Thread: OSB Shims

I remember this going around a couple weeks ago.... I hope I remembered correctly that it's wrong. Also, I wasn't able to find the specs for the brackets before I issued the report but I'm pretty certain these are used incorrectly.

The brackets were only on a small part of the house. The OSB shims were around an entire perimeter of a 3300q house and many interior foundation walls as well.

Similar Threads:

• Shims under sill plate
• Are these shims legit?
• Shims in the garage door track
• Shims on Piers
• rafter shims

Nope, OSB shims are not allowed. Don't ask me for the documentation to back it upthough. It's been a long week.

Originally Posted by Matt Fellman

I remember this going around a couple weeks ago.... I hope I remembered correctly that it's wrong. Also, I wasn't able to find the specs for the brackets before I issued the report but I'm pretty certain these are used incorrectly.

The brackets were only on a small part of the house. The OSB shims were around an entire perimeter of a 3300q house and many interior foundation walls as well.

MF: Assuming we are looking at sill plates, the answer is no. The reason is:

R319.1 Location required.

Protection from decay shall be
provided in the following locations by the use of naturally
durable wood or wood that is preservative treated in accordance
with AWPA U1 for the species, product, preservative
and end use. Preservatives shall be listed in Section 4 of
AWPA U1.
1. Wood joists or the bottom of a wood structural floor
when closer than 18 inches (457 mm) or wood girders
when closer than 12 inches (305 mm) to the exposed
ground in crawl spaces or unexcavated area located
within the periphery of the building foundation.
2. All wood framing members that rest on concrete or
masonry exterior foundation walls and are less than 8
inches (203 mm) from the exposed ground.

3. Sills and sleepers on a concrete or masonry slab that is in
direct contact with the ground unless separated from
such slab by an impervious moisture barrier.
4. The ends of wood girders entering exteriormasonry or concrete
walls having clearances of less than 0.5 inch (12.7
mm) on tops, sides and ends.
5. Wood siding, sheathing and wall framing on the exterior
of a building having a clearance of less than 6 inches (152
mm) from the ground.
6. Wood structural members supporting moisture-permeable
floors or roofs that are exposed to the weather, such
as concrete or masonry slabs, unless separated from such
floors or roofs by an impervious moisture barrier.
7. Wood furring strips or other wood framing members
attached directly to the interior of exterior masonry walls
or concrete walls below grade except where an approved
vapor retarder is applied between the wall and the furring
strips or framing members.

The first three pictures, if the OSB was underneath the sill plate I would agree with you A.D. Miller. But if you are correct, then the floor joists and rim joist would also need to be treated.

The last picture is just wrong per R319.4, #4, and the hanger isn't nailed off.

Originally Posted by Fred Weck

The first three pictures, if the OSB was underneath the sill plate I would agree with you A.D. Miller. But if you are correct, then the floor joists and rim joist would also need to be treated.

The last picture is just wrong per R319.4, #4, and the hanger isn't nailed off.

FW: Well, you cannot say I did not try.

Originally Posted by Fred Weck

The last picture is just wrong per R319.4, #4, and the hanger isn't nailed off.

Not only is the hanger not nailed off, but the joist does not even appear to be bearing on the hanger, it appears to have an air gap between the hanger and the joist, leaving the nails to hold the joist in position (that at 400 X zoom)

Regarding the OSB, installed on top of the sill plate, is not rated for the same loading as the joists. All shims must be of the same species, or stronger, than the wood bearing on the shim, and the shims are to be independently secured to the joists/rafters/trusses.

Originally Posted by Jerry Peck

Regarding the OSB, installed on top of the sill plate, is not rated for the same loading as the joists. All shims must be of the same species, or stronger, than the wood bearing on the shim, and the shims are to be independently secured to the joists/rafters/trusses.

If the OSB cannot support the same loading as the joists, then why do I see it under bearing walls?

For whatever reason the framer needed to raise the floor joists up, I would rather see this than small individually cut shims under each joist that would be suscetible to spliting.

