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How to skip the engineer or architect, and make the township happy?

matt2021 | Posted in General Questions on

For an addition I am creating, from an existing porch that already has a roof, I’d like to remove the existing shingles and install a “thick” roof along the lines of the attached drawing.  The township is asking me to produce “a sealed architect’s or engineer’s drawing showing the roof details, load calculations including snow load for all the addition weight being added to the existing roof assembly.”  If I go for this option, which will be unvented, the only additional weight will be that of the foam, of the wooden blocks, and of the insulation panels.  Can I calculate the additional load, add the snow load, and sign a statement myself?  Has anyone tried to do this?  With all due respect, so far my experience with architects (I have not tried an engineer yet) has not been positive: in my area at least, they are never happy to just do and certify a calculation for you; they always want to become project managers of sorts; and that goes beyond the scope of my project.

Any suggestions?

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  1. Expert Member
    BILL WICHERS | | #1

    If the city wants a set of sealed drawings, you'll need an architect or engineer that can "seal" them. There isn't really any way around that. My recommendation is to find a consulting engineering firm who will be more willing to do a "plan review" and seal a set of drawings for you without further involvement with the project.


    1. matt2021 | | #2

      Thank you, Bill! So, under the plan-review approach, will I be the one who does the drawings? (If you know.).

      I can do the drawings, by the way; I don't yet know how to do the load calculation, unfortunately.

      1. Expert Member
        BILL WICHERS | | #8

        You would do the drawings and as much of the design as you can. You would then pay the consulting engineer to do anything else required by the city, and apply the seal. The more work you can do, the less you're likely to have to pay to the consulting engineer. Note that the engineer's seal means the engineer takes responsibility for the design, so you CANNOT CHANGE ANYTHING after that sealed drawing is submitted to the city, unless you update the drawings, get the updated drawings sealed, and resubmit the updated drawings.


        1. matt2021 | | #9

          Thanks Bill. That make sense. I suspect that I need to let this bit of news sit with me for a bit. I think I have the relevant details, to be transferred onto drawings (pencil and paper drawings, which no engineer might be happy with these days), and contact a couple of engineers to see whether they would ever consider only doing the load calculations for me, and seal drawings I have produced. It might be a very long shot, but maybe worth at least a couple of phone calls.

          1. Expert Member
            BILL WICHERS | | #10

            I have started many a project with a sketch on a piece of paper, and I've filed permit drawings that way sometimes too. Everything starts somewhere, that shouldn't be a problem. What will happen is that if you only have sketches for the engineer, the engineer will charge you their hourly rate to "clean up" the drawings and make a nice CAD drawing for submittal. No consulting engineer will seal and submit a hand drawn sketch from their client to a municipal building department.

            Basically the more work the consultant does, the more they will bill you. You can save money doing as much of the work yourself as you can. Being a consulting engineer myself, I can speak with some authority on this particular matter :-)


  2. Patrick_OSullivan | | #3


    I recall from previous posts you live in NJ. By statute, NJ allows homeowners to do basically all their own work on a single family residence. I have not delved into what that truly means for the design side, but I do know that some towns allow homeowners to do their own design for certain projects, but those would typically fall into using prescriptive design tables in the code, because it's easier for them to 'check your work' in plan review.

    You could look at the prescriptive roof designs and tables in the IRC, determine what additional dead load the materials would add, and confirm that your rafter size is appropriate for those things, and then convince the town you did it correctly.

    You can go the "plan review" route Bill suggested, but I would do that only if you're confident your work product is sufficient and won't cause the engineering company any difficulty.

    Another option: I've recently found out that there are a lot of licensed architects and engineers on Upwork ( that handle hourly projects. Might be a quick way to get drawings, calcs, and seal.

    1. matt2021 | | #5

      Thank you, Patrick. You're right, I am in NJ (thanks for remembering!). Indeed, I am doing all my drawings; for a project like this, there is really no need to use an architect, I think. At least, that's the approach I have taken. When I used a "draft person" (so, not an architect, though a person with an architecture degree, and quite a bit of experience), I was disappointed: the work was not precise, and what I intended to do with this room, using exterior insulation, was quite foreign to them.

