I run into this all the time. You can't know cost without knowing the allowances provided for the items to be installed. One estimate can have a $250.00 faucet another has a $750.00 faucet.
If every selection has this variance you end up with vastly different prices but in your eye the same project. A quick example-
You meet with the D/B contractor/architect show pictures of what you want, when they go back to the office one may not price for the higher end finishes that were in your project pics the other does.
Second, Take a look at structure, one company handling from design through construction can sometimes be less expensive than design firms that then take bids because you have two separate overheads both with staff.
Finally, My strongest advice is to list out the expectation of details, building products, finishes etc with regard to quality and or brand and review it in their showrooms or offices to make sure everyone is on the same page. Ask lots of questions and listen closely to the answers.

After that meeting you will have a strong gut feeling on which way to go. Good luck!

We also face this question with clients everyday. The brief answer is that details are your friend and anyone telling you $140k or $200k should be able to provide you a scope of work with that price.

As a builder I would be Leary of design/ build firms for large projects. Smaller projects they can be great. D/B companies have been frowned upon by many states as their is a lack of checks and balances for the client.

My suggestion: find builder or architect or D/B firm that will create a scope document and are ok with you shopping it too 2 other contractors. Everyone should guarantee their cost to be complete and require no additional costs to finish the job, unless specified in the contract.

good luck

The biggest difference is the limitations. You're confined to the products the DB contractor has in his showroom. What if they don't have the cabinets you really want? Add. What if they don't have the tile you really want? Add. Windows, doors, trim, countertops.....you name it.........anything they don't have is going to be an add. And we haven't even begun to discuss the "hidden" issues...........

As both an Architectural Designer / Project Manager and GC, I can tell you, my vote every time would be a Design - Bid process. I've known and worked with some excellent DB Contractors and for some projects it's an excellent method. But I don't think anything can beat a completely detailed and designed package (translation: finishes, equipment, materials, etc.,, etc.) that is bid out for the following reasons:

1. There are no unanswered items. Everyone is bidding the same thing. Materials, quality, fixtures, finishes, equipment, etc., etc..
2. A competent and knowledgeable designer (Architect or RD) will be able to investigate existing conditions that will be involved in the renovation and the new work that could have major impacts on the cost Ii.e. deficient structure, soils, plumbing, electrical service, etc., etc.).
3. You're right......this is a major investment, why would you limit yourself with somebody else's idea of products (in their showroom) that make up good design. For tract homes that's fine.......but do you really want a tract home finish?