Newbie and Questions about my homestead - Structural Questions

[Sixfold]

Hi everybody! 

Just stumbled upon this site a few weeks ago while doing some research for my homestead.  You guys have a great community here and tons of helpful people and information.  I would just like to say thanks, I've learned so much already just from reading old posts. 

So I have an idea I'd like to run by you guys and some questions about design. 

I recently purchased 20 acres in middle Missouri.  I spent about 2 years looking and managed to get what I wanted for the price I wanted.  My wife and I are just married and as such would like to get onto the land as soon as possible.  To facilitate this, I am planning to build a 2 story Garage/Workshop to live in while we save and then build the house proper.  I want to keep the garage to dimensions and features that will make it most affordable to build.  I also want to get it dried in quickly so I will probably contract the shell, then finish the inside myself.  Codes are lax here roughly following IBC 2009.  Once we have the main house constructed we will be using the garage primarily as a workshop and offices upstairs.

The design goes as follows, let me know if you see any problems or have any suggestions:

Slab foundation with 24in footers for the frost heave here (county recommends 30in but local university says it has never exceed 20in).  20' x 28' 2 story design with standard 8 ft 16" OC walls.  Scissors Truss across the 20' length.  An overhang extending 12' out from the front (south side) of the building spanning the full 28'.  A man door in the center of the front (south side) under the overhang, a garage door on the east side, off center towards the south, and several windows throughout.  Stairs located next to the garage door in an L shape bordering the east and north sides.


County recommends:
Roof Snow Load:  20
Wind Speed (mph):  90
Seismic Design Category:  D-0
Subject to Damage From Weathering:  Severe
Frost line depth:  30
Termite:  M to H
Decay:  S to M
Winter Design Temp:  8
Ice barrier required: No
Flood Hazards:  Firm
Air Freezing Index: 1000
Mean annual temp: 55


I have two main questions.

1) Should I extend the slab/footers to include the 12' overhang? Or can I pour this without the footers and just bury the front support posts deep.  I know very little about cement work.

2) I imagine 20' is a bit far to span for the second story floor joists.  I prefer to not have any posts in the center of the workshop downstairs.  Can I put some sort of I beam across the center and do 14' spans on the floor joists?  Can I use 2 x 12s for this?  Or is 14' too far? Would I need a center support pole for a 20' I beam? 

I have read through several of your projects already and am envious of your progress    

Thanks for taking the time to read my post.

-Nathan

[MountainDon]

I just saw this... I have comments but I'm out the door; might take a day or so to get back....

[Sixfold]

I await your return.  Been reading through your project.  Really nice setup you got.  I love all the pines, but I wouldn't be able to drag my wife to any place with that much snow.    For whatever reason pine grows like crap here.  I have only 1 nice pine on 20 acres.  I do have a lot of Junipers but they don't smell quite as nice. 

-Nathan

[Don_P]

While the other Don goes to play and before this one heads back down to fix the throttle and face the pile of pines again... I'm assuming the shed/porch roof is not part of the truss but is attached to the wall with a ledger. Spot footings would be fine for that. For the garage it is often better to build stemwalls that extend above grade a bit to set the walls on and pour a floating slab within. Do remember that the stairs from the habitable quarters cannot lead through the garage. Dump the occupants outside and through a protected stairwell, they cannot egress through the fire that is in the garage. The garage must be isolated from the living quarters with 5/8 type X drywall and all penetrations between the two must be protected, doors, plumbing, etc. Basically the upstairs shouldn't have anything to do with the downstairs. Check the garage door size and portal framing requirements. Build 9' garage walls so the door works with normal tracks. TJI's or floor trusses to get the 20' span.

[Sixfold]

Yes that's correct.  The overhang will be attached in between the first and second floors using a ledger. 

So there are fire restrictions when building on top of a garage?  In that case.  Since I don't need to use it as a garage, I just wanted the rolling door more for easy access when using it for storage and for my workshop after we build the house, can I call it something different and bypass the restrictions?

I guess, what officially makes it a garage?  If I replace the rolling door with a more standard double door, does that change the fire restrictions?

21 20' TJI's is actually more affordable than i thought.  Thanks for the Advice!

