Adding on a 3rd stall to existing garage

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Old 02-15-14, 08:01 PM
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Adding on a 3rd stall to existing garage

Hello Everyone,
I am seeking some advice on how i can go about adding on a 3rd stall to my existing garage. Unfortunately, the setup of the roof on the current house may make this tricky. When i purchased the home, it had a 2 stall attached garage, and at one point it had a side access door to the outside. Somebody boarded it up before me, so i just put some peg board over it. Now I would like to open it back up and build a single stall addition next to the current garage and make that my primary workshop, adding heat to only the addition. I'd like to do as much of it myself as i can, other than probably pouring the concrete. The tricky part is the location of a storage shed, and the roof line. I have added photos of the space that i would like to use for the addition. I would appreciate any advice or suggestions.

The photo below shows the space that I want to add the extra stall in. The current garage is about 21.5 feet deep from the garage door to teh back of the garage.
The back of storage shed is right at the back wall of the current garage and its entrance faces the backyard, and is inside the fenced in back yard. If it were possible to move it further in to the back yard so the extra garage could be deeper, that would be fine, but I'm not sure it possible or practical. I would love for the new addition to have a single stall overhead door and regular access door both on the front wall, and eventually i'd add a small curve to the driveway to lead to the existing driveway. My main concern is how to handle the fact that the roof line is awkward on the side of the house. Here are a few more pics and I can certainly add more if it helps. I realize its a bad time to get photos cause of all the snow. There is a cement pad from the old side access door on the existing garage that came out right about at the back of the shed.



If anybody can tell me how you would handle the addition and any ballpark costs that would be helpful. Thanks for your time.
 
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Old 02-15-14, 08:29 PM
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A lot of this may depend on how your garage is currently framed... an architect or structural engineer may be needed to come up with a framing plan that won't put any stress on the existing frame that it can't handle.

But here is just a quick sketch of what I would suggest. It's a continuation of the left garage slope up to a new peak, that might be centered on the existing garage wall on the right. The back of the new garage wall would probably best line up with the centerline of the existing gable end that faces to the right. So yes, definitely move the shed!

The setback of the new addition (just a few feet) helps maintain the original look of the two car garage, and also probably makes it a bit easier to frame and trim. As far as the cost is concerned... I would say that it would be a small fortune.

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Old 02-15-14, 08:35 PM
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Thanks for the suggestion. I like the look of that, but i don't like the small fortune part. Seems like in order to do it right i'm going to have to change quite a bit of the existing house rather than just an "add on."
 
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Old 02-15-14, 08:56 PM
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No, it's still an add on. You will just need the help of an architect and/or structural engineer to help you come up with a plan of how to do it. If they approve, it could all be done as a build-over, where you just add new framing onto the existing. I'm not going to take the time to do a materials and labor estimate for you... its not like I'm getting paid to do this... and it is a DIY site, so this gives you something to do. And it does give you a place to start.

If I had to guess, based on maybe an additional 360 sq ft @ $75 sq/ft... I'd say that it would probably run you $25000-$30000 if you were going to have a contractor come and do it. If you did it yourself, you could probably do it all for under 10K. But that's just a ballpark number. It could be lower (closer to $50 sq/ft) if there are no structural issues. Maybe someone like Chandler will have a better idea.

Here's a crude picture of the back side, if it helps you picture what it would be like. Doing it this way gets rid of that valley entirely.

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Old 02-15-14, 09:11 PM
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Again, i appreciate you taking the time to post. 10k is about the range i was hoping to stay in. I am a bit confused on the drawings. I can't really picture what the backside drawing is showing. The initial drawing looks like it's changing the structure of the original roof quite a bit. Maybe i'm not understanding correctly, or perhaps I should have included an image further from the house where you can see more of the existing roof.
 
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Old 02-15-14, 09:20 PM
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The first picture is not changing the structure, it's building onto the existing structure. Sometimes called a build-over.

New picture is the existing back side of the house (your first picture minus the shed) on the right side... and the new garage addition on the left, with the new build over extending to the right over your existing roof. You will notice that in both pictures the new "peak" or ridge, of the roof is higher than the existing peak. That highest peak is the same elevation in both the front and back illustrations.

Sorry if you can't picture it. I suppose it's hard to picture if you haven't done much roof framing.
 
