Designing a garage; engineering help?

I'll throw in my 2 cents as a mechanical (not civil) engineer for the steel beam option. Steel is more...predictable, let's say, than concrete, less sensitive to installation/ mixing/ etc errors, and has strength in tension and compression, whereas concrete is only strong in compression. That's why you need 20" of concrete to support that floor; you're essentially asking it to be a tensile member. Parking garages do it by reinforcing the crap out of the concrete with steel. And they still fail sometimes.

I designed and built my own garage, and built a mezzanine-like second story similar to what you have shown. Except mine is only for parts storage- not for vehicles. I used some load beam equations that were pretty standard. My main goal was to not have ANY posts beneath it- it spanned 28' with only support at the ends, and ied into the rafters about 4' from the ends. I ended up with 2 x 10's doubled up every 12" to support a floor load of 100 lbs/ ft^2 (standard commercial floor loading rate) and the floor still deflects noticeably if you jump up and down in the middle. But it's strong, and wood has enough flexibility that it won't be a problem. That garage should last 100 years.

If you're going to be parking cars, you have the very real liklihood of having loading of 10X what I calculated for, since the car's weight is distributed among 4 points. Granted, you're allowing yourself to have support posts underneath, but still...wow. Yeah. Steel beams, man.

Ian F wrote:

novaderrik wrote: didn't you post a similar question a few months ago? if so, i still say you should make the floor in at least one bay of the upper level have removable panels in the middle to allow you to work on the bottom of a car.. or maybe put a 4 post lift there to use as an elevator..

Yes, we did have this discussion... (no 4-post lift will go high enough to use as an elevator)

then have the company build a custom 4 post lift that goes higher.. elevators are cool, and we are pretend spending someone else's money here...

novaderrik wrote: then have the company build a custom 4 post lift that goes higher.. elevators are cool, and we are pretend spending someone else's money here...

You do realize we're talking about Curtis, right?

Ian F wrote:

novaderrik wrote: then have the company build a custom 4 post lift that goes higher.. elevators are cool, and we are pretend spending someone else's money here...

You do realize we're talking about Curtis, right?

he is "someone else", is he not?

Curtis doesn't even spend pretend money.

I'm trying to figure out if we could build this out of scrap pallets for him.

I've got it!...

If we all work together and pool our resources, he can build this thing out of donated beer can flip tabs daisy-chained together with JB Weld.

The spans can be conquered with the given loads by filling the car tires with helium!

I drink mostly out of bottles, so I can donate beer caps.

Duke wrote: Tom Woods, PE Baker Ingram Associates Newark, Delaware 366 East Main Street Newark, DE 19711 302-456-1757 ph 302-456-1759 fax They have PA offices, but Tom is the guy I know best, and he is registered in PA. He's a good sensible engineer. Call him and tell him I sent you (Duke Wilford from FC Architects); he'll at the very least give you some good advice. His professional services fees are really reasonable, too.

That rocks. That's what I'm looking for. I've had too many quotes from companies who are going nuts with over engineering things. I obviously want it to be safe but not a fallout shelter. I understand they need to cover their ass but there has to be middle ground.

Basil Exposition wrote: Here's a guy I know that had a similar problem and his solution: http://newhillgarage.com/other/construction-of-the-new-hill-garage/

salivating and researching....

SVreX wrote: Curtis doesn't even spend pretend money.

Correction... Curtis doesn't even HAVE pretend money

But Curtis does have good credit.

Trust me guys, I really do understand that I am quite the fodder for jokes (and I actually like that I am), but I am incredibly serious about this project. I have never owned a garage and I refuse to compromise on what I want. BUT, I will also never be happy if I don't research every possibility and then realize that I spent $60k too much and only got a half-assed result.

Things like the pre-cast concrete stuff like was posted before are exactly why I posted here. It is an avenue that I hadn't even known existed and I'm thrilled. The thought of getting some neighbors and 6000 concrete blocks to painstakingly assemble over weeks of occasional free time is just scary. 5 hours of pre-fab panels going together? I will have to weigh the cost of the panels vs my sanity, my chiropractic bills, my confidence, and paying labor/being indebted to my friends for the rest of my life.

I don't mind paying for a premium result, but I refuse to accept that throwing large sums of money at the one idea that I've explored is the proper path.

Thanks for the input folks.

Yes, the savings with pre-fab panels is usually in time and labor. How much savings will depend on the size of the building and area labor costs. Plus, as you mentioned, the idea of having things assembled quickly vs. weeks or months.

One thing that may throw a wrench into things is the excavation. It just dawned on me that digging that much into the side of a hill in PA is rarely done without breaking rock. A lot of rock. On the good side, you may end up with a nice, solid "wall" to build against with minimal worries about it pressuring the foundation. On the down side, the excavation may be more than a typical back-hoe can do.

Ian F wrote: One thing that may throw a wrench into things is the excavation.

An intuitive observation. I have access to a strong background on this property because the man living next door was born in this house, performed much of the maintenance, repairs, and updates to the property, and has a fantastic recollection of all that has been done.

The area where I would be digging into the hill is all fill that has been deposited between 1960 and 1990. In an effort to increase the flat, useable part of the front lawn, the matriarch of the family struck a deal with local cemeteries, landscapers, and other dirt-types to dump fill on the property. While there may be rocks, they are rocks that were successfully dug before, then deposited with dirt on this spot. I don't anticipate difficulty with excavation into the hillside.

It is also for this reason that I don't want to build on top of that grade. Since it is fill, its load-bearing capabilities aren't something I want to trust. Someone had suggested I forgo the mezzanine idea and just build the upper parking level on the upper grade and sacrifice the useable area under the mezzanine. Not only does that force me to abandon 800 ft^2, but the stability of the structure might be in question without using very deep foundation footers.... at least that's what the local code guy said when I was talking to him about my plans.

Had a guy from a pre-cast wall company come out today. He is going to get back to me on Monday with an estimate.

By the way, the pre-cast stressed panels that are used for the mezzanine floors? $32/sq ft. Ouch.

If you can live with a couple rows of columns (it seems like you can) they can just be planks like you'd build a Motel 6 out of. You can get them as small as 6"x16" so you could set them with a backhoe probably. You lay them down and pour a 2" concrete topping over them for a smooth leakproof floor. You may not even need the topping.

http://www.oldcastleprecast.com/plants/building-systems/products/HollowCorePlank/Pages/default.aspx

http://www.hollowcoreplank.com/sections-details/

curtis73 wrote: By the way, the pre-cast stressed panels that are used for the mezzanine floors? $32/sq ft. Ouch.

Ouch, indeed. Figuring a 20x40 mezzanine, that's over $25,000.