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Discussion Starter #1 (Edited)
Bleh. A 4.4 quake this morning opened up (or at least made me notice) a new crack in the kitchen that I'm none to pleased about. What do you make of it?

This is an opening through the center load bearing wall. The crack on the left happened in the 7.0, a new crack has opened up on the right spanning all the way from the corner of the opening to the closet door:

20190218_095403.jpg 20190218_095358.jpg 20190218_104249.jpg

I'm sure you can see why I'm fretting from the third picture there, that's a lot of gap even for a 40+ year old house isn't it? Thing is, lower down that wall and around it in general is pretty close to plumb so I'm not sure if it's just drywall bowing out or if the header is twisting or something. Some more pictures (this going to take two posts)

This is the inside of the opening closest to the crack, top of the opening, and from front to back on the opening:
20190218_104510.jpg 20190218_104449.jpg 20190218_095743.jpg

Continued...
 

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Discussion Starter #2 (Edited)
This is the wall on the opposite side of the crack:

20190218_100503.jpg

Inside the closet on the right side of the crack:

20190218_103936.jpg

And the far side of the opening from the crack; same "face" as the new crack and second pic is the opposite side of it:

20190218_104407.jpg 20190218_100410.jpg

I've checked the plumb all over along the rest of the wall and the entire wall is surprisingly close to plumb.


Full background for anyone who hadn't read it in my other posts: On November 30, 2018 we had a 7.0 earthquake, the epicenter was 10 miles from the house and only about 6 miles deep. Since then we've had thousands of after shocks, probably 30 or so above 4.0, and 20ish in the 5.0 range. These are hitting the house roughly back to front - perpendicular to the only load bearing interior wall; the wall in question which is located in the center of the house. The load bearing wall is about 28 feet long in total, 2x4 construction with studs 16" on center, there are 3 openings in it; a closet door that's 2' 5" wide, a kitchen opening that's 2' 7" wide, and an opening into the game room that's 4' 2" wide. I have a 4' wide by 7' tall commercial fridge roughly in the center of this load bearing wall and during the 7.0 quake the fridge punched the 3" PVC drain pipe from the upstairs bathrooms through the game room drywall [so I'm hyper sensitive about every little thing on this wall now heh)
 

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retired framer
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The beauty of wood constructions is that it can move with a shaker, at least that is what we were always told. The bad part of drywall is, it con only move in 2 directions and it will crack.
The problem with what you are looking at is what did it look like before or when it was new.
If you have a crawlspace or basement I would be checking the wall or beam below this to see if you have had some shifting.
I am not sure we have seen enough damage to loose a lot of sleep over.
 

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Discussion Starter #4
That's the unfortunate part, I can't say that I've ever measured that particular area for plumb. I know I checked plumb further down the wall to hang the cabinets and it didn't need an unusual number of shims.

I've checked the basement beam and all it's posts now, plus the upstairs hallway wall directly above this wall - it's all plumb-ish (the bubble was nearly all the way between the black lines everywhere I tested.)

I had previously noticed that the 2x6 beam in the basement isn't exactly the same thickness as the 4x4 posts so there's a slight inward bow on the metal brace plates (that's been there since before the quakes) I was thinking maybe it's the same kind of thing with the header beneath that drywall being a hair thin allowing the drywall to "cave in" a bit there in the rockin' and a rollin'.

I've added pulling down that section of drywall to check plumb on the actual header to the do-to list. We've got quite a bit to do before we could get to it, a couple weeks at least. Unless ya'll think it needs to be bumped up the list anyway.
 

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retired framer
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That's the unfortunate part, I can't say that I've ever measured that particular area for plumb. I know I checked plumb further down the wall to hang the cabinets and it didn't need an unusual number of shims.

I've checked the basement beam and all it's posts now, plus the upstairs hallway wall directly above this wall - it's all plumb-ish (the bubble was nearly all the way between the black lines everywhere I tested.)

I had previously noticed that the 2x6 beam in the basement isn't exactly the same thickness as the 4x4 posts so there's a slight inward bow on the metal brace plates (that's been there since before the quakes) I was thinking maybe it's the same kind of thing with the header beneath that drywall being a hair thin allowing the drywall to "cave in" a bit there in the rockin' and a rollin'.

