There's no reason to go through the whole process of engineering and architectural plans if the city has a different idea than you for your site.

I don't know of any developer in Atlanta using pins right now, so you'd have to have all kinds of third party letters for it.Suspended foundations (IE: above ground piers with framing suspended) are cool and there's some very solid modern architectural roots in it (See, Villa Savoye).

An architectural designer can also draw the plan for you and have the engineering signed off.

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I finally got a drafter to start the architectural plan for a low cost of $1,650 for my 500 sqft ADU in San Leandro, CA. 

But added expense are architectural design, Soil Engineering, but some communities have pre-approved ADU designs at no addittional cost to $500.00.

@Amir Boneh I work for an architecture firm in Memphis and a real estate investor.

I haven't used this company yet but they were recommended to me because they have residential focus and do remodeling architectural plans. 

In regards to which option works best for your situation, I wouldn't make the decision based on WHETHER a company is a DB or DBB, I would make that decision based on WHICH representative I felt most comfortable around and who I thought would best represent my interests of helping build a high-value investment property from the ground up.How I would go about that decision would be to reach out to people I already trust and ask them if they knew anyone that they trusted or if for some reason that is not an option, I would reach out to several Design-Build General Contractors and several architecture firms  / architectural designers and meet with the ones that sound trustworthy over the phone. 

Sunnyside residents are working on a conversation overlay to prevent the modern new builds you see in the area and preserve the bungalow architecture.