What does your contract say?

It would be appropriate if the architect was the person who designed the addition, supplied the modular system, and supervised it's installation. Of course, he/she would be acting as a Design-Build contractor.

Normal architect fees stop with construction phase "observation" ("supervision" is the role of the contractor rather than the architect because it would make an architect responsible for work he/she does not control)

In terms of ethics, an architect can bill you for anything you agreed to pay him for as long as it isn't an illegal activity. I see no professional ethics involved.

Somehow I find it difficult to believe this person is really an architect.

proposing services that aren't needed sounds unethical to me. You most likely don't need items 2 & 3 - especially 3.

Have the architect draw the plans, make sure they are reviewed by your builder, make any mods needed, then pay them. That is all you really need.

Our drafting services contract with our architect essentially stated what I just sayed. And I would have laughed my rear end off if he proposed supervising the build. Now that would have been a complete waste of his time and my money.

I would have thrown him out of my house if he proposed charging me a percentage of the build as part of his fee.

If the architect is procuring the materials he can certainly mark them up. However, I don't think markups are usually stated in an invoice. If he has nothing to do with the materials then the fee is totally bogus.

We have been presented with an invoice but no description of the scope of the architect's services. There is no way to know if the invoice is appropriate.

But, as far as we know, there is no reason to think that there are any issues of professional ethics involved. An architect is not prohibited from acting as a contractor or as a material supplier or for billing for those services and the fee can be based on anything the two parties agree on in advance. It's just a business transaction that we don't know much about.

princeton

Is the architect in your case also the builder? I read your item 2 as architect watching over what the builder does and not being the builder who would typically manage the construction process. Is it a design/build firm?

Can you also provide a little more detail on what you are planning - how extensive is the addition and how will it impact the existing structure.