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Badfish740 05-02-2007 11:20 PM

Span 30' with a steel I beam?
I'm interested in using a steel I beam for the main support beam(s) in my yet to be constructed project. When my father built our log home he was lucky enough to come across some very heavy duty steel beams for free. His cousin was the GC on our house and had demo'ed a commercial building a few years before and had salvaged some of the structural steel and hung onto it. The beam currently supports the length of our entire house (32 feet) with one support column made from some extremely heavy box channel from the same demo job in the center. Needless to say, if there's any sag after 23 years, it's a tiny fraction of an inch. The dimensions of the beam are:

Top/bottom flange - 6"
Height - 8"
Flange thickness 5/16"

Its pretty heavy duty, but I was wondering if I could get a beam heavy enough to span 30' with no support columns in order to allow for a more open plan when finishing the basement? This would be for a Cape Cod with a fully finished upstairs with a shed dormer on the back and doghouse dormers up front. Would it be too cumbersome to handle or so large that it would interfere with headroom? What about cost? As far as I know, structural steel is going for about $0.40 a pound, so even if I needed two beams at 1000 pounds each I'd be spending $800 not counting delivery. I figure that's a small price to pay for not having any columns in your basement.

AtlanticWBConst. 05-03-2007 06:39 AM


When you span an area with any kind of structural beam; the wider the span, the wider the width of the beam, so, inevitably, you will always loose some headspace. A 30' span will definitely create a loss of headspace, especially so in a basement location.

I have a link to a company that we have done business with (used their steel structural beams) They fabricate beams that a 'square shaped' and hollow in the middle. This allows them to use less width to create higher deflective strengths = beams that save on 'headspace'.

They have an engineering dept. that you can contact by phone to discuss your design requirements with. Generally, companies are eager to help customers figure their structural needs out....and very few companys will charge you for the actual engineering services required, as long as you end up purchasing the beam from them.
FWIW - We found their pricing surprisingly very reasonable.


Beam information:

Picture of one of their beams for spanning:

Here is a link to the phone number for their engineering dept:

Badfish740 05-03-2007 09:15 AM

Wow, exactly what I was looking for. Thanks! I'll certainly be bouncing some ideas off of them in the near future.

robertcdf 05-03-2007 06:00 PM

I seen one span a 3 car garage... It was 14.5" WIDE! and I think it was roughly 14-16" DEEP. It held a floor and a roof above it.

So yes it can be done... But they are some hefty beasts.

But what Atlantic is linking looks like a better solution.

SCengineer 07-16-2013 02:20 PM

I am an engineer. The problem with calling a fabricator and asking them to design the beam is that you need to make sure the loads they are using is correct. These loads change for every area, as well is the use of the space above the beam. For instance, in my area there are flood loads, wind loads, and earthquake loads to consider. The design of the entire structure comes into play. In my experience, an engineer will design the entire house for for a few thousand dollars. They will consider all options and cost will be their primary concern. A steel fab shop is not going to tell you that an LVL will do the same thing for cheaper.

yellowkid 07-16-2013 03:06 PM

I did this with a garage i built - the beam span was 28' and supported by 2X4" posts in the walls. so an open floor plan and no columns.

GBrackins 07-16-2013 05:10 PM

if you have stairs coming down to the basement you have the perfect place to hide 2 columns (if the stairs are for a typical cape). won't need as deep of a steel beam this way. just my thoughts

oh'mike 07-16-2013 05:19 PM

2007 thread---but helpful info---so post away---Mike----

sixeightten 07-16-2013 05:57 PM


Originally Posted by GBrackins (Post 1216761)
if you have stairs coming down to the basement you have the perfect place to hide 2 columns (if the stairs are for a typical cape). won't need as deep of a steel beam this way. just my thoughts

When we built our house years ago, we used a 16" beam that was 54' long. We have a small laundry room in the center of our lower level, and two support posts are hidden within their walls. It does span about 26' across the garage portion.

jcrack_corn 07-17-2013 08:20 PM

sometimes it easier to get an hungry architecht/designer or a student to whip up some quick options that incorporate the post into a wall.

they are good at seeing the space and making it function in ways you havent considered.

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