If you have a design you should be pricing it instead of looking for % costs which aren't very useful.

I think instead of working with percentages, you should get real numbers for as much as possible. For example, you should be able to get hard numbers for the permit fees and survey. Same with the cost of the septic in your area (are you likely to be able to have a field or will you have to put in a mound?-- A mound costs more, and not in a way that scales with the house). The cost of connecting to utilities can vary widely-- if you're in a development, it's probably free, but otherwise it can vary dramatically, up to tens of thousands of dollars.

In the end, dividing the cost of building up by percentages doesn't really work, because the cost of a lot of things is a personal choice, and they don't all necessarily scale together. Two houses with the same foundation could have radically different final price tags, if one was done all builder grade and the other was top of the line. Pricing out your specific choices would be much more useful, IMO.

Since you will be doing a lot of the work yourselves a normal % of cost breakdown (if there were such a thing) would need to be modified and it would affect all of the other percentages.

I hate to say it but if you are not able to estimate the cost of the construction you should not be acting as the GC or you should at least hire someone to help you manage the project. Most of the expensive parts of a house can't be done by non-professionals anyway so the cost savings is often minimal and the additional time required to build can be expensive.

Thanks for the feedback. We plan on getting hard numbers and having everything picked out before we start. I was just looking for a "jumping off point".

The builder you bought you plan from should be able to help you estimate the cost for your house.

Put your quantity and cost information into a spreadsheet. Percentages don't matter. If you built a 2 story house instead of a 1 story house, the basement slab would cost considerably less and so would the excavation and the roof. the percent of total cost would only be useful for billing or loan drawdown purposes.

Buy a book on how to manage the construction of a house.

As has been said already, percentages really don't add anything to one's knowledge. It's the bottom line that matters!

The cost will result from so many project, site, regulatory specific conditions that no one here (and certainlly no web site) could give you any useful and dependable cost information.

As has been suggested, you either need:
--a negotiated construction contract, with the builder providing cost control information, or
--fully complete construction drawings and specifications for competitive bidding.

You can compare these costs to whatever it is you think you can do yourselves. By the way, have you ever built a house before?

Good luck on your project.