The city where I had my building business started requiring microlam beams, and I was amazed when using them how much they sagged. The things are plywood, and have layers of grain going both ways, so makes sense that they are not as strong as they look. Wonder if there are charts so you can determine what size steel I beams you could use in buildings? No charts were available 10 years ago, but my experience tells me that a small I beam would be stronger than micro lams.
Don't confuse sag with flex. Microlams really don't sag much and being an engineered product are much stronger and more dimensionally stable than dimensional lumber. They will flex however, but are so strong per length that they flex much more then dimensional lumber without breaking. Microlams are not appropriate in all situations and the flex can be objectionable. There are many different types of microlam with different properties, too. Some are like little I-beams while some are solid- I believe per unit weight a microlam is stronger than a steel I-beam.
Charts and online calculators are available for all that stuff.
...here we go...
I did something very similar to what you are contemplating. The shop is on the 2nd floor, access by stairs from the lower garage bay or double doors on the upper level. I put a deck out front and I can back the pickup right up to the deck to unload heavy items. The stairs are a mixed bag of pros and cons. I lose storage downstairs, though here is a closet under the staircase, and I lose space up stairs occupied by the stairwell. The upside, I don't have to walk around to the front of the building through 4 feet of Upper Michigan snow during the winter! Overall I'm pleased with the way it's worked out. garage2.jpg
Reality continues to ruin my life!
I wasn't giving out specific "design advice" and no one asked you to. But microlams, glulams, LVL's, etc. are a viable alternative to steel for OP's situation.
I and others might benefit from your wisdom and knowing where I was wrong.
As to my statements-
You agree microlams are stronger and more stable than dimensional lumber.
You can't disagree that there are "many charts and online calculators"- a quick Google search will quickly support that. I didn't and would never recommend a layman attempt to use them to design a house, however. Many building codes do not recognize them yet, while others will accept the design from the manufacturer, but often require a structural engineer sign off on it.
Do you disagree, that "They will flex however, but are so strong per length that they flex much more then dimensional lumber without breaking." ? If you look at any of the substitution tables in this Engineered Wood Systems reference. you will see for a given deflection the replacement Glulam shear strength is in some cases almost doubled and bending strength almost 1.5 times the replaced Doug Fir lumber beam. You can theoretically reduce the size of the microlam, still have enough strength, but have greater deflection- note it says "deflection."
Of course it depends on what you compare to what- just like a 2X10 will support more than a 2X8. But since they are engineered and do not have all the fibers running in only one direction like dimensional lumber, microlams are stronger per unit weight.
Stiffness or resistance to failure are design issues as I just said. In addition to style (solid or I-beam shape), the thickness and height of shear web are major factors. To quote just one of the many sites like Georgia Pacific, microlams have:
"High design values for bending, stiffness and shear strength
High strength-to-weight ratio - more than 50% stronger than solid sawn products"
Do you disagree with "Microlams are not appropriate in all situations and the flex can be objectionable. There are many different types of microlam with different properties, too"? All sources support that, what is the basis for saying that is incorrect?
How about, "Some are like little I-beams while some are solid"? Again, a quick Google supports that.
As to "I believe per unit weight a microlam is stronger than a steel I-beam. You can't disagree with what I believe, but to quote just one of many sources: "Glulam and Microllam LVL Beams are a laminated timber that has been re- engineered to be stronger and more versatile than traditional wood products. Pound for pound it is stronger than steel so it can span long distances with minimal need for intermediate supports."
So that just leaves us with "sag." Again, I refer to the tables. You can design a microlam that will support a given load with no problem, but may have objectionable flex. I lived in a house like that- the living room floor was strong, but flexed like a trampoline.
So again, what was so wrong with what I said previously? You can tell us without committing a crime.
The reason I posted the possiblity of using steel beams vs microlam beams, is that I have seen very small steel beams replace very large wooden beams, and seem to be straighter. When we would put up a microlam, sometimes 2 or 3 layers to get the size of beam we needed, the microlam would droop maybe 1/2" before we even put the load on it. Didn't drop a whole lot more with the load. And when we used long microlams for hip rafters, when you couldn't buy a board long enough, we had to brace them up in the middle. And amazingly, wasn't hard to put a good crown in them.
Jim, I understand and don't doubt that is true, but even steel will droop (deflect ) a little. But, microlams can be engineered to limit that. They can be designed like a pre-stressed concrete bridge beam- with a certain amount of crown built in, so that under normal static load they will sit flat. Most homeowners and builders wouldn't be able to do the required engineering, but a microlam engineer can. Similarly, though technically strong enough, not all microlams are appropriate for all situations like your hip rafters. It is easy for a builder to get a generic one from the building supply house, but it may not be engineered for their specific application. Another issue that was not a problem for me gets back to the height of shear web. A microlam may be lighter for a given strength, stiffness, and span, but it may be too tall for the location. In my garage photo- the microlams are obviously much taller than the floor joists between them. Unless you can accept a boxed beam that extends down like that, it certainly wouldn't be appropriate for a living space.
Finally, price- there may be applications where a steel I-beam might actually be cheaper.
I didn't mean to stir up a hornets nest, but wanted to make sure the correct info was out there.
Microlams are about the only thing you can buy to use for a long hip rafter, otherwise you have to splice 2 pieces of lumber. And the inspectors don't have any problem with you using them.