How to Core Fill An Existing Block Wall [7 Easy Steps]

If you’re on the budget or simply love DIY, it’s smart building your homes yourself. Cinder blocks used to make walls in your home are an economically sound option. But they are far from a structurally sound material. Especially if the cores used are without reinforcement, as flexural stresses may displace them.

So, you’re wondering how to core fill an existing block wall?

To fill the core of an existing block wall, you need some necessary supplies. Firstly, you need a hammer drill and mixer. This is for the 80lb of quick concrete mix or core fill concrete. You also need some essential gardening tools and steel rebars. The steps entailed afterward are easy to follow.

Does the whole process seem a tad daunting already? Don’t worry. We’ve mentioned 7 quick steps to fill the wall cores easily.

So, keep reading!

What Is Core Fill And Why Do You Need It?

Core fill is a combination of sand and aggregates. It is used as a stabilizing agent to strengthen any given masonry product.

Core filling block walls can be mixed with cement to make concrete and fill in masonry voids. Cinder blocks are used to build walls.

But they aren’t structurally strong enough. To resist large flexural stresses that affect every home, they aren’t built strong. 

The core fill is a mixture applied to the cinder block voids. Steel rebars can also be used to improve the reinforcement of the wall.

Without core fill, it’s difficult for walls to remain stable when stresses are applied. This includes earthquakes and even the gradual shifting of grounds. Storms too, which can be quite difficult for walls to put up with.

During storms, the wall is unable to withstand the movement under its weight. This is due to the lack of core fill reinforcement.

You need core fill to resist geological and weather stresses. Without this, walls in your home become severely damaged, especially under their own weight. 

Can You Core Fill An Existing Block Wall?

Core filling a wall that is already built can seem difficult. If you’re not trying to hire a professional to do this, it can at first seem quite messy.

You need some good gardening or masonry supplies. Moreover, you should follow some safety procedures while completing this project.

Wearing safety glasses, appropriate garments, and gloves that are waterproof are a given. 

Steps To Core Fill An Existing Block Wall

Breaking down this daunting process into 7 easy steps helps you understand what to do. The steps mentioned below make this process easier for you.

Step 1: Drilling

First off, you need a cement drill to drill into pre-existing walls. Take special care in doing this and drill a hole in a cinder block in the wall.

The block should be in one of the rows that’s above 4 or 5 others. Meaning start from the top row blocks and move your way down.

Step 2: Installing a Rebar

The second step also needs extensive care when being carried out. You need to slide steel rebar through the hole you have drilled.

Then you force it into the cells. This takes care of the first stage of reinforcement. 

Step 3: Mixing the Concrete

Get a mixing tub or wheelbarrow, and pour around 4 gallons of water. Add in a standard 80 lb bag of quick-set concrete or Quikrete.

This is the core fill concrete that is going to be used. Mix until the proper consistency is reached and apply it to a trowel.

Step 4: Use a Cell Funnel

Place the end of a cell funnel into the hole you just made. Then scoop in the core and fill concrete into the funnel.

This may require the help of another person. To save time that is.

Step 5: Pour the Concrete

Now you need to use the trowel to shove in the core fill concrete. The concrete you just made needs to be pushed into the hole gently. Make sure you don’t carry out this step too quickly, especially if you use grout.

Step 6: Smoothen the Surface

This part is rather self-explanatory and easy. Use the trowel to flatten the surface of the core fill concrete that you have just used. This way the exterior of the wall appears to be flat and seamless.

Step 7: Repeat

Repeat this process to the adjacent cinder blocks using the same techniques. Finish repeating the process in vertical rows or columns. Keep going until the blocks at the bottom are done.

Here are some recommended products below!

Product NameOrder Info
Electric Hammer DrillCheck On Amazon
WheelbarrowCheck On Amazon
Quick Setting CementCheck On Amazon
Hand TrowelCheck On Amazon

These products are recommended if you are trying to  core fill an existing block wall on your own. Check them out!

FAQs

Are cinder blocks good for constructing walls?

Yes! Cinder or concrete blocks are versatile in terms of compression strength. The walls need support to combat the natural forces and their own weight. They’re great for reinforcement through steel rebars, which essentially provide vertical cross support and bracing. 

What’s the difference between core fill grout vs concrete?

Grout is a thinner mixture of the same components used to make concrete. It is mainly used to fill in the cracks inside the wall. Grout’s lighter consistency enables it to be much more flexible with the same durability. But a drawback is the price, concrete is usually cheaper and a little stronger too.

Can you hand mix the concrete for a core fill?

Yes, but mixing concrete by hand is only recommended if you’re short on supplies. Measure your materials first. After understanding the proportions, place the dry ingredients on a plastic sheet. Make a pile and a crater in the center. Add water and mix the dry quick cement by folding in constantly.

Wrapping Up

By filling and reinforcing your concrete block walls, you enable them to withstand many things. Filling the core helps to stand up to the stresses of time and natural forces. We hope now you have a better idea of how to core fill an existing block wall.

It is more economically sound should you rent out the equipment for the mixing. This is for enthusiasts that don’t feel like doing many concrete projects in the future.

We hope this article answered most if not all about your wall-building queries. Thanks for reading!

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