You can use a w8x31 50 ksi steel beam for your 18 clear span beam.
Garage door header steel beam.
Tables providing size selections for various beam spans and loading combinations for southern pine dimension lumber and southern pine glued laminated timber are available for the following applications.
A beam with a 10 span carries 15 0 simple span joists on each side.
The beam is 8 wide and 8 deep.
Select the span carried by the beam across the top of the table.
What you re seeing here is a header built with a 2 6 bottom plate 2 4 cripple studs and a 2 4 top plate resting on the adjacent block walls.
The only added weight on the header will be 4 by 8 joists 3 4 plyw read more.
You will need to have a local engineer detail your connections size your column supports and determine foundation requirements.
The person doing the takeoff had interpreted my request for an 18 9 garage door header to the least expensive 20 long beam.
What size and guage of steel i beam do i need for a garage header.
Lvl is ideal for floor beams garage doors window and door headers and ridge and hip beams multiple pieces of boise versa lam laminated veneer lumber can be assembled for greater thicknesses that can carry even heavier loads across even longer spans ordinary nail assembly installs as easily as ordinary lumber.
The beam they have specified now is 3 1 2 x 12 x 18 9.
Using the continuous span floor joists table with 30 0 span carried select either 3 1 2 x 11 1 4 or 5 1 4 x 9 1 4.
Opening is 18 ft wide and beam will rest on 2 18 by 18 posts.
Wait it gets worse.
It weighs 31 pounds per foot of beam length.
Window door garage door headers supporting roof wall floor loads.
On previous projects i have been supplied a glu lam boise makes specifically for garage door headers that was 3 1 2 x 11 1 4 x 18 9.
Read the beam size or choice of beam sizes from the table.