Severe WX December 10 & 11, 2021 Severe Threat

[buckeye05]

I really do think that the tornado reached EF5 strength in Bremen, I just don’t think there’s any structural damage there though that quite meets the criteria though. The home pictured above, even if well built, isn’t what I’d call swept clean. The ones that were swept away appeared to have weak foundations. It’s frustrating, as the contextual damage in that area paints a pretty clear picture imo.

 

[TH2002]

The church in Earlington was a frail-looking structure that seemed to be constructed similarly to a garage.

I will admit that the 2008 street view shows a frail, shed-looking structure. However it is clear that a lot of modification was done to the building between 2008 and 2021, as you can tell by the part of the foundation that is lighter and was therefore poured much more recently. It also seems the parking lot was new.


Now, I'm curious if there are any ground level photos of the structure before the tornado (but after the modifications were done) and after the tornado. What construction methods were used would also be tremendously helpful to know, including but not limited to if any anchoring was used. It is possible that the structural additions may have not had much effect on the building's structural integrity, or even compromised it. I'm no construction expert so it would be interesting to get someone like @Sawmaster's input.

Of course, it would be foolish to say this structure is a no-brainer EF5 candidate based on anchoring alone, even if it was well anchored. That would be like saying the slabbed pole barn in Cayce constituted solid EF5 damage, but I have wondered about this structure for a good while now.

 

[Shakespeare 2016]

I will admit that the 2008 street view shows a frail, shed-looking structure. However it is clear that a lot of modification was done to the building between 2008 and 2021, as you can tell by the part of the foundation that is lighter and was therefore poured much more recently. It also seems the parking lot was new.
View attachment 14161

Now, I'm curious if there are any ground level photos of the structure before the tornado (but after the modifications were done) and after the tornado. What construction methods were used would also be tremendously helpful to know, including but not limited to if any anchoring was used. It is possible that the structural additions may have not had much effect on the building's structural integrity, or even compromised it. I'm no construction expert so it would be interesting to get someone like @Sawmaster's input.

Of course, it would be foolish to say this structure is a no-brainer EF5 candidate based on anchoring alone, even if it was well anchored. That would be like saying the slabbed pole barn in Cayce constituted solid EF5 damage, but I have wondered about this structure for a good while now.

The context behind the building may be stronger but based upon the building damage it was maybe low-end EF3 damage from what you seem to be saying.

 

[Austin Dawg]

For Bremen, most likely the strongest part of entire path. The tornado probably didn't swept away other well built house other than the 190mph rating hoise. But I noticed that some extent of back convergence treefall pattern in certain places. It has already been proved that only really high end tornados can do back convergence treefall pattern in some researchs, especially for fast moving tornados. And I only noticed a few cases in reality includes Smithville, Hackleburg and Bassfield.
View attachment 14152
View attachment 14155
I didn't notice this kind of treefall pattern in any other part of its path.
View attachment 14153View attachment 14154
The most perfect example of back convergence

Sometimes you have to admit this tornado is in its own league.
Recommend to read:https://www.mdpi.com/1999-4907/12/1/17/htm

I think I understand that this is talking about the forest damage with the Smithville F5? One of the things I wish I could have let you guys see was the beginning of the forest land where the tornado exited town on the Northern side at the county line. It was a remarkable sight even from the highway two years after the event. Was mature, thickly matured land and it was as if you took a giant push mower and started a perfectly cut swath where it had a hard edge at the sides and on the bottom.

 

[CLP80]

I tried searching this thread to see if anyone had posted these pictures, but I didn't find anything. This is from the real estate listing of one of the homes in Cambridge Shores that was totally leveled. The house was built in 2004, and from the pictures, seemed to be as high quality as you will find any home in the US. You can also see a glimpse of the house next door, which also looked to be a nice home.






Below is from the drone footage taken the day after the tornadoes and I circled this house's location in the red. The house next door was completely slabbed, but it appears the subfloor was left behind. The damage to the trees in that area is also extremely impressive. EF4 or EF5, there's no doubt that this is some of the most high-end damage that you'll see from a tornado!

 

[tornado examiner]

the only thing not impressive in that area is scouring....by that i mean, there's almost none of it. which is understandable since those are front lawns and not some field.

