It totally depends on your area. My builder is charging closer to 12% from what I have calculated, but we have a small pretty simple home and he uses panelization construction (which cuts down on framing costs). We are in the PNW, actually in a very high end area but our builder is from a much lower cost area a few towns away. Had we used a builder in our actual town...it would have been much more expensive. Everyone seems to mention 15% so that could be a good starting off point.

For me, it was not as much about what the builder charged but could the builder build the house I wanted for the price I wanted. Also, I had to like the builder and trust him! It was also important to me that everything be bid out and the close to exact price was known upfront.

If builders aren't as busy in your area as they have been in years past, I think 10% is a good place to start if your floorplan isn't too crazy.

A good friend of mine used to say, "That is fraught with fraughtness!" In other words, a catastrophe waiting to happen.

I don't know you or your father, but it seems that this is a situation that could quickly blow up in your face. You've got a red flag already - "My father doesn't want to build in the spring but we are ready to get this project started! What do you think?" It shouldn't matter what a bunch of strangers on the internet think about when your father (who is presumably an experienced builder) should build your house.

I'm with littlebug, and wondering why you would ask this question on WC when your father/builder has already given experienced advice.

That and you question about builder expenses suggests you are considering having someone else build your house (or use as a bargaining chip with your father, which seems pointless). If this is your plan, you should do a lot of study on the types of construction contracts, since there are several. Costs vary based on the type of contract.

Good luck on you project. Seems like you may need it.