24' wide 1.5 story

[dablack]

Ok, I have already bought the 2 story plans and we will be building that later.  First we will be building a "garage" to live in.  20' wide for a garage just isn't going to cut it.  I want to go 24' wide and put in a center support beam with support posts between the "bays".   Right now I'm thinking 24' by 51'.  I'm thinking 9' doors with 3' between doors and 3' between the end of the corner doors and short walls.  So, that means three support posts.  The two posts closest to the walls will be 13.5 from the wall.  Then the center post will be 12' from the other posts.  Upstairs will be three bedrooms and a bath. 

So, my questions is, if I balloon frame, how tall could I make the upstairs wall if I go with the site built trusses (assuming the site built trusses will span the 24').  I'm ok with putting in some kind of center support in the upstairs if that would help.  Also, I'm not stuck on the site built trusses.  I would gladly do rafters or whatever. 

How about it?

thanks
Austin

[MountainDon]

So let's see if I understand this correctly. You want to build a 24 ft wide x 50+ long structure based on the 20x30 1 1/2 story?   Using what type of foundation? A perimeter foundation with concrete footers approx 12" deep, and a concrete slab for the entire floor, or something else?  And more questions, are there inspections and have you checked what the local soil conditions dictate for the foundation?

24 ft wide would be easiest built using factory made roof trusses and attic floor trusses. The roof trusses can be designed to provide space upstairs. A factory truss would be engineered contain all the roof loads within the truss and therefore not place any outward stress on the side wall tops. The would also preclude the need for interior load bearing walls or piers/posts. I, for one, would not want a garage in particular that had posts in the middle unless there was no way around it. That's just my opinion on that.

The end wall where double garage doors would be placed needs some special considerations with respect to a proper braced wall system. The doors remove almost all the structural sheathing and that loss should be made up to retain performance of the end wall under conditions of high winds, and I believe your area can get some. It can be done; there are prescriptive designs in the IRC that can help with that. Or a design professional.

[John Raabe]

Yes, it would help if you could provide a sketch of what you are envisioning.

If you want you could modify the main floor of the Universal plan with the center line beam for a 24' wide building. There would need to be posts at the garage level below as you suggest. Alternatively you could use full span I-joists or floor trusses for the 24' wide span.


You will need some local help sizing this floor system and the supports and foundation plan. If you only need the main floor above the garage for living space, I would suggest what Don has mentioned - full span attic or another type of roof truss (such as scissors or sloped trusses). For maximum living space (and ease of construction) you would place these on a full height upper level wall platform-framed on the floor (rather than balloon framed from below). These trusses would eliminate the need for a beam and posts in the upper living area. You will likely need extra hold-downs and bracing at the corners, as Don mentions, since you will not have much room before the garage doors eat up the end wall. There are standard details your inspector may have available for this.

[dablack]

MD,

As always, thanks for the help.  It will be a concrete slab foundation similar to the one used in the 2 story plans with the support posts in the middle. 

There are no inspections and we are on mostly clay and rock up on the top of the hill.  We will have zero water problems.  It is all down hill from where we are. 

I can't impagine factory trusses leaving me enough space to have bedrooms and a bathroom upstairs.  Plus, I don't mind the posts in the middle of the garage at all.  I actually like it breaking up the space a little. 

I won't be putting double garage doors on the short walls.  I will be putting four 9' garage doors on the long wall.  That is why there will be three posts seperating the four "bays".  In the begining, that lower area will be the living and dining area, with kitchen along the long back wall (oposite of the garage doors).  Also, I'm not going to be putting in the garage doors, but I will be framing for them.  We will be living in the garage while we build the two story.  Once the two story is done, we will put garage doors in the garage and the upstairs will become a MIL suite plus storage. 

thanks
Austin

[John Raabe]

I see I have also visualized the doors on the shorter end walls.... Never mind!

[dablack]

John,

Thanks for the info.  I will have to look into the attic trusses more.  I really don't want this building that tall.  I'm really trying to keep it smaller looking (I know 24 by 50+ isn't exactly tiny on this site).  If scissors or sloped trusses can be used that would be nice but probably too expensive for me. 

Who should I be contacting for finding out about the different type of trusses and getting bids?

thanks
Austin

[John Raabe]

Call the local lumber yard you use and they will have a truss supplier who will probably do a free initial layout.


