What building technique for a attached garage?

[Timf1981]

I would like to build an attached garage.


Roughly 26'w x 30'deep. With 14ft garage ceiling with living space above with 8 foot walls.


I live in Minnesota, so deep footings.


I would like to possibly do as much work myself as possible.


I would like if possible to not have any supports or interior walls in the garage area. But I will do what I need to do.


To get started. What type of garage wall construction is needed to support a living space above and a snow load?


I can think of three construction methods.

1. Wood frame..I have never framed anything taller the 8 ft.

2. Block... I have never done block. But I would not be in a hurry.

3. Interlocking Styrofoam forms with poured concrete ... I have not done this before. There are some very good videos. I suppose I could come right off of the footings with this.


Exterior walls capped with 26 or 30 ft trusses. Unless some interior garage walls or beams are recommended.


Price and ease of construction are main priorities.

The roof trusses is something over my capabilities and will definitely hire out.


All ideas welcome.


Thanks...

 

[mike93lx]

Tons of ways to do this, but most importantly, that is not a back of the napkin building. You want this engineered and designed, regardless of permitting. Clear span over those distances is not impossible, but it isn't something you slap together.

My approach might be 2ft of block, 2x8 walls (strength and insulation), and floor trusses for the 2nd floor. If you can give up some space upstairs, attic trusses could save a lot of money and not make the building look like a high rise

 

[Garcky]

That's a very ambitious DIY project. First step would be to talk to an architecture engineer, really. It's not a standard building, and will have to be carefully designed. Having the lower floor unobstructed is the real challenge. It could be done, but building it yourself might be very difficult. You could start by doing a tentative floor plan drawing to show the architect or engineer. That way, you'd get a better idea of what you want and it would be a place to start.

It's not going to be inexpensive and easy to build, I'm certain.

 

[duneslider]

Getting 26' for the floor above with no supports will not be super easy. You will want to check with the truss company about floor trusses, that might be your best bet. Or a big steel beam to run down the middle to to cut the span to either 15 or 13 depending on which way you want to run it. You are going to need an engineer for this building no matte what so just work with them to figure out the best way to make that upper floor. You might be able to get away with some really deep I-joists like some 16-24 deep to span 26'. I've just never done more than 20' before.
Attic trusses will be less expensive than a full second level but not sure if that would meet your needs. My garage is 24.5' wide and I have a 13' wide room above with the attic trusses.

 

[K'ledgeBldr]

I would like to build an attached garage.
Attached to what?

Roughly 26'w x 30'deep. With 14ft garage ceiling with living space above with 8 foot walls.
Will this tower over whatever it's attached too? Is there an AHJ? Is there a HGT restriction?

I live in Minnesota, so deep footings.
And, what about snow load?

I would like to possibly do as much work myself as possible.
If you think you're handy- leave the building to a GC. Save the inside stuff for yourself.

I would like if possible to not have any supports or interior walls in the garage area. But I will do what I need to do.
With a correctly designed "attic truss" you should not need any "mid-span" supports.

To get started. What type of garage wall construction is needed to support a living space above and a snow load?
It would require 2X6 studs

I can think of three construction methods.
The construction method "used" is what your wallet can afford! Because "you" are not doing the foundation, framing, roofing...
1. Wood frame..I have never framed anything taller the 8 ft.

2. Block... I have never done block. But I would not be in a hurry.

3. Interlocking Styrofoam forms with poured concrete ... I have not done this before. There are some very good videos. I suppose I could come right off of the footings with this.


Exterior walls capped with 26 or 30 ft trusses. Unless some interior garage walls or beams are recommended.
Previously mentioned...

Price and ease of construction are main priorities.
As previously mentioned...
The roof trusses is something over my capabilities and will definitely hire out.
Again, as previously mentioned...

All ideas welcome.


Thanks...

Answers in Blue!

