How to seal baseboards: A guide for every homeowner

This guide will show you how to seal baseboards. We cover how to choose the right type of sealant for your project and provide you with step-by-step instructions.

• How to seal baseboards and why it’s important
• How to seal baseboards: Choosing the best sealant
• How to seal baseboards: Step-by-step instructions

How to seal baseboards and why it’s important

Baseboards give a nice clean finish to the bottom of any wall. However, unless they are sealed or a carpet is laid, in most cases you’ll notice a gap between the baseboard and the wall as well as between the baseboard and the floor.

Sometimes a large gap will appear. This can be down to several reasons:

• settling of the foundation and or sagging floor joists.
• the walls or floor are not perfectly straight.
• expansion and contraction of the building materials.

An unsealed baseboard also leaves an entry point for insects, moisture, drafts, or dust. Make sure to seal the baseboard with a high-quality sealant for a truly beautiful job. We’ll help you select the best sealant for your application.

How to seal baseboards: Choosing the best sealant

Use a high-quality latex sealant for most applications. It is easy to work with, cleans up with water and is paintable. Silicone-enhanced acrylic latex sealants are just as easy to use and stand up well to moisture.

For areas subject to frequent water or moisture, choose a silicone sealant, as this is more resistant to water and mould than latex. However, silicone cannot be painted so you will want to select a sealant in a colour that matches the surroundings.

If you need to seal your baseboard in a wet area, such as a bathroom, you’ll love Loctite Re-New which comes in an easy-to-squeeze dispenser with an auto-smooth nozzle. That means you never have to touch the wet sealant. And it can be applied directly over old sealant. You’ll get a professional finish in minutes.

How to seal baseboards: Step-by-step instructions

1. Gather your tools and materials. You’ll need a caulking gun and sealant, a sealant tool (if available), a utility knife, painter’s tape, nitrile gloves, and paper towels or clean cloth.
   
2. Clean the baseboards. Make sure all areas to be sealed are clean and dry. Remove old sealant, loose paint, or residue. Tip: Baseboards tend to collect dust. Vacuum the baseboards first, then wipe them down with a damp cloth. (Use some paint thinner for any oily or sticky residue—be mindful of the wall paint.)
   
3. Apply painter’s tape to the floor and/or wall parallel to the baseboard to ensure straight edges.
   
4. Load the sealant into the caulking gun and cut the tip to the desired bead size with a utility knife.
   
5. Apply the sealant starting at one corner. Apply an even bead along the joint.
   
6. Immediately smooth out the sealant. Use a sealant tool or a dampened fingertip to press the sealant into the gap and smooth out any imperfections in the bead.
   
7. Apply additional sealant and smooth out any remaining gaps.
   
8. Remove the painter’s tape.
   
9. Allow the sealant to dry before painting or normal use. 
10. If you are going to paint the baseboard, use high-quality latex paint.

Note: If you have an unusually large gap between the baseboard and the wall, use a backer rod to seal the baseboard first, then apply sealant as described above. A backer rod is a round strip of soft foam material that is pressed into the gap between the trim and the wall before applying sealant. It reduces the amount of sealant needed and prevents the sealant from sagging down into the gap as it dries.

Clean up as soon as you finish the job. If you are employing an acrylic latex sealant, just use a clean cloth or paper towel and some water. If you chose a silicone sealant, you may need some paint thinner or mineral spirits to remove the residue. Avoid getting paint thinner on your skin.