If you want trusses that would sit on a shorter wall (such as a 4' or 5' sidewall), they can likely do that as well. That would lower the roof peak.

[dablack]

If I put it on a 4' side wall, could I still balloon frame and then use a let in for the 2nd floor?

[MountainDon]

Nine foot doors in the side load bearing wall will need some very hefty headers; probably 4 - 2x12 for each door opening. And that is without any considerations for any unusual loads from the upper floor or roof. Plus the footing is going to be subjected to heavy loads under the narrow walls between the doors and at the ends. You will need more than just a pos between the doors for that. Engineering advice might be suggested.

You mentioned clay soil. If your soil is at all similar to that in Dallas, if this was me, I would seek the services of a soils engineer or geotech. The Dallas phone book is full of contractors that specialize in foundation repair. I think that says something about the possibility of foundation problems, especially with uneven wall loads. Easier and cheaper to be sure it's done right in the beginning than to make repairs later.

If this is going to be a garage, utility building in the end have you given any thought to a steel building? A friend of mine found that was quite cost effective for his garage / workshop. No interior posts anywhere, with a ceiling/roof height of something like 14+ feet. Just a thought.

[Bob S.]

   Have you seen Mikkelibob's metal cabin? You moght look for (metal Building Weekend Cabin) in the owner builder forum.
   As mountindon suggested something like that only bigger might work for you.

Bob

[dablack]

Thanks guys, but metal building are not for me.  The whole point of this is to build it myself with wood.  Yes, I was planning on beefing up the foundation under the long garage door wall.  Yes, a 9' door will require a large header as most garage doors do.  The rent house we are in right now (moved up to Lufkin from Houston last year), has a three car garage and the doors are on the long wall as you might assume.  I have been checking it see how it was done. 

I'm more concerned on the truss or rafter issue.  I was really hoping to get all this done without any engineered lumber.  There is no snow load where we are and we will have a metal roof.   Also, I can have support post upstairs and down.  We have plenty of room to build around those.

thanks
Austin

[John Raabe]

You have the potential of a ridge beam down the center of the 24' wide structure that would allow for a full cathedral ceiling with ridge beam posts going down to footings in the garage floor. Then the floor joists can likewise sit on a beam and you can use 12' span standard 2x lumber for joists and rafters. No engineered wood or trusses involved.


The floor beam carries the floor loads and the ridge beam carries the roof load. Both will need to be sized for the span and load.
The spacing of the support posts will be important to your design. You might use 6x wood beams or glulam beams sitting on 6x6 posts.

[Don_P]

Let's look at that 24' first. The walls will take a foot off of that and the door a few more inches, then a foot or so at each end of a vehicle... what are you planning on putting in there and will it fit? Just sayin, I built a 24'er once for a fellow, his design, and then he went to pull his lead sled in. It fit with 2 folks waving him in but I'll bet that back wall took some damage over the years.

Nine foot walls leave room for normal operators, again look at what goes in there, my truck won't go in a 7' tall door.

With open web or I joists the 24' can be spanned without interior posts and you could stick frame rafters on top. If you want more room up there I'd look to cantilevered attic trusses. From there you can start popping dormers out for more room if needed.

Back to the first question though, is 24' really enough?

[dablack]

Don,

Is 24 enough?   Well, is any garage really ever big enough?  I'm sure I will fill it but the garage we have right now is 25' deep (outside dimension) and everything fits fine.  My Mercury Grand Marquis is 17.5' long and my wife's explorer is 16.5' long (just ran out and measured both).   So, it looks like we will be ok.  Even in the garage we are in now, we have 3' deep counters at the back wall.  I'm thinking we will most likely have something similar in the new garage (once it is a garage and not a living room).  Would deeper be better?  Sure, but I'm not sure it is needed.  We are on 30 acres.  If I want to build an open pole barn to put a roof over larger things, that wouldn't be too difficult.  I don't want to build this thing so large that we can't finish it with the cash we have.  Also, I think you are 100% correct that the lower floor would need 9' walls.   Thanks for reminding me.  This thing needs to be designed as a garage and then lived in, not a house that is then converted into a garage. 

