# OSB for building a house???



## tdsapp (Apr 23, 2009)

Ok, I stopped in and took a look at a house being built not to far from where I live. I was surprised to find that this two story house was being built with OSB framework. The framework for the second story floor is designed like I-beams but it's using what looks like OSB. Is this normal now days? I guess I have seen all the "old school" builders that use 2X12's for most work like this.


Tim

Here are a couple photos I took with my phone....


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## bobj3 (Jan 17, 2006)

Hi Tim

That's is norm now days  it's very strong plus it saves a ton of money..

On the TV show "This Old House" they did a test on both ways and the new way won hands down..

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## Ghidrah (Oct 21, 2008)

I'm sure they have improved the product by now to some degree. In the mid 80s one of a few developments I worked in tried OSB to cut costs, it failed.

At the time even though it was "KNOWN" that OSB had an exterior face and interior face, once any significant amount of water got into the board it swelled like a sponge and then flaked apart. It was a costly and time consuming mistake requiring removal, disposal and replacement.

In an attempt to recover damage costs and place blame the developer tried to prove the material was installed incorrectly, it wasn't. Then the board had a glossy ext. face and a matte int. face. The glossy face was a water/moisture repellent.

It probably wouldn't have been an issue if the structure could be enclosed, (Tyvek papered or tarped) before any repeated normal or extended rainfall occurred but that isn't/wasn't conducive to condo development.


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## MikeMa (Jul 27, 2006)

I have seen on one of the home improvement shows where they were using engineered lumber (studs and such) for the framing. It appeared they were all a type of OSB as well. The big benefit being that they don't warp and to spot on accurate. I would think (and hope!) that the glues used to hold it together would be better able to with stand water, otherwise one good flood and the house would be coming down!


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## Cochese (Jan 12, 2010)

I'd bet on a marine adhesive.


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## BearLeeAlive (Mar 22, 2010)

We use OSB and engineered wood products for the structural components in all our builds for as much as is available. It is much more stable dimensionally. There are no bowed boards with it, and the strength to weight(and size) ratio is really high.

With OSB it make absolutely no difference strength wise which side is out. We always use the rough side out for a couple reasons. On roofs it is for safety, the smooth side is treacherous with just a wee bit of moisture. On most OSB sheets we get the rough side is marked for nailing on 16 and 24" centers, which speeds up the framing. We always push to get the roof on, and at least the moisture barrier on the exterior as prolonged exposure to the elements will cause some damage, but it does take a real long time.

We have used OSB studs as well, but they are still a bit pricey. The excel when balloon framing a second floor and lengths of studs of 20' are needed. We also try to use them in kitchens and wherever building in cabinetry will happen as the perfectly straight run of studs is a blessing when installing cabinets.

I love real wood for finishing work, but for structural give me an engineered product any day.


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## CanuckGal (Nov 26, 2008)

I know OSB is the standard for roofing but is there any gain to using say 1/2" ply instead of OSB? Money being no concern of course.


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## Ghidrah (Oct 21, 2008)

BearLeeAlive, 
Unless they've changed within the last couple of yrs., the Ext. face (smooth/shiny) is/was for moisture/water proofing.

Are you aware of the number of grades? It's possible that even though you may install the product you may not be aware of all the grade classifications regarding where and when any of them can be used and or bond classes.


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## BearLeeAlive (Mar 22, 2010)

CanuckGal said:


> I know OSB is the standard for roofing but is there any gain to using say 1/2" ply instead of OSB? Money being no concern of course.


Deb, cost is one of the biggest considerations, but among other things two other factors are key too. OSB is a bit stronger then an equivalent size of plywood sheathing, and has a much lower impact on the environment as fast growing smaller trees can be used putting less stress on old growth forests.


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## BearLeeAlive (Mar 22, 2010)

Ghidrah said:


> BearLeeAlive,
> Unless they've changed within the last couple of yrs., the Ext. face (smooth/shiny) is/was for moisture/water proofing.
> 
> Are you aware of the number of grades? It's possible that even though you may install the product you may not be aware of all the grade classifications regarding where and when any of them can be used and or bond classes.



Ronald, unless it is a regional thing that I am unaware of, there is no right side out for OSB as far as weather proofing goes, it is made the same right through, the only difference being the surface texture. Both sides are equally water repellent. Some of the first OSB made years ago was smooth on both sides, but it was proven to be a hazard when used on roofs, thus the rough surface now seen on one side. With floor and roof applications the manufacturers grading info does have to be on the underside so it can be identified by a building inspector.

