If you want to add a room or change the function of a room, especially if that includes running plumbing or additional wiring, be sure to do this prior to starting production. It is always easier and less costly to build it originally rather than to renovate.
Modular home companies will offer custom paint, flooring and added options, but talking up front about what you want is crucial. If you have samples, colors or fabric swatches you want to match bring them in and share them with the architect or designer.
A picture is worth a thousand or more words when you are trying to describe your ideas. Look for online pictures, bring in pictures from magazines or even floor plans that you like. All these ideas will help the designer or architect understand exactly what you are looking for in the final product.
