Been dreaming, finally starting, need advice on loads

[bigburb]

Hi everybody, I've trolled these forums for a couple of years now and have always drooled over some of the great garages I see. A few months ago my wife and I bought 2 acres outside of Houston and it looks like we'll start to build next year sometime. My wife has also (graciously) agreed to live in a garage apartment while we build the house, which means the garage gets built first!

I've doodled around a little with sketchup and we think we've come up with a plan that works for us. Its a 30x36 w/ a 1 bedroom apartment on top, 9 foot wide doors, and a 10' ceiling inside the garage. I wanted enough room for a 2 post lift but I couldn't make that work with the living space on top.

Anyways what I'd like to know is how to go about finding out the lumber dimensions I need use for floor joists, roof rafters, headers, etc. This is serious stuff and I know it has to be right. Would this be something an architect does? Structural engineer? Lumber yard?

 

[bigburb]

Thought I attached some pictures, did they come through?

 

[yucholian]

2009 International Residential Code. Go and buy a copy and follow the design requirements. That's if you really want to do it yourself instead of hiring an engineer architect. I found it easy to decipher myself.

 

[PittsS1]

Agreed on the IRC book. I bought it for my remodel and garage build, and it was money well spent. From the looks of your garage, most of it is pretty typical simple span stuff, for which there are tables for various species of wood, etc.

Another good place to look is the manufacturers for headers and the like. Most LVL companies will publish guides for the exact situation you have (i.e. header with floor load above) and you can read right off the charts. I have used the MaxLam LVL Guide, GP Guide, Boise Cascade, etc. This goes for the I-joist and truss joist manufacturers as well. Worst case, you can have the place you are buying the materials spec it for you, but I personally like to know where the sizes/numbers come from.

If you really want to get in depth, I was able to find the USDA "Wood Handbook, Wood as an Engineering Material" guide online- 486 pages of information. Most people wouldn't hire an engineer for a garage build like you've shown (and I'm an engineer), because the span tables, etc., have been developed for many decades to allow for common practices.

Good luck!

 

[Old Moparz]

In addition to the above info, it could be worthwhile to consider buying an inexpensive set of garage plans similar to the building you want. I did it to help get a better idea of how I was going to draft up my own. I got them from a lumber yard for like $15 or so, & used it as a guide line.

You should also consider speaking to a professional about a few things prior to any actual work. When I was planning my garage 15 years ago, I had asked an architect, a friend of my boss, about what was needed as far as having a licensed architect sign & seal plans. He told me that in the state of New York where I am, an "accessory building" (garage, shed, etc.) under 1500 sf didn't need it. You may want to verify what's needed where you are before diving into a design or the architect you end up with may not want to sign off on something that they did not design.

If I were planning the same set up as yourself in NY, I'd be concerned that part of the garage will be used as living space & not considered an accessory building. It may have different building requirements.

 

[K'ledgeBldr]

What's the planned use of the "apartment" after the house is built?
Will the garage be attached? If so, will the "apartment" be accessible from the house?

The amount of usable sq/ft for the apartment would be approx 780sq/ft total. Do you think you could sacrifice about 300 of that for scissor trusses over an end bay? Granted, <500 sq/ft isn't a whole lot of space for everyday living, but remember it's only temporary.

 

[805gregg]

Get an architect or designer, they will solve the engineering for you.

 

[Cheap5.0]

My parents garage looks almost identical to it, except theirs is 30x40. They did theirs about 15 years ago, and at the time totally finished out with concrete and dry wall it was about $20k.

 

[bigburb]

Thanks for all of the excellent recommendations. Looks like that book would be a good investment, 80 bucks on amazon.

moparz - In my area there really aren't any strict requirements, I need to pull a permit to build and for septic, but as far as I know no inspections, stamps or anything are required (it is quite rural). $15 bucks sounds like a good deal, garage plans online are considerably more than that!

K'ledgeBldr - It will likely be a standalone apartment after we move into the house, probably for guests or family members staying over. We definitely need all of the space that is there, but I'm thinking about designing it so I can easily raise the floor joists above one of the bays should I get a 2 poster in the future, turning it from a 1 bedroom to a studio apartment.