John,

The ridge beam sounds like a good idea and I know I have seen other builds in the build forum where people have used that to keep their ceiling open where they don't have a loft.  I will have to look into a glulam beams but could I build a beam like the beams used for the foundations on the pier and beam foundations? 
I'm thinking for spacing, since the beams downstairs would fall between bays, from the "east" wall to the first post would be 13.5'  (wall to edge of bay = 3', bay is 9' wide, other edge of bay to post = 1.5'), then from the east post to the next would be 12', then from that center post to the west post would be another 12', then from that west post to the wall would be 13.5' again.  So, our spans would be 13.5', 12', 12', and 13.5'.  How does that sound.  How do I calculate the size of the beam?  I was already planning a 6x6 for the posts.  Yes, I know I need to post some sort of picture to show what I'm talking about.   

Also, guys, thanks for the help.  This isn't some "maybe someday thing".  Once I get this nailed down, I can finish planning the slab, get bids and start.  We have some cash saved up, we have bought the land and we are eager to get started.  You will get to see pictures of all this built in my project forum under my Rusk build thread. 

thanks
Austin

[dablack]

Ok, tons of ridge beam info on here.  I did a search and found the calculation part here:  http://countryplans.com/smf/index.php?topic=9544.msg122692#msg122692

Now I just need to find out if I can build one of these myself or have to buy one (or some).

thanks
Austin

[dablack]

Last post of today.  Did more research and it looks like home made glulams (glued laminated beams) is not something one would do.  I don't think I want to try and move a 51' long beam, I will see if there is any loss of performance if two or four of them are spliced together over the supporting post.  This week I will calculated the roof load and figure how big of a beam I'm going to need and then figure out how much it is going to weigh.  My day job is a design engineer for a large gear company.  I'm the nut that likes to figure out why the computer says a certain number.  I just like to know and run my own numbers sometimes.  I think it is actually fun to calculate how big of a beam I need.  With that being said, if someone wants to give me a number to check against mine.......cough, mumble DON mumble, cough..............then that would be fine too. 

Thanks guys.  This is getting really exciting. 

[John Raabe]

For your floor load you can use 40 psf live and 10 psf dead load.

For a lightweight roof use 10 psf dead and whatever your snow or live load is. This will give you a general beam calculation that can be checked with the local powers that be. There may be wind and bracing issues in addition to these downward loads.

[Don_P]

I was doodling in a little different direction, see if there is anything of use and redirect.

this uses 16" I joists with no posts below. The rafters are drawn as 2x8  here which is about the minimum but think about how you are insulating. There is no ridgebeam since the rafters tie to the floor. The room is about 14' wide of 5' or greater headroom. You can see the hint of a dormer I was playing with on the backside. In this version I'd check the garage door headers for 10,000 lbs

[dablack]

WOW DON!  You just blew my mind.  I would have never thought of that.  That would surely make things simple.  How far will 16" I joist span?  Since I would be losing four feet of "living space" compaired to having a 2' pony wall, I would most likely like to make the garage 26' deep to make up for about half of that.  I'm going to have to lay all that out and see if it would work.  I want all three bedrooms upstairs to have a window and that would mean putting them in the corners so they could have a window on the gable wall.  HMMM!  I'm going to have a tough time sleeping tonight.  It is basically a 1 story with an insulated "attic".   

[John Raabe]

Interesting model Don!

Simple, relatively inexpensive and adaptable.

[Don_P]

The 16" joists can go 26'... 14" joists will actually work on the 24' span but were getting close so I bumped up a size.

Don't forget that in this and all future renovations, you cannot exit the habitable area above through the potentially burning garage... the stairs need to be enclosed and lead you out.
The ceiling of the garage needs to be 5/8 type X drywall. Any penetrations between those areas needs to be protected.

[dablack]

Thanks for the reminder on the stairs.  My father in law lives in an above garage apt at the eldest SIL's house.  I've noticed that he can come down the stairs and go outside or into the garage.  I will build it where the stairs are mostly enclosed while the lower is still living area, then when the lower becomes an actual garage, I can finish enclosing the stairs.

I just picked up 3D Home Architect Version 3.  It looks like it is time for me to learn to use it.  The way I have the upstairs laid out right now would probably require a centered shed dormer to let light into that area. 

I really think this one story plan is the way to go.  I just need to lay it all out. 

thanks
Austin