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How To Fill Gaps Between Foundation And Sidewalk?

Gaps between the foundation of a home and the sidewalk are a common household problem. If you are planning to fill the gaps between your home's foundation and sidewalk, look no further, because we have done the research to provide you with all the important information you will need.

Use caulk and a backer rod to fill up the gaps between a foundation and a sidewalk. Fit the appropriately sized backer rod into the gap and cover the material with caulk until the gap is completely filled in. For gaps that are less than 1/4 inch wide, forgo the backer rod and just fill it with caulk.

Gaps between a home's foundation and the sidewalk are a fairly common issue that the homeowner can easily resolve. Continue reading as we discuss in depth how you can repair the gaps on your own and other essential information that can help you properly accomplish the task.

A flat front view of a section of raised sidewalk and street on a plain wall background - How To Fill Gaps Between Foundation And Sidewalk

How Do I Fill In The Gap Between The Foundation and Sidewalk?

Filling in the gap between your home's foundation and sidewalk can be done without professional service. The task is not tedious and can usually be completed with one or two materials. Due to the simplicity of the task, you can even finish it within 30 minutes.

What Materials Should I Use To Fill In The Gap?

The process only includes caulk and backer rods, which you can buy at a home repair shop. These materials are cheap and straightforward. Caulk and backer rods are easy to use as long as the usage instructions are followed properly.

Caulk is a waterproof material that can be used to fill in gaps between buildings and sidewalks. Traditionally, caulk has been used to seal gaps between materials to prevent leakage in pipes.

In modern use, due to the development of the product's flexibility, caulk is used to fill in the gaps caused by the shrinkage of concrete that would otherwise crumble instead of expanding.

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Backer rods are closed-cell foam pieces that are used to fill in larger gaps before caulk is applied. The material developed for backer rods prevents gasses from escaping the gap and creating bubbles in the caulk or sealant that is laid over it.

This helps the caulk to form properly without any tiny creases that will eventually cause the hardened material to tear.

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How Do I Use Caulk And A Backer Rod On A Gap?

As we mentioned, filling in the gap between your home's foundation and the sidewalk is simple and quick. Follow the steps below to fill in the gap outside your home.

Identify What Materials Are Actually Needed

Before repairing the gap, you must first assess the situation to identify what materials you need to acquire for the project.

Usually, gaps between the home's foundation and sidewalk are filled in with a backer rod. Once the backer rod has been placed into the gap, caulk is used to top up the gap until it is level with the ground's surface.

Closeup image of Applying silicone sealant by Caulking gun ,silicon adhesive for general and industrial application. Maintenance concept.

First, you must measure the width of the gap. Backer rods are sold in multiple measurements to accommodate different gap widths. Once you have the measurement of the gap, purchase the appropriate size of the backer rod.

The smallest backer rod is 1/4 inch, and the widest could go as thick as 2 inches. If the gap between your home's foundation and sidewalk is less than the smallest backer rod width, then you can choose only to use caulk.

If you are not satisfied with only using caulk, you can use a 1/4" backer rod, as long as the gap is not less than 75% of the diameter of the backer rod.

This is because backer rods, even if they are made of foam, are not made to be squeezed into gaps that are less than 75% of their size. This means that it is not advisable to purchase backer rods that are half as thick as the gap that you would be filling in.

Clean Out The Surface Of The Gap

Before inserting anything into the gap, make sure that the surface that the backer rod will be squeezed into is clear of any dirt and debris.

This will help ensure that there is no significant space between your backer rod and the bottom of the gap that can lead to air bubbles. You want the surface to be thoroughly cleaned to provide a level surface for the backer rod to lie on.

To clean out the surface, use a normal garden hose and clear the gap of anything that could be stuck inside. You can also use a leaf blower or even a vacuum to properly remove all the small debris inside the gap. After cleaning out the gap, make sure that the surface is dry to the touch.

Insert The Backer Rod

Gray Caulk saver Backer Rod for Gaps and Joints acts as a filler in large gaps before applying caulk.

Once you have cleaned out the surface of the gap, you can install the backer rod and then fill it up with caulk.

Figure out the length of the span of the gap between your home's foundation and sidewalk. Using the measurement as a reference, cut out a backer rod that's long enough to fill up the gap.

Carefully insert the backer rod into the gap. You can use your fingers to push the backer rod into the gap until you can feel that it has reached the bottom surface.

If the gap is too deep for your hands to reach, you can use any tool that can push the backer rod down. You should avoid using a sharp tool that could pierce the material. Instead, try using a blunt object, like a spoon or the handle of a screwdriver.

As we mentioned before, if the gap is too small for any size of the backer rod, simply skip this step and fill the gap with caulk. Avoid slicing the backer rod or cutting it up to accommodate a smaller gap.

Fill The Gap With Caulk

Refer to the width of the gap to figure out how wide the opening of your caulk cartridge should be. Once you measure that, insert the caulk container into the caulk gun and secure it in place.

Cut out the mouth of the caulk cartridge at a 30-degree angle to allow the caulk to squeeze out evenly while holding the gun sideways.

Self-leveling caulk is available for purchase online or at your local home repair shop. Self-leveling caulk allows the user to simply apply it over the surface before leaving it for a time while it settles into the gap.

Carefully apply the caulk over the backer rod. Even if you have purchased self-leveling caulk, apply it carefully to avoid clumps. This will allow the material to dry evenly and more quickly. If self-leveling caulk is not available, smooth out the surface of the caulk with the back of a spoon.

Repair of an expansion joint between two buildings involves caulking, and cement. This is a new repair done by a professional.

Once you have filled up the entire length of the gap with caulk, let it dry for 30 minutes up to a whole day, depending on the type of caulk you used.

Which Caulking Is Best For Outdoors?

Silicone caulk is one of the most common caulks to use for outdoor projects due to its resistance to weather and chemicals. Silicone caulks are also resistant to extreme cold and heat.

This type of caulk can be used outdoors because it is waterproof and will dry quickly. Below is a list of other popular choices for outdoor caulking.

  • Hybrid caulk (mix of polyurethane and silicone caulk)
  • Polyutherane caulk
  • Acrylic Latex caulk
  • Solvent-based caulk

How Do I Fix Gap Between Foundation And Soil?

A number of factors can cause a gap between a home's foundation and concrete. The most common reason is that the cement's water has evaporated, which can lead to shrinkage and cause the concrete to pull away from the foundation.

This type of gap is irreversible due to the solidity of the cement, and it can only be fixed by the installation of backer rods and caulk.

However, the gap between a home's foundation and soil can be easily fixed by watering the soil and adding moisture to the ground.

This gap is also caused by the evaporation of water from the ground, but unlike cement, soil can be watered to regain its size. You can install a soaker hose around your home's foundation and activate it during hot days.

Laying of gray concrete paving slabs in the house courtyard driveway patio. Professional working masons install new tiles or slabs for the driveway, sidewalk or patio on a flat sandy foundation.

To Wrap Up

Gaps between a home's foundation and the sidewalk are a common household issue that can be easily fixed with backer rods and caulk installation.

This article discussed how you could fix the gap between the foundation and the sidewalk. We also discussed which caulk is best to use outdoors and what you should do if the gap is between the foundation and the soil.

Make sure to repair any gaps properly so that you can avoid more repairs in the future.

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