How to Fill a Gap Under Vinyl Fence: 6 Steps


Vinyl fencing is cheap and beautiful, but it often results in gaps between the bottom of the fence and the ground. That’s especially true where the ground dips or you have slopes, because the fence is built to be level on the top. 

Filling those gaps between your fence and the ground is important, whether you want to maintain an aesthetic, want to keep dogs inside, or are having issues with flooding.

Luckily, there are also plenty of different ways you can bring the ground to the bottom of your fence. 

How to Fill a Gap Under Vinyl Fence Easily

There are many ways to block gaps between a fence and the ground. Here, the most common fence gap filler ideas include: 

  • Vinyl boards 
  • Stone filler 
  • Dirt filler 
  • Concrete filler 
  • Wood pickets 

Each of these methods is relatively simple. Here, you take a material and you build it up to bring the height of the ground to the bottom of the fence. 

This tutorial will cover using stone, brick, or small cement blocks to fill the gap. This is the best fence gap filler for dogs because they can’t just dig it up. 

Things you’ll need: 

  • Stones or blocks
  • Mortar
  • A stone chisel (at least 6” wide)
  • A heavy hammer 
  • Mortar trowel
  • Mixing bucket 
  • Safety glasses

Importantly, the smaller your stones, the less likely it is you’ll have to cut them. In addition, if you prefer, you can dig the hole out further to avoid cutting the blocks as well. 

1. Assess your holes

Take some time to assess your holes. Check where they’re located, how deep they are, and if you have enough materials. You’ll also want to ensure that your fenceposts are stable. 

For example, if you have large holes around your fenceposts, it’s usually a good idea to pour mortar around them first. This ensures the fence stays stable.

Holes and gaps around posts usually only happen if you have dogs digging under the fence. In this case, you’ll want to dig out around the post and then simply pour mortar into the hole. Use a metal rod to stir the mortar after pouring to reduce air bubbles. 

2. Dig out a flat surface to lay bricks

If you’re using flat building stones, such as retaining wall blocks, cement blocks, or bricks, you’ll want to start with a flat surface.

If you’re using irregularly sized stones, you don’t have to bother, although you will get a stronger wall if you do. 

You’ll also want to use either stakes driven into the ground or dig the wall into the ground to ensure it’s stable if you’re building a short wall with no corners. 

Here, you’ll want to dig out a gap further into the dirt and level out the entire surface. It doesn’t have to be perfect. However, a line-level bubble should be relatively in the center if you want a stable construction. 

If you want to keep dogs from digging the wall out further, consider digging about 6” down. You can start your wall there and then build the dirt back up around it after the cement dries. Then, if dogs do dig, they’ll hit stone.

Use a brick to compact the dirt where your line of stones will be. You can hit the dirt hard, with the intent of compacting everything together. Some people also use a shovel. 

3. Lay out the blocks 

Lay out your first line of blocks and use a mallet to pound them into the ground. You’ll want a small amount of space between each to add mortar. 

In addition, if you’re using concrete blocks, just have a straight wall, or want to ensure the wall stays stable, you’ll want to use iron stakes or rebar driven into the ground on either side of the corners of the wall and in the center. 

4. Mortar bricks in 

Mix your mortar or cement according to the instructions on the package. Then, use a mortar trowel to apply the mortar to the dirt. 

Place your first line of bricks. Then, use the trowel to tap them back into the mortar. Normally, you should lay a line of mortar wide enough for about 5 stones, then repeat.  

Here, you can use a layer of mortar anywhere from 1/8th of an inch thick to 3/4s of an inch thick. Thinner mortar will dry faster. However, it’s largely a matter of aesthetics as your brick will not bear any weight. 

Add a layer of mortar to the top of your row of bricks. Place mortar on the sides of your new bricks and place the bricks on the row. 

Here, you want to stagger the stones. Your second line should always cover the gaps between the bottom blocks. Normally, this means you’ll have to cut your blocks or dig a hole that accommodates a staggered pattern. 

Why should you stagger blocks? Aligning the seams puts all of the stress on mortar, which is weak. Staggering the seams means there are no vertical stress lines, which means your wall is less likely to collapse in the wind. 

Finally, if your wall is very short, you’ll want to allow 10-15 minutes for your mortar to set further in between courses or rows. If your line takes that much time, you should be able to immediately lay the next level. 

Additionally, if your gap is a few stones high, you can probably fill it blind. If you have half a foot or more, you’ll probably want to put up strings to ensure you keep the line straight. 

5. Cutting blocks

If you’re using blocks, cement, brick, or stone, you can normally cut it with a hammer and chisel. Here, you should expect to spend quite a bit of time per block, so avoid it where you can. 

To get started, measure your brick and mark where it has to be cut. Then, use a chisel and hammer to tap out a groove at that point around the full block. It should be about 1/8th of an inch thick.

Once you have a groove, you can place a masonry chisel in the center of the groove. Hit it with a hammer until the block splits. Here, it’s important to ensure you wear safety glasses. 

In addition, you may have to clean up splits if the brick doesn’t’ split cleanly. To do so, simply chisel off any lumps or bumps from the break. 

6. Finishing the seams 

Use the corner of a trowel to go over the seams in your brickwork. You can also use a custom tool for this purpose. Press evenly into the mortar, pressing it back in between the bricks. 

Make sure pressure is localized so you don’t accidentally topple your wall. You’ll also want to ensure that you don’t push too hard. 

Other Ideas to Fill the Bottom of a Fence Gap 

If laying brick or stone is too much work, you can also choose alternative fillers. For example, you can purchase chain or white vinyl fence gap blockers from hardware stores like Home Depot

These can be cut to size and to meet the contours of your property. Once cut to size, you can simply hammer stakes into the ground to align the barriers with the dirt. 

These types of barriers may also include interlocking PVC boards. These function very similarly, except you won’t have to cut them lengthwise. Instead, you’ll click them together, in line with the vinyl boards on top. 

In most cases, ready-made barriers to fill gaps under a fence are a two-part system. These include stakes that you hammer into the ground. Then, you add wire, netting, or vinyl over the top. 

Often, the advantages are that these are cheap and easy to install. They may even match your existing vinyl fence. However, they may degrade and may not be as stable as a more permanent solution. 

Temporary Gap Fillers for Fences 

If you have pets or dogs and need a temporary solution to fill gaps while you work on a brick or stone solution, there are plenty of options. Here, hammering wood or metal stakes into the ground is the easiest.

Stakes should be close enough together that your pet cannot get through. Normally, that means no more than the width of the dog’s head.

You may also want to string chicken wire or netting between stakes if your dog is very good at escaping. 

Conclusion 

Gaps between your fence and the ground can be annoying. That’s especially true if you have pets or your neighbors do.

Luckily, filling those gaps is relatively easy – whether you choose a cut-to-size vinyl barrier or install a stone or block wall to fix the issue. 

Good luck fixing the gap under your vinyl fence.

Brandy Cross

Brandy is a freelance writer with a background and strong interest in DIY and home repair, stemming from her childhood and days spent helping her dad who worked as a handyman. Today, she's renovating an apartment she shares with 100+ houseplants.

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