If the OSB cannot support the same loading as the joists, then why do I see it under bearing walls?

FW: Did you absolutely HAVE to ask that?

Originally Posted by A.D. Miller

FW: Did you absolutely HAVE to ask that?

Am I picking at a scab?

Originally Posted by Matt Fellman

The OSB shims were around an entire perimeter of a 3300q house and many interior foundation walls as well.

A shim is used to adjust leveling. If you level the entire building by the same, 1/2" ?, you are back where you started.

Builder has used the OSB as a sill sealer.

I have no idea why. Sill sealer sells for pennies.

Originally Posted by Fred Weck

Am I picking at a scab?

FW: Not here, but you have just managed, I am nearly certain, to extenuate this thread ad infinitum . . . good call though.

Originally Posted by A.D. Miller

FW: Did you absolutely HAVE to ask that?

Man you guys build stuff funny down there.

Why DO you put OSB under bearing walls?

Sill Sealer is the foam under the sill plate, not the OSB.
The framer either built an interior bearing wall (or more) a 1/2 inch to high, or had a beam pocket that was a 1/2 inch to high, and decided it would be quicker to do this than to reconstruct the wall.

Originally Posted by archivoyeur

Man you guys build stuff funny down there.

Why DO you put OSB under bearing walls?

Peeper Boy: I did not say we did, but in fact, we often do. I am not now, never have been, and do not intend to become a fan of OSB. It's crap and should be outlawed or at least confined only to use in dog houses and FEMA trailers.

Originally Posted by A.D. Miller

I am not now, never have been, and do not intend to become a fan of OSB. It's crap and should be outlawed or at least confined only to use in dog houses

You must not like your dog, do you?

Originally Posted by Jerry Peck

You must not like your dog, do you?

JP: It's not that I dislike dogs. I do not have a dog and I do not like other peoples' dogs. The dogs themselves are OK. So then . . .

Originally Posted by A.D. Miller

Peeper Boy: I did not say we did, but in fact, we often do. I am not now, never have been, and do not intend to become a fan of OSB. It's crap and should be outlawed or at least confined only to use in dog houses and FEMA trailers.

You can say that again. Eternal Skeptic here.

Fred, Thank you for setting me straight on that point. The picture confused me momentarilly.

Speaking of funny ways to build things - A.D. have you seen ZipSystems Rim Board? Just makes me shake my head and walk away.

AND - engineered wood products turn out to be more expensive than the real thing up here.

Speaking of funny ways to build things - A.D. have you seen ZipSystems Rim Board? Just makes me shake my head and walk away.

Makes me cry . . .

AND - engineered wood products turn out to be more expensive than the real thing up here.

More expensive, not intuitively obvious installation instructions, not as durable - just really, really effing inexpensive to produce.

Originally Posted by Fred Weck

The last picture is just wrong per R319.4, #4, and the hanger isn't nailed off.

The guy's plain ol' got the wrong hanger.

The one shown here is not rated for nailer fastening, although there are plenty of hangers that can be fastened only at the top.

The inside dimension of a Simpson wood hanger is finished to the 1/8th", while 2x's are finished to the 1/4". That can sometimes lead a framer to want to notch a 2x that doesn't quite sit properly. Fight the force Luke

Thanks guys... JP - Some of the joists that go into the hangers are notched too.... That was the least of my concerns

As for the OSB under bearing walls, I'm thinking the point load of a 1.5" wide joist is much greater than a constant distribution of a base plate from a load bearing wall. I think OSB has no place in either application but under the joists seems worse.

And fwiw... the joists in question are spanning 14 feet or more which makes the load on that OSB all the more.

Originally Posted by Matt Fellman

And fwiw... the joists in question are spanning 14 feet or more which makes the load on that OSB all the more.

14 feet? I can't quite make out the stamp on those joists. Might not be a bad idea to check the span and spacing tables, just for giggles.