 

[CLP80]

Yeah, the one particular house does still have an extremely green lawn. I have noticed that from the drone footage that there seems to be a very noticeable difference in color between the two sides of the neighborhood. From my understanding, most of these homes are second homes (the second home in the edge of the photo is owned by a state politician I believe even) - so that also explains the reason that you don't see many damaged vehicles. That entire area has lots of rolling hills, so I wonder what kind of effect that would have on ground level winds compared to the extremely flat areas you find in the plains.

 

[pohnpei]

I tried searching this thread to see if anyone had posted these pictures, but I didn't find anything. This is from the real estate listing of one of the homes in Cambridge Shores that was totally leveled. The house was built in 2004, and from the pictures, seemed to be as high quality as you will find any home in the US. You can also see a glimpse of the house next door, which also looked to be a nice home.

View attachment 14203 View attachment 14204


View attachment 14207

Below is from the drone footage taken the day after the tornadoes and I circled this house's location in the red. The house next door was completely slabbed, but it appears the subfloor was left behind. The damage to the trees in that area is also extremely impressive. EF4 or EF5, there's no doubt that this is some of the most high-end damage that you'll see from a tornado!

View attachment 14205
View attachment 14206

The house was nice and damage was impressive but the anchorage system seems questionable at least.

 

[CLP80]

Well, you can't see the anchoring (if any) since the subfloor is covering it. It seems that any newer home, with a basement, has a subfloor like this - and obviously the walls will shear off at the weakest link (the nailed connections). I'm sure it's happened somewhere, but are there examples of homes, with a basement and anchored sub-flooring, that the subfloor was also removed?

I feel that once the house is sheared away from the subfloor, if the subfloor is actually bolted into the concrete slab of the basement, that it would take an *extremely* powerful EF5 to remove that. We've seen examples of tornadoes moving concrete parking stops, but I would have to think a subfloor would be far more difficult for even an EF5 to remove (assuming it's bolted properly).

One more thing to note is that this home actually seems to be on the very edge of the damage path. I would have to think that the homes a few lots over experienced even higher winds?

 

[Sawmaster]

The house was nice and damage was impressive but the anchorage system seems questionable at least.

I've built plenty of similar homes and they're not any better for strength than anything else, only more carefully crafted. A lot of what seems big and impressive about them is more aesthetic than substantial. The main reason they cost so much is that the premiun materials used for what you see costs a lot more, but underneath them is a normal wood-framed home "built to code" which means a minimum standard. And with most of them the 'open floor plan' means a weaker structure than the average single-story "ranch" style home built on a slab.

On the subfloor being bolted or strapped with the walls being nailed down, well it "meets the letter" of building codes, but not necessarily the intent. We all see the results of that constantly. With these, the straps or bolts only act to prevent "sliders" where a house is shifted off it's foundation more or less intact. The 'plywood' flooring is held down with the same nails used to nail roof sheathing on, yet we constantly see sheets blown off of roofs. The difference here is that pressure building inside a house from the wind entering pushes this down while it pushes the roof up, and that is why we see flooring systems left intact with the rest gone. This also presents less surface directly to winds, which blow across it and not against it. Much better could be done, but it isn't because it's not required by code and like the fancy houses I spoke of above, people don't want to spend on what they can't see and you can't convince them of the merits- especially when the next builder (and the next) will tell them "It's not necessary or it would be code required" which is BS but that's how things are in the world I operate in.

Phil

 

[TH2002]

Well, you can't see the anchoring (if any) since the subfloor is covering it. It seems that any newer home, with a basement, has a subfloor like this - and obviously the walls will shear off at the weakest link (the nailed connections). I'm sure it's happened somewhere, but are there examples of homes, with a basement and anchored sub-flooring, that the subfloor was also removed?

I feel that once the house is sheared away from the subfloor, if the subfloor is actually bolted into the concrete slab of the basement, that it would take an *extremely* powerful EF5 to remove that. We've seen examples of tornadoes moving concrete parking stops, but I would have to think a subfloor would be far more difficult for even an EF5 to remove (assuming it's bolted properly).

