How JustAnswer Works:

  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.

Ask StructuralEng Your Own Question

StructuralEng, Consultant
Category: Structural Engineering
Satisfied Customers: 6641
Experience:  Structural Engineer
Type Your Structural Engineering Question Here...
StructuralEng is online now
A new question is answered every 9 seconds

Beam, joist, angle iron size ? , wood, steel, lvl - span 12

This answer was rated:

Beam, joist, angle iron size ? , wood, steel, lvl - span 12 feet, total weight 22,500 (support half - 11,250) evenly distributed
angle iron size on other half of load bolted to concrete wall,
joist size with 8 foot span , 16 inch on center

StructuralEng : Hi
StructuralEng : I can help
StructuralEng : Let me read closer
StructuralEng : Before we get started I’d like to point out that a Professional Engineer’s standard of care typically includes a site visit to assess field conditions and get an overall understanding of the structure.  This can obviously not be accomplished through the internet.  The information provided here is meant for informational purposes only (general sizing and budgeting) and is based on the information provided by you.  The information should be verified by a professional engineer who can visit the site to ensure that potentially important information has not been overlooked or omitted
StructuralEng : I'm not quite clear. What is the span and the actual distributed load?

The beam size request refers to the minimum size of beam required between two posts with a span of 12 feet that would carry half of the total weight of 22,500 lbs. There joist size refers to the minimum size joist required to carry the same load that are 16 inch OC. The angle iron minimum size refers to the minimum size of angle iron required to support the other end of the load of 22,500 lbs.


The load is 4 inches of concrete on top of a plywood base on the joist structure

StructuralEng : Let me catch up.
StructuralEng : The angle as a post or beam?
StructuralEng : Is this two separate questions?

It is one question with three parts. What are the structural requirements for this problem. I want to build a deck. It will have joists that go from a concrete wall to a beam that is on two posts. The posts are 12 feet apart. what size is the minimum required to to carry half the total load of 22, 500.


What are the minimum size of joists that are spanning 8 feet from concrete wall to beam between posts. What are the minumum size of a piece of angle iron bolted onto the concrete wall.

StructuralEng : That's quite a bit for one question
StructuralEng : How did you arrive at the load of 22,500 pounds?

The load is 4 inches of concrete on top of a plywood base on the joist structure, 8' x 15 = 120 square feet. Added 30 square feet for triangles at ends of rectangle, times 150 lbs per square foot.

I have signed up for the unlimited questions if these are outside the one question issue


is an answer forthcoming or is this it?

StructuralEng : I apologize for the delay. I had to take an urgent phone call
StructuralEng : So the one beam is spanning 12' between posts with a 1.5' cantilever on each end?



StructuralEng : Where did the 150 psf come from?
StructuralEng : Was that 50 psf for the concrete and 100 psf for the LL?

that is the weight of 4" of one square foot of concrete (450 lbs per cubic foot)


live load would be typical for a deck, but it is 150 psf for the dead load


StructuralEng : Concrete is only 150 pounds per cubic foot.
StructuralEng : Is this a residential deck?

ok, that is not what i thought, lets go with 50 psf,


It is a residential deck


StructuralEng : You can plan for a W6x20 beam with 8' joists being angle 4x4x3/8 @ 16" o.c.
StructuralEng : The ledger angle can be the same, you'll just need to have the bolt pattern designed to support the joists
StructuralEng : If you could rate my answer, I would appreciate it

I was looking for wood sizes first, steel second



of course, the angle iron would have to be steel

StructuralEng : Give me a few more mon
StructuralEng : Min


StructuralEng : 2x10 joists @ 16" o.c. Southern pine no. 2 pressure treated.
StructuralEng : Will need some kind of barrier between wood and concrete
StructuralEng : Beam can be triple 2x12 southern pine No. 1 pressure treated
StructuralEng : If you could rate my answer, I would appreciate it

will do, thanx

StructuralEng and other Structural Engineering Specialists are ready to help you

Related Structural Engineering Questions