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Old 02-15-14, 09:25 PM
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Yes i get it now. Thanks. Unfortunately I have not done any framing. My girlfriends dad used to frame houses for a living so i'm hoping for his help. Based on your original sketch, it looks like there would be a huge space above the add on. Also, the chimney for the fireplace is in the middle of the family room which is the room right behind existing garage, on the outer wall. So in the photos i posted, it would be about smack in the middle of the shed, so would that cause an issue with your suggestion?
 
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Old 02-15-14, 09:46 PM
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No, I think it sounds like the chimney is in the back half of the existing roof, not in the front half. Even if it is in the part of the roof that gets changed, it's not a big deal.

Here is one last picture from above if it helps you visualize the roof line. Just compare the new with the proposed and note the changes. Each area represents an entire plane. So you will notice how the existing left side of the garage roof just becomes larger and longer in the proposed plan. The peak is higher than previous. The valley is gone. The back side of the proposed garage addition is lined up with the center of the gable end on the right side of your top picture. And then you can see how that creates an inside corner in back... where the front edge of your shed is kind of currently sitting. It would need to be moved away just so that a guy could get in there and work.

One last thing... if that fence on the right represents your property line, you will want to check into how close you can come to the property line with your addition. You may need a variance to build closer to it than they allow... if the local zoning board would even consider it.

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Old 02-15-14, 10:00 PM
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Awesome. Thanks so much for your time in posting replies and generating diagrams. I very much appreciate this. The property line does not represent my property line on that side. My side yard is pretty large. I think there is about 30 feet from the fence to the street. Hopefully i won't have to get any kind of variance.
 
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Old 02-17-14, 06:47 PM
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The only way you'll get Sleeper's roof plan (right side, last sketch) to work is if the gable lines have two different slopes, making things look awkward. The new (add-on) ridge line has to be midway between the two exterior walls (original on the left, add-on on the right) for the slopes to be the same. His first sketch appears to show a 2/3--1/3 configuration, implying that the add-on will be approximately one-half the width of the existing garage, or 10' wide. For both gable slopes to be the same, the add-on will have to be the same width as the existing garage, or about 20' wide.
 
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Old 02-17-14, 06:51 PM
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None of that is to scale or drawn with the correct pitch. It was a fast sketch on MS Paint. The intent was to have the exact same pitch on the addition as on the original. By having a taller exterior wall on the far right side of the picture (as I tried to depict in the first illustration) and maybe 2x the amount of side wall on each side of the addition's garage door, that bay of the garage would not necessarily have to be 20' wide. In my mind I was picturing maybe 15 or 16' wide. (4+7+4) Didn't take the time to draw it to scale to see what would look best.
 
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Old 02-17-14, 07:53 PM
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Out of curiosity of what it WOULD look like, drawn to scale, here is a picture. In the 1st computer drawing I posted, I tried to depict the addition wall on the right as being taller than the existing (since it would obviously HAVE to be) and on the 2nd computer drawing that depicts the back side, I again tried to depict that wall as being taller than the existing... but it was obviously not to scale, and I tried to include some perspective, which was probably not helpful.

So here is a straight on elevation that *is* drawn to scale, but I had to assume a few things that were not provided. (front garage measurement of 21'... sidewall measurement of 8'... roof pitch of 4:12... and I also assumed that the garage gable and house gable are at the same pitch and are the same total height.)

This proposal as drawn would make the addition roughly 16' x 22 1/2'.... which is how I came up with the 360 sq ft earlier.

Bridgeman is right that the top view of the roof (bottom right side picture in post #8) is way off on scale. The garage bays are drawn as if they were 10.5/10.5/10.5 when it should have been drawn as 10.5/10.5/16.

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Old 02-18-14, 03:02 PM
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bdawg8569,
I am in the planning stage of a similar project and I think we have the exact same challenge. My house looks just like yours. See pic of my house below.

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Only difference is that my garage addition will tapper at the back end slightly since my lot is pie shaped. But the roof line designs would be similar.

In my town I don't believe I need an architect since it's just a garage with no plans of a 2nd floor. I plan to be the general contractor on my project.

Here's my first pass at the roof, "NOT TO SCALE". It's basically an offset gable roof (one side will be at a different pitch so I don't interfere too much with the existing roof over my family room). Only problem I see is that it creates a small horizontal valley where the roof over the existing garage, new garage, and family room meet. roof over the garage addition is in brown color. Front of the house is to the left.