Let's say the joists are 16 feet long, 16" on center: 8' x 1.33' x 55# = 585# Weight on the 2 x 4 sill plate and OSB.
1.5" x 2" = 3" joist bearing area
585# / 3" = 195# / square inch
The American Plywood Association gives a design bearing stress for plywood and OSB of 360 psi http://www.apawood.org/pdfs/managed/...TOKEN=90099653

You may have to register to view the document.

Originally Posted by Fred Weck

The American Plywood Association gives a design bearing stress for plywood and OSB of 360 psi http://www.apawood.org/pdfs/managed/...TOKEN=90099653

Fred,

Read that document again.

Note that this area in the photo is not "dry-use", and that the other option is "wet-use" and under wet-use the OSB bearing is 1/5 or 0.2 of the dry-use factor, or 360 x 0.2 = 72 psi. Which is about 1/3 of your calculated bearing load.

Originally Posted by Jerry Peck

Fred,

Read that document again.

Note that this area in the photo is not "dry-use", and that the other option is "wet-use" and under wet-use the OSB bearing is 1/5 or 0.2 of the dry-use factor, or 360 x 0.2 = 72 psi. Which is about 1/3 of your calculated bearing load.

JP: I saw that coming . . .

Generally, dry use would be interior, wet use would be exterior. The insulation and wood looks dry to me, does it appear to have a moisture content of 16% or greater?

Originally Posted by Fred Weck

Generally, dry use would be interior, wet use would be exterior. The insulation and wood looks dry to me, does it appear to have a moisture content of 16% or greater?

That location is in a crawlspace, outside the thermal envelope of the conditioned space. That will vary in moisture content depending on the humidity in the air, hour to hour, day to day, month to month, which is likely why one part of it has already swelled up (see photo 3, it has done so big time already).

The question of whether the furring needed to be pressure treated was simple...No.
The discussion of wet or dry is, to me, irrelevant. OSB, as some of you noted, does not have the strength to support the load. Period. The framer should be shot; and, the jurisdictional inspector should be fired!

Fred look at the pictures, the OSB is doing what it pretty much always does when it is put under heavy load. The loaded are compresses, the adjacent area expands.
If I've seen it once I've seen it a thousand times on jobsites. OSB does NOT maintain it's thickness under heavy load. I call out any OSB like that every time. Give it a while the floors will be up and down 3/8".
Pathetic job.

The design compression perpendicular to the grain Fc┴ 0.04 for OSB and plywood is 360psi, the Fc┴ for SPF South is 335, western woods 335, northern species 350, northern white cedar 370, eastern softwoods 335, eastern white pine 350, cottonwood 320, Eastern hemlock - balsam fir 335, alaska spruce 330, hem-fir 405, redwood 425, western cedars 425, yellow poplar 420 (numbers are from the 2005 edition of the National Design Specification for Wood Construction).
The deformation you are seeing is pretty locallized between the joists and was probably caused by the impact of a hammer or board to the edge of the OSB, not from it squirting out from underneath the joist, the wood is not a balloon that will bulge in one place when squeezed in another, it will just crush.
No one has my original comment about it being under bearing walls. 99.9% of the wood frame buildings I have seen are platform framed, not balloon framed, which means the floor sheathing is underneath the walls.
Any swelling of OSB that you are seeing is from water not compression. I have seen plywood swell and delaminate as fast as, or faster, than OSB when it gets wet, and I have seen my share of rotten OSB as well.

Any swelling of OSB that you are seeing is from water not compression. I have seen plywood swell and delaminate as fast as, or faster, than OSB when it gets wet, and I have seen my share of rotten OSB as well.

Fred,

Would you write anything about this installation in your report if you were to see this while on a job?

Thanks.

No, no code has been violated. I might comment on the reason why I think it is there though.

