Does Putting Tornado Shelter in Garage Floor Compromise Slab? (Dallas: houses, construction)

[Ghengis]

Originally Posted by TGentry

We are considering installing a tornado shelter in the ground below the garage floor slab. They will remove a section of the concrete and install it below ground.

Someone told me that this will compromise the post-tension support (or what-ever it is) of the slab. I mentioned that to one installation company rep, and he hemmed and hawed and finally said the way they do it, the slab will be fine.

Any thoughts? Thanks.

any reason to think that you do have a post-tension garage floor slab?

there's typically a prominent stamp in the concrete identifying it as such.

even if it were PT, they cut and core drill thru these slabs all the time but would x-ray the slab to see where the cables are.

if your storm shelter does nothing else but function as a root-cellar, the peace-of-mind you place in it is money well spent

[SouthernBelleInUtah]

There is a TON of new construction all over the northern area. I have seen lots of pours and the garage IS always part of the main slab. It's under the main roof so it has to be on the main slab.

[serger]

I'm amazed by some of the posts. I guess the tornado that went right through my house in Allen in 2008 didn't get the memo to go to Oklahoma. Granted that was a small one, still messed up bunches of roofs, and collapsed some chimneys. Now, that all was just damage, and shelter wouldn't make a difference.
But speaking of EF-5 not happening in Texas. Google Jarrell.
And that's near Austin, where tornadoes are actually really rare.

[ChristieP]

Yes, I remember Jarrell. That was one in a million. And, again, that wasn't in the DFW area. Jarrell is 2 hours to the south.

[Threestep2]

Originally Posted by ChristieP

Using examples from MS and AL tornadoes is irrelevant to Texas. As many of us have said before, we just do not get F4 and F5 tornadoes in DFW. Sure, they do get those occasionally in Kansas, Oklahoma, and parts of Missouri.

Unless you live in Cleburne, Granbury or Lancaster, the risk of even a minor tornado is so rare that it's not worth potentially structurally damaging a house and spending thousands of $ on an underground shelter. I've lived in Texas for 40+ years and I've never been hit by, or even seen a tornado.

If you want to spend $3000 to improve your home, put on a metal or tile roof. We lose a lot more $ due to hail claims here than to tornadoes!

How does a tile roof improve a house during tornado activities?
You can run from hail maybe get bruised up pretty bad. But you did not experience the tornadoes in DFW's area during the last five years? Videos of 18 wheelers flying in the air, Meecham airport looking like a scrap yard, BSN scrambling, we watched Keller getting hit, ... The question is not about how much money does one loose why but - in- ground with existing slab.
If you have never seen one and have never bee in one please count your blessings. I have seen and been in enough for the both of us. This summer my hometown in Germany got hit pretty hard. People did not know what it was and there was no insurance coverage for an unknown. Mother Nature is going through menopause.

Again it is everyone's decision what to do.

[serger]

Originally Posted by ChristieP

Yes, I remember Jarrell. That was one in a million. And, again, that wasn't in the DFW area. Jarrell is 2 hours to the south.

Well, my point was that it happened there, and Austin is not in the tornado alley, while DFW is.

[Rakin]

Originally Posted by ChristieP

Yes, I remember Jarrell. That was one in a million. And, again, that wasn't in the DFW area. Jarrell is 2 hours to the south.

Yep, They also had one in Iraan about 20 years ago that sucked up the asphalt off the streets.

And the Biggie was back about 1979 that almost wiped out all of Wichita Falls.

F4 & 5's do happen just not very often. So far the biggest one here in the last 40 years has been FW back about 2000 that hit that bank building.

They do happen just very rare.

[ETex2]

It's just like insurance...you may never need it, but you'll be awfully glad you have it if you do. I've known people who had tornadoes hit their house. And there was a couple killed in Van a few months ago. That woman was a classmate of mine from high school.

[MckinneyOwnr]

Originally Posted by ETex2

And there was a couple killed in Van a few months ago. That woman was a classmate of mine from high school.

Small world. I went to school with their son. That was an EF3 tornado.

At any rate, I don't think $3k to spend is a waste of money if it buys peace of mind and security for the homeowner. Some people spend far more than that on security systems, only to never need them.

[escanlan]

Originally Posted by TGentry

We are considering installing a tornado shelter in the ground below the garage floor slab. They will remove a section of the concrete and install it below ground.

Someone told me that this will compromise the post-tension support (or what-ever it is) of the slab. I mentioned that to one installation company rep, and he hemmed and hawed and finally said the way they do it, the slab will be fine.

Any thoughts? Thanks.

There is a simple answer to your question. Post the name of this company on the BB so every can "RUN FORREST, RUN!" and never get near this company!

It would be difficult for us to provide you an exact answer since there are no details regarding your home. If you have already determined that you do have a Post Tension Cable slab design, and for the garage as well, then I most certainly would not allow anyone to cut into the slab unless absolutely needed. PT cables are under a significant amount of stress to perform their job. If you strike, break, and release a viable PT cable the results are unpredictable. It can be as simple as the tension releases and the cable draws into the slab. Or worst case is a major blowout of the slab. If you have ever seen the end result of a blow-out it can be pretty dramatic and very expensive to repair!