I've added pulling down that section of drywall to check plumb on the actual header to the do-to list. We've got quite a bit to do before we could get to it, a couple weeks at least. Unless ya'll think it needs to be bumped up the list anyway.
Often the header is not as thick as the wall and usually there is a 2x4 sill at the bottom to correct that for the drywall.
In the one picture you checked the bottom of the beam, that area is often not level and if it has moved you would see some distortion at the corner where the studs are. I don't think this has much to find if you open it up.


If this is the same wall as with the fridge problem and if you did open it I would make the whole wall a stress wall.
A stress wall has plywood or OSB behind the drywall with a very specific nailing pattern and has flat straps that goes thru the floor and ceiling to join everything together as one.


The need for that might be directly related to the amount of panic you are experiencing. :devil3:
 

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Just a thought...Couldn't you just call your insurance company for this? I guess it depends on your deductible, but this way they get a structural engineer involved, and would fix everything. I am all for DIY, but sometimes...
 

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Discussion Starter #7 (Edited)
Just a thought...Couldn't you just call your insurance company for this? I guess it depends on your deductible, but this way they get a structural engineer involved, and would fix everything. I am all for DIY, but sometimes...
Wouldn't be covered, not even rich people or businesses can afford earthquake insurance in Alaska. :vs_laugh: True story, our McDonald's is still closed down from damages.


@Nealtw

I'm hyper-sensitive for sure, though not especially panick'ed, after all the house made it through the 7.0 that took out hundreds of other houses and buildings in town here, they even say it hit buildings under 2 stories the hardest in general - this is all more of a better safe than sorry since we know that there's going to be more aftershocks, and since we've got to make repairs anyway.

I have been seriously considering the sheer wall idea; we have damages to repair and/or remodeling to do along both sides of this entire wall which makes putting up plywood backing a relatively minor inconvienience, it's the straps into the floor and ceiling I'm not so sure about. I'm already pushing my luck with my husband to replace all the sub-floor upstairs, basically only convinced him to do it because we can get into the ceiling downstairs to do some other projects. I think he'd bulk at pulling up all the sub-floor downstairs too. (I do almost have him convinced to put in another post in the basement for the fridge weight though :p)

Edit: not sure if I mentioned it in other threads, but we did have a city structural engineer out last month as part of the state/federal emergency aid program whatever. He checked the basement and said everything looks good.
 

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Discussion Starter #10
@Mystriss The straps I have installed are these, you cut a slot thru the floor and nail then to a stud with a block beside it above and below the floor.


Slots would be pretty easy since most of it's in the kitchen and we're planning to put in new flooring in all the other rooms anyway. I'll run it by my husband.
 

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I don't see why not.


I would have an engineer go over everything, they all seam to have a different idea of what works best.

I agree with this^^^ strongly! In a case where your house is literally on the line here and no insurance to cover it, you really need things examined. Do NOT call on a builder, framer, etc, you need what is called a residential structural P.E. that is doing seismic assessments. What people fail to understand is you don't need that engineer to fix anything, but you really need them to look at the structure of the home before giving advice. I work in structural engineering but probably not as competent in seismic work as guys right in the thick of it.


Pinning the columns under the home (assuming crawl space?) won't do much for you in the way of structural improvements. Those are purely to relieve the bending moments in the floor joists and reduce "creep" (floor gets a dip in it over time).

You would want to focus on the "box" or perimeter of the home and improve shear stiffness. You need to ensure the concrete you are attached to has rebar and you attach in such a way that you can take advantage of it. I think I explained this before somewhere but concrete by itself can only handle about 1/10th of its compression force in tension. That is what the rebar does. When a structure moves due to seismic activity, the foundation will cycle from compression to tension many times. You just want to make sure you get the concrete connection that you need.

Personally, knowing that you have serious seismic activity and cannot even get insurance, I would be taking it very serious and my personal approach might include steel pretensioned straps or rods throughout the home. Steel is just much more efficient for such violent events and will take immense tension. The reason I say "pretension" is I would be adding some way (threads) to tension things so if a bad quake hits, they can be checked and adjusted.

The wooden panels on the home act as a diaphragm but what might have been a good design back then may have been butched by cheap labor. It ultimately comes down to the guy with the hammer! One the cheapest and easiest things you can do IMO is add nails!!!!! And I mean lots of them.

