I'm in the process of wanting to do some renovations and increase the size of my windows and patio door to maximize the view. I'm wondering if my current space will allow to put big enough headers for the size of windows and doors that I want. I would like to know the approximate size of glulam (enginieered) beams would be required for a span of 9ft and for another one of 11 feet. the exterior walls are 2x4. It's on the main floor and there is a second floor with truss span of 24inches that sits on that wall. Living in Ottawa Canada, we do have snow so there's a snow load to take into consideration. My question: is using a 3 1/2 x 11 1/4 safe? Can a 3 1/2 x 9 1/4 do the job? I would much rather oversize it by far then cutting it close so by using a 3 1/2 x 11 inch beam, am I oversizing it? The next size after that is 3 1/2 x 18 3/4 but i'm hoping that what I want doesn't require that size as I don't have 18 3/4 inches between my opening and ceiling. Any insight would be so appreciated. Thank you kindly

You're asking for structural design services, and unfortunately, I feel it is improper and unethical to attempt to do so, without seeing the structure and all factors that affect the design first hand. It is too easy to miss something that would affect the design when only going by a homeowner's description.

I will tell you that the loads involved are quite large, and the design of the headers is certainly not a matter for guesswork. I suggest getting some advice from a qualified design professional.

I thought this was a message board. If that is the case then I'm not sure why this would be unethical or improper. If this is not a message board then it shouldn't be positioned that way.

And you were expecting free, professional, engineering services on a message board?

quote:

I thought this was a message board. If that is the case then I'm not sure why this would be unethical or improper

It is improper, primarily because the homeowner's description could easily be inaccurate, or have left out vital information that needs to be considered. For example, you describe a truss floor framing system. Other people have done the same, and we found out later, after asking some questions, that it wasn't a truss system at all. Most homeowners do not use the proper terms for structural elements, and to give an answer based on information that could easily be incorrect would certainly be improper.

It is unethical because people make their living by providing such services, and we on a message board should not try to do, perhaps very badly because of insufficient information, what those people do properly, and get paid to do. Another issue is that we may not be licensed in your state to provide such services. I use my real name, not a screen name, so I could get myself in trouble by providing such services without a license.

If you called a structural engineer or an architect, and got an answer over the phone, without that professional examining the site first-hand, would you be confident in their answer? Even more to the point, would you expect them to answer over the phone, free of charge? If you do, it says a lot about you.

This forum is very useful for much advice, and people like Maintenance6, ConcreteMasonry, Home Care Club, LicensedWaterproofR, Jay In Minnesota, and many others, myself included, take it very seriously, and try to give advice to the best of our ability. We all devote a lot of time to this forum, on an unpaid volunteer basis, but we are not about to risk giving structural or other life-safety affecting advice, based on what could easily be false information.

Quite often people like yourself ask questions that require design specs such as beam sizes. Like Richard said, there are simply to many factors other then what is typically provided to us to answer this question properly. Simply saying that one size beam or another is correct could compromise you and your familys safety if something was missed. Thus the reason for it to be improper as well as unethical to do so.
Do not feel offended. We all are trying to provide the best advice we can.