      Of course, now, with the roof assembly I wanted to create, things change because, understandably, the township wants to be sure the structure's rafters are sufficient to hold the additional load. It's a big disappointment, as I might have to give up on that whole idea, and go for what the township had recommended from the start, as a way to address the insulation of the roof (to get to R38): closed-cell spray foam between the rafters. I don't like that option at all, for a number of reasons, and I was open to spending a little more (compared to the not-s0-cheap closed-cell spray foam) to have a better roof. But I can't add any more complications and expenditures with architects. Nonetheless, I might check that network you mention (and the information is helpful to have for the future, too).

  3. kurtgranroth | | #4

    In a similar case to this, I just searched for structural engineers in my area and sent them each a query asking if they would create a structural plan for my drawings. One agreed.

    All the engineer needed at a minimum was my drawings but since this a (small) house, the lack of DWG/DXF file would have meant an additional charge for him to generate those, as well. I did have those available so I saved that charge.

    It was decently expensive and I wasn't very happy with the end result, but the town accepted it and I got my permit so it was worth it.

    1. matt2021 | | #6

      Thanks, Kurt. As I mentioned above, I wasn't crazy with the experience I had with the craft person I used at the beginning. Indeed, I had a fairly negative with an architect and the suggestions he gave upon his first visit. The visit was free, but the suggestions were all wrong. Like with all things, there is variation in quality. Yet, now, I don't think I will have time to select the right person; nor can I add any further expenses to the project. It's too bad though. I had two options for the roof, both excellent and cost effective. But it sounds like I will have to go for closed-cell spray foam between the rafters after all, and stay with the conventional roof I have.

  4. DC_Contrarian | | #7

    You need to ask your local building official.

    1. matt2021 | | #17

      Thank you. I have been in touch with the township inspector. We'll see how things develop.

  5. Expert Member
    Michael Maines | | #11

    If your situation fits within the prescriptive code, most locations will allow you to engineer your own design. But if it does not fit within the prescriptive code, even if it's existing, when the scope of work is significant enough--generally when you are touching at least 50% of a space--then it needs to either be brought up to prescriptive code standards, or an engineer needs to sign off on the work so the municipality is not liable in case there is a failure. In most places architects can also sign off on structural items but most architects aren't very comfortable with structural decisions and defer to licensed engineers.

    1. matt2021 | | #16

      That's exactly the situation I am facing, I think. What puzzles me, if in part, is how, in a state like New Jersey, where permits for re-roofing are no longer needed, redoing the roof without changing anything structural (it seems to me) but adding rigid foam insulation, which has marginal weight, and changing nothing else, would fall under "construction" and not more simply re-roofing.

  6. huey_ce | | #12

    If you lived in a state that adopted the International Existing Building Code (IEBC), you would just need to show that you are not increasing the stress in the rafters by more than 5% per one of the structural exceptions in the alterations section of the IEBC. As an engineer, I would take your existing roof assembly and compare it to the proposed new roof assembly, and if the stress increases less than 5% write and seal a quick letter for the town and call it a day.

    Note I said stress not load, not sure you have the capabilities to do this.

    Note 2, I started that whole statement with if. You are in NJ, and I learned the hard way that NJ does not just adopt the IEBC, they have their own code for existing buildings. It is similar in a lot of ways, but also has a lot of unique requirements. I had to read the whole thing front to back a few times for a NJ project and had to increase the scope of work from what I was expected from my previous work in New England and NY. I don't know the NJ code well enough to know if the same 5% exception will apply. My advice is to reach out to a local professional for guidance.

    1. matt2021 | | #15

      Thank you!

      Each inch of the insulation I would have added to the existing structure (while removing some wood boards -- "sleepers" -- from the current assembly) would have added .15 Lb/sq ft. I really don't see how the "added load" can possibly be a real problem. The possible result (though I am investigating alternatives) will likely be a worse roof and ceiling (one with closed-cell insulation between the rafters -- one to which some like to attribute an R value it will never in fact have, as Martin has well explained in a very good post on this website.

  7. Deleted | | #13


  8. matt2021 | | #14

    @BILL WICHERS Thank you (and sorry if it took me long to acknowledge your response)! I've been producing hand-drawn drawings; they are decent, though not comparable to what can be produced with the right software. It seems to me that the inspector's request has to do exclusively with having an architect/engineer take responsibility for the soundness of the proposed roof assembly. I think that, in my circumstances, abandoning my original project is pretty much the only option. I am now looking at two alternatives, and I might post separate questions about them.

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