How to fix gap between door jamb and floor.

After installing your new flooring into your home, you may find a noticeable gap between your original doorway molding and your newly installed floor and may be wondering how to fix gap between door jamb and floor. Don’t worry, this is an easy fix and will be seamless by the end of this project.

The tools you will need.

  • Measuring Tape
  • Piece of Molding/Plywood
  • Saw (if wood not previously cut to size)
  • Rubber Mallet
  • Tapping Block
  • Writing Utensil (Pen, pencil)
  • Shims
  • Pilers
  • Nails
  • Wood Filler
  • Putty Knife
  • 120 Grit Sandpaper
  • Painter’s Tape

How to fix gap between door jamb and floor

First you’re going to want to take your measuring tape and measure the width of the Gap underneath the molding. Measure the length of the Gap as well. If you are using an extra piece of molding that you have from your original project, and sure it is a flat piece of molding. You don’t want any ridges or bumps poking out.



Once you have cut your pieces cut to size, Place underneath the original molding to ensure a snug fit. Use your tapping block to Center the peace and check from all angles to ensure a seamless fit. If you have any overhang on any sides, Using your measuring tape and a writing utensil, mark where needs to be cut.

If you are unable to get the molding to sit flush, pull the piece out. Get to your shims and your saw. Cut the shims to whatever length, and shape you will need them to be in. Place these items behind your piece of molding, and then utilizing your rubber mallet as well as your tapping block, place the molding back into its original spot. Once again, observe from all angles to ensure a seamless fit. Repeat these processes, either removing or adding as many pieces of shim that you need in order to have a seamless fit.

Once your base is flush, you will notice the middle of your molding may have a piece of wood that extends out by about half an inch. If your molding is level all the way across, you may skip this paragraph and continue to the next one. Grab an extra piece of molding and place it underneath the middle portion. Place the side that you want facing out, against the molding (it will be facing backwards) and utilize your writing utensil to Mark the place where you need to cut in order to get it to fit. Be very careful when cutting the excess off of this piece as it is most likely very small. It is recommended that you use a pair of pliers, or other form of clamp in order to ensure the piece is secure while not putting yourself at risk of injury. If you find your peace as slightly Too Short’s, cut another piece of shim and place underneath the peace in order to allow for a flush Edge on the upper side.

Using your framing nails, secure each end of the base part of the molding. Be cautious when completing this, as the piece can crack. If applicable, nail these smaller piece we created in the previous paragraph to the base piece. It is recommended here to either use a level, or a book to place against the edge in order to ensure it is on their straight. If after nailing the pieces down, you realize you have a small gap left behind, do not panic. This is easily fixable with a little wood filler and sanding. If the other side of the doorway has an identical to the side we just fixed, repeat the steps above in order to fix that.

Grab your wood filler as well as your putty knife, and begin covering any gaps that are left behind. Using the end of the putty knife, remove some putty from the container and insert into the gaps. When using wood filler, you want to over fill the gaps slightly in order to allow for proper sanding. It’s okay for the area to look a little messy as we are going to sand the area down and paint.

Check the back of your wood filler packaging and take note of how long it takes for the filler to dry. Once that amount of time has passed, use your 120 grit sandpaper to begin sanding the areas covered with your wood filler. Take the necessary precautions while doing so such as wearing a N95 mask as the dust is not healthy to breathe in. Focus on the more round parts of the filler, and sand until you have a finish which is flush with your original molding. Make sure to clean off any dust that results from the sanding. A vacuum, wet cloth or paper towel are all fine ways to clean the area. Wipe the area down with a dry cloth or paper towel before proceeding to the next step.

Using your painters or masking tape, tape around your molding to ensure you do not end up with any paint on your new floor. It is always better to use too much tape versus too little. Make sure you press the edges of the tape down tightly in order to prevent leaks or bad paint lines. If you do not have any paint left over from your molding, determine what color molding is, as well as the sheen. If you are unsure or unable to eyeball it, take a scrap piece of molding to your local hardware store and they will assist you in getting the correct color and sheen for this project. Using a paint brush or very thin paint roller, apply the paint to the newly patched part of the molding. Allow the paint to dry for 24 hours, and add a second or third coat if necessary. Repeat all steps on the opposite side as well in order fix gap between door jamb and floor.