Gap Between Slab And Foundation Wall[Solved]

Many homeowners don’t know much about the reason behind the gap between the slab and the foundation wall and become anxious when they find them. 

But this is not an issue in most cases. 

Let’s have a look about…

What Is The Main Cause Of The Gap Between The Slab And Foundation Wall?

As a result of the development in the field of building, a gap between slab and foundation wall is getting more common. It is quite common to see a gap between the slab and foundation wall when you are installing a new home.

Most of us live in a house that has gaps either between the garage wall and the floor or between the slab and the foundation wall. The gap is not an issue, while the gap between the slab and the foundation is kept deliberately. 

This gap is known as the expansion gap and is helpful for the expansion and contraction of the wall due to temperature changes. 

In summer or in hot weather conditions the wall expands a little bit, and in winter or in cold weather conditions it shrinks. The gap provides the required space for this expansion and contraction of the wall and prevents serious cracks and damage. 

But you have to be aware of the size of the gap if it is not bigger than the defined parameters. 


What Size Gap Between The Slab And The Foundation Could be Problematic?

Monitor the size of the gap carefully and measure the size of the gap, if it is between 0.4 to 0.5 inches. There is nothing to worried about if the size of the gap is around 0.4 inches or below, but if its size is bigger than that then you have to fix it as soon as possible. 


What Problems You Can Face With The Gap Between Slab And Foundation Wall?

As I earlier stated that the gap having a size of about 0.4 to 0.5 inches is not a problem, the bigger gap would be serious. 

This gap is not only a problem for the people who are building a new house but also for the people who are selling their old house. If you are planning to sell your old house, then it is important that you should know about the gap between the slab and foundation wall. 

A large and wide gap gives rise to many problems such as:

  • Its cause water leakage problem in your home. 
  • The slab might sink. 
  • The foundation wall can damage.
  • Crack and damage in the slab. 
  • This is the cause of dirt and debris between the gap.
  • You will face additional unwanted cracks over the wall and foundation which can create serious issues.  

How To Fix The Gap Between The Slab And Foundation Wall?

how to seal the gap of foundation wall and slab

The gap between the slab and the foundation wall is a problem that most homeowners have been dealing with for years. It’s not something that can be fixed overnight.

But if you don’t want to hire a contractor and want to fix this issue on your own then this simple guide will help you. 

Note: If you are not familiar with construction techniques and materials, you may end up doing more damage than good. The best thing you can do is to call a contractor to come out and fix it right away.

However, this guide will show you how to fix the gap between the slab and the foundation wall in a safe, and simple way.

Gap Between The Foundation Wall & The Slab: [A Quick Fix Guide]

two effective methods to fix the gap between the slab and the foundation wall

You can fix the gap by applying these simple steps, It doesn’t take lots of time and money. This is an easy, quick, and economic solution to this problem.

1. Caulking Method

This is one of the effective methods to fix the gap between the slab and wall permanently.

Essential Tools For Caulking:

  1. Caulking Gun.
  2. Wooden Piece Or A Spoon For Finishing.
  3. Hand Gloves

Essential Materials:

  1. Urethane Based Caulk.
  2. Mineral Spirit
  3. A Backer Rod

Steps To Apply Caulk In The Broken Concrete Or Gap Between Foundation Wall And Slab:

1. Inspect The Size Of The Gap:

The first and very important step before applying to caulk is to carefully inspect the size of the gap. If the gap is bigger than the 1/4 inches then you must have to use the backer rod to support the caulk. 

If its size is smaller or equal to 1/4 inches then you can caulk the gap without using the backer rod. 

The backer rod is easily available in any local hardware store. 

Useful Tip: Always buy the backer rod one size bigger than the gap, It will stick with the gap tightly. 

2. Safety Precautions:

To perform any DIY or repair work must ensure your safety first. Wear safety glasses and safety hand gloves to prevent any injury during work. Urethane caulk can stick with your skin or clothes, that is why wear all the safety gear first. 