Nice lab math but irrelevant in the real world.
Having rehabbed and built many platform homes I can tell you that that crap work won't fly on my jobsite. I use min. 2x6 or 8 wolm sill plates. Sill plates are leveled along the foundation wall with anchoring mortar underneath to fill gaps as needed, then joists are set on top of the sill plate, no OSB.
Your comment about platform construction is flawed. I believe what you are failing to grasp is the overall method and load concentrations.
In standard platform construction there would be a 2x4 base plate on top of the OSB or CDX subfloor thereby distributing the load across the OSB. In the pictures, the load is concentrated on those 1.5" spaces. That is why the OSB is compressing. Water may be a factor in this situation, I don't know. Once again from my experience OSB will compress like in the pictures with a concentrated load such as a joist.
Your last post is disturbing at the least. If you don't see anything wrong with that OSB the way it is, I suggest you spend more time on the board.
As I tell my clients, "The Code is not a ceiling to reach but a floor to work up from".

Originally Posted by Fred Weck

The design compression perpendicular to the grain Fc┴ 0.04 for OSB and plywood is 360psi, the Fc┴ for SPF South is 335, western woods 335, northern species 350, northern white cedar 370, eastern softwoods 335, eastern white pine 350, cottonwood 320, Eastern hemlock - balsam fir 335, alaska spruce 330, hem-fir 405, redwood 425, western cedars 425, yellow poplar 420 (numbers are from the 2005 edition of the National Design Specification for Wood Construction).

Fred,

And the correction factor for those "sawn lumber" woods is ... ?

The problem with you using your lab math IS IN NOT APPLYING the correction factors AS REQUIRED.

See my post above for those correction factors.

Now, tell us, what are the correction factors for sawn lumber in a not-do-dry (i.e., "not dry" = "wet") location ... oh, by the way, a crawlspace IS NOT considered a "dry" location. Sure, it "may be" dry some of the time, but it is not "dry" all the time, it depends on the weather, whereas OSB and plywood inside is protected from the whether, so your examples are not applicable.

Originally Posted by Fred Weck

No, no code has been violated.

The code HAS been violated as that is being used outside its design limits, as provided by you as stated by the manufacturer.

YOU provided the reference which showed that WAS NOT an acceptable use.

What are you now trying to convince us of? That you were wrong at first? Or that you are wrong now? Or that you were wrong both times - yeah, that's it.

What are you now trying to convince us of? That you were wrong at first? Or that you are wrong now? Or that you were wrong both times - yeah, that's it.

JP: Give the poor guy a break. At least he is consistent.

My, you all can get uppity, can't you?
I tried to post pictures of 2 pages from the NDS bu it didn't work.
The deformation for sawn lumber is the same 0.04. The wet service factor is 0.67.
I am still not buying that the crawlspace in the OP is a wet service condition. Where is Matt who was there?

And if someone could tell me how to post pictures here, I'll post the relevant pages.

Real world, these sub flooring materials disintegrate when wet and can compress under even the more widely distributed load upon a bottom plate in platform construction.

Here's an example where water from a leak at a roof-wall flashing ran down the interior of the wall, disintegrated the sub flooring, dropped the junction of two load bearing walls, and left the rafters in this area floating 3/16" above the top plate.

I am not arguing that OSB gets trashed when wet, I am just saying that this location does not appear to be a wet service location.

It may have happened at some point in the past but I do not recall seeing a 'dry' crawlspace during my many years of inspections. I'm sure there may be one out there, I just haven't seen it in Chicago.
Matt is in Oregon. Pacific northwest, lots of rain, dry crawlspace, I kind of doubt it. But hey what do I know.
Fred is in Minnesota, land of 10,000 lakes. You guys have dry crawls up there. I'd be surprised.
Remember Fred, not dry doesn't mean pools of water necessarily. Damp = not dry also.
You can post all the pics you want, the reality that you wouldn't report those pics as a problem in your report is the real issue. I suggest you really give some thought to how you do inspections and reports.
You don't work for a franchise and do checkbox by chance?

Markus,
I am a Building Official and work for a municipality. And Minnesota is one of those odd places where we actually have basements and crawlspaces that are built to keep water out of the home.

Originally Posted by Fred Weck

I am a Building Official and work for a municipality.

No wonder we see what we see wrong with construction.