Since it is technically a 2 story, would I need to do a rim joist all the way around?

 

[James E]

FWIW, I dislike single garage doors because they limit where you can place items inside. Plus, when I have two bays empty and I'm working on something, I can park right in the middle of them.

I just finished a 3 bay garage and I did a single and a double door.

Also, make sure at least one of your doors is extra tall to allow for loaded trailers, tractor, boat, lift on casters, etc.

 

[bigdav160]

What your looking for is right here:

SYP Span tables

I'm in your general area so PM me if you need some advice.

 

[bigburb]

James, I know where you are coming from, I have a 2 car with 2 8' doors and wish I had a single door. However, I think with the dormers 3 single doors look better, I don't think my wife would have it any other way

BigDav160, thanks for that link, its awesome! What would a typical live/dead load be for this area?

 

[mellamoesrico]

I believe typical residential flooring requirement is 40 lb/ft live load and 10 lb/ft dead load. Saw it in a table somewhere.

 

[ddawg16]

I believe typical residential flooring requirement is 40 lb/ft live load and 10 lb/ft dead load. Saw it in a table somewhere.

That is typical.....but also remember that span tables are min requirements.

FWIW, I dislike single garage doors because they limit where you can place items inside. Plus, when I have two bays empty and I'm working on something, I can park right in the middle of them.

I just finished a 3 bay garage and I did a single and a double door.

Also, make sure at least one of your doors is extra tall to allow for loaded trailers, tractor, boat, lift on casters, etc.

If you have been here long...about every 3 months you see a post from someone who can't get their F350 in the garage because the door it too small. You might want to consider one single and one double.

Get an architect or designer, they will solve the engineering for you.

If it was just a regular garage....yea....just do it.....but 2-story? My garage is 2-story....I needed engineering......

I was going by the span tables....but there are a lot of little details that those span tables don't tell you about.....like loading on the foundation.....you can build the strongest garage in the world....but if you foundation is not right.....the whole thing is a waste......

Case in point.....I have a large PSL beam across the middle of my garage....with 4x6 posts on each end....under those posts and part of my foundation are some 3x3x2 concrete pads to carry the loading. I would not have thought of that on my own....span tables don't tell you that....

 

[1965gp]

Where in houston? The contractor that built my garage extension was very easy to deal with, fast and pointed out a few things that I hadn't thought of that made the property much more functional. He is also qualified to design the building so you won't need an architect as well- he does a lot of custom homes.

Let me know if you need his info

 

[sabercatt]

talk to whomever you will be buying your building materials. They will usually have an in-house designer who works with engineers to draw everything up to meet your requirements. It can cost several hundred dollars, but usually they will do it for free if you purchase the materials from them.

 

[bigburb]

Been out for a while, sent you a PM 1965.

I am considering a large 18' door and a 9 or 10' door. I don't think it looks as "good", but would certainly be more practical. 2 doors would also be cheaper than 3.

 

[6768rogues]

As others said, get a copy of your building code. Many jurisdictions have adopted the IRC and some have "enhancements". NYS is one of those states. You have to build to the code that was adopted by your jurisdiction, and if that jurisdiction changed something in the IRC you will need a copy of your code.
The code has span tables for dimensional lumber. Different species of lumber have different strength. Learn what species and grades are readily available in your area and design around the tables for that species and grade.
You will see a ratio of 1/180 or 1/360, etc. in the code tables. They are allowable deflection under full design load. You want 1/180 for roofs and 1/360 for floors.

 

[bigburb]

I'll check with the county, thanks for the tip.

 

[bigburb]

I've been eyeing this garage plan, http://ryanmoehomedesign.com/garage/planpage.php?plan=43107, with a little modification it would be almost exactly what I'm looking for. Is there any reason not to just buy a plan off the shelf like this? On the one hand it would be nice to work from a set of plans, on the other how difficult could a garage be to build without plans? Its just a garage.

 

[theoldwizard1]

For a span 30-36' span, you will want "wooden I-beams". Much lighter and stronger than SYP.