# Steel Trusses



## vpapai (Nov 18, 2010)

Thinking about using steel trusses for a pole barn type garage. Looking at 50 foot long by 26 wide. Want to make it two story so we could have storage/living space above. Planning to store the RV on one side, and tractor and equipment on the other. 

Trusses would span 26 feet, plus would like to have about a 3 foot overhang on each side, as well on the front and back. 

Anyone have experience using these rather than wood roof rafters? 

Something along the lines of the ones on this site. http://www.buildyourown.ws/garage-kit-construction.html#.UtV9fLQqeSp


----------



## Darren (May 10, 2002)

Those aren't the ones you'd need for a second story floor. Depending on the layout below, you'll need a hefty header over any opening for equipment access. You'll have to go with larger vertical columns (poles) too. You'll also need a way to brace the trusses to resist side loads. You can't just bolt them to a top plate.

I'm interested in others' suggestions or experience. I've thought about doing something simila rin the past. I was looking at a steel frame building instead to avoid the complications.


----------



## jwal10 (Jun 5, 2010)

Why? Wood is cheaper, easier to work with and easier to insulate. I can see using them if your posts are steel or an open building but for housing, no....James


----------



## Darren (May 10, 2002)

I can see an advantage in load carrying capacity with steel. Unless you're going to have a library upstairs, it might be worthwhile to talk to a wood truss company.


----------



## jwal10 (Jun 5, 2010)

I have seen a lot of them for loafing sheds and commodity buildings on dairies with steel pipe posts. Closing them in becomes the hard part....James


----------



## NorthwoodsMike (Jun 10, 2013)

I'm not sure if this helps, but we used wood floor trusses on our house. Our build is 40x24, and the 24' is free span. The trusses cost about $2100 for this size per floor. It makes running mechanical/plumbing/electrical so much nicer. I know you asked about steel, but like the others said, it might not be necessary.


----------



## bigjon (Oct 2, 2013)

u'll need concrete footers,with steel uprights bolted at both ends (top&bottom)


----------



## travisn (Dec 3, 2013)

NorthwoodsMike said:


> The trusses cost about $2100 for this size per floor.


$2100 for each truss??? or $2100 was the total for the whole structure, per floor?


----------



## NorthwoodsMike (Jun 10, 2013)

$2100 for all the trusses on the first floor. The second floor was slightly higher, but had some cantilevered dormers.


----------



## travisn (Dec 3, 2013)

doesn't seem too bad, did you quote steel beams?


----------



## NorthwoodsMike (Jun 10, 2013)

I didn't, but based on the cost of the steel supports I ended up not using, I suspect it would have been a lot more.


----------



## vpapai (Nov 18, 2010)

The trusses would only be for the rafters, not the floor between the first and second floor. I think the trusses would be quicker/stronger than wood rafters.


----------



## Darren (May 10, 2002)

They would be stronger. The problem is trusses aren't designed to be connected to wood. The way the load is transferred to the support is different. When sitting on a concrete block wall, they're welded to an embedded plate for a couple of reasons. You may have to weld plates on the ends to do the same thing to reduce the bearing pressure. You're not concerned about uplift for a floor. The bearing pressure may be an issue and you'll still need the connection to tie the structure together to resist wind loads.

Part of the benefit of using steel is to have a greater span between them. That means more weight at the bearing points than floor joists at a much closer spacing.


----------



## rod44 (Jun 17, 2013)

Why not use "floor trusses"? Here is my shed and the room above it. The floor trusses were not that much more than regular trusses. They are engineered to hold the same weight as a house floor. You could use these trusses over where you have your tractor and smaller stuff and a cathedral ceiling type truss where you need more clearance for the RV. Here are picts of the shed and the room above. I think my main level ceilings are 10 or 12 feet. Shed is 30 by 50 and you need a steeper pitch for the room above. Sorry I didn't have a pict of the shed without me in it.


----------



## NorthwoodsMike (Jun 10, 2013)

Darren said:


> Part of the benefit of using steel is to have a greater span between them. That means more weight at the bearing points than floor joists at a much closer spacing.


Actually, this is true for all trusses, including wood. Steel probably just takes it a step further.

For what it's worth, my floor trusses are spaced 19.2 OC, when conventional lumber would have required 16 or 12 OC, plus support beams. I wanted free span, and the trusses weren't much different in cost than LVL's/I-Joists.


----------



## haypoint (Oct 4, 2006)

Local Township was gifted a building kit for the Fire Dept. Open steel span. The concrete footers had to connect, under the floor from side to side to hold the building from splitting. Cost more for extra concrete than a pole barn would have cost.

