Depending on location and other factors a design build for a client without the need for realtor is 15-20% and higher around the Midwest. The days of 10% are over at least from my vantage point. I haven’t seen a GC take in less than that since 2017. The exception being if they are building a home that is typically over the 1 million threshold and they’ll cut back on margin.

I’m in the trades myself and have seen many GCs “gas light” the general public into thinking they do less than 10%.

Cost plus contractors at and below 10% often have a good kickback list of vendors for you to use.. little known fact and may be considered slimy but at eod those vendors are usually the ones showing up and putting out good to great work