One more thing to note is that this home actually seems to be on the very edge of the damage path. I would have to think that the homes a few lots over experienced even higher winds?

Multiple homes in Cambridge Shores did lose their subflooring, but the most "by-the-book" example I can think of is Chapman, KS 2016:

 

[tornado examiner]

my only question is why aren't anchor bolt mandatory in the united states?

 

[TH2002]

my only question is why aren't anchor bolt mandatory in the united states?

@Sawmaster would probably be able to answer this question better than me, but I do know that in my state (California) and Washington, anchor bolts ARE mandatory for earthquakes. There are probably other states too, but I guess there's the argument that "contractors have the right to build as shoddy houses as they please" then be shocked when an EF2 throws the damn thing into a treeline resulting in inevitable deaths and/or gruesome injuries.

Anyways, sorry if that came off as a little insensitive, but the quality of construction of many US homes is quite... sad. Even California and Washington are no exceptions to that, as it doesn't take too much driving to encounter an unreinforced masonry structure or the like that would stand absolutely no chance against even a moderately strong quake.

edit: In the first part of my post, I was referring to the contractors who build those shoddy homes, not the poor folks who end up living in them. Like Sawmaster said in reference to the Andover tornado, it makes me want to do some "tornado damage" to the builders' head.

 

[MNTornadoGuy]

Well, you can't see the anchoring (if any) since the subfloor is covering it. It seems that any newer home, with a basement, has a subfloor like this - and obviously the walls will shear off at the weakest link (the nailed connections). I'm sure it's happened somewhere, but are there examples of homes, with a basement and anchored sub-flooring, that the subfloor was also removed?

I feel that once the house is sheared away from the subfloor, if the subfloor is actually bolted into the concrete slab of the basement, that it would take an *extremely* powerful EF5 to remove that. We've seen examples of tornadoes moving concrete parking stops, but I would have to think a subfloor would be far more difficult for even an EF5 to remove (assuming it's bolted properly).

One more thing to note is that this home actually seems to be on the very edge of the damage path. I would have to think that the homes a few lots over experienced even higher winds?

Almost all EF5s remove subflooring from homes. It is one reason why Washington wasn’t rated EF5 as it didn’t sweep away the subflooring.

 

[locomusic01]

I've built plenty of similar homes and they're not any better for strength than anything else, only more carefully crafted. A lot of what seems big and impressive about them is more aesthetic than substantial. The main reason they cost so much is that the premiun materials used for what you see costs a lot more, but underneath them is a normal wood-framed home "built to code" which means a minimum standard. And with most of them the 'open floor plan' means a weaker structure than the average single-story "ranch" style home built on a slab.

On the subfloor being bolted or strapped with the walls being nailed down, well it "meets the letter" of building codes, but not necessarily the intent. We all see the results of that constantly. With these, the straps or bolts only act to prevent "sliders" where a house is shifted off it's foundation more or less intact. The 'plywood' flooring is held down with the same nails used to nail roof sheathing on, yet we constantly see sheets blown off of roofs. The difference here is that pressure building inside a house from the wind entering pushes this down while it pushes the roof up, and that is why we see flooring systems left intact with the rest gone. This also presents less surface directly to winds, which blow across it and not against it. Much better could be done, but it isn't because it's not required by code and like the fancy houses I spoke of above, people don't want to spend on what they can't see and you can't convince them of the merits- especially when the next builder (and the next) will tell them "It's not necessary or it would be code required" which is BS but that's how things are in the world I operate in.

Phil

100%. And even in cases where proper anchoring is required and where the homeowner thinks that's what they're getting, that doesn't necessarily mean they will. I remember watching a presentation Tim Marshall did (I think?) a while back after Moore 2013; he checked on some of the homes that were being rebuilt (ostensibly to code and well-anchored) and there were still the same issues as before - nails instead of anchor bolts, bolts spaced far too widely, no washers, etc.

It's crazy, but not really surprising unfortunately. And that's in probably the most tornado-prone place on Earth.

 

[buckeye05]

Well, you can't see the anchoring (if any) since the subfloor is covering it. It seems that any newer home, with a basement, has a subfloor like this - and obviously the walls will shear off at the weakest link (the nailed connections). I'm sure it's happened somewhere, but are there examples of homes, with a basement and anchored sub-flooring, that the subfloor was also removed?