The Building Official sees nothing wrong with a wrong installation.

And Minnesota is one of those odd places where we actually have basements and crawlspaces that are built to keep water out of the home.

It is one thing to build dry basements as that is not exposed to the weather.

It is another thing to build dry crawlspaces as they are exposed to the weather, unless, of course, they are sealed and insulated crawlspaces.

But that is not what is shown in that photo, is it?

Fred, know what helps keep home inspectors in business? Contractor doing what they do and Building Officials allowing it - when the code and the manufacturers do not "allow it".

I am a Building Official and work for a municipality.

FW: Advice: immediately don your best hard hat, turtle-neck waders (preferably Kevlar) and duck and run like hell. . .

Originally Posted by A.D. Miller

FW: Advice: immediately don your best hard hat, turtle-neck waders (preferably Kevlar) and duck and run like hell. . .

AD, I put my waders on as soon as the B.S. started getting deep.

I submitted a link to one of the pictures to APA for their opinion about OSB being used as a shim. I'll let you know what they say.

As for the wet service condition for the subject crawl space, we can just agree to disgree.

AD, I put my waders on as soon as the B.S. started getting deep.

FW: It started just as soon as the forum was up and running. Gets deeper with each passing day. I've only been posting here for about 2 or 3 years and my wader inseam has increaded from 32 to 145,206.

Originally Posted by Fred Weck

I submitted a link to one of the pictures to APA for their opinion about OSB being used as a shim. I'll let you know what they say.

"one" of the photos?

Which one? The one which shows the crawlspace vent below it?

As I said earlier, we can agree to disagree about whether it is a wet service location. This is what I sent:
Help Desk,
Is the use of OSB under a floor joist as shown in the picture in the link acceptable or not? And why or why not.
http://www.inspectionnews.net/home_inspection/attachments/structural-components-home-inspection-commercial-inspection/13419d1250221209-osb-shims-img_5262.jpg

Thank you for your help in advance.

Fred Weck
Building Official #MN1825

A Government worker, Imagine my lack of surprise.

I asked APA a similar question, only I linked to this photo: http://www.inspectionnews.net/home_i...s-img_5257.jpg

I wonder if we will get different answers back?

Originally Posted by Jerry Peck

I asked APA a similar question, only I linked to this photo: http://www.inspectionnews.net/home_i...s-img_5257.jpg

I wonder if we will get different answers back?

JP: If it is anything like the rake starter strip issue, we have heard the last news from them.

Originally Posted by A.D. Miller

JP: If it is anything like the rake starter strip issue, we have heard the last news from them.

Yes, I have followed up on that a couple of times to no avail, but this question was simpler, so there should not be any delay in answering.

This is the response I received:
I cannot access the picture without registering for the site, which I’m not inclined to do. However, plywood and OSB are suitable materials for shimming under framing members. The allowable design capacity for loads perpendicular to the face is 360 psi. Reference the attached document for details.[/font]
Regards,
Merritt Kline
Product Support Specialist
Wood Products Support Help Desk
APA
Southern Forest Products Association
253-620-7400 (phone
253-565-7265 (fax)
merritt.kline@apawood.org
APA - The Engineered Wood Association
www.SouthernPine.com

Neither, APA, the Southern Pine Council, nor their members make any warranty, expressed or implied, or assume any legal liability or responsibility for the use, application of, and/or reference to opinions, findings, conclusions, or recommendations included in this communication. Consult your local jurisdiction or design professional to assure compliance with code, construction, and performance requirements. Because APA, nor the Southern Pine Council have control over quality of workmanship or the conditions under which wood products are used, they cannot accept responsibility of product performance or designs as actually constructed.

The document that was attached was the one I linked to in an earlier post.
We can still disagree about the wet service condition.

