Advice for residential flat roof installation in New England

[austinb]

JPM - Would you be willing to give me a reality check on the "evaluation of roof structure for roof loads" engineering letter? I can't really interpret it and I want to make sure that the unsupported span is properly accounted for...

[J.P.M.]

JPM - Would you be willing to give me a reality check on the "evaluation of roof structure for roof loads" engineering letter? I can't really interpret it and I want to make sure that the unsupported span is properly accounted for...

The short answer is no.

I'm not sure what you are asking for. What is the document you reference here, what is its purpose and where did it originate ? Have you asked for an interpretation from the author(s) of the document ?

If you are asking for my opinion as a P.E., I'm unable to do that as I retired my license a long time ago, as well as the liability insurance that I no longer need to carry.

Another obstacle would be that we (you and I) have no way to communicate beyond this forum. Can you attach the document to a post and let everyone here have a look at it ? None of us is as smart as all of us. More eyes, more comment.

Sharing knowledge of a general or mostly general nature on a subject is fine for a venue such as this and can help folks avoid ignorance induced errors and safety issues, and maybe help some folks to avoid going down a dead end or to a bad outcome. Real specifics are another thing.

A full and professional review/comment on an engineering analysis done by someone else is a lot of work. At least it would be for me.

Respectfully,

[austinb]

Got it. I'm not asking for review, just trying to understand what I'm looking at and don't know all the terminology (never took structural engineering courses). The solar company outsources to an engineering firm for structural calculations and says that the engineering firm doesn't typically interact directly with the customer. I'm basically just trying to figure out if they measured correctly or if something got lost in the communication chain.

We have two adjoining structures.
-The smaller one is 16' X 23.5'. The smaller one has no load bearing walls. This was an addition.
-The larger one is 29'X32' and has load bearing walls
There are two design check calculation sheets. Each shows a length, but not a width.
- Sheet 1 - shows a total length of 18' and a clear span of 17.9'
- Sheet 2 - shows a total length of 28' and a clear span of 9.2', 9.2', 9.2' (so suggests load bearing walls, which makes sense)

NOTE: The first floor of the smaller structure (the addition) is 16'X18'. The second floor has a 5' overhang, making it 16'X23.5'. Thus, I am hypothesizing that they used the first floor dimensions, instead of the second floor dimensions. Have put in a call to the company to double check this.

So, something seems a bit off.