Some things I know, and some things I’m pretty dumb about. This is one of them.
I need to span my basement with two beams. The beams will be holding floor joists at 16″ o.c., and the joists span 14′. So, each beam will be holding (at 40 psf) 560 pounds per lineal foot (live load only). They will be supported underneath with columns at 12′ from each end, so each beam really only spans 12′ maximum.
My dilemma – I know what I have for loads, I know what I have available for beam pockets and bearing surfaces, but I can’t make up my mind whether to go with steel wideflange beams or Parallam beams. If you were in my shoes, and only had to choose between steel beams or wood beams, which would you go with and why?
PS I’m leaning towards the Parallam, only becuase I think they will be easier to work with, and the beam pockets were “sized” to fit a 5-1/2″ x 9-1/2″ Parallam. But, I have no problem getting steel either.
Replies
Steel is a usually thought of as a superior structural element. But if heat ( a fire in your basement) is entered into the equation, then you may want to think again. When steel gets hot it looses much of it's structural integrity and may even fail if the fire is hot enough. This will happen much faster with steel than wood. I've seen cases where a fire department would go into fight a fire and "bug out" when they saw a steel girder. In the end the structure and all contents were lost. Had there been a wood beam it probably would have given fire fighters time to save the home.
That said, I would stay with engineered wood products for most light construction applications. It's easier to work with, readily available, and often engineered at your local lumber supply. It most likely will come with a warranty also.
kcoyner
Building codes typically require that any structural members in garage supporting living space above are provided with a 1-hr fire protection rating. This includes, beams, columns, joists, and bearing walls. Theoretically, there shouldn't be any exposed steel in the garage.
AKENGINEER
Absolutely,
I was only addressing the issue of steel girders in a basement.
k
No argument from me on the fire issues - I'm a firefighter. I know what happens to steel in the heat of a structure fire. Nevertheless, that wasn't a major consideration for me.
So far, I'm leaning more heavily toward the wood beam. Anybody want to argue in favor of steel?
Are your intermediary support footings already poured? If not, consider increasing the span and using steel. I just "finished" remodeling and I have almost 200 linear feet of steel in the house doing things that wood can't do. I got a w12x50 spanning 25' clear, and I got another w16x45 spanning about 24' clear. Some carry just floor load and some carry roof and floor load.
I really dig the steel for it's span characteristics.
But if the posts are already set and your span remains at 12', then I would use wood beam unless the steel would allow you to recover some height in your basement. Maybe install steel as a flush beam?
MERC.
I just finished a house where we used steel I beams over the basement, only because the home owner wanted to use them and already had them on site when we arrived.
IMHO, It is always a pain when you mix structural steel with wood framing members since you have to drill thru the steel to fasten your wood usually with carriage bolts.Therefor I think it would be much faster and easier to use a Parallam in this situation.
Dave
>> ... you have to drill thru the steel to fasten your wood usually with carriage bolts.
Powder actuated fasteners are a lot quicker.
USE THE STEEL .YOUR STEEL SUPPLIER WILL PROVIDE THE ENGINEERING REQUIREMENT, AND AS ALREADY MENTIONED YOU CAN GET SOME NICE WIDE OPEN ROOMS WITH STEEL. THE HOLES YOU NEED TO DRILL ARE DONE IN MINUTES IF YOU ARE PROPERLY EQUIPPED. IN MY AREA STEEL IS REASONABLY PRICED. IF YOU ARE WORRIED ABOUT FIRE, DRYWALL AROUND THE STEEL WHEN YOU FINISH YOUR BASEMENT.(WHEN YOU FINISH THE BASEMENT YOU CAN USE STEEL STUDS ALSO!)
HAVE FUN