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How to Spot and Handle a Sinkhole

 

If you live in Florida even a few weeks out of the year, you know what a paradise it is – endless sunny days, breathtaking sunsets, and soft sandy beaches. And while that beautiful sugar sand feels amazing between your toes, it can become a real liability when it starts to give way under the foundation of a home. Hence, a Floridian’s (and insurance adjuster’s) worst nightmare: Sinkholes.Before you start shuddering at the thought of your home being swallowed up by the earth, know this: there is an exact reason that