[Don_P]

I think it would be hard to call it something other than a garage with a garage door in it, But, if it is ever going to be used as a garage or for the storage of garage type things I think I'd build it as a garage firewise, it isn't as onerous as you might think, we can kick some plans around. But right now, fixed the throttle, turned 2 round pines into many square things and I'm out the door for the evening

[Erin]

So there are fire restrictions when building on top of a garage?

It's pretty straight forward stuff, sixfold.  Things like X-thickness of dry wall between the garage and living space.  Don't let it throw you off.  We have a garage in half of our basement.

What does your county have for code requirements?  You say lax, but what do they actually inspect?
My county has "lax" codes, too, which means they inspect the septic, and that's it...

[Sixfold]

What does your county have for code requirements?  You say lax, but what do they actually inspect?

Well officially the county specifies 2009 IBC as the standard but as far as what they actually enforce/inspect. My friend is in the same county.  He built a small barn with electrical.  The county just asked him if he knew what he was doing, he said yes, so they signed off on it.  They never even went out to his property.  He is not certified in anything. And speaking with locals its generally the same for residential.

The code also specifies that you need to obtain an occupancy permit to reside in your structure, but when I called the county to ask about them they said they do not use them. 

Don't let it throw you off

I'm not worried about complying with most of the fire protection issues.  I think that is rather prudent.  But I did want to have a staircase inside of the structure.  And I would like to heat the whole structure. 

I think it would be hard to call it something other than a garage with a garage door

I'm not dead set on a garage door.  Any large door would do the trick. 

[akwoodchuck]

Long as you have Type X rock and a self-closing fire door between garage and living space (garage door CANNOT lead into sleeping quarters), and egress windows upstairs, you should be good to go. Maybe plan to add an upper deck or balcony with outside stairs later? I've seen this done both ways, sure is nice to have that interior staircase. I wouldn't want anything but an overhead door in the "workshop".

[Don_P]

You can have an interior stair, it must exit to the outside and be isolated from the garage by 1/2" drywall, in other words a walled stairwell with a door at the bottom to the outside. I've had them drop to a landing area, one door led outside and another 20 minute door led into the garage. In the event of a fire in the garage the occupants from the upstairs wouldn't have to exit through the burning garage. There really ought to be an inswing passage door (a bedroom type door that doesn't sweep over the stairwell) at the top of the stairs as well, the stairwell becomes a cold sink in the winter that impairs the living area above.

The heating system should not be common to both areas, each should be seperate. My Dad did this by buying an old unit from a motel remodelling job, heat and air, and stuck that in the garage wall. Something quieter in the living area would be good. A non flame unit in the garage makes more sense, if there is a flame it needs to be at least 18" off the floor (this assures that there will be one helluva vapor load downstairs before she blows, don't go there!)

I brought in water down low in one, put in the water heater and a laundry sink in the garage and then got dinged because of the penetrations to upstairs. The easy solution was to build a closet to house those items and put a 20 minute door on that closet... hindsight, should have slid it all under the stairs and put the door there.

[Sixfold]

Thanks for all the great information! 

After talking with you guys I'm definitely going to scrap the "garage" and just make it a small "house" with an unfinished bottom other than insulation and a rough drywall.  I'm doing this so I can heat the structure as one unit.  And so that the stairs are cheaper and don't require 3-4 more doors than I planned on.

Until I move into the main house, the storage I want the bottom part for will be mostly furniture, clothes, and other typically non-garage items. 

I Will most likely add a deck to the upper story so I can have a secondary egress. 

I'll see if I can't whip something up in sketchup.  Never used it before but I'll give it a go. 

Thanks again,
-Nathan

[Sixfold]

OK so I used sketchup to model what I had in mind.  Took alot longer than I thought it would.  I was learning how to use sketchup and how to properly frame at the same time so dont hesitate to point out any and all flaws. 

Sketchup file is here.
http://www42.zippyshare.com/v/24895204/file.html

Stairs are a placeholder.  Might put in a window in the bathroom. The ceiling will be engineered scissor trusses.   Bottom floor will just sit on the foundation/slab.