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Maybe someone can suggest how to eliminate the horizontal valley. I figured I could fill it in and pitch it down a bit.
 

Last edited by Shadeladie; 02-21-14 at 09:45 AM.
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Old 02-18-14, 06:07 PM
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You could eliminate that horizontal valley (which I suspect you already know will be prone to leakage, over time, regardless of how much you try to "fill it in and pitch it down" to drain), by orienting the new roof in line with your existing gable, just like Sleeper suggested to the OP for his addition. Your proposed gable is at right angles to your main roof's ridge, instead of tying into it in the same orientation.

Before you get too far along, you might want to inquire with your local AHJ regarding their minimum side-yard setback distance. The aerial photo makes it look as if you'll be extremely limited on the width of your addition (even with the taper at the rear), without encroaching on even just a 5' setback from your neighbor's property line.
 
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Old 02-20-14, 11:22 PM
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I found a way to eliminate the horizontal valley and make the roof over the garage addition a little more subtle. With *******I was able to scan in my plat of survey, scale it and draw my addition right on my plat to scale. With the 3D feature I was able to play with the walls and roof design.

Here's pic of the plat with garage drawn:
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Here are few 3D views. Note I have to tapper the backend of my garage to fit within my lot lines. This resulted in having to raise the walls a few feet in the rear of the addition in order to keep the roof all on one plane. Disregard the red triangle shooting out of the roof, I'm still learning how to use this SW.

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So for your situation I think you can use the same roof design.
 

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Old 02-20-14, 11:59 PM
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Is it just me? Or have you really replaced one short horizontal valley (parallel to the front of the house) with one very long horizontal valley perpendicular to the front of the house? That space at the bottom, between the blue and red roofs, sure looks like a horizontal valley to me.

And have fun with the roof framing, on the tapered rear of your addition. Could prove to be a challenge, making it look "not awkward".
 
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Old 02-21-14, 09:24 AM
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I don't think there are any horizontal valleys, the blue and dark red roof meet at the same ridge, no higher than the existing roof over the 2 car garage. I just backed the red roof off a bit to show the lines of the existing blue roof and how the new roof would share the same ridge. I just added a hip roof design (shown by the light red roof) to soften the roof.

The back end of the addition is not ideal, but no one will really see it from the back yard. It should create an interesting ceiling in the garage though. And this allow me to make the addition bigger.

If you want to have a gable end you can take the point where the blue, red, and light red roofs meet and bring it forward creating a gable end. Very similar to XSleepers idea, but smaller in scale and at a lower pitch.

I also tried lowering the ridge of the new roof so it's balanced with the existing porch roof on the other side of the 2 car garage, but the pitch is even lower and I might be getting a head of myself here. At this point I would need to make sure the pitch is not too low.
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Old 02-21-14, 10:04 AM
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OK. Now that you changed the sketch a bit (by lowering the intersection of new roof to existing), I see what you want to do. Your original version showed what appeared to be two separate gables and ridge lines at the same elevation, but now the red one appears as a low-slope hip. Don't think I would do it, as you will be creating something that will always (very obviously) look like an addition. And I've never cared for the "cluttered" look of mixing hips and gables on the same structure. Good thing we all have different tastes.

Keep in mind that set-backs are always measured to any projecting part of a structure (meaning roof overhangs), and not to the wall or foundation lines.
 
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Old 02-21-14, 10:42 AM
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Great point to make about the overhangs. I set them just shy of the 5' set back so the walls are more like 7' behind.

I will keep playing with the design, hopefully this gives bdawg8569 some ideas.
 
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Old 12-17-14, 12:58 PM
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Hi bdawg8569 and everyone else,

I wanted to update everyone on how I solved a similar issue with added a 3rd car garage and how I tied it into the same kind of roof line.

Note that my garage tapers at the end since I had to follow the lot line setback, but creating a traditional rectangle shaped garage would have the same roof line.

Let me know if anyone wants any more detail.
-MIFW

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Old 06-13-16, 08:53 AM
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Future follow up question on this topic.

Did anyone go through with completing this project? And if so what we're the construction costs. Thanks! Looking at possibly doing this in the future.
 
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Old 05-21-17, 09:33 PM
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I can see by the page views that this a hot topic. Since each application is very involved it's important that each member has his own thread. Please feel free to start a new thread with your question.

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