 

[Timf1981]

Getting 26' for the floor above with no supports will not be super easy. You will want to check with the truss company about floor trusses, that might be your best bet. Or a big steel beam to run down the middle to to cut the span to either 15 or 13 depending on which way you want to run it. You are going to need an engineer for this building no matte what so just work with them to figure out the best way to make that upper floor. You might be able to get away with some really deep I-joists like some 16-24 deep to span 26'. I've just never done more than 20' before.
Attic trusses will be less expensive than a full second level but not sure if that would meet your needs. My garage is 24.5' wide and I have a 13' wide room above with the attic trusses.

Thanks for the three replys above.
I will add some pics of what the house was like when I moved in. And what it looks like now.
The house without the garage stalls is 30x30. I took off the old roof and put 30ft trusses across front to back. Put in the floor and hire a guy to put the walls and trusses. I took care of the rest. But that was 25 years ago.
I currently have two small tuck under garage stalls with 7 foot ceilings. And I getting to old (60) to work in cramped quarters. I picked up old 9 ton two pole lift real cheap but no place to put it up.
I have recently visited two acquaintances with spacious garages and left in envy.

The basement has 7ft ceiling plus 10 or 12in floor joist. Main floor 8ft. Then 20in floor trusses. Top floor 8 ft walls..So about 26 ft high to the top of the top floor walls.

So with 14 foot walls and maybe 2ft trusses the 8 foot walls on floor above garage (which I have no real plans for that space. It will have nice views if the wooded swamp land behind us.)
So 24ft from garage floor to top of space above garage.
So if I add windows to the front of the garage at the same level the main floor.
No one will know there is a tall garage.

 

[racecougar]

I would like if possible to not have any supports or interior walls in the garage area. But I will do what I need to do.
With a correctly designed "attic truss" you should not need any "mid-span" supports.

The concern is the 26' floor span (2nd floor) w/o any support beneath in the garage.

 

[619DioFan]

You should take a look at a YouTube channel called " Kens Karpentry" he specializes in building garages. Lots of great info on his channel.

 

[75gmck25]

If you want to span 26', and want to have the 2nd floor support structure short enough to allow for a floor above, it seems like you are in the steel beam category.

Manufactured wood beams are taller or thicker to support that big a span. If you google for manufacturers, most of them have the specs online for spans and how tall and thick the beam has to be.

 

[Timf1981]

Tons of ways to do this, but most importantly, that is not a back of the napkin building. You want this engineered and designed, regardless of permitting. Clear span over those distances is not impossible, but it isn't something you slap together.

My approach might be 2ft of block, 2x8 walls (strength and insulation), and floor trusses for the 2nd floor. If you can give up some space upstairs, attic trusses could save a lot of money and not make the building look like a high rise

What do you mean by "attic trusses"?
I would definitely go with pre built roof trusses.
I believe I have a 4/12 pitch. We live in an old neighborhood. Only one newer house has the steep roofs
The new addition won't be any higher then the existing house.

Thanks...

 

[billconner]

Foundation - footer below frost, stem walls, and slab on grade OR Frost Protected Shallow Foundation - a thickened edge slab with foam under and extending out about 4'.

Walls - I'll assume garage is to be insulated and heated so that leaves block out as hard to insulate. ICFs are great but expensive and needs an experienced crew. Stick frame makes sense and is diy-able. I'd go 2x4 16 oc with 2" of continuous insulation on exterior except limited to 12' without an engineer. I'd lean toward 2' of ICF and 12' 2x4 walls on them, and probably leave the thicker ICF exposed inside.

TJIs for second floor. 2x4 walls for second floor. And roof trusses.

I like the attic truss but much better with a much steeper pitch than 4:12. 14' + 1'-6" + 8' + 4'-6" for trusses is around 28'.

Can you access upstairs from existing house or need a stairs in the new garage? Beware you can't egress from upstairs living space through garage - has to be separated by a wall with drywall. Stairs are big space eaters - try to use existing house - but beware second floors seem unlikely to align.

I don't think the design is beyond diy but it's definitely advanced diy, with ability to go through the residential code. Partnering with a builder might work, they frame and sheath with windows and doors, along with permit, you side and finish.