3. Install The Backer Rod:

You can apply caulking directly into the gap that size is smaller than the 1/4 inches, but for bigger gaps take the backer rod and put it into the gap by pressing your fingers in such a manner that it can go inside up to 1/4 inches below the surface. 

baker rod to fill the gap wider than 1/4 inches
backer rode for the gap wider than 1/4″

4. Use Tape Mask Around The Caulking Area:

This is also an important step to tape off the sides to ensure you can apply caulking neat and clean by removing this masking tape when the caulking is completed. 

5. Prepare The Caulking Gun:

Cut the tip of the caulk gun as wide as the gap is. Take the caulking gun at a 30-degree angle, and apply the caulk with smooth and even motion.

6. Smooth The Surface:

Now use a flat wood piece or a spoon to smooth the surface where you have applied the caulk. When the smoothing is completed you can clean the spoon using the spirit mineral or a reg.

7. Lets Dry The Surface:

Leave the caulk for 24 hours so that it can dry and create a tight seal across the gap.

8. Cover The Sealed Surface:

After successfully applying the caulk over the gap between the concrete floor and wall, it’s time to cover up with a concrete mixture so that it can overlap the looks of the floor. 

For this take the wet concrete mixture and paint it over the sealed surface. 

2. Use Window Seal Tape:

This is one of the easiest methods which can be completed within a few minutes. But this is not a permanent solution to this problem. You have to apply the same process again after a few months of installation. 

window weather sealing tap to fix the gap between foundation wall and slab
Window weather sealing tap

Let’s have a look at how to apply window sealing tape over the gap…

Tools To Fix The Gap:

  • Weather Strip or Window Seal Tape.
  • Stripping Knife.

Method To Fix The Gap:

Now take the weather strip or window seal tape which is available, keep it over the gap, and push it using a stripping knife. Your window seal tape or weather strip must be as wide as the gap so that it can seal the gap properly. 

Also Read: Gap Between Asphalt Driveway And Foundation [Solved]


Benefits Of Fixing The Gap Between The Foundation Wall And Slab:

1. Strength

Any kind of gap minimizes the strength of the structure, this is why fix the large and widen gaps as soon as possible to avoid further serious damage. If you fix the gap between the slab and the foundation wall, then it will become strong enough to support the weight of the house.

2. Waterproofing

If you have a gap between the slab and the foundation wall, then it means that there is no waterproofing for the slab. The slab has to be sealed with waterproofing material so that the rainwater cannot enter the slab. It also has to be kept clean and free from moss, algae, and other things.

3. Noise

This gap also affects the noise cancellation of your room. If the gap between the foundation wall and slap is broader then this is going to be very bad and you might suffer from the noisy surrounding sounds in your room. You can get rid of this problem by fixing the gap. 

Also Read: Seal Around PVC Pipe Through Concrete: [Solved]


FAQ

Q.1 How Do You Seal A Slab Foundation?

Ans: The Slab foundation can be sealed by two simple methods. 
The first one is by applying to caulk, and the other one is using either window seal caulk or weather strip. The first one is a little bit time taking but a permanent solution to the problem, while the second one is one of the easiest and quickest ways but is a temporary solution to the problem. 

Q.2 Why There Is Gap Between The Concrete Floor And Wall?

Ans: The gap is known as the expansion gap. It allows for expansion and shrink the wall according to the temperature changes and prevents any serious damage to the wall. 

Q.3 How Do I Fill The Gap Between The Concrete Floor And Wall?

Ans: There are several methods to fill the gap between the concrete floor and wall some are listed below:
1. Caulking
2. Spray foam
3. Window seal tape
4. Weatherstripping
5. Vinyl based molding


Conclusion

It is very important to have a gap between the foundation wall and the slab because it prevents any damage due to the expansion of the floor. 

But make sure that the gap should not be too big otherwise it will create a problem. This detailed guide is written after going through the expert solutions, It takes a lot of research and countless hours, I hope this article will help you short out this problem. 

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