I-beam size 30' span

[the old grind]

I had to take a 3rd, 4th look at the pic to see what you are talking about. Wouldn't the truss lose a lot of it's span strength hung like that??

I've been here 15 yrs, the house almost three times that. Had to look up at the ceiling(a) in several steel buildings (Parker store, tooling house, recycler) with flat roofs to see steel versions hung from the top chord with nothing fancy on their ends either. (much like my wood trusses) This a one-story house w/trussed roof so no extra loads (2nd story walls) mid-span anywhere.

Nothing heavier than a piano or small gun safe above, but no unevenness when placing furniture against a wall, so no floor-sagging at truss ends ever noticed. Can't imagine how anchorage embellishments would affect o'all strength, deflection, etc but I wondered the same thing when I moved in. btw, fella who built & lived here first 20 yrs weighed ~375lbs and no cracked plaster to patch even today. I can show it, just can't explain it better. (usually the other way around )

Mentioned a basement I-beam we wrapped in oak for looks. 'Liquid Nails' on 2x6 blocks to 'fill' web to flush & oak-veneered plywood glued/clamped to them. Cover & trim cap spot-glued to bottom of beam has never sagged or came loose. (15 yrs, now) Makes me think nailing atop steel beam not necessary to handle a compression load.

I came near to removing two posts in my previous home, but didn't want steel beam below joist centers. (Joists were NOT o'lapped at center of house as should be, butted atop triple 2 x 8 beam.) 10" x 4" x 22' steel beam was to have 12" x 1/4" plate welded to bottom as lintel. Well, shoring up both floors to trim joists & tuck the beam between the ends was more than I wanted to tackle by myself, so it never happened. btw, local inspector wished me luck shimming joists on the lintel to preserve flatness of sub-floor above but said the plan was ok to local codes. (or his taste, whichever)

I do like the OP's original idea since he'd have plenty of headroom in the garage. Tucking a girder between joists vs below would seem overkill and tho' I wasn't aware of them when I planned that beam job, having hangers as shown above could make things easy. Steel is cheap lately, and wood other than std 2-by could run into serious bucks to go 30' at 16" OC. I'd bet that when the numbers are crunched our guy's original plan wins out. (sometimes 'thinking outside of the box' teaches you to go back inside it when the work begins and the bills roll in. )

 

[dieselcrawler]

Wow... thanks for all the replys and excellent information. Very helpful.

Several things to point out, that are going to steer my decision in which materials I use.

Hight of ceiling is higher than I would like, but due to current grade, slope of driveway into garage space, and hight of current 2nd floor, both are set, and I can only fill in the space between. Which leaves plenty of room for a beam to hang below the floor joist, waaaaaay below, and won't hurt anything.

I have timber to cut, and access to a sawmill, so I might use rough cut lumber if possible, so keeping floor joist down to 12' by running the beam as in my drawing will allow me to do so. I will be on a tight budget, so using rough cut or recycled materials will be part of the plan.

I do not plan to use this space for automotive type work, for two reasons. One, being attached to the house, I do not want to be welding or grinding, catch the garage on fire, and the whole house burns. So not likely to use the beam for pulling motors or other hoist work. There's a shop in the barn for that. And on that same note, 9x9' garage doors will be fine.

My next step will be finding a cheap used heavy beam. Guess I need to go thru those beam tables and figure out the right size. Unless someone can just tell me...

 

[LD1]

My next step will be finding a cheap used heavy beam. Guess I need to go thru those beam tables and figure out the right size. Unless someone can just tell me...

Post 6, Paragraph 3

 

[ovrszd]

Good stuff concerning the "upside down" trusses. Now that it is discussed I do recall seeing metal trusses hung upside down like that in large commercial buildings. Thinking thru it, I see the point. And in the case of Old Grind's house they have proven themselves for a long time!!!

 

[LD1]

Good stuff concerning the "upside down" trusses. Now that it is discussed I do recall seeing metal trusses hung upside down like that in large commercial buildings. Thinking thru it, I see the point. And in the case of Old Grind's house they have proven themselves for a long time!!!

Yep, metal trusses are hung from the top chord all the time.

Also, think about metal buildings built with I-beams. LOTS of them use a tapered I-beam, where the center of the span is a lot deeper section than than where it connects to the walls or posts. Same for the vertical columns. Might be small where it attaches to the floor and much larger at the top.

 

[ovrszd]

Yep, metal trusses are hung from the top chord all the time.

Also, think about metal buildings built with I-beams. LOTS of them use a tapered I-beam, where the center of the span is a lot deeper section than than where it connects to the walls or posts. Same for the vertical columns. Might be small where it attaches to the floor and much larger at the top.

Yep, my shop is all metal. I-beam frame. Center beam is clearspan 42'. Vertical wall beam is smaller at the floor. But roof beam is larger where it fastens to vertical beam and smaller out in the center of the building where they bolt together.

 

[pmsmechanic]

Since I have a wife that has trouble driving through narrow doors I would consider installing one wide door instead of two narrow ones. Especially if you are going to park a pickup in the garage. This wouldn't necessarily be just for my wife as I am at the present time getting older too. I'm derailing a bit but just wanted to add my thoughts.

Make sure you make the space around the vehicles wide enough to open the vehicle doors completely. Park two full size vehicles side by side and open the doors. Then start to get in and out of the vehicles. Walk around them with the doors open. Once you see how nice it is to have the extra room then decide how wide you want your garage to be. Often a little extra width is very cheep to incorporate in the overall picture.

Of course it's easy for me to spend someone else's money. Enjoy your addition.

 

[pmsmechanic]

Grrrr double post!

 

[LD1]

Yep, my shop is all metal. I-beam frame. Center beam is clearspan 42'. Vertical wall beam is smaller at the floor. But roof beam is larger where it fastens to vertical beam and smaller out in the center of the building where they bolt together.

View attachment 454223

Thats just the opposite of how most of them I see are. But given the pitch of the roof, about the only way that center connection at the ridge can fail is if it pushes the wall out. Most of the ones that I have seen are flat or near flat roofs. And the beams always seem to have a deeper section in the middle of the span, where it is needed for the deflection.

But steel aside, look at any type of wood truss. The "deepest" section is the middle. The end supports where it sits atop the wall, not so much. Only have to be strong enough to overcome the shear.

 

[LD1]

Yep, my shop is all metal. I-beam frame. Center beam is clearspan 42'. Vertical wall beam is smaller at the floor. But roof beam is larger where it fastens to vertical beam and smaller out in the center of the building where they bolt together.

View attachment 454223

Thats just the opposite of how most of them I see are. But given the pitch of the roof, about the only way that center connection at the ridge can fail is if it pushes the wall out. Most of the ones that I have seen are flat or near flat roofs. And the beams always seem to have a deeper section in the middle of the span, where it is needed for the deflection.

But steel aside, look at any type of wood truss. The "deepest" section is the middle. The end supports where it sits atop the wall, not so much. Only have to be strong enough to overcome the shear.