Wind exposure information for porches on truss design sheets.
Wind exposure information for porches on truss design sheets.
(OP)
I currently am a building plans examiner, and am talking about residential trusses. If I'm looking at a design with a porch, how can I tell if that section has been designed as exposed. I see Alpine, MiTek, and Robbins design sheets. MiTek provides the most information, and will say if it is an exposed cantilever, or exposed porch. Robbins provides some information, but it's generally a line that says that portion is specially designed. Alpine shown litle information other than interior or exterior location.
If you are the Truss Designer for these truss companies, how do you know what's been done? And shouldn't the EOR or reviewer get this information? Shouldn't this information be required to be provided?
And what do you think is the proper design for a porch, as an overhang, or as partially exposed?
If you are the Truss Designer for these truss companies, how do you know what's been done? And shouldn't the EOR or reviewer get this information? Shouldn't this information be required to be provided?
And what do you think is the proper design for a porch, as an overhang, or as partially exposed?





RE: Wind exposure information for porches on truss design sheets.
woodengineer
RE: Wind exposure information for porches on truss design sheets.
In the past when I was the EOR on a project, I often found it necessary to request additional information from the truss supplier.
You might sit down and talk with one of the local truss suppliers who has a staff engineer. Normally they are more than willing to help educate people about their product. They should be able to give you a better understanding of how they treat porches in their designs.
How you approach the problem also depends on whether or not there is a EOR for the project. If you are dealing with single family homes with no EOR then it may not be as critical as whether the porch is treated as an overhang or not. In a single home the important thing is that the design provides some resistance to the wind load imposed on the trusses by the porch.
RE: Wind exposure information for porches on truss design sheets.
RE: Wind exposure information for porches on truss design sheets.
Thanks for your responses, and thanks woodengineer for pointing out that the design of the truss itself is not very sensitive to the exposure. That helps.
RE: Wind exposure information for porches on truss design sheets.
RE: Wind exposure information for porches on truss design sheets.
I am interested in knowing what is the problem with this "exposed or not exposed" consideration. In other words, what behavior problems have you seen when this consideration is overlooked? Does the problem occur often? That last question could apply to both the problem of this condition being overlooked in the design and any behavior problems with the "in use" condition.
Don't get me wrong, I want things to be done right too so I am not questioning the need to consider this item, but I occasionally find mysef in the middle of a situation where the parties involved are wondering why they need to re-do something or why something might be rejected when some of these considerations would often go without notice or incident.
I just want to know what field problems would you expect to develop if such a consideration is not taken into account.
Thanks
RE: Wind exposure information for porches on truss design sheets.
RE: Wind exposure information for porches on truss design sheets.
I was hoping you wouldn't focus on the answer you gave. Perhaps it's unavoidable. I am an engineer too so I spend much of my time in the position of having to encourage that way of thinking.
I am looking for insight beyond that. I appreciate your reply though.
RE: Wind exposure information for porches on truss design sheets.
RE: Wind exposure information for porches on truss design sheets.
What I was looking for was some insight into what specific structural problems sould be expected to be the result of the design oversight that was indicated.
RE: Wind exposure information for porches on truss design sheets.
That might be an interesting idea for a thread, considering the general public is oblivious to what we do for them.
RE: Wind exposure information for porches on truss design sheets.
To the general public and the residential contractors, I'm just someone that's delaying their house.
RE: Wind exposure information for porches on truss design sheets.
If you would like to have some example profiles, along with the load case reports showing exactly how the trusses are engineered and the coefficients, please drop me an email.
RE: Wind exposure information for porches on truss design sheets.
I'd like to learn all I can. I think Truswal is a great idea.
I know emails are frowned upon. I wish there were an internal message exchange based on Forum ID's. Could you post any useful information so ALL could benefit, or show a link that others could review your examples?
RE: Wind exposure information for porches on truss design sheets.
As you may have noticed, My response got edited. I did find trusswal.com and truss-frame.com which seem to have some info. Thanks
RE: Wind exposure information for porches on truss design sheets.