 

[mike93lx]

What do you mean by "attic trusses"?
I would definitely go with pre built roof trusses.
I believe I have a 4/12 pitch. We live in an old neighborhood. Only one newer house has the steep roofs
The new addition won't be any higher then the existing house.

Thanks...

Just Google attic truss and you will see. It creates a room inside the truss. That said, it won't work in a 4 pitch roof, so forget that idea

 

[Timf1981]

Foundation - footer below frost, stem walls, and slab on grade OR Frost Protected Shallow Foundation - a thickened edge slab with foam under and extending out about 4'.

Walls - I'll assume garage is to be insulated and heated so that leaves block out as hard to insulate. ICFs are great but expensive and needs an experienced crew. Stick frame makes sense and is diy-able. I'd go 2x4 16 oc with 2" of continuous insulation on exterior except limited to 12' without an engineer. I'd lean toward 2' of ICF and 12' 2x4 walls on them, and probably leave the thicker ICF exposed inside.

TJIs for second floor. 2x4 walls for second floor. And roof trusses.

I like the attic truss but much better with a much steeper pitch than 4:12. 14' + 1'-6" + 8' + 4'-6" for trusses is around 28'.

Can you access upstairs from existing house or need a stairs in the new garage? Beware you can't egress from upstairs living space through garage - has to be separated by a wall with drywall. Stairs are big space eaters - try to use existing house - but beware second floors seem unlikely to align.

I don't think the design is beyond diy but it's definitely advanced diy, with ability to go through the residential code. Partnering with a builder might work, they frame and sheath with windows and doors, along with permit, you side and finish.

In m

 

[Hank11]

You should take a look at a YouTube channel called " Kens Karpentry" he specializes in building garages. Lots of great info on his channel.

Definitely look at this ^^^^^^^^^^^^^^^.
You sound like a guy who needs a gambrel roof shop.

 

[mike93lx]

You should take a look at a YouTube channel called " Kens Karpentry" he specializes in building garages. Lots of great info on his channel.

I've watched a lot of Ken's videos and there may be some general building advice in there for sure, but he doesn't really do attached stuff and definitely doesn't do stuff like floor trusses or really tall stuff

 

[Timf1981]

I am in Minnesota so footings 36-48in down.
Current roof pitch is 4:12 so I will probably match it.

? 2x4 garage walls , 12 ft on top of two foot kneewall. with fiberglass insulation then 2 in solid pink foam on the outside.

How far can tell span?
Floor trusses would be difficult to insulat unless spray foamed.

Frost protected foundation? I will need to look that up.

2x4 for second floor walls. It may be difficult to meet minimum R value.

2x4 for garage walls? Will it hold the weight above? Yes. This will need to pass inspection. So an engineer will get involved. I currently have no idea to contact for engineering. I prefer to understand and plan as mutch as possible before leaping.

I may want to go up some stairs in the garage for easy access to kitchen and living room. If not, then go directly into basement from the garage through existing door.
This house has been added onto many times. In 1956 it was a 30x30 flat roofed house. The basement floor is actually 6 inches below the garage floor.

We paid $75,000 . 31 years ago. 40 acres of wooded swamp land / city owned behind us. No neighbors to the west.

Yes, second floor will not align. Probably off by 4ft. Could be an opportunity for some unique architectural design.
Maybe a fire pole

I dont think a support pole in the middle couldn't be worked around.

Where would you want foam board under the slab? Did you want it extended out 4 feet from the walls?
35 years ago in trade school I did some heat load calculations and remember a little bit about heat transfers down and around.
Thanks again to everyone

I knew this was going to be a crash course with nothing being finalized.

Any free/cheap easy to learn house designing software you have experience with?

 

[Timf1981]

Any free/cheap easy to learn house designing software you have experience with?

 

[Timf1981]

Definitely look at this ^^^^^^^^^^^^^^^.
You sound like a guy who needs a gambrel roof shop.