Mt son designs trusses. I think he'd suggest an attic truss, putting your second floor within the roof truss. 12:12 pitch or gambrel.


----------



## haypoint (Oct 4, 2006)

NorthwoodsMike said:


> Actually, this is true for all trusses, including wood. Steel probably just takes it a step further.
> 
> For what it's worth, my floor trusses are spaced 19.2 OC, when conventional lumber would have required 16 or 12 OC, plus support beams. I wanted free span, and the trusses weren't much different in cost than LVL's/I-Joists.


Is that a misprint? 19.2 inches? Really? How can you build anything with truss spacing that doesn't match anything?


----------



## wy_white_wolf (Oct 14, 2004)

haypoint said:


> Is that a misprint? 19.2 inches? Really? How can you build anything with truss spacing that doesn't match anything?


96" / 5 = 19.2"

If you look at floor trusses you will see that spacing quite often. More span than going with 24" spacing and cheaper than going all the way down to 16" and gives more room for ducting between the trusses.

WWW


----------



## rod44 (Jun 17, 2013)

Mine is 30 feet wide and there are no support beams other than the side walls. The trusses are engineered to handle it. 

If you ever have a fire with something in your shed, you are better off with wood than steel. The steel will collapse way sooner than wood due to the heat.


----------



## rod44 (Jun 17, 2013)

My term was incorrect on my trusses. They are "attic" trusses not "floor" trusses. They cover a 30 foot wide building with no interior support poles.

Sorry


----------



## Sawmill Jim (Dec 5, 2008)

rod44 said:


> Mine is 30 feet wide and there are no support beams other than the side walls. The trusses are engineered to handle it.
> 
> If you ever have a fire with something in your shed, you are better off with wood than steel. The steel will collapse way sooner than wood due to the heat.


Would like to see a real time test of steel giving up first . eep: I would think the flash point of wood would happen way before bending time on steel . Long about either time i would say the whole thing would of been a death trap a few hundred degrees back


----------



## rod44 (Jun 17, 2013)

The wood starts burning but retains it's structural integrity longer. You see sheds around here that have had a fire, such as hay, and the metal have fallen in and the wood is still standing but burned.

some excerpts

Wood Is Safer in a Fire
While it sounds hard to believe, it&#8217;s absolutely true. Wood retains its structural strength at temperatures higher than 2000Â°F, while steel loses 80 percent of its strength at 1000Â°F. As it&#8217;s melting during a fire, steel bends and twists. According to many firefighters, it is extremely difficult and dangerous for them to stop a fire in a steel building and for people to escape. Firefighters often use the term running time, which is the amount of time they have to get everyone out of the building before the steel is too dangerous to work on.


Q.Is it true that a wood beam is safer than a steel beam in a fire? I&#8217;ve heard that metal twists and deflects in the presence of heat, while a wood beam will withstand the heat and a great deal of fire before burning through enough to collapse.
A.Brad Douglas, director of engineering at the American Forest & Paper Association, responds: Large solid-sawn and glulam timbers provide a substantial degree of fire endurance. The superior fire performance of large timbers can be attributed to the charring effect of wood. As wood members are exposed to fire, an insulating char layer is formed that protects the core. Thus, beams and columns can be designed so that a sufficient cross-section of wood remains to sustain the design loads for the required duration of fire exposure.

A fire test conducted in 1961 at the Southwest Research Institute compared the fire endurance of a 7x21-inch glulam timber with a W16x40 steel beam. Both beams spanned approximately 43.5 feet and were loaded to full design load (approximately 12,450 lb.). After about 30 minutes, the steel beam deflected more than 35 inches and collapsed into the test furnace, ending the test. The wood beam deflected 2 1/4 inches with more than 75% of the original wood section undamaged. Calculation procedures provided in a new publication available from the American Wood Council, entitled Technical Report 10: Calculating the Fire Resistance of Exposed Wood Members, estimates that the failure time of the 7x21-inch wood beam would have exceeded 65 minutes if the test had not ended at 30 minutes.

For additional information on the fire performance of wood, contact the American Wood Council at 202/463-4713 or www.awc.org.


----------



## Sawmill Jim (Dec 5, 2008)

As i said along about 1,000 f it don't matter a whole lot . If you an't out you would be dead long before that .


----------



## rod44 (Jun 17, 2013)

I never said that either wouldn't be a death trap. Just said that wood would last longer than structurally than steel.

According to many firefighters, it is extremely difficult and dangerous for them to stop a fire in a steel building and for people to escape. Firefighters often use the term running time, which is the amount of time they have to get everyone out of the building before the steel is too dangerous to work on.


----------

