How to Identify Door Frame Rot and Eliminate It Once and for All

Lawrence Bonk
Written by Lawrence Bonk
Updated July 27, 2022
Woman pets dog by front door
Photo: Halfpoint / Adobe Stock

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Wood door frames are functional and aesthetically pleasing, as nothing beats the look of real wood. However, these frames are susceptible to wood rot when exposed to moisture and mold, with exterior frames at particular risk for the dreaded rot. Putting in a new door frame costs $200 to $650, so avoid this hassle by identifying the problem quickly and sending that rot back to whatever shadow dimension it hails from. 

What Is Door Frame Rot?

Wood rots when exposed to moisture and various forms of fungi. Due to millions of years of evolution, trees have many tricks to combat most forms of rot. Door frames? Not so much. It only takes a small amount of moisture to invite fungal growth, such as mold spores, and left unchecked, the fungi reproduce and feed on the wood frame, leading to rot. Wood frame rot impacts the door's structural integrity, leading to increased air drafts, higher energy bills, various structural issues, and water damage.

How to Identify Door Frame Rot 

Don’t worry. There are some recognizable signs that your door frame suffers from wood rot. Here are some tell-tale indicators. However, these signs are for rot that is fairly far along. To catch wood rot at its earliest stages, hire a local door contractor for a professional examination.

Crumbling Wood

One of the quickest ways to identify door frame rot is to look for crumbling wood. You can do this by examining every door frame nook and cranny, looking for obvious splinters and the like. For a more thorough approach, use a screwdriver or a similar tool to gently poke the frame and feel for softness in the wood. If you feel any give and see wood crumbling or splintering, that’s a sign of rot damage.

Dark Areas

Another visual indicator of wood rot are dark areas throughout the exterior of the door frame. These dark areas announce the presence of mold, mildew, or water damage, and all three are precursors to wood rot. The sections of the doorframe closest to the ground are particularly susceptible to damage from rain splashing against the frame and threshold, so start your examination at the bottom and work your way up. Use a flashlight to get a really good view. 

Improperly Shutting Doors and Air Drafts 

Rot warps the wood, which leads to improperly shutting doors, as they no longer sit plumb in the frame. If your doors won’t shut right, or if they struggle to open, a likely culprit is a rotting door frame. Rotten spots also let in air and moisture, pushing your HVAC to work harder because your front door isn’t energy efficient. This leads to air drafts throughout the home, as do any cracks in an improperly fitting door. 

How to Repair Door Frame Rot 

Think the wood frame is rotted? Don’t worry—there are ways to repair or replace the damaged wood to get your frame looking and acting brand new. 

Install a Replacement Piece

This method is only applicable when the wood rot has not spread throughout the entirety of the frame, though you can repeat this process for several infected areas.

  1. Start by measuring the damaged area you previously identified using a tape measure, a ruler, or a preferred measuring tool.  

  2. Remove any weatherstripping before going in and making any cuts. 

  3. Use your preferred tool to cut away the rotted area, choosing from chisels, saws, knives, or related gadgets.

  4. Confirm the measurements of the removed area and shop online or at a hardware store for a replacement kit. These kits include everything you need to cut out and install a new piece easily.

  5. If you have experience with this type of thing, skip the kit and cut your own replacement piece using the same type of wood, filling in the space with an epoxy wood filler. 

  6. After installing the new piece, sand any seams or cracks to create a smooth and seamless door frame. 

  7. Prime and paint the area to match the rest of the frame. 

Use Polyester Filler 

Polyester filler won’t rot and takes to paint well, making it a great choice for smaller patches of rotting wood that don’t require an entire replacement piece.

Repairing door frame rot with filler requires some unique tools and supplies.

  • Putty knife

  • Sanding block

  • Utility knife

  • Wood chisel

  • 100-grit sandpaper

  • Polyester filler

  • Wood hardener 

Once you’ve gathered your supplies, it’s time to get to work.

  1. Start by identifying the rot and removing it with a utility knife or any other preferred tool.

  2. Coat the area with wood hardener and mix in the polyester filler as indicated by the instructions. 

  3. Use a putty knife to press the compound into the recess left by the wood rot, filling up any available space.

  4. Shape and smooth the compound with the putty knife and wood chisel, adding more layers if necessary. Keep in mind that polyester filler dries in just 15 minutes so work quickly. 

  5. Once dried, carve off any excess or sagging filler, again using the putty knife or chisel. 

  6. Use a sanding block or sandpaper to smooth out the area. Work carefully here as there is no time limit.

  7. Prime and paint the impacted area to match the rest of the door frame. 

Replace the Frame 

If you’ve already got the tools, you can frame a door yourself in about five steps. 

  1. Measure the height and width of your door and mark the opening at the top and bottom plate

  2. Cut the lumber for the door frame with a miter saw. You’ll need to cut a bottom plate as well as two king studs, a header, and two jack studs.

  3. Attach the sole plate, king studs, and jack studs to their appropriate location on the frame. Keep your level handy to ensure all pieces line up.

  4. Install the header and cripple studs.

  5. Remove the sole plate by cutting directly next to the jack stud using a reciprocating saw. This completes the rough opening. Secure all nails and clean the opening.

If DIY frame building feels a bit too complicated for your skills, contact a local front door repair service to purchase a new door frame and make the necessary installation. Going with a reputable pro ensures a successful installation, a quick turnaround, and some peace of mind via work guarantees and the like. 

How to Prevent Door Frame Rot

Once the issue is resolved, via a full-frame replacement or a DIY fix, prevent reoccurrence by following some basic steps. 

  1. Moisture is the main offender here, so start by addressing drainage issues. 

  2. Clogged gutters push overflow rainwater down into the door system below, so clear out those gutters every six months. 

  3. Take a look at your porch overhangs, ensuring they don’t funnel large amounts of water on or around the door frame. Rejigger the downspouts so the water lands somewhere else.

  4. An improperly installed storm door traps water in the space between the entry door, so hire someone to conduct an inspection to ensure proper operation. 

  5. Install a sill pan at the bottom of the door to direct any water elsewhere.

  6. Consider composite door frames, which are better at resisting mold, mildew, and, of course, wood rot. 

  7. Conduct regular examinations of the door frame to catch wood rot at its infancy, especially following rain storms.  

DIY vs. Hiring a Pro

For small outbreaks of wood rot, DIY fixes are available, as shown above, and help to save money on repairs. A free weekend and about $500 will get you a new frame. According to HomeAdvisor, door repairs cost $120 to $600, while frame piece replacement kits and polyester filler cost $10 to $50 and $20 to $90, respectively. 

When it comes to larger repairs, including door frame replacements, go with a professional with plenty of experience with wood rot. These pros offer work warranties, a quick turnaround, and access to high-quality materials. The average cost of replacing a door frame is about $400, including labor. The frame itself can cost anywhere from $80 to $500, depending on the material, type, and style you choose.

Additional Questions 

Does wood rot impact other parts of the home?

Yes, any part of the home where wood meets water is susceptible to wood rot. This includes underneath sinks, decks, windowsills, window frames, basements, attics, and eaves, among other locations. Conduct regular inspections of these areas to spot the beginning stages of wood rot. 

Can you still paint the front door if the wood is rotted?

Paint does absolutely nothing to minimize the spread of wood rot, so painting an infected door is a waste of time, as repairs or replacements are still necessary. Wait until after handling the rot problem before whipping out the paintbrush. 

Does wood rot spread? 

All forms of wet rot caused by fungi spread throughout the frame and door, but will stop when encountering non-wood materials. Dry rot, on the other hand, spreads throughout the area to any items of wood with porous openings to accept the spores. 

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