DEAR TIM: My house was constructed in the early 1960's. The interior is quite plain looking. All of the interior doors are smooth hollow core painted slabs. I was thinking of installing new decorative paneled pre hung doors. However, I hesitate to do this because the frames and door trim are in excellent condition. My doors fit perfectly in each frame. Is there an easy way to simply change out each door? How would you do it? S. T.

DEAR S. T.: Talk about an excellent indoor project for a serious do-it-yourselfer, this is it! The simple process of changing out interior doors can make a dramatic difference on the inside appearance of your home. Many of my past clients were delighted with the look and feel of their new doors.

During the past five years, interior door manufacturers have expanded the styles and options of interior doors. Numerous styles are available that allow you to match virtually any architectural style or time period. Many of the doors can be purchased as solid or hollow core units. Some home center stores have specialized door machines that will actually machine a new door of any style to match your existing doors. If you can locate such a machine, you can change all of your doors in less than a day!

If not, you will need a router, drill, hole saw, spade bit, wood chisel, and various screwdrivers in order to tackle this project. The hard work has already been done by the carpenter or mill that hung your original doors. You simply need to create hinge mortises (recessed slots) and door knob holes in precise locations on the new door. To accomplish this, you are going to use the old door as a template.

Using a pencil, write lightly on each new door its intended location. Now, go through the house and do the same thing on the existing doors. While you are at each existing door, write in bold letters the word TOP on each side of the door. Don't guess where doors go or came from, you will get confused!

Remove an existing door from its frame. Strip the door of its hinges, doorknob, and latch. Stand this door on edge with the old hinge locations pointing up. Slide the new replacement door next to the old door being careful that the top of both doors are pointing in the same direction and flush with one another! Using a square and a sharp pencil, transfer the old hinge locations onto the edge of the new door. Use the hinge to create the shape of the mortise. Adjust the router depth and get to work.

After the hinges are complete, recreate the door knob holes using the same transfer process. However, if you intend to purchase new decorative door knobs let me share a secret. Consider purchasing knobs that have a two and three-quarter inch back set. This is three-eighths of an inch larger than most standard knobs. Your knuckles are less likely to rub against the door frame with this measurement.