You can rent a concrete saw at most rental places. Looks like a chainsaw with a big abrasive wheel instead of a chain. You'll need ear muffs, eye protection, and a dust mask to use it. It's loud and dusty, for sure. You just mark out your line and use it to cut the concrete, just like cutting plywood with with a Skilsaw, just slower. Once you get your square cut out, sometimes you have to make a few more cuts to section out the square to help when you break up the concrete with a sledge. Have a shop vac handy.

 

"Also, when I do this I am going to have to have the garage doors open or off for some time. Does anyone have any good ideas for me as to sealing out the garage area from intruders. I do not live in a bad neighborhood but I wouldn't want to come home and see some of my fun stuff missing. "

How far away is one of those storage rental places?

Boy your having fun now! Just keep reminding yourself how much money you are saving.

 

Boy your having fun now! Just keep reminding yourself how much money you are saving.[/QUOTE]

 

Hey guys,

I finally got around to taking off the aesthetics so you can all see the structure. Check out my web site updates and let me know what you think now.

Thanks!

http://www.angelfire.com/trek/dan_s_johnson/home.htm

 

BTW, those lolly columns may only adjust a few inches at a time but many of them are made of telescoping steel pipe with holes thru them for a couple of pins that adjust the height in 3" increments. Then the screw mechanism can be used for fine adjustments. The telescoping portions adjust over a wide range of heights but the columns still come in several sizes or adjustment ranges.

Two bits those headers have a but joint over the top of the 2x4 support column, any takers?

The supports are probably plain 2x4's in direct contact with the cement and rotting at the bottom also. Never set wood on concrete without being treated wood and some sort of moisture stop. The new EPA approved treated wood will rust any metal that it contacts so I am not sure what type of moisture stop to use and of course you will have to use stainless steel screws, bolts and fasteners. Galvanized fasteners are supposedly OK but they seem to be attacked too. Until they get this new treated lumber situation fixed we are all out of luck!

An old general rule of thumb I use is to make sure there are as many 2x4 type pieces of wood in the supports for an opening as there would have been in the opening itself.

You will need to cut out the concrete garage floor and drive to see what is under it and to pour a new support pier.

Nail some plywood or OSB sheets over the opening while you are working. Just make sure they can move and give when you lift the structure. Don't make them too easy to remove either.

 

I'm not betting anything about a possible butt joint on this..

BTW Dan, those two 2x10's with the spacer IS the header. 2x material is really 1 1/2" thick. The "4" part of a 2x4 is 3 1/2 inches wide. When you make a header for over a window or door you nail and glue two 2x together with a piece of 1/2" plywood between, so that the overall width is 3 1/2" - the same as your 2x4 wall. (I've used a lot of that polyurethane glue the last couple years - it's like my new duct tape.) Kind of like Eric was saying, you always want to fill up a hole with wood. It's one of those carpentry rules..

When I added a second story over my garage years ago, I planned on putting in a glulam the span of my garage. The footer under the foundation at the back of the garage would support the weight, but I figured I would need two more footers, one at the mid point and the other at the entrance, (where you need yours). I'd done it before, so just went to work on the center hole. I cut down 13" before I hit gravel - the footer only needed to be twelve. I couldn't believe it. I dug around a bit outside and found the whole slab was that thick. I called the inspector to take a look and he said not to worry about the one at the front, (frost heave - what's that?) I've never had a crack in the floor, because I estimate they used 30 YARDS of concrete to pour the garage. Must have been cheap back then. In this case someone screwed up in my favor.

 

I'm sorry if this has already been mentioned I didnt' read all the threads. If you like to go with a larger door and support the above structure have you thought about erecting a new wall in front of the existing gararge doors that would sit flush with the above facing walls. A new wall system about 2'-3' beyond the existing doors. This would depend entirely on the way the upper floor system has been cantilevered. If they used one solid joice across the width of your home as they should have you could erect an engineered wall that would carry the upper weight as well as the header for the garage. The wider the span of the door, the higher your beam will be in terms of dimension. This would eliminate any make shift fabrications while the work is performed, safety! Aesthetically, it wouldn't change the face of the home that much. Both piers on either side of the garage door could be easily excavated and poured along with a footing across the opening. I'm sure you have lots of information on what you can do but I love construction so I just had to throw an idea your way. Good luck on it. Whatever you do check your codes and more importantly the contractors that you might end up using.

 

That is good advice. We did talk about that option and that is definitely the way I wanted to go but at that point didn't know if the cantilever was solid joists going all the way across. I took some more of it apart this weekend and it appears that the joists do run all the way across so I can support from the front. I also found that the headers are solid all the way across without any butt joint. However, the builders should be shot for using such crappy wood for headers as there are big knots at the bottom and one of the headers is actually cracking through one of the knots in the wood right near the center support. I also measured from the garage floor to the headers on the outsides vs the insides and found that the center actually only sunk 1.25". This is not as bad as I thought but it is evidently significant enought to crack a wall, window and make doors out of alignment.
I am fairly sure a header will be able to be supported all the way across with no problems at the center of the house because I can have it resting on a good couple of feet of brick and concrete block. The other end of the house though has brick and concrete block only 1 foot deep total and I am not sure if that would be distributed well enough. Then I am not sure if those footers are able to support the added weight as well. From the joists to the brick I have 8.5" now. I suppose I could always sand down the brick to get it to 10' if needed. Any other opinions on whether columns like that which are 17' apart could support the weight? I know I am basically at the point where I need to get the structural engineer in but I figured I'd ask again as there has been lots of good feedback so far.
Also, how would you build the support wall on the canteliver? I imagine I would anchor about 4 lolly columns to the driveway at equal distances and use some kind of a header on top of them so that all the individual joists were held up evenly. It is the construction of this header and how to keep it from tipping off the joists that has me confused. Obviously if that wasn't secure and that temp header came down I'd have a real bad day.

 

Check the cantilevered joists, they may not be large enuf to span the full distance if supported at the end.

 

I'm not quite sure what you mean on this...Are you saying that supporting it from 1-2' further out would be too much stress on the joists?

 

Yes, there are span tables for floor joists. Codes require minimum joists for spans and Architects have figured out that floor stiffness is important. Check with your local codes officer and an Architect if you move the support point. If it is the same size joist and the same span as the rest of the dwelling you are probably OK. Just check!

 

The 20x30ft extension on the back of my 20x20 garage is like that, they used about 36yards of concrete (2 truck loads) for 600sqft...

 

36 Yards for a 20x30? That would make it more than a 1 1/2' thick. Figure concrete at about 4k#/yd. and each truck would have weighed more than 90,000#GVW, well beyond the legal limit and capacity of the truck. If it was me, I'd be calling about a refund. A regular slab doesn't need to be more than 8". If you want stronger, add more rebar. Am I missing something, like footers?

 

How is concrete measured in yards? Wouldn't it be some kind of a volume measurement? Are you implying cubic yards then?

EDIT:
Nevermind I gotcha...
600^2 ft of garage to cover with 36^3 yds of concrete (1^3 yd = 27^3 ft)
36*27 comes out to 972 and 972/600 is just over 1.5ft deep like you said.

Wow it is amazing how quickly you lose the math skills once you are out of school a few years and don't use them.

 

While we're on the subject... When you do your footer, (pier and pad), a rule of thumb is one 90# bag of premix = 1 cubic foot of concrete. They sell them in 80# now, I guess to save peoples backs - but you get the idea. Or you can get them in 60#'s, so you can mix them in a 5 gal. bucket. Always better too much than not enough.