I tried to find a manufacturers spec and could only find where they refer to making sure the textured side is up on roofs, but could really find nothing about walls as far as which side is out. I did find THIS page which has lots of interesting info.

Most OSB used on floors is still smooth on both sides.


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## tdsapp (Apr 23, 2009)

Thanks for the reply guys... Good information here. I figured that it had to be a good product to work with considering the cost of the builder being used. I had just never walked into a construction site in a while and it was new to me. 

Makes me wonder if our house was built this way. (We bought a foreclosure and did not get to see it built.) It makes for some large air space between the floor of the second floor and ceiling of the first floor. It would be great for speakers, can lights, or items of that type. 

I always recall seeing OSB 10 years ago or so and it never seemed like a good flat wood. We just used it for flooring or somewhere that a ton of nails would hold it flat. I am glad to see that things have improved with it.


Tim


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## xplorx4 (Dec 1, 2008)

The construction you observed has a name that for now excapes me. This is part of what is refered to as engineered system of construction and is very strong provided one does not cut into the top or bottom 2x's. The construction is per a pre determined set of drawings and cannot be modified in any way. The great part is that the center "web" can be penetrated with no loss to the structural strength. This allowes running plumbing and HVAC duct between the top and bottom 2x's with no loss of structural strength. I just remembered!!! TJI is the standared term for these joists Floor Joists Systems using Engineered Lumber Glulam, LVL, I-Joists this page can tell you all about them. Another structural member in home construction is the LVL used to span long distances and carry a tremendous load. These however cannot be cut drilled or altered in any way with out a lot of grief with the builder and architect. This link will explain the LVL Vs dimensioned lumber, Versatile Beam for Residential Construction - iLevel Trus Joist Microllam LVL Beam. Some time when you can't sleep check them out.


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## CanuckGal (Nov 26, 2008)

When we got our roof replaced (shingles and sheeting) 2.5 yrs ago, I went with 1/2" ply instead of OSB because the OSB that was on the roof was delaminating inside the attic and was pretty squishy to walk on (20 yrs old). Seems most roofers use 3/8" OSB, at least that's what they all kept quoting us for, which seems a little thin for a roof to me. Let me add I know ZILCH about house construction. The research I did at the time suggested ply was stronger then OSB. This is the first house I owned that had OSB sheeting. Every other roof I had was plank. Even when I asked for 1/2" ply the roofer tried his damndest to talk me into 1/2" OSB if I didn't want the 3/8". I don't regret the decision in the least. But seeing the developements in OSB I would give it a second look if I ever had to replace a roof again. (I hope not!)


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## TRN_Diesel (Feb 24, 2009)

CanuckGal said:


> When we got our roof replaced (shingles and sheeting) 2.5 yrs ago, I went with 1/2" ply instead of OSB because the OSB that was on the roof was delaminating inside the attic and was pretty squishy to walk on (20 yrs old). Seems most roofers use 3/8" OSB, at least that's what they all kept quoting us for, which seems a little thin for a roof to me. Let me add I know ZILCH about house construction. The research I did at the time suggested ply was stronger then OSB. This is the first house I owned that had OSB sheeting. Every other roof I had was plank. Even when I asked for 1/2" ply the roofer tried his damndest to talk me into 1/2" OSB if I didn't want the 3/8". I don't regret the decision in the least. But seeing the developements in OSB I would give it a second look if I ever had to replace a roof again. (I hope not!)


When I was was framing house 3/8" OSB was the minimum under the ALberta Building code but 7/16" OSB is better and stronger. It depends on your area dn the snow load as well and the pitch your roof is at. Lower pitch means more weight of the snow and hence warrants the thicker material. 

The other thing some builders did not do was add in "H" clips to help reduce the flex between the sheets of OSB. You will find a big difference between a roof with H clips and those without.

TGI's for floor joists work very well. They are light and easy to cut and handle. The only down size is the effect under fire conditions. As a firefighter we dread this type of construction for many reasons. The primary one is there is little to no indication the floor is about to collapse compared to a solid floor joist timber built floor. Exposed OSB TGI joist will collapse in just under 10 minutes so we have to be very time aware and be very quick if we enter fire involved structures in new homes.

The other nice thing about TGI's is they are pre-drilled for running electrical and plumbing. Just a tap of the hammer in the holes punches them out. Enclose the bottom with plywood and you have a cold air return.

Just be aware of the off gasing with OSB and keep the area well ventillated or your headed for one hell of a headache.


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