Joist Attachment

The cellar floor slab is formed and ready to pour ... coming next will be the (heavy) block walls . Got the rebar and filled columns figured out , next up is the attachment of the floor joists to the top of said wall . The plan is to set some carriage bolts into the top run of block at suitable intervals and use those to secure a 2X plate - width TBD . I'll want to be able to secure a ceiling of some type to an overhanging top plate , independent of the structure above - this will also serve as a storm shelter . The question is , how best to secure the floor joists to that same top plate , so that they are both stable and secure and yet if a storm strong enough comes thru to part without taking my ceiling with it . Or , should I use the floor structure as the top/ceiling , and let the wall/floor interface part if it comes to a tornado etc ? We're actually pretty sheltered , down in a pretty deep bowl - when the tornado took out half of the nearest town (and many others on it's way to here) it skipped over The Holler , all we got was some torn up trees . Possibly pertinent detail - the bottom part of the structure - probably up to window sill height- will be clad with native stone . Probably 5-6" thick , depending on what I collect and bedded on a footing 16" below grade - frost line is at around 12" .

Reply to
Terry Coombs
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If you are really going to make this strong you pour a bond beam on top, one or two courses of "U" block with 2 #5 rebar in it, with rebar hooks tied to the horizontal rebar and tied to the ones coming up. Then you pour those 2 solid. Simpson also makes connectors to attach the studs to the plate, the top plate to the studs and then up over the trusses.

I think they have the whole system on the web site.

I don't see much that is stick built around here. It is block all the way up.

Reply to
gfretwell

Since he lives in a tornado area and is building a whole new house, wouldn't it be a better and probably simpler idea to build a small tornado shelter room that will be underground, off the basement, that's independent of the house above it?

Reply to
trader_4

you need to hire a structural engineer forthe best alternatives and specifications

Reply to
bob haller

We're not so much a tornado area , but we do get some from time to time . A bigger concern is the ice storms in winter . As far as a separate room , the cost makes that a non-solution . We're building on a budget ... This cellar will be about halfway in the ground , and the plan is to push the soil removed kind of up the sides of the cellar - ground will slope away on 3 sides and the 4th is to be decided . Entry door details are still tbd , but I'm hesitant to just hang a regular vertical door . IMO best option will be stairs with sloped doors , one door set up to it can be opened from inside if necessary - probably a removable panel or something .

Reply to
Terry Coombs

Thanks for your opinion bob . I've been in building trades for forty years , and some of the most f***ed up messes I've ever seen were designed by "structural engineers" and "architects" . I trust my own design capabilities , just trying to decide where to put the "weak link" in this assembly . As far as load calculations and truss design type stuff -, there are great calculators available on line ...

Reply to
Terry Coombs

I can't imagine what kind of ceiling is going to stick around after the floor joists have blown off, except maybe a concrete slab.

Can anything wood resist the forces of a tornado? I don't know. I'd expect you'd need a lot of bracing if you wanted to try.

You could do something like anchor the joists to the sill plate bolts with steel brackets. gfretwell mentioned Simpson ties. They do have hurricane ties for decks, but with those any pull is against the tie itself, so they're very strong even though they're not so thick. If you use ties to the sill plate then the resistance to pull will be weaker because it will be pulling the nail out. So I guess if it were me I'd want the joists anchored to the actual bolts coming out of the foundation wall, and then put 3/4" plywood on the bottom of the joists. The idea that comes to mind would be a thick angle iron, possibly even folding over the top of the joist. Custom made, probably.

But if you're building a new house then why not build the whole thing with extensive bracing and interconnections? I would think there must be officially tested methods for that, just as there are for earthquakes.

Reply to
Mayayana

The wind code in coastal florida is 150-170 mph and that gets you up into the low end (F2-3) of tornado speeds so the idea that you should count on the house blowing away may be over stated. You certainly want a shelter you can get out of if it does come down tho. That is why they usually dug a hole out away from the house for the shelter.

On doors you have two issues. For the best wind speed protection, you want doors that open out but for the best egress with debris outside, you want one that opens in. You may want a door and a hardened window at grade. I think that if I was really making a tornado shelter it would just be a room with a concrete ceiling.. FEMA has plans on their web site. The time to do it is before you top out your block so you can get the right tie beam configuration. You will be blocking up a couple of walls inside too.

Reply to
gfretwell

The last time I hired an engineer, required by the plan review in my county, the guy ended up using my plans and some details he got from the state, after his plan was rejected twice.

These codes are changing rapidly and usually the state construction boards have details that they want to see on plans that they hand out to engineers.. It simply becomes "cut and paste" on that big copier they have. This guy ended up using my plan in the middle of the documents and ringed it with the appropriate details from the state. It sailed right through because plan review saw what they are used to seeing.

Reply to
gfretwell

There's no really perfect place to build a tornado shelter. A house or debris could fall on the entrance and people would be trapped. I think a good idea would be to build a couple of access entrances to an under ground shelter. Store food, lights, batteries, a working cell phone, and other essentials in the shelter. I'd love to have a tornado shelter, but they're so darn expensive.

Reply to
Muggles

If you're going to use it as a shelter, I'd suggest building in more than one escape route.

Reply to
Muggles

At the early construction phase, adding a hardened safe room does not add that much incremental cost.

Reply to
gfretwell

That's a good thing. If it can be done at that stage I think it's a good idea. Better to have a safe room like that and never need it.

Reply to
Muggles

Of course ! Not certain of the exact location yet , but there is a hatch and ladder planned for access from the kitchen pantry above . As soon as the wife makes her decision on cabinet/island/ etc layout that will be firmed up . She can't envision from a drawing , I'll have to lay it out on the floor for her ... some people just don't have that ability .

Reply to
Terry Coombs

She's a lucky woman that you're planning for such a safety issue.

Reply to
Muggles

Terry Coombs posted for all of us...

If you know so f*n much why do you ask?

Reply to
Tekkie®

Because different people have different perspectives ... and another perspective may show me something that otherwise i might have missed . Now how about you f*ck off and die ?

Reply to
Terry Coombs

I'd say same. How come did he have to ask? Does not make sense. Maybe he spent in the trade just digging dirt around with shovel.

Reply to
Tony Hwang

Ya know , I was going to write a blistering diatribe . But you aren't worth the effort .

Reply to
Terry Coombs

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