Most people, even designers, have trouble visualizing the "end product." A designer tells you - "Let's put built-in shelves on both sides of this room and then we'll put wallpaper behind the shelves and put a new sofa here, two chairs here and here are all the fabrics and here's what the new chandelier will look like!" You, the client, looks back at them and says "Uhhh, okay, I guess" while not having a clue what it will look like in the end and feeling slightly dizzy at the prospect of it all. Sometimes, the designer's not even clear on what the end product will look like!
Sketching out the room before anything's been purchased, built, decided on 100% is soo worth the little time it takes to do. You are paying for a well-thought out design. It makes sense to be absolutely confident that you are going to be happy with the final look, and an easy way to do this is by looking at a sketch.
Here's a sketch we did for a living room:And, here's a photo of the final product (different angle):
There are a few differences, but the "look" is the same. The sketch doesn't need to be polished, just a rough idea of the look and what colors go where can help most people say, "Aha! I get it now!" and either sign off on the idea, or decide that maybe they don't love the color green as much as they thought they did and tweak it a bit.
Sketching is a great communication tool - don't feel shy to ask your designer for this. Please check out our "Conceptualization" page at O Interior Design to see more examples!