Homebuilding: Setting Basement Steel

One of the first steps in the construction of a new home is
setting the steel beams and columns in the basement and/or crawl
space. This supports the floor joists and usually runs the length
of the house at mid span in most homes. Not only does this system
support the floor, but usually has the weight of bearing walls,
ceilings, second floors, second floor bearing walls and sometimes
roofs transfered down to it.

The first step is to install the sill plates on the foundation
wall. This gives you a place to nail 2x4 bracing to hold columns and
beams in place while you install them. Once set in place these
braces hold the steel till the floor joists are nailed in to take
their place.

Before I continue, a word of caution. Homebuilding can be a
dangerous activity. Care and safety are a must in all phases of
the construction process. Setting steel definitely falls into
this category. Beams can weigh anywhere from 100 to 400 pounds
depending on their size and length. Beams can be lifted into
place manually but I would recommend the use of a crane. Not only
can the beams be put in place safely, but it can also quicken the
process.

With the sill plates in place the steel can be set. One end of
the first beam typically starts in a beam pocket formed into the
top of the foundation wall. The other end sits on top of a lally
column. A typical column is 3 1/2" in diameter and filled with
concrete. It has a flange welded to the top with holes in it that
match holes in the bottom flange of the beam. The beam is lowered
onto the column and then bolted together.

To make this happen, I like to use four people. One to hold the
beam in the pocket, one to hold the column, one man on a ladder
to guide and bolt the beam onto the column and one man to nail
off bracing to sill plates. Braces (2x4's) are laid flat on the
bottom flange of the beam on both sides of the web and then
nailed to the sill plates on opposing walls.

The next beam is now ready to be set. With one person holding the
next column, the next beam is lowered onto the new column and the
previous column. Men on ladders guide it into place and bolt it
down. Again 2x4's are used to brace the beam to the outside
foundation walls. This procedure is repeated until you get to a
beam pocket at the other end of the building, or a column that
terminates at an opening.

To keep beams level and straight, I like to use a dry line from
beam pocket to beam pocket (this can also be done with a laser).
First I drive a nail in the sill plate corresponding with the
edge of the beam. Most beams run pocket to pocket. If this is the
case I'll drive a nail in the plate by that pocket at the same
dimension as the first nail, measured from a common reference
point, usually the front or back sill plate. I now have a
reference point to line up the edge of the beams with and result
in a straight installation.

Assuming the foundation and sill plates are level, this string
can be used to level the steel beams (again, a laser can be
used). After most beam installations a 2x plate is either bolted
or shot with a powder actuated tool to the top of the beam. This
is to bring it level with the sill plates and to provide nailing
for the floor joists. Using a 2x block as a gauge, lay it on the
top of the beam where it sits on a column. This simulates the
plate that will be installed later. Shim the column till the
block touches the bottom of the dry line. Repeat this for every
column. Columns are shimmed with steel plates of various
thicknesses. These shims are provided by the steel supplier.

The next step is to plumb the lally columns on their concrete
pads. Using a 4-foot level, the columns are tapped into plumb
with a sledge hammer. Make sure the steel shims remain under the
columns. After all columns are plumbed up, the concrete floor can
be poured. This holds the columns in place.

The next step is to frame the floor. Once the floor joists are
nailed in place all bracing can be removed. The joists are now
holding the steel in place.

Just like the foundation, setting the steel straight and level is
important to producing a quality home.

(c) Mike Merisko www.sawkerfs.com