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How To Seal Between Foundation And House

By November 12, 2021Home Maintenance
Gravel foundation sealer

Knowing when to seal the gap between your foundation wall and the home itself is important. You won’t want to seal this gap too soon as the foundation typically shifts as the home settles. How to seal between foundation and house? You need basic tools and polyurethane caulk to accomplish this project.

It is a simple process that requires time, based on the size of the home. This project is possible by the homeowner, however, it is recommended that a professionally licensed building contractor assist.

Let’s take a look below at how to accomplish this project.

Rubber cement can seal foundation base on a house
Rubber cement sealer to a foundation base

What Is A Foundation

The definition of a home’s foundation is a load-bearing portion of the building, usually built underground. The home’s foundation must act as a vapor barrier to the soil and water, as well as support the entire structure of the home. Foundation wall gaps are utilized to allow for expansion and contraction.

Why Is There A Gap

You will find that on all homes there is a foundation gap. The expansion gaps are designed to allow the building materials some relief over the stress of moving. This movement is caused by thermal expansion and contractions. In addition, your concrete home shrinks and stretches due to temperature changes.

Underlayment foundation seal for a house.
Underlayment foundation sealer

How Should I Seal The Gap

If you are fortunate enough to complete this project of adding a seal between the foundation and the house yourself, here are the steps that you should follow:

  1. Install the foam backer rod-this foam rod is installed in cracks wider than 1/4 inch. Gently press the foam rod into the foundation gap. The foam backer rod will act as a support for the caulk that you will add to the joint.
  2. Fill and smooth the joint-apply the polyurethane caulk over the foam backer rod and use the spoon to smooth out the polyurethane caulk that you have applied to the foundation gap. Clean your spoon with mineral spirits and rags as needed.
  3. Caulk narrow cracks-use your caulk gun to seal any narrow cracks to the foundation and patio spaces. Cracks that are 1/4 inch wide or less are where you should caulk.

Items That You Will Need

Luckily for you, there are not that many items needed to seal the foundation gap of the house. Let’s take a look below at the items:

These items will allow you to complete the job on your own. However, consulting a licensed building contractor is always your best bet.

How Much Will This Cost

Sealing a foundation gap is important if the gap is bigger than half of an inch. The typical cost range to seal a foundation gap on a house is $2,000 to $7,000. This cost range varies by the cost of materials in your area, and how big the foundation of the home is. It is always a great idea to get multiple estimates from local building contractors before diving into your home expenses.

Other Recommended Maintenance

While you are in the process of caulking areas of your home, you might want to consider inspecting the inside of your home. Specifically, caulking of the baseboards. It is always a great idea that while you are using certain tools and materials, to utilize them for all projects as needed, rather than completing one project and then later on re-using those tools elsewhere.

Next, consider your landscaping. Making sure that you have the proper slope in your yard so that water can flow away from your home is important. Water pooling up next to your home can cause damage to your foundation. So, this is a great area to address when finishing up with your caulking of the foundation gap.

Lastly, keep in mind that the foundation of a home takes time to settle. So, do not get too upset if you see cracking of your stucco or foundation. Read up on how long does it take the home to settle, so that you can fill the foundation gap after and not before.

Foundation that needs attention.
Foundation that needs attention

When Do I Call A Professional

Call on a professional when you do not feel that you have the time or the patience to caulk the foundation gap. A professionally licensed building contractor knows the ins and outs of what is necessary to close off the foundation gap and properly seal the foundation of the home.


It is best to consult a professionally licensed building contractor on this project. Not everyone is capable of digging up their soil to locate and caulk the foundation gap of your home. Although it seems like an easy project, it could be very time-consuming and messy if not done correctly. Boggs Inspection Services can check your foundation during a home inspection in the Olympia, Washington area.

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