These are things your engineer can review and they may have some other ideas. Its going to be easier to beef it up now than figure out how to fix it later.
 

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Any building must have a reference points and standards. Your wall is heavily textured and you can't use the wall to get the "first" measurements. Also there is absolutely no house (excluding multi million/billion dollar structures) or general building that will withstand things like earthquake. So if you hear on the radio that your quake was 4.4 or 7.7, where was the epicenter, shallow/deep, etc, so that what you hear about the quake is, basically, meaningless. The question important to you is what happened to your house. A good perspective is a factor, as nealtw says, wood building can move with the quake. My monkey wrench to that perspective is that flexibility is its weakness as well.:smile: You can and should add reinforcements, if none, but that does not mean you will have a house that sees no damage at all. Reinforcements are basically to give you enough time to get away.

To compare, you need a detail of what you have and what else happened after. Since this is the first time you noticed, you need to get details on your house. To get the details, you need a reference point. This is similar to measuring your property.

A level is no good since your wall may/may not be good places to rest the level. In past posts, when somebody wanted to know the progress of damage or movement, usual answers were to establish a point and measure time to time. Since level may be deceptive, you want to use the gravity or relatively immoveable point. A hung string with weight. A point on a slab. These points can move, but for a house, about as good as they can get.



About the engineer vs carpenter. I guess the final word would be the engineer's. That is because engineers have more knowledge and their education is standardized. Experienced carpenter can give you all the info you need as well as a lot cheaper, but a carpenter may/may not be good. Your house is built with past knowledge that's built on past standards. That means a house is not that special structure. Again, nealtw posts some reinforcements you can use. Meaning the knowledge is already free on the net.



I know that my post here is not a specific help but I needed to disagree that any carpenter is no good.:smile:
BTW, now you know that your walls are not flat. Using the level, now you know how much gap there is at some areas. Write this down and measure again next quake. If the gap is plus/minus 1/8", you can assume the quake didn't have much effect.
 

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Discussion Starter #15
@viper

For the record, it's really not that big a deal for us not to have earthquake insurance. Insurance is for people who don't have the cash/savings to fix their house/car/health in the event of an emergency. If the house has any serious damage from future aftershocks we'll just pay out of pocket to fix it instead of having insurance pay to fix it. Ironically, it'd probably actually /save/ us money if it collapsed right now because we could build from scratch rather than paying through the nose for what amounts to three separate additions :vs_laugh:

All the "damages" we sustained in the Nov quake were cosmetic - cracked drywall. I just happened to have noticed this one after the latest quake. I've been "monitoring" the other cracks and there's no changes to any of them, nor were there any other new ones. The structural engineer that was out here last month as part of the state/federal emergency declaration inspections said everything here was fine. (Except for a largely unrelated to the quake spot under the front porch that showed evidence of water penetration, which we'll be fixing [almost accidentally] with our addition(s) - exterior water barrier and a full length french drain across the front of the house to deal with the neighborhood's melt water that all comes straight down our driveway.)

I think the basement here is classified as a crawl space. It's 6' tall but I think you have to have 8' for it to be an "unfinished basement" classification. Whatever it is we have a full cinder block perimeter that's fully back-filled on the exterior. The center beam is on the 4x4 posts on cement tube footings. Looks like this:
20190123_070816.jpg
The span is under 30' total and there's two more 4x4 posts to the right and one more to the left of the wider spacing shown in the picture.

The guy who built the house (and lived in it with his family until 2000) ran a well reputed construction company up here until retirement so I assume he followed some measure of the muni building codes, which are some of the strictest in the nation when it comes to seismic's (due to the 8.0 in 1969.) In any event, all the engineers and inspectors we have had come in since we bought it almost 20 years ago have not found any issues with the bones of the place.

We have a family friend who was an Army, then later, state structural engineer for 30 years who had checked it off as good to go when we bought it - and I'd argue he was right, we've never had any issues with the bones, despite all the quakes big and small. He is coming up here to visit family in a few months so I'll have a chat with him about the sheer wall thing. I was pondering a steel sheer wall thing I was reading about online; it's apparently better in a quake and provides more structural support. I wouldn't mind re-vamping the center wall on the first floor to steel studs and plate provided it's not too much of a PITA to attach our kitchen cabinets to it. I'm not sure how to attach anything to metal.
 
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