I feel that once the house is sheared away from the subfloor, if the subfloor is actually bolted into the concrete slab of the basement, that it would take an *extremely* powerful EF5 to remove that. We've seen examples of tornadoes moving concrete parking stops, but I would have to think a subfloor would be far more difficult for even an EF5 to remove (assuming it's bolted properly).

One more thing to note is that this home actually seems to be on the very edge of the damage path. I would have to think that the homes a few lots over experienced even higher winds?

Tornadoes remove anchored subflooring from homes in the US on pretty much a yearly basis, and they certainly aren’t all EF5s.

 

[CLP80]

Tornadoes remove anchored subflooring from homes in the US on pretty much a yearly basis, and they certainly aren’t all EF5s.

I'm sure I have seen those situations, but just not realized it since there's no subflooring left behind! I do have to ask though, if tornadoes are leveling brick homes like this one pictured above on a yearly basis, and they're also removing the anchored subfloor (from a poured concrete foundation) in the process - then what more is needed to rate that as EF-5 damage? Tree debarking, ground scouring, and things of that nature? Aren't the upper bound winds for that particular DI well into EF-5 range at that point?

Is the subfloor such as the one in the picture above built using the same typical construction as they have been for decades (where the subfloor is , or have construction methods for those changed in the last 15-20 years? Just curious because that subfloor above looks like they build a "box" on top of the basement foundation, anchor the "box" to the foundation, and then nail the frame/studs to the top of that.

Someone mentioned the Washington tornado as having a lot of homes with this same issue, and from looking at a lot of those homes, it seems that they were also built around the same time period as some of these in Cambridge Shores.

 

[MNTornadoGuy]

I'm sure I have seen those situations, but just not realized it since there's no subflooring left behind! I do have to ask though, if tornadoes are leveling brick homes like this one pictured above on a yearly basis, and they're also removing the anchored subfloor (from a poured concrete foundation) in the process - then what more is needed to rate that as EF-5 damage? Tree debarking, ground scouring, and things of that nature? Aren't the upper bound winds for that particular DI well into EF-5 range at that point?

Is the subfloor such as the one in the picture above built using the same typical construction as they have been for decades (where the subfloor is , or have construction methods for those changed in the last 15-20 years? Just curious because that subfloor above looks like they build a "box" on top of the basement foundation, anchor the "box" to the foundation, and then nail the frame/studs to the top of that.

Someone mentioned the Washington tornado as having a lot of homes with this same issue, and from looking at a lot of those homes, it seems that they were also built around the same time period as some of these in Cambridge Shores.

A well-constructed and well-anchored (preferably a concrete slab foundation with anchor bolts and toenailed) house needs to be completely swept away with high-end contextual damage such as debris granulation, tree debarking, ground scouring, and stripping of shrubbery.

 

[Lake Martin EF4]

A well-constructed and well-anchored (preferably a concrete slab foundation with anchor bolts and toenailed) house needs to be completely swept away with high-end contextual damage such as debris granulation, tree debarking, ground scouring, and stripping of shrubbery.

No, the trees need to be granulated too. If the trees didn't need to be granulated, instead of whining over the fact that Mayfield was EF4, you would be looking back on the tornado that ended the EF5 drought.

 

[CLP80]

Do survey teams typically make note of the anchor bolt sizes when surveying home damage? I know that I have seen some detailed engineering post analyses of storms that look at this stuff after the surveying has been done, but I wouldn't imagine NWS survey teams looking this close at the details for each home.

I've seen anywhere from 3/8" diameter to 1" diameter being typical, with 1/2" being most common. I think that just even comparing one house that has 1/2" bolts next-door to another home with a 3/4" bolt diameter (increasing the width of your shearing face by 1/2" total) could result in pretty significant differences in the amount of shear that a piece of lumber is seeing from its particular anchor bolt. Obviously, the larger the anchor bolt diameter, the lower the shear in the frame.

I suppose that because of all these types of variables, this is why they also need to see the wide variety of contextual damage around the home as well.