I've seen it done. While I'm not an engineer I think the explanation is that "wood" sheathing would add little to the structural integrity of the house in the areas the foam board is used. The structure needs wood sheathing in the corners and other areas, not in the middle of walls.

That would not meet the local building codes. I've built houses that were done with OSB used as sheathing, then the rigid foam and vinyl siding. Those houses are now almost 20 years old and still doing just fine.

There are several reasons for the sheathing. Frame stiffening, siding base, insulation, and fire break are the main ones.

Yes it is and was a normal construction practice, for that period.
Design criteria are a "developed" science and are adjusted as events occur which cause those specific elements of those criteria to be shown as deficient, to ensure safety.

As an example, both residential as well as commercial design criteria for Oklahoma will be substantially changed.

Thanks to all that responded. It is good to get informed feedback. Now I must decide what to do to stiffen up the frame, so the house does not shake in the wind and maybe that will put an end to these nail pops and drywall seams.

I can tackle it from the outside or inside. One idea I had is to get someone to tear off all the siding and foam board, and nail up wood sheathing and then put new rigid insulation on top. This would be a waste if it does not make the house more solid.

The alternative is to open up drywall at key points and put in horizontal wood bracing between the joists. I doubt there is much or any of that now.

Please weigh-in with your judgments.

This house has those complex prefabricated attic rafters that are supposed to mean no interior walls are load-bearing. It has a very open first floor, with the dining and living room sharing a cathedral ceiling. There is no pattern to the drywall cracks and seams that I can discern. I'd say that the interior walls have it worse than the exterior walls. The floors are all pretty creaky now, worse than when we moved in about 5 years ago. Foundation is fine.

Thanks again. I've been pretty stressed out over this and it helps to "talk" it over.

While I agree that building practices and code change as time go's by,sheathing was required long before 1990. But that is not the question here. Sheathing adds 10 fold the streanth that foam board and vinyl siding combined does. This was not oversite,it was a scamm perpitrated by the builder. Were I in your position,I would be talking to a realeastate attorney. There is a chance you might have recourse if the origional or subisent loan including yours was government backed such as FHA,VA,HUD ect. The builder and an inspector sighned a sworn statment that everything met FHA requirments as each phase of construction was complete and another draw was made against the loan. Similar affidavates attesting to proper construction were sighned every time a new loan was origionated. You would probly not be on the hook for attorney fees beound initial title search(refundable when case settles) at which point the case would be handed off to a government attorney. Do yourself a favor by at least going to a title company and talking to them. Man I don't blame you for being uptight over this but there might be light at the end of the tunnel. There is no way in h&ll the house has gone through 4 transactions without lies told and now it's time the liers face the music.

In many locations, even in seismic or high winds, the only actual sheathing that's required are at a building's corners, and around windows and doors. On many homes though, by the time you've done that, you're only 10 sheets of OSB from sheathing the whole thing. Unless you're a tract home builder going for volume profits , adding in those 10 sheets and the labor to install them doesn't add $500 to the total. Which you then charge an extra 1K to the client and don't lose any money at all.

You are certainly free to follow the logic of klem 1.
However, before you jump on the "legal" bandwagon, obtain a copy of the permitted plans for your dwelling and from there the fun begins.
You can remove either the exterior or interior wall surface to determine if the called out framing elements exist, on the schedule for them states.

Structural resistance to lateral forces are "fondly" referred to as "shear," and can be achieved in several ways when applied, either singly or in conjunction, to the interior surface of exterior walls, as well as the exterior.

Any or all of the following can be the case in your dwelling. All of which can be verified by xray.

Drywall can be thicker, doubled and shear nailed.
Shear panel, "X" metal straps, single "L" diagonal metal strap or diagonal let-in bracing, all have a prescribed nailing schedule.
There is also blocking required near doors and windows.

Before you embark on such an endeavor, you would be well advised to determine if the builder, engineer and any of the tradesmen involved, are still above ground, and lucid.

You see, municipalities have some immunity.

Please post back how you make out. I've had the same GC do several decent size projects here, and we are pretty certain my home was part of a big scandal in this area at the time with rampant bribery and paid off inspectors.

Our house was built in 1988/89. We had particleboard on the outside of the frame, then regular vinyl siding. No insulation, no Tyvek, no flashing. What a mess! It's now properly wrapped and we put up insulated siding. Huge difference! Plus a list of other problems. It took a whole day to figure out how the electrical was run during our recent kitchen remodel, it made no sense. And we had a bonus, unlabeled, live lead taped off with just a ton of tape, just dangling in the wall behind our range. What kind of jacka$$ does that?!

I'm interested to hear how things go for you.

In '89 the metal diagonal bracing that was let in to a 1/2" deep saw kerf was all the rage because it was now possible to have rack bracing quickly (no 1x6's to let in laboriously) and be able to sheath entirely with insulation board (celotex,R-max, etc). Then a year later the metal stuff was gone. Apparently too many structural failures, or maybe testing revealed it was of no value. So back to plywood at the corners, or let-in 1x6's.
I'd be interested to hear if it is still in use in some jurisdictions, or if they improved the design or application technique.
Casey

In most jurisdictions code compliant lateral bracing can be provided by continuous structural sheathing, structural sheathing at the corners, or diagonal bracing. The larger the house and the greater the lateral forces, the stronger the required bracing. You haven't told us enough to know if your house is compliant.

I was appalled to learn of this while an outside salesman in the Pittsburgh area in the late 80's/early 90's.
Not on my house, it got sheathed in OSB.

"The alternative is to open up drywall at key points and put in horizontal wood bracing between the joists."

This makes no sense at all. You are in way over your head. Find a local person who knows how a building should be braced to resist wind loads and stop guessing or relying on people on the internet who have not seen the building.

If you start tearing off exterior finishes the first thing to do is add vertical sheets of plywood or OSB starting at the corners and nail them 6" o.c. with 8d ringshank nails. That will also work on the inside as long as it doesn't disrupt the movement of moisture through the wall. I don't know where the house is located so I can't comment on that issue.

If a building permit is required you must show what you intend to do and that it meets the current building code.

Never guess when you can know.

"If you start tearing off exterior finishes the first thing to do is add vertical sheets of plywood or OSB starting at the corners and nail them 6" o.c. with 8d ringshank nails."

Thanks. Yes this will be the first thing I do. There is OSB on some of the frame, I am not sure if they did not nail it properly, of perhaps skipped some corners or what. Any reason I could not use screws instead of nails? I know nails are stronger, but I suspect all the hammering might cause even more drywall nail pops.

"That will also work on the inside as long as it doesn't disrupt the movement of moisture through the wall. I don't know where the house is located so I can't comment on that issue."

I am close to the East coast. Humid summers and cold winters.

You can rent/purchase a nematic nailer or an airless model.
Cheaper when you value your time.

You can use a deck screw, but not a drywall screw, which are brittle. Either of which are expensive.

"You can rent/purchase a nematic nailer or an airless model.
Cheaper when you value your time.
You can use a deck screw, but not a drywall screw, which are brittle. Either of which are expensive."

Good advice. Thank you.

screws have more holding strength than nails.

in new construction the technique you describe isn't
unusual. corners are solid sheated with osb or plywood,
foam sheathing to add insulation value & air sealing
properties to walls.
we do this in my hurricane area.
although some opt to solid sheet walls with plywood
and foam sheating over. or to solid sheet the interior.
either way...sheeting to exterior or interior of walls
adds strength to walls.

I think you are in over your head with what you
propose to do. if there have been no problems with
your home...why are you 'improving' the walls?
or is there some issue that you are having?

best of luck.