Stone Basement Walls Crumbling – Causes, Signs, And Solutions

Here we’ll be discussing stone basement walls crumbling, the possible causes, the signs, and definitely the solutions.

Stone basement walls have been around for a good number of years, which is why they are more commonly found in very old homes.

They are very sturdy and can serve for long periods, but just like any other piece of old material, they can also develop problems too. One of which is crumbling.

If you have stone basement walls, and you notice some chips here and there, then you’re reading the right article.

Keep reading!

Signs Of A Crumbling Stone Basement Wall

Let’s start with the signs. If you notice one or more of these, then you can be certain that your stone basement walls have begun crumbling.

  • Cracks appearing in the foundation
  • Whitish powder-like debris coming off, especially when you touch it
  • High level of basement humidity
  • Brittle joints in the walls
  • Little pieces of stone chipping off the wall
  • Visible cracks

 What Are The Risks? 

Structural damage is no small issue and must be treated urgently.

A major downside involved with crumbling stone basement walls is that it significantly deteriorates the entire building and reduces its market value.

It also carries risks with regards to the safety of the occupants of the building. If the structural damage has become too severe, the building may eventually be condemned.      

Causes Of Crumbling Stone Basement Walls

Your basement’s stone basement walls may crumble for a good number of reasons. We will be listing them out below.

  1. The age of the building

Stone basement walls can be commonly found in buildings that are a hundred years and above. This means they are really old, and with age comes wear and tear.

This and nothing more could be the reason they are crumbling.

  1. The geographic location of the building

If your building is located in an area with “wet” soil, the structure will be more prone to damage than those built in areas with dry or sandy soil.    

  1. Urban development

If your house is located in an area where there are busy roadways, or where other construction work happens regularly, the walls would be at a higher risk of crumbling.  

  1. Humidity

Humidity over time can push the minerals out of the stones and cause them to decompose. This can also lead to crumbling.

How To Repair Stone Basement Walls

Now that you have understood the signs and causes of crumbling stone basement walls, let us discuss how you can get them fixed.

Follow these steps.

  1. Expose the Stones

The first thing you need to do before attempting to repair the crumbling stone walls is to expose the stones. Remove anything that could potentially obstruct the repair work.

You can use a duster to clean off dust particles from the wall so you can have an excellent view.

  1. Check for damage

Now that you have a better view of the wall, take a thorough look at it to see where the actual damage lies.

During your inspection, you should notice one or more of the following –

  • loose stones
  • Loose chunks of mortar
  • crumbling mortar
  • cracks in the stone or mortar

As you notice the signs of damage, keep in mind that crumbling stones could mean the presence of an underlying problem. Be sure to fix that first before fixing the stone wall itself.

  1. Replace Stones

Take out the old stones and determine what kinds they are, then find the appropriate replacement stones for the wall. The most common atones used for basement walls include sandstone, limestone, and rubble stone.

Sandstone is the softest among all 3, while rubble stone is the hardest.

Don’t assume you can replace one stone type with a different stone type. They have different properties that determine their longevity, expansion, and decomposition rate.

To replace a damaged stone, simply chisel out the mortar from the sides of the stone until it can be pulled off from the wall. Now replace the removed stones with the appropriate pieces, but leave some space for mortar by the sides.

When mixing the mortar, be sure to follow the specific instructions on the pack so it can hold the stones in place just as it is meant to. You can use a large mixer for this, or a hand trowel and a small container.

It all depends on the amount of mortar you need to fix the crumbling stones.

With the trowel, you can place a thick layer of mortar around each side of the stone as you fit it in nicely. For a more beautiful finish, get a brush and clean the mortar line.

  1. Fill Cracks

You can use hydraulic cement to fill all the cracks in the walls. All you have to do is push it deep enough into the cracks to make sure they are filled all the way.

Once the cracks have been filled up, you can be sure that the wall will be stronger for longer.

Don’t neglect any crack, because even the very small ones can expand into larger ones over time.

  1. Mortar Joints

If the old mortar has shrunk, then you can replace it quickly by chipping off the old mortar about 3 inches deep.

You can then scrape away the old mortar and replace it with your freshly mixed pudding!

Don’t forget to mix according to the manufacturer’s specifications for the best results.

Now grab your trowel and push the freshly mixed mortar deep into the joints to fill up the spaces. Be sure to clean away the excesses when you’re through.

You should also clean the stones before you apply fresh mortar.

  1. Brace Walls

In a case where the walls are bowed, you should install wall anchors or steel beams to keep them from bowing further.

This may not be something you can do on your own so you may need to hire a professional to handle this particular task.

  1. Vapor Barriers

In a case where your stone basement walls have been hit with dampness or a mold infestation, you should use a vapor barrier to counter this problem.

Vapor barriers are simple sheets of rubber materials that are placed on the inside of the wall. This will keep moisture from penetrating your stone basement walls from one end to the other.

Use a pair of large scissors to cut the sheets into the appropriate sizes then fix them to the walls using nails. You can use some tape to completely seal any gaps.

Installing your drywall is the final step you should take.

Steps You Can Take To Protect Your Stone Basement Walls From Moisture

There are several reasons why your stone basement walls may begin to crumble. Movements in the Earth, industrial activities, the age of the building, and the type of soil it is built upon are all factors.

And while we have no control over some of these factors, there are steps you can take to ensure your newly fixed walls are at least free from moisture, and in prime condition for many years.

Follow these tips

  1. Build a Gutter System

If water keeps flowing towards the direction of your foundation and settling there, it will eventually seep through your stone basement foundation walls and begin to damage it.

This is why it is important to have a good gutter system around the perimeter of your basement. This will not only collect water but will also channel it away into the main sewer system.

Make sure you do regular inspections of the gutter to ensure there are no blockages.

Clogged gutters do not flow freely, and will overflow during heavy rainfall, thus channeling more water to the foundation and into the stone basement walls.

  1. Use Plants to Divert Water

Another tactic that can keep water away from your stone wall is planting flowers and thick shrubs many feet away from your foundation.

Plants have the natural ability to absorb standing water, and while this isn’t the most efficient method, it could still help.

Keep in mind that you shouldn’t use big trees for this, since their roots can extend into the foundation and cause cracks in the walls.

If you would love to have a large tree in your yard, then plant them at least 25 feet away from your building.

  1. Use a Urethane Sealant

You can use this material to waterproof the outer parts of your foundation, which will in turn help protect the stone basement walls from moisture.

Waterproofing sealants can be purchased from a home maintenance store so they aren’t hard to find.

It will take the urethane sealant about 48 hours to dry after spraying.

  1. Protect The Window Wells

Once the window wells are properly guarded, then the chances of moisture seeping through your stone basement walls will be reduced.


Stone walls can last for a long time, but that doesn’t mean they can’t get damaged. Many factors can compromise its being, but there are also steps you can take to fix them.

We hope this article has been helpful.

Good luck!

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