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Ace of baseboards

Walk the walk and caulk the caulk: How to caulk baseboards

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Knowing how to caulk baseboards will let you give your baseboards a perfect finish and create a beautiful seal. This guide tells you what you need to know to select the right caulk, how to caulk baseboards to floors and walls, and how to caulk large gaps in baseboards.

Why learn how to caulk baseboards?

When baseboards do not align perfectly with the floor or wall, unsightly gaps appear. They usually form for the following reasons:

  • floor joists sag and foundations settle.
  • walls are not flat.
  • materials expand and contract over time.

Learning how to caulk baseboards is a great way to get rid of these gaps. However, if your gaps are very large, you may need to replace the moldings.

One hand holds a baseboard horizontally to the wall, and on the backside is a line with glue dots.
Apply caulk to the back of the baseboard with a caulk gun to bond it firmly to the wall

The right adhesive for caulking baseboards

Choosing the right sealant is a key step on your path to beautiful, clean baseboards.

If you need a product for caulking baseboards to floors and walls, Loctite PL Heavy Duty Sealant is a great choice. The all-purpose sealant is specially formulated to create strong bonds between many materials in and around baseboards, such as tile, wood, and drywall. This flexible product expands and contracts without cracking or shrivelling, making it perfect for caulking large gaps in baseboards as well. You can use Loctite PL Heavy Duty Sealant to bridge gaps up to 1/4” and paint it to match your baseboard just 30 minutes after application. Watch this helpful product video to learn more.

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If your gap is between 1/4” and 3/8” wide, reach for Loctite Polyseamseal All-Purpose Adhesive Caulk instead. It is another premium product you can use to seal cracks around baseboards, and it bonds to most indoor surfaces, including wood, ceramic, plaster, and concrete.

How to caulk baseboards

Once you have the right caulk, you can begin. Always read your product instructions before starting – application may vary from the instructions on how to caulk baseboards and how to caulk large gaps in baseboards provided below. Also wear the protective equipment mentioned in the instructions.

How to caulk baseboards to floors and walls

  1. Gather materials. You’ll need a caulk gun, utility/putty knife, vacuum (optional), protective gloves, painter’s tape, acrylic caulk, paintbrush and paint (if applicable), warm water with mild detergent, and clean, dry rags. Also get any protective gear mentioned in the instructions.
  2. Clean joints. Caulk bonds best to clean surfaces, so clean surfaces thoroughly of any old sealant, dust and debris using your utility/putty knife, water and detergent, and rags.
    Tip: Vacuuming can help clean baseboards better.
  3. Let joints dry thoroughly.
  4. Protect surfaces. Apply painter’s tape to the floor and/or wall parallel to the baseboard to protect surfaces from excess caulk and guarantee clean edges.
  5. Prepare caulk tube. Load the acrylic caulk into the caulk gun and cut the tip to the desired bead size with the utility knife.
  6. Apply caulk. Apply a long, steady bead along the joint.
  7. Smooth caulk. Smooth the caulk immediately after application. Dip your finger in a bowl of water and run it along the wet caulk bead, exerting just enough pressure to force the caulk into the gaps. Rinse off your finger as needed.
  8. Inspect and correct. If any gaps remain, apply additional caulk and smooth it as described in step 7.
  9. Remove painter’s tape.
  10. Let it dry. After the caulk has dried, inspect it again to see if any small gaps have formed. If so, apply additional caulk and smooth it as described above.
  11. Optional: paint the caulk to match nearby materials.
A hand runs a finger over a fresh baseboard sealant; the edges are taped.
Tape the edges and smooth the caulk immediately after application with your finger

How to caulk large gaps in baseboards

The larger the gaps between baseboards and other surfaces, the more dust, pests, and moisture can accumulate in them. Make them a thing of the past by following these easy instructions for gaps exceeding 1/4".

  1. Follow steps 1 to 3 from the section above. You also need a backer rod.
  2. Insert backer rod. Push the proper size backer rod into the gap so it is below flush with the surface.
  3. Follow steps 4 and 5 from the section above.
  4. Apply caulk. Apply a surface bead of caulk over the filled gap, using only as much as you need.
  5. Follow steps 7 to 11 from the section above.

Products used

  • loctite pl 375 heavyduty 10oz cartridge
    Loctite PL375 Heavy Duty

    Heavy duty bonding of all common building materials. Low VOC formula.

  • loctite polyseamseal all purpose clear 10oz cartridge
    Loctite Polyseamseal All Purpose

    Provides a durable bond and seal for general sealing projects.

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