How to Replace Exterior Door Trim

In this video, Nathan Gilbert helps a homeowner struggling with the look of a plain front door trim in a neighborhood full of ornate entryways. After explaining that the homeowner’s current entryway is a very common design, the two look at some PVC moldings Nathan thinks will do the job.

How To Replace Exterior Door Trim

1. Don a pair of safety glasses and remove the existing trim around the door. Use the hammer and prybar to get behind the nailheads and remove the trim one piece at a time. For stubborn aluminum flashing, it’s possible to score it with a utility knife and snap it off the door. Remove the original wood trim behind the door as well.
2. Create a flat, even surface by padding the space overtop of the door, as well as either side, with filler boards. Measure the space with a tape measure and cut boards to length on a miter saw. Then use the nail gun to nail them in place.
3. Protect the exposed wood by placing a layer of waterproof membrane over the top. Use a utility knife to cut it to length and width. Start at the bottom, then move to the sides, and finally over the door. Be sure each layer overlaps the previous layer to allow it to shed water properly. Simply peel and stick the membrane in place and roll it smooth with a roller.
4. Install flat ¾-inch-thick PVC stock all around the door. Start overtop of the door, then move to the sides, then finish at the bottom. Take accurate measurements with a tape measure and cut everything to length with a miter saw. For custom widths, rip the PVC stock to size on a table saw. Attach these boards with the finish nailer.
5. Use the miter saw to cut the premade head casing to the proper length. For a truly upscale look, cut a 45-degree angle on each end. You’ll install “returns,” or small pieces of mitered trim, later to allow the casing to wrap back toward the house.
6. Measure the width of the casing and mark its center, and measure and mark the center of the doorway. Lining up the two marks, install the head casing over the door using the screw gun and stainless screws. Use a level to ensure it’s installed correctly.
7. Double up two short pieces of ¾-inch PVC stock to create a plinth block. Carefully aligning it with the head casing, install one of these blocks at the bottom of the door on both the left and right. Secure them in place with stainless steel screws.
8. Cut a small block to the exact width of the fluted molding and the exact height of the small PVC moldings. Install this filler block, centered on the top of the plinth block. Do this on both sides.
9. Measure and cut two pieces of fluted trim, one for either side of the door. Nail them in place with the nail gun.
10. Cut the two returns on the miter saw by first cutting 45-degree ends and then cutting them off at the appropriate length. Secure them in place using two-part PVC glue.
11. Use the small PVC trim to dress up the header, the bottom of the fluted moldings, and anywhere else an extra detail might be necessary.
12. Install the PVC plugs in any of the visible screw holes using a mallet to prevent marring the PVC. Pressure wash the door once a year to keep it looking bright and fresh.

Resources

To build out new front door trim and plinth blocks, Nathan used flat PVC stock in 1×10″ boards. For the plinth blocks, Nathan used flat PVC stock in 1×4″s boards. For decorative elements, Nathan used stock PVC head casing for above the door, stock PVC profiles for under the header, and fluted trim to the left and right of the door. Stock PVC can be found at home or lumber centers. To attach the PVC to the exterior, Nathan used stainless steel brad nails and 2-part PVC glue.

To cut the PVC, Nathan used a sliding compound miter saw, which is manufactured by Dewalt.

Under the PVC, Nathan used Henry Blueskin VP100 Self-Adhered Water Resistive Air Barrier Membrane.

Shopping list

• Filler material (typically 1×8 pine)
• PVC square stock
• PVC premade head casing
• Fluted PVC trim
• Small PVC moldings for accents
• Stainless steel screws
• Finish nails
• PVC plugs
• Two-part PVC glue
• Brad nails
• Self-adhesive membrane

Tools