Many companies include the necessary details on their detail pages in the plan set. To my knowledge, it is not expected that the engineer of record (you) was in responsible charge of that portion of the design. It's just the local code mandate, to which your plans refer.

Yeah, good luck with that. My experience is that you're expected to use their details and take ownership enough to seal them. Trying to get the provider's engineers to seal them is very difficult, and that's if they are registered at all. They can smell a construction issue from a hundred miles away that they don't want to deal with.

You should not seal their details. If you include them in your plans, add a note that the details were provided by X and they are required by X, but you have made no evaluation or assessment as to their viability.

In civil, sometimes a custom manhole or headwall may be needed, in which case you would have to create your own detail. Usually city details are created for city property, that's why they don't want it changed, but If you have a custom detail and can explain why its needed than that is up to you to argue your case.

as Ron notes, you do not want to affirm them... and, if you can, just reference their details that are applicable, without including them in your documents... I've done that often.

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So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

I call this engineering by code, the plans should identify which procedures and standard details are required and that lovely appendix compiles all the standard drawings from the local municipality and provincial standards applicable or referenced in the drawings.

As Ron said, do not stamp and sign the agency's standard details. They are not yours and you did not supervise their preparation, so you can't be the EOR for the details. Now, if you take the picture from a standard detail, remove all references to the agency, and make some changes (or not), then it becomes yours, but this is outside the scope of your question.

I have handled standard details three different ways over the years, depending on company and agency practice:
1. Include copies of the standard details in the plan set. In this case, I would stamp and sign the sheet as part of the plan set, but I would also include a note like Ron suggests.
2. Include copies of the standard details in an appendix in the specifications book. The appendix divider sheet would include a note like Ron suggests. The cover or inside cover of the spec book gets stamped and signed, but no other pages.
3. Refer to the standard details in call-outs, but do not include them in either the plans or the spec book. A typical call-out would read like this: "Fire hydrant assembly per City of Podunk Standard Detail W-5."

I prefer Method #3. It's quick, it's clean, and it's the least amount of work on my part.

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"Is it the only lesson of history that mankind is unteachable?"
--Winston S. Churchill

#3 That's my approach.

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So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

Thanks for all of the responses, you have certainly given me some ideas as to how to handle this going forward.