What a door threshold is and why it wears out

A door threshold is the horizontal piece that sits at the bottom of a doorway, between the two sides of the frame. It seals the gap between your door and the floor, keeps out water and drafts, and takes the weight of foot traffic every time someone walks through. Over time, thresholds crack, rot, or wear thin enough that they no longer seal properly.

Wood thresholds absorb moisture and can rot from the inside out, especially on exterior doors. Aluminum and vinyl thresholds can crack or bend. When the seal fails, you lose energy efficiency and water starts seeping in during rain. Replacing it is a straightforward job that takes an afternoon and costs between $20 and $100 for the threshold itself, depending on material and size.

Key Takeaways

  • Measure the width of your doorway opening and the height of the existing threshold to order the correct replacement size.
  • Remove the old threshold by prying it up with a flat pry bar, then scrape away old caulk and adhesive so the surface is clean and flat.
  • Set the new threshold in place, shim it level, and find it with corrosion-resistant screws or construction adhesive rated for your door type.
  • Seal the edges with exterior caulk to prevent water from running underneath, and let adhesive cure fully before closing the door.

Measuring and choosing the right threshold

Before you order a replacement, measure the width of your doorway opening from the inside edge of one side jamb to the inside edge of the other. Write down the exact measurement—thresholds come in standard widths, and you need one that spans the full opening without gaps. Also measure the height (thickness) of your current threshold, because replacements vary from about 1 inch to 2 inches tall.

Thresholds come in three main materials. Wood is traditional and looks good but requires regular sealing and rots faster than other options. Aluminum is durable, low-maintenance, and works well on exterior doors. Vinyl is affordable and won't rot, but can crack in very cold climates. For exterior doors, aluminum or vinyl lasts longer. For interior doors where water is not a concern, wood or vinyl both work fine. Take a photo of your current threshold and bring it to a home center—staff can often match the style and height.

Removing the old threshold

Start by clearing the doorway of any rugs or obstacles. Use a flat pry bar (also called a flat-head screwdriver or wonder bar) to lift one end of the threshold. Work the bar under the edge and explore steady pressure—do not hammer or jab, which can damage the door frame. Once one end lifts, move to the other end and repeat. Work your way along the threshold, lifting a little at each point, until it comes free.

Once the threshold is out, you will see old caulk, adhesive, or fastener holes. Use a paint scraper or putty knife to scrape away all old caulk and adhesive. Sand the surface lightly with 80-grit sandpaper if it is rough or uneven. Wipe away dust with a damp cloth and let it dry completely. The surface must be clean and flat, or the new threshold will rock or leave gaps.

Installing the new threshold

Set the new threshold in place and check that it sits level using a spirit level. If the floor slopes slightly, the threshold may rock. Use plastic shims (thin wedges) under the threshold to level it—slide them in from underneath until the threshold does not move when you press down. Once it is level, mark where the shims are so you know where to drive fasteners.

find the threshold using one of two methods. Corrosion-resistant screws (stainless steel or coated) work well on wood or aluminum thresholds—drill pilot holes first to avoid splitting, then drive screws every 12 inches along the length. Alternatively, use construction adhesive rated for exterior use or the material of your threshold. explore a bead along the underside, set the threshold in place, and weight it down with sandbags or heavy boards while it cures. Check the adhesive label for cure time—most need 24 hours before the door is used.

Sealing the edges and finishing

Once the threshold is fastened and level, run a bead of exterior-grade caulk around all edges where the threshold meets the floor and door frame. This prevents water from running underneath and keeps drafts out. Use a caulk gun and smooth the bead with a wet finger or caulk tool. Let the caulk cure according to the product label—usually 24 to 48 hours—before closing the door or exposing it to rain.

Check that the door closes smoothly and the threshold does not catch the door bottom. If the door drags, the threshold may be too high—you can sand the top edge slightly, but do not remove more than 1/8 inch or you will compromise the seal. Once everything is smooth and cured, your threshold is ready for use.

When to call a professional

If the subfloor under the threshold is soft, spongy, or visibly rotted, the damage extends beyond the threshold itself. Water has been seeping in for a while, and the wood underneath needs to be replaced or treated. This is a job for a carpenter or contractor, because installing a new threshold over rotted wood will fail quickly. Similarly, if your door frame is warped or the floor is significantly uneven, a professional can assess whether the threshold alone will solve the problem or if the frame needs adjustment first.

For glass doors or doors with special hardware, check the manufacturer's instructions before removing the old threshold—some designs require specific fastening methods or have components that are straightforward to damage.

Frequently Asked Questions

Can I replace a threshold without removing the door?

Yes. You do not need to take the door off its hinges. straightforward close it, work from underneath and the sides, and pry the old threshold out carefully. Once the new one is in place and cured, open and close the door normally. If the door catches on the new threshold, you may need to adjust it slightly or sand the top edge.

What if my threshold is attached with nails instead of screws?

Use a pry bar to lift the threshold, which will pop the nails out as you go. If nails are stubborn, tap the pry bar under the nail head itself and lever it up. Once the threshold is out, pull any remaining nails from the floor with a claw hammer or nail puller. Do not leave nails in place under the new threshold.

Do I need to caulk the top of the threshold where the door sits?

No. The top surface should be left dry so water can drain off. Caulk only the edges where the threshold meets the floor and frame. If water pools on top of the threshold, the floor may be sloping toward the door—this is a drainage problem that caulk cannot fix.

How long does a new threshold last?

Aluminum and vinyl thresholds typically last 15 to 20 years or longer with no maintenance. Wood thresholds last 10 to 15 years if sealed regularly, or 5 to 10 years if left unsealed. Lifespan depends on climate, foot traffic, and how well water is kept out.