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The basics on baseboards

How to caulk baseboards: The DIYer’s guide

Painting or upgrading a room? You need to know how to caulk baseboards for a truly finished look. Get the details in our free guide.

6 min read

Knowing how to caulk baseboards properly is a great way to show you care for your home. Properly sealing and filling gaps before painting gives the project its final touch. Here are the details on how to get the job done right.

How to caulk baseboards: The basics

When new baseboard is installed, there will nearly always be a need to fill gaps in baseboard trim as well as to caulk the new baseboard to the floor. This is just the seam between materials, but it will be more noticeable if the wall or floor is not perfectly flat. This is often the case due to:

  • sagging floor joists
  • warped studs in the wall
  • expansion and contraction of materials 
  • tile with an uneven surface


Properly sealing the baseboard before painting will provide a neat look and seal up any gaps in the trimwork or between the baseboard and surrounding materials.

How to fill gaps in baseboard trim

Sealing gaps and cracks around baseboards is actually not all that difficult. Before beginning, collect your tools and supplies. Here are some things you will need:

  • caulking gun 

  • high-quality sealant 

  • utility knife

  • clean cloths and water

  • painter’s tape

  • putty knife or a caulk tool (one end removes old sealant and the other has a rounded rubber end to spread the new sealant)

  • protective gloves


You’ll find LePage 2in1 Seal & Bond Interior to be an excellent all-around product for interior trim projects. It will provide a barrier against mould and mildew even in moisture-prone areas like kitchens and baths.

Follow these step-by-step instructions to caulk baseboards:

  1. Remove any old sealant with your caulk remover tool or a putty knife.
  2. Clean the areas to be sealed. Remove dust, debris, or leftover residue. This will allow for a stronger bond.
  3. Apply painter’s tape to either side of the joint to be sealed. This will protect surrounding areas and leave a nice clean edge to the sealant. Make sure the tape is straight and parallel to the joint.
  4. Load the sealant into the caulk gun and cut the tip to the desired size.
  5. Apply the sealant starting at one corner. Use steady pressure and motion to leave an even amount of sealant along the crack.
  6. Smooth out the sealant with the caulking tool or your finger. Press the caulk into the gap and feather the edges onto the tape or surrounding material. Ensure there are no gaps in the sealant. Apply more caulking if needed.
  7. Gently remove the painter’s tape.
  8. Allow the sealant to fully dry before painting.
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Do you know how to caulk large gaps in your baseboards? Prefill these gaps with either wood filler like LePage Polyfilla Spackling Big Hole Repair or a backer rod before applying the sealant. 

How to caulk baseboards to a tile floor

What about the bottom of the baseboards? These are handled the same way. Of course, if you are installing carpet, the bottom of the baseboards will be hidden. That’s not the case with tile or other hard-surface floors.

When you want to caulk the bottom of baseboards, first clean and prepare the area as detailed above. Using painter’s tape is important if you are sealing onto a tile floor with a somewhat uneven surface, as it will help prevent wide variations in the thickness of the sealant giving you a clean and sharp line. Follow steps 4–8 above when applying the sealant.

How to caulk baseboards: Choosing a sealant

When you are selecting a baseboard sealant for your project, here are a few things to keep in mind.

Use 100% silicone for sealing exterior areas and areas subjected to frequent water or moisture (such as the bottom of baseboards on a tiled basement floor). Silicone is available in a wide variety of colours, so you will likely find one that matches your décor perfectly.

Knowing how to caulk baseboards is key but if you intend to paint the baseboard, you need to choose a paintable sealant. Pure silicone is very durable and highly resistant to moisture and mould, but it is not paintable. However, many acrylic trim sealants now have added silicone, gaining its benefits while still accepting paint.

For general purposes, a flexible acrylic latex sealant will do the job and LePage Polyfilla Trim and Baseboard Filler is an excellent choice. This formula has added silicone for extra durability and strong adhesion. You can paint it in as little as 30 minutes after application, and uncured sealant cleans up easily with water.

Related Products

  • lepage 2in1 seal bond interior 295ml cartridge
    LePage 2in1 Seal & Bond Interior

    LePage 2 in 1 Seal & Bond Interior Adhesive is a premium adhesive that is specifically designed for sealing projects indoors.

  • lepage polyfilla big hole 900ml tub
    LePage Polyfilla Spackling Big Hole Repair

    LePage Polyfilla Spackling for Big Hole Repair is formulated to fill large holes and cracks up to 13mm deep in just one application.

  • lepage polyfilla trim baseboard 162ml tube
    LePage Polyfilla Trim and Baseboard Filler

    LePage Polyfilla Trim and Baseboard Filler is formulated to fill gaps and cracks in and around the home.

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