From: Rob Munach 
Newsgroups: sci.engr.civil misc.consumers.house
Subject: Re: Wall Removal Question?
Date: Fri, 18 Mar 2005 18:02:36 GMT

mattfracassa@hotmail.com wrote:

> That's why I figured I might as well overdo it.
> 
> I've now decided to go with a Steel I-beam (looks like it will be the
> same or cheaper than lumber - but will make a much smaller header.)
> Question now is, should I go with a 4" 6" or 8" IBeam?  What iBeam size
> would be equivalent to Three 2X12 at 13 feet??
> 
> Keep in mind, the only thing holding up the wall I plan on removing is
> Two 2X12's
> 
Assuming the (3)2x12's are SYP (wont't make much of a difference).....

For equiv. stiffness, you need a steel beam with an I (moment of 
inertia) of about 30 in^4
For equiv. strength you need a beam with an S (section modulus) of about 
  4.5 in^3

W6x15 I = 29, S = 10
W8x10 I = 31, S = 8
W4x13 I = 11, S = 5  (not stiff enough)

Regards,

-- 
Rob Munach, PE
Excel Engineering
PO Box 1264
Carrboro, NC 27510