal on it & it'll hold up for Years!👷🏾‍♂️

[jons]

Hello, Ethan;
Thank you for all you do.
OSB is really far superior for replacing the "particle board/"dust board"" in mobile homes.
Have a GREAT day, Neighbor!

[markhooker]

In order of ability to release moisture / avoid mold:
1. BEST: conventional lumber
2. OKAY: plywood
3. POOR: Oriented Strand Board (OSB)
4. HOPELESS: Medium Density Fiberboard (MDF)

Use the above when planning a basement remodel.

[LuciFeric]

I remember paying ~ $6 a sheet for 7/16 OSB. Sheetrock was $5 so i did everything in OSB. $22 per at HD yesterday

[kevinharding]

You cover the basics and essentials that many of us are just not aware of in a clear, comprehensive manner. Thanks.

[josereyna]

While OSB may have structural integrity, it also contains and emits toxins. Part of the binding material has formaldehyde which causes irritation to skin, eyes, and other areas and it has been linked to asthma. Consider a healthier alternative.

[jhans]

Thanks Ethan, for another informative video. As a homeowner, I’ve always stayed away from OSB because it looks cheap. To me, cheap usually = failure. Plywood has served my purposes.

[jamescalkins]

Engineer/large home project DIYer. This is a great video on content - I haven't found an equal to you on YT. Keep up the great work!

[virtualfather]

I used it to frame in a 2 ft high concrete wall around patio. I was surprised when I peeled it off it left a interesting pattern in the concrete better looking than just smooth concrete I think