Roof line goes east west. Front of house and garage doors face North.
Current roof is 4/12.
I dont think a gambrel roof fits in.
And with tons of insulation in the ceiling. So no real usable attic space gained . Unless I am missing something. Which is not out of the question

 

[Timf1981]

Just Google attic truss and you will see. It creates a room inside the truss. That said, it won't work in a 4 pitch roof, so forget that idea

I might be able to go a little steeper. And if I do go with a 4/12 roof. I might be able to go with 10 foot walls to make roof lines match. I am not sure if I want to make the match because failure is always an option. Plus I will probably go with a 12 inch energy heel on the roof trusses to prevent ice dams.

Are you suggesting attic trusses for storage space above?
What minimum pitch would make sense for attic trusses.

The half of the house (top floor) touching the garage is a 30x23 foot vaulted ceiling play room.

 

[mike93lx]

I might be able to go a little steeper. And if I do go with a 4/12 roof. I might be able to go with 10 foot walls to make roof lines match. I am not sure if I want to make the match because failure is always an option. Plus I will probably go with a 12 inch energy heel on the roof trusses to prevent ice dams.

Are you suggesting attic trusses for storage space above?
What minimum pitch would make sense for attic trusses.

The half of the house (top floor) touching the garage is a 30x23 foot vaulted ceiling play room.

I was suggesting attic trusses for an option to create the space for the second floor. But unless you go steep, like 10/12 pitch, you wont have room and you lose floor.space from the roof

 

[billconner]

How far can tell span?
Floor trusses would be difficult to insulat unless spray foamed.

Frost protected foundation? I will need to look that up.

2x4 for second floor walls. It may be difficult to meet minimum R value.

I think these are questions. Generally 2x4 with R13 and 2" of foam exterior is accepted as equal to R25 - at least around me on St Lawrence River. I'd guess as cold or colder than MSP.

FPSF may or may not be simpler than deep foundation but if insulating under slab anyways so it may save money.

second floor with R13 in wall cavity and 2" foam continuous insulation.

Implicit in my suggestions is trying to comply with the prescriptive requirements of the residential code, and this not require an architect or engineer. If you do retain a registered design professional, than they are likely to have other options and preferences.

 

[billconner]

Just to confirm I think you are in zone 6 like I am. R13 + R10 continous or R20 + R5 continuous. Basically high performance batts in either 2x4 or 2x6 and than 2 or 1 inch of foam. The costs will not be hugely different. I think the 2x4 with 2" performs better plus 2" extra space all around.

As far as second floor, if heating garage than no insulation required. You may want some for acoustical reasons. Or put in R30 Batts between TJIs. 5/8 gypsum ceiling required usually.

 

[dmittz]

you defnietly need to get a building like this designed and engineered. I suspect that will all be required when you apply for permits. Part of that will involve a geo tech report to determine the bearing capacity of your soil which effects the design of the footings in your foundation. A 26ft clear span with living space above is doable but requires significant planning.

On my shop i've got a mezzanine level that is 24ft x 32ft I have a bathroom and stairs at the back of the lower level so the clear span area is 24ft wide x 25ft deep. My foundation footings were massive under where the weight rests. 2 PVL beams (I think) were used with floor joists tied into them and into the one side wall with a ledger. My beams measured about 27ft long, 5.5in wide and 24in tall. each one weighted about 1300lbs. So the structural beam required for clear span is significant, its not a trippled up 2x12 type of thing

Again, I'd highly recommend have and architech and engineer design your building.

 

[billconner]

Timf - in my experience - designing and constructing buildings - you need to be able to work in drawings and you need to be able to read and understand the residential building code for your jurisdiction. If you can do that, you can design, get a permit, and build this, either all your own labor or some and some hired.

If you can't, then you need to find/hire someone to design and provide documents for permit. Contractors can often do that, with varying good design sense ability, or hire an architect as dmittz suggested.

 

[Slednut]

I actually did a 26x30' addition to my 26x26' existing attached garage. Here's the plan for the garage ceiling, the blank space on the bottom right are the stairs to the second story. The thing sticking out the top is a cantilevered deck.