When it comes to the specifics of interior designer cost, labor is the largest expense in any home renovation project. This includes contractor and builder fees, interior design and architect fees, and any tradespeople and consultants that are needed, such as a specialty painter or structural engineer. The more work that you can complete at one time, the better. For example, if you are considering a kitchen redesign and bathroom renovation, group this work together to save money. Designers have startup costs associated with setting up a project and maintaining our knowledge of the project and job site, as does the builder and any other trades involved with the job. In the long run, completing multiple home projects at once—while a more significant investment from the get go—will save you money.