Similar to my reply which is as follows (and to which I replied with the photos, and am awaiting that second clarification):

~~~~~~~~~~~~~~~~~~~~

I cannot access the image you reference, however, as you point out plywood and OSB are suitable materials for shimming under framing members. The allowable design capacity for loads perpendicular to the face is 360 psi.

Are the floor joists or other floor members considered to be in a wet use environment? If the floor framing and OSB shim are covered by an overhead weather barrier, and the sides and ends are not subject to direct wetting from precipitation APA would not consider the application exposed. In that case wet use adjustment is not necessary.

I hope this information will be of assistance to you. Please let us know if we can supply you with further information.

Regards,

Merritt Kline
Product Support Specialist
Wood Products Support Help Desk
APA
Southern Forest Products Association
253-620-7400 (phone)
253-565-7265 (fax)
merritt.kline@apawood.org
APA - The Engineered Wood Association
Southern Pine Council™ | 1-504-443-4464 | decking, docks, marinas, bridges, roofing, windows, lumber, treated wood and gardens

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

My reply back: blue text is where I inserted the photos as *photo #1 was attached here*

Merritt Kline,

Thank you for your response. If you are viewing this as text only, the photos will not show up.

The photo is here (I could not attach it to my previous inquiry from your web site): *photo #1 was attached here*

As you can see, the OSB is swelling in places.

In this particular installation the OSB is used as a continuous shim (for whatever reason is unknown) and is directly above various crawlspace vents, which appear to be allowing sufficient moisture into the crawlspace to affect the OSB’s integrity.

Below are two more photos, all depicting various amounts of swelling of the OSB, some near crawlspace vents, some not. Note that the OSB is being kept crushed down under the floor joists, and allowed to expand where there is no direct load on the OSB, which indicates (to me) that the OSB is not suitable for that location.

Do the photos provide any additional information?

Thank you,

Jerry Peck

Jerry Peck
Codeman
codeman@AskCodeMan.com
www.AskCodeMan.com

*photo #2 was attached here*
*photo #3 was attached here*
~~~~~~~~~~~~~~~~~~~~~~

Originally Posted by Fred Weck

My, you all can get uppity, can't you?
I tried to post pictures of 2 pages from the NDS bu it didn't work.
The deformation for sawn lumber is the same 0.04. The wet service factor is 0.67.
I am still not buying that the crawlspace in the OP is a wet service condition. Where is Matt who was there?

And if someone could tell me how to post pictures here, I'll post the relevant pages.

As far as crawl spaces around here go it wasn't particularly wet but that seems to be splitting hairs. A sill plate is to be PT lumber because of the damp location and propensity for insect damage. I find rotted rim joists and joist ends (where they bear on the sill) all the time. Putting OSB as a shim is just plain crazy.

Ask the tens of thousands of homeowners around here that had LP siding how good of a product OSB is. I'd bet none of them woudl accept it as a shim to hold up their house.

Damp, wet, dry... who cares? Bad idea all the way around. If anyone needs pictures emailed directly PM me or email me through my website.

Matt,

What did you write in your report?

I've been known to post a question on these forums, and then provide my clients with a link either in the report or in a separate e- mail......

From the report -

****All areas around the perimeter where there are not the metal brackets described below, wafer board has been used as a shim between the sill plate and the joists that are intended to bear upon it. This was also done throughout any interior foundation walls. Wafer board is not intended to be used in this application due to it’s tendency to compress and generally deteriorate. Although an overall failure of the floor system appears unlikely, it is quite possible that the joists could settle enough to cause cracking in the floors, door/windows to function poorly and other problems. Further contractor evaluation and repair is recommended.****




I just got copied on a letter from the contractor that came behind me and he agreed the OSB is wrong and is proposing installing posts/beams and footings just inside the foundation walls and elsewhere which seems like a good enough solution.

The funny thing is he disagreed about the Simpson brackets. He says they're okay.... I'm guessing he missed the fact that they aren't even attached to the sill in places... not to mention all the missing fasteners. Nobody's asking me for my opinion of his opinion and I'm not offering it up. I'm fine with it just going away.

It's an interesting debate anyway. I like what somebody said a few posts up about the code being a floor to start from rather than a ceiling to reach for. That's a great way to put it.

Thanks.