Steel Beam Question

MohaimenK

Hello, I am currenty drawing an idea of extending a house. There will be a garage, 25ft x 26ft but the owner wants to make a home theater underneath the garage. They want to be able to keep the entire room from having any supporting beams in the basement. I spoke to an architect and from what he explained, it's possible, quiet easily.

He says, I can put steel beams on the concrete. 1 every 5 ft. Then put steel slabs on top of it then cover it by 4 inch of concrete and that will hold just fine, even if they were parking 2 5,000 lb vehicle.

Now, I am questioning that opinion. I am sure, many of you have done this. What would you suggest for this?

I have drawn a picture to explain. I did not draw beams over the concrete walls, just to show a clear viwe of the walls, but there will be total of 7 beams altogether. Thank you

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thom

You can do it the way you drew it, or you could do the whole thing with reinforced concrete. Look at the typical city type multi level parking garage. There are only two simple issues.

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tinner666

Or even add 1 or 2 beams if that will make you feel better.

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Frank Slate Roof Repairs, Richmond, Va.

MohaimenK

Thank you. I was thinking, most of the cost would be for digging the space out. But building a basement, regardless to where, would cause us to dig anyway. I figured, w/ the beams and concrete should cost us $10k more at the most. I haven't worked w/ concrete much so my price may not be correct? As far as 4", I was thinking more like 6-8" of concrete.

joasis

Here are a few shots of one we poured this summer. 24x24 with a 5 inch cap supported by two 10 inch beams.

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Aggie67

Find a local engineer. Make sure you get signed and sealed prints for the slab. It's a simple design, but do the right thing and get an engineer. I do this work all the time, but I'm probably not in your area.

genecarp

recently did one with steel, i will try to get a photo, kind of what you drew but with one main steel girder down the middle. you also want the beams close to the walls to pickup the Q deck . i did the Q deck spot welded to the steel, then chairs, then rebar, then 6x6wire, then radiant heat, followed by 6'' of concrete. it is a BUNKER.....


steel for a 24x 26 cost me about 6,000

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genecarp

J, what is the surface your poured on? cant see in the photos, thanks G

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joasis

I used 3/4 plywood and 2x10 joists between the beams. The walls are ICF.

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MohaimenK

Any idea of how much load capacity on that concrete? I am guessing it's a double car garage?

joasis

That end of the larger building is for living quarters and a game room....but it hold the weight of my scissor lift. Should be 400 lbs./per/sq/ft.

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MohaimenK

Oh ok, that sounds good to me. An average vehicle weights between 2500-3500 lbs. Even at 400lbs psf that's should hold a pickup truck or even a large SUV.

It's hard to find that info online. I did find something, but wasn't very clear when I read it. It suggested that with 6" concrete slap, it should hold 550lbs psi (per sq inch)! Now, I am not sure if they're speaking of that being as a driveway or they were talking about it being as what we're talking about.

If any engineer around here wants to chime in, please, you're welcome to

BTW, Joasis, was that opening large enough for stairs? Things look very different in pictures. Maybe it's quiet large, just can't tell.

Driftwood

Take a look at a parking garage. You could go q decking,Pre stressed slab, No wide flanges

MohaimenK

I gave them a different option to all of this. Instead of building under the garage, they may be able to enlarge their basement. I've been reading about lifting houses and saw some prices between $10-15K. I have to do more research. But this was my idea. They want to remodel the front of the house as well, also add rooms on the side so instead, we could start digging from where their exterior walls would be for the new construction and then lift the house. Then we could put 2-3 rowes of blocks and sit the house on top of that. That way, they should have a 9.5 ft ceiling. They can have 9' w/ dry wall and the 6" can be used for all the ducts going upstairs (as now their ducts are visible which takes away from their low ceiling they have now.

Now this brings to 1 issue. The span of the house. Right now, it's at 25' but it might end up being around 30'. Their preference is NOT to use any colums to hold the beams up. I know that's possible but inspectors in Fairfax County are bunch of ___________ (fill in the word). They might say, there's no support for the Above walls. Coulld this be soved by using steel beams instead?

Anyone have done either one of these proceses?

joasis

At this point, you really do not have the experience to proceed....the best thing for you to do would be to get an architect involved. Advice is not going to get you the information you need.

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MohaimenK

Well, just trying to get some ideas of anyone that has done it before I take it to the architect. Eventually everything will go through him but if this is something that cannot be done, or costs way too much, I'll speak to the owners and maybe just go with the original plan.

joasis

It can be done, but at what expense? Without actually seeing detailed pictures, I can only visualize what you are doing, and therefore, my advice wouldn't be feasible. What I would do, if I was in your position, is invest in the consulting fee with an architect or engineer and get them on site...what they can tell you in an hour is well worth it. You can run your ideas by them while they have eyes on the project and say yes or no. Best I can offer, good luck.

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MohaimenK

Joasis, I am AN IDIOT! I just remembered what you did in your first pic. Using a T-Beam (or maybe you're using an I-Beam, can't really see the top of the beam) but that should work just fine. Just as your picture, the joists are not running through the entire span of the house just cut in half.
Currently, they use a 6" joist vs 10" so chaing that will definetly beef things up and if I MUST use columns for the beam, I can do easily do that but will also be able to space it out a few feet (which will place it between a wall). Does that make sense?

As for house lifting, that's no issue either as there are several companies that do this here. Just have to sit w/ them. But I have to wait a few months for that to happen. Because as you mentioned earlier, an architect is needed and fortunately, I have free access to one (family relative) but due to the fact that he's out of the country for a few months is the issue. He does commercial work so he's a very busy man but once he's back, we can sit down and together we can decide something and look into companies for the lifting process. Construction won't begin for another few months so we have some time.

Sometimes too many thoughts come to mind and people just get confused and totally miss things. Reason I didn't remeber your joist and beam set up.

CaliDesigns

The last house i did used hollow core. 4 car garage with basement underneath.

MohaimenK

Well, I think we're most likely going to scrap that whole idea of of the basement being under the garage. We might instead just spend the money on the current basement.

Having height difference, not sure if we DO end up making the basement under the garage, how we can connect it to the old basement. Again, we're still working on it.....

Also, their current basement is 7' tall (finished) and I think they just want to get an extra ft of space so depending on the footing (should be 24") we might as well just dig down a ft and that will save a lot of money rather than to lift the house.