I'm favoring Paul's idea to build a proper footing and frame a new left wall same height as the existing wall that is on the property line.
Then build or buy trusses (or just stick frame rafters for ) for the roof, add girts and plastic corrugated roofing. Yank out the existing left wall and foundation but keep the existing slab. Boom bigger garage. Season to taste with electricity if desired.
In reply to VolvoHeretic :
Exploratory surgery is definitely on the to-do list. Sidewall height is (trying to remember) either 7'4 or 7'8. Somewhere in there. I remember measuring many moons ago so I could cut some metal shelves to fit under the joists.
Re: 90-degree ridge... I'm picking up what you're putting down. A 6' side addition with a perpendicular ridge would work. Might be a lot of framing for only four trusses and a pretty shallow slope fore/aft, but I'll draw it up and see what it looks like.
Just seems like when I come up with an idea it always has more drawbacks than benefits. Hence why I'm asking people more expert than I.
In the next few days I'll try to come up with a CAD for the existing structure.... at least what I can figure out about it.
OHSCrifle said:I'm favoring Paul's idea to build a proper footing and frame a new left wall same height as the existing wall that is on the property line.
Then build or buy trusses (or just stick frame rafters for ) for the roof, add girts and plastic corrugated roofing. Yank out the existing left wall and foundation but keep the existing slab. Boom bigger garage. Season to taste with electricity if desired.
I think I'm following, but just so we're on the same page... basically you're saying:
1- dig and pour an extension foundation,
2- continue the walls out another 6',
3- strip the 12' wide roof,
4- add 18' wide trusses,
5- ditch left wall.
6- fill in gables.
7- pour extra slabby part.
Something like this? This leaves your existing roof but needs to be trimmed so that the left side rafters hang from hangers attached to the new LVL beam sized for a 16' opening, but is full length of the 24' side wall with a 48" shear wall at each end of the wall to control lateral wind and snow loading. You will have to chop out the block wall at the opening to the next full block and pour the new slab over it with a thickened edge with dowels drilled into the existing slab.
In reply to VolvoHeretic :
Ah... makes sense. I gotcha.
Go as wide as you can. The shell is about the cheapest cost of your project. I have had too many people than I can count that brought me their dream house from some book or internet site that they wanted me to modify and after growing the house to realistic 2 foot increment sizes and fit all of the things they wanted to change (how can designers draw houses in fractions of a foot outside demensions?) they would get a square footage price for their dream home. It would always be over budget and they would want me to trim some odd square footage out of the house to reach their financial budget. I always told them that the shell size of the house never equaled the square footage price they where trying to save and after ruining the design, they still couldn't afford it. It's what you put in that square footage that cost big $$$. End rant now
In reply to Curtis73 (Forum Supporter) :
Depends how thick you are thickening it.
Dig a trench 2 feet ( or whatever frost line is for you) down around the edges and pour it with the slab, it's called a Monoslab
Fun fact. My brother lives in Boulder, CO. They where trying to control growth and costs in the old downtown area and passed a law that required everybody to not just tear down old tiny houses and build all new Mc Mansions. So, people would still build their mega $$$ homes, but would bury the 100 year old tiny house somewhere inside the new mega house and just call everything an addition improvement.
VolvoHeretic said:Something like this? This leaves your existing roof but needs to be trimmed so that the left side rafters hang from hangers attached to the new LVL beam sized for a 16' opening, but is full length of the 24' side wall with a 48" shear wall at each end of the wall to control lateral wind and snow loading. You will have to chop out the block wall at the opening to the next full block and pour the new slab over it with a thickened edge with dowels drilled into the existing slab.
I like your idea, but it is still transferring point loads to the existing E36 M3ty foundation.
If the entire roof is removed and longer trusses are installed, they would bear on the new turn-down foundation.
Tearing the roof off is a pain, but it's a known quantity. Chopping up parts of the foundation to pour footings for new point loads in the existing footprint is a can of worms.
If you leave the existing right wall (on the property line), it's a remodeling job to an existing structure. Sitting on the property line is not (generally) an issue. A new building will have to maintain setbacks.
Curtis, the cheapest option is a crappy lean-to addition to a crappy building. The "best" option is something entirely new. But the best option for your situation is probably to do a full remodel to the existing building which includes a new larger roof system.
In reply to SV reX :
You are right, but I don't really think that there will ever be that much load on that middle bearing footing spread over 4 feet on each end on that little structure (although I am no structural engineer). The next alternative is to turn the addition roof 90 degrees and use the new addition side walls to take the new loads. This can all quickly turn into a can of worms when you consider the cost of time and labor versus material costs. An entirely new roof might be the best and cheapest solution. I only draw the pretty pictures.
Normally, you can construct a vaulted ceiling truss 1/2 of the top chord roof pitch. Pick your ceiling pitch. If you want to increase the wall height, just start adding top plates to the existing right side wall until you get what you want and then build the left wall to the same elevation with just 2 top plates. 6/12 is the steepest pitch you can walk on without roof cleats with shingles. I am a big fan of steel pole barn siding for garages and roofs. On my 6/12 cabin roof, I bought 1.5x1.5x1/8" aluminum angle that I screwed to every steel siding rib. It was way cheaper than buying the steel roofing light weight steel anti ice system they want to sell you.
So, Curtis73, the minimum width for a 2 stall garage in my opinion is 24', might as well just add another 4' and make it so. You will wind up using only the right wall as it's existing structure along with the footings and slab, but it will still be an existing structure and still meet any pre-existing building codes. 
In reply to Curtis73 (Forum Supporter) :
Sounds like we are all in agreement when it's your money we are spending!
Go big! Lol!!
In reply to Curtis73 (Forum Supporter) :
Rather than all the remedial work to end up with a patched up shanty, at this point go ahead and investigate just getting a variance to build a real garage. You'll probably just need written approval from your immediate neighbors.
You may make this elaborate salvage plan and find you need the variance anyway once you go for your permit.
VolvoHeretic said:Something like this? This leaves your existing roof but needs to be trimmed so that the left side rafters hang from hangers attached to the new LVL beam sized for a 16' opening, but is full length of the 24' side wall with a 48" shear wall at each end of the wall to control lateral wind and snow loading. You will have to chop out the block wall at the opening to the next full block and pour the new slab over it with a thickened edge with dowels drilled into the existing slab.
If you're doing that and have that kind of depth, skip the LVL and use the extra height to make it a girder truss. Hang the existing framing from the bottom chord of the girder. MUCH less wood than that much LVL. Clear span 24 feet and add a post footing at each end where the new front and back walls join the old at the corner.
Have the ridge on the addition run 90* to the existing. Your addition would have sufficient foundations in the wall immediately adjacent to the existing garage to take the front to back truss loads. Have the first truss be of sufficient strength to support the ends of the existing rafters and just build your new hip extension over the top of the existing roof half. Then you can go as wide as you want on the lean too.
If you use post beam type construction if should be trivial to have the new building built for being an engineered rated 3 sided building that just happens to be adjacent to an existing structure. The beams being in the ground provide most of the resistance to wind load on the open walls. Extra Bonus is at 8' addition you may only be buying 2 big trusses.
This design would impact the existing structure the least and transfer your loading to the new structure. After it's built take down your existing left wall and enjoy your wide open span.
Locally Menards would be able to provide a rated engineered design using their software for IIRC $250 for the plans. If you don't need stamped prints they do engineered trusses for free. Just don't complicate what you need from them with the integration to the existing building. You do that part.
In reply to nocones :
I agree with your idea, but the truss immediately next to the existing building would have to be engineered to carry the roof load of the existing building.
I don't know how you avoid complicating the engineering when it needs to deal with the integration to the existing building.
Here you go, 8' gable addition w/ girder truss. Still need the two 4' shear walls at both ends of the left existing wall.
VolvoHeretic said:So, Curtis73, the minimum width for a 2 stall garage in my opinion is 24', might as well just add another 4' and make it so.
I agree with you 2000%, but two problems. The property is only 50' wide, so legally I'm only allowed 20' width. Second, as you can see from the aerial photo, the left side (as we've been calling it) is already parallel with the side of the house and only about 15' behind the patio. The only things that would fit on the yard side of this building are the motorcycle and lawnmower. No way to turn a car 90, then 90 again unless I suddenly develop an affinity for Smart cars. I also use my backyard for entertainment frequently, and even with an 18' wide garage I'll have to move the fire pit. 20' wide I'll have to move it too close for comfort to the neighbors's evergreen trees so bye bye backyard. At 18' wide (which is less than I want) I already have resigned myself to no longer really having a back yard (which is not ideal). Just trying to find the least-sucky answer so I can actually do some work on cars. Moving is out of the question right now for so many reasons.
I already know that on this property I will never have a 2-car garage by the letter of the law. I thought about putting it in the front yard and destroying my curb appeal/property value as well as make my views out the front window crappy, but given the width of the property and legal setbacks I'm limited t0 20' wide if I keep the door orientation or 20' deep if I rotate it 90 degrees and do front yard.
Also, please enjoy the name of the street where I live.
VolvoHeretic said:Here you go, 8' gable addition w/ girder truss. Still need the two 4' shear walls at both ends of the left existing wall.
In reply to VolvoHeretic :
I like that a lot. It strikes a balance between good usable space, structural considerations, and cost. It can also be built in a minimally disruptive way (the addition can be built first over time, then tear down the wall)
I'd use scissor trusses and add some windows up high- it will make a nice "zen space" with a view and light.
In reply to SV reX :
That's a good point. You probably couldn't if the entire structure has to be stamped. But if you just need engineered trusses figure up the live/dead load on the existing roof and have it as the floor load on sistered Room In attic Trusses . I'm not saying it's "right" but it's within the realm of DIY engineering this way.
And again if your municipality requires stamped plans your in Pay the man hire an architect/engineer.
Fortunately the township doesn't care about signed plans for this kind of thing. I got a permit to jack up the house and replace the foundation, tear out part of a wall and install a wood burning fireplace. I submitted a pencil drawing and when they came for inspection, the guy was signing off on the paperwork as he walked in the door. Never even lifted his head up to see the work.
I don't even need a permit for a detached structure under 800sf, I only have to call zoning once I stake it out so they can verify setbacks. Setbacks seem to be a big deal here. I could likely build a 60' high Rapunzel tower and no one would care... as long as it's more than 5' from the line.
I will also add to this... Not only do I appreciate the input and the drawings, but all of you shouldn't hesitate to reach a point where you say "hey, I get paid to do this." I'm overwhelmed with the generosity, and if you get to a point where you think it should be a paid gig, let me know.
As an artist myself, I am keenly aware of when money should be involved in my work.
OK. You can Venmo me. 
In reply to Curtis73 (Forum Supporter) :
Your welcome, and no money required.
Also, when you dig out the left wall corners to add the new footings, you can underpin the existing corner footings by undermining the corners and pouring a large pad footing under the existing corner to support the girder ends.
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