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Seal Baseboards to Stop Draft | 3 Easy Ways

If you’ve noticed that you’ve got a draft coming up from the floor, your baseboards are a likely culprit. While there are arguably more than three methods to seal up these gaps, my opinion is that the three that I am going to take you through are the most effective, long-lasting, and practical. You can decide which is best suited to you and your home, or even if all should be employed at once.

Before attempting to seal your baseboard gaps, you need to determine if they are innocuous gaps or if they indicate a structural or poor design issue that needs to be remedied.

1. Apply Caulk over Cracks

The most common fix for stopping the drafts you feel coming from the baseboards is simply to caulk over any gaps or cracks around your baseboards.

Caulking over the gaps is a rather easy job, even for beginners. Additionally, using a latex-based caulk will allow you to paint over the caulk if necessary to ensure that your room aesthetic is not impaired by this practical repair. 

Dap 18128 Alex Plus Acrylic Latex Caulk Plus Silicone 5.5-Ounce

There are two things I’d like to point out with caulking. One is that, when used alone, it is only really a fix for smaller cracks, but it is valuable for larger cracks when used in conjunction with another method. The second is that it can sometimes be a messy job.

Preventing Mess

When you’re looking to fill the top edge of your baseboard, you can apply painter’s tape onto your wall before caulking. Leave a sliver of space between the gap and the tape’s edge to give the caulk room to taper off cleanly.

While caulking, the top gap of your baseboard will be the same regardless of what kind of flooring you have. Caulking the bottom edge of your baseboard is a different story.

With hardwood or tile flooring, you can apply tape to the floor along the edge of your baseboards, just like you would apply tape to the wall when filling the top gap.

For a carpeted floor, you can caulk the top of the baseboard, but you shouldn’t normally need to do anything to the bottom of your baseboard. Baseboards and carpets are generally installed so that there is no gap (any natural gap that exists as a result of slight unevenness of the flooring is filled by the carpet’s edge).

Of course, that might night be the case for you. If the space between your carpet and the bottom of your baseboards is very large, you should use a different method instead of or in combination with caulk to fill the gap.

Tools and Products

Before you begin, you will need to make sure you have all the necessary materials.

ToolAmazon link
Utility knifeView
Latex-based (or primarily latex-based) caulkView
Caulking gunView
Caulk finished tool (you can also just use a plastic spoon or even your finger. But the tool is less messy)View
Rag (onto which you can wipe the excess caulk)
Painter’s tapeView

How to Caulk

Clean the baseboard of dirt and, with the utility knife, remove the previous caulking.

Using the gun, apply caulk along the edge of your baseboards. After filling each section, you will want to run your caulk finishing tool or wet finger over the strip you just caulked before it becomes too stiff. This will push the caulk into any small holes that were missed and smooth out the bead. 

If you are a visual learner, this video will help you learn to caulk.

2. Seal Larger Cracks With Spray Foam Insulation

If you have a wider gap along your baseboards, just using caulk may not be enough. In this case, you might choose to use spray foam insulation.

There are two types of spray foam—high expansion and low expansion foam. 

Unless you are experienced with using spray foam insulation, it can also be hard to gauge just how much the foam will expand after application. Because a baseboard gap is a relatively small area, it may be best to use a low expansion foam to avoid overexpansion.

Spray foam is cheap and easy to get the hang of, but it can be messy, much messier than caulk.

In addition, the foam can even be harmful if you don’t provide ample ventilation to the area you will be working in. This is because spray foam insulation releases gas compounds that can be harmful to the body.

Preventing Mess

As with caulk, you can tape off the areas you don’t want to get messy with foam. However, you’ll want to place the tape flush with the gap instead of leaving a small space. This leaves room for the caulk to lie over the foam, creating a better seal.

If you have flat flooring, like wood or tile, taping is easy to do. But if you have a carpeted floor, you will need to be extremely careful and use plenty of tape and newspaper to protect your flooring. It is difficult to get the foam off of any surface, but it is particularly tricky with fabric or carpeting. 

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You may even want to look into peeling up the edges of your carpet before using foam, then replacing them once it has cured.

It’s also not a bad idea to test the spray foam outside on a sheet of paper to get the hang of controlling the flow before using it indoors.

Tools and Products

Luckily, there aren’t many materials needed for using spray foam insulation.

ToolAmazon link
Spray foamView
Rag to clean off spray nozzle and other messes
Utility knife to cut through any foam that expands too farView
OR putty knifeView
Painter’s tapeView

How to Apply Spray Foam

As mentioned, spray foam is very easy to use. Once you have properly protected your working area, you’ll want to insert the straw of your spray foam can into the gap and gently squeeze the trigger to fill the space.

Seal Spray Foam High Performance Closed Cell Insulating Foam Can Kit w/Gun Foam Applicator and 1 Can of Cleaner (150 Board FT-6 Cans)

Remember to allow the foam some space to expand, as it is easier to apply more foam if needed than it is to remove excess.

After the foam has been applied and allowed enough time to dry, you can caulk over the foam to provide an extra seal and give your baseboards a professional, finished appearance.

If you peeled back the carpet to access the gap, you would replace it after everything has cured.

3. Install Foam Backer Rod Behind Baseboard

If you have very large gaps below the baseboard, or if you simply prefer to avoid the mess of spray foam, you may opt to place a foam rod behind your baseboards instead.

If your home’s walls and/or flooring are primarily constructed with wood, using a foam backer rod may actually be in your best interest because wood expands and contracts with changes in weather. So, using a foam rod instead of a more permanent sealant gives your home freedom to “move.” 

If your home’s walls and/or flooring are primarily constructed with wood, using a foam backer rod may actually be in your best interest.

Foam backer rods are far less messy than spray foams, and they are both easy to install and easy to remove.

However, they are also very easy to compress. This is good in theory because you can stuff the rods into spaces that are much smaller than their diameter, but this can also make it difficult to figure out your sizing.

A good rule of thumb is to pick a rod size that is just slightly wider than the gap you wish to seal, but no larger than twice the diameter of the gap.

Tools and Products

Because foam backer rods are so easy to install, there are no real precautionary measures needed to prevent mess. For this reason, we’ll jump straight to the materials you’ll need for the job, which is very simple:

  1. Correctly sized foam backer rods.
  2. A putty knife (or another thin, solid tool).
  3. A utility knife to cut the foam.

How to Install the Foam Backer Rods

To install the foam rods in the gaps under your baseboards, make sure the area is clean first.

Remove old caulk if there is any, then simply cut your rods to length and shove them snugly into the gap under your baseboards using your putty knife or similar tool.

For solid flooring, you can now caulk over the gap.

For carpet, you may want to consider a few different options.

  • If you peeled back your carpet to access the gap, you can now caulk over the foam and put the carpet back into place once it dries.
  • If you did not peel back the carpet, the gap might not be so big that it is easily noticed, and you may choose to leave it without caulking it now that it is more airtight.
  • However, if the gap is clearly visible, you may choose to disguise the space by attaching a matching shoe molding or quarter round to the bottom of the baseboard above the edge of the carpet. If this is the route you choose, you will want to caulk the top gap, where the shoe molding meets your baseboard, to give it a finished look.

Tips to Increase Effectiveness of Seals

There are additional steps to take after sealing your baseboards that can help mitigate any other factors that may be contributing to the baseboard draft in your home.

Seal the Ceiling

Cracks and holes in the sealing allow air to escape your home at a faster rate than it is meant to, drawing air upwards. This loss of air will cause more air to be pulled into the home from gaps and cracks in other areas like your baseboards.

If your ceiling is not properly sealed, you may still feel a draft even after closing up gaps in your baseboards. Even if you don’t feel a draft you could still be losing air, running up the cost of the energy used to keep your home at the right temperature.

Mesh tape and joint compound can be used to seal small cracks in the ceiling. However, if your ceiling has large cracks that are wider than ⅛”, you may want to have your home assessed to ensure that these cracks are not a sign of structural damage before you repair them.

Seal the Windows

If your windows are not sealed well, then this is another factor that could be causing the draft in your home.

MOPMS Draft Stopper Sweep, Door Weatherproofing Stripping, Window Seal Strip Self-adhisive Soundproof Seal Strip Cuttable Window Weather Stripping, Length 6.56Ft - Grey

Depending on how air is flowing through your home and where your windows are located, air could be leaking out through these gaps much like it would through cracks in the ceiling. Alternatively, air could be being pulled into your home through these cracks. Of course, neither of these scenarios is ideal.

It is possible that you will need to seal or redo the seal around the edges of your window frame. This can be done with caulk, using the same methods you would use for filling the gaps along the edges of your baseboards, or it may be a matter of installing weatherstripping.

Ensure Good Wall Insulation

If your walls are not well insulated, air from outdoors will have an easier time making its way into and filling the space inside your walls. When there are gaps in your baseboards or around fixtures like doors and windows, this air is what will be pulled into your home.

Worker filling walls with insulation material

By ensuring that your walls are insulated well, you are reducing the entry of air in the space between them, which slows the air from inside your walls from being pulled into your home. This also helps to keep the interior of the building from being as affected by the temperatures outside. 

This all means that not only can insulating your walls properly stop or reduce draftiness, but your HVAC system won’t have to work so hard to keep you comfortable, helping you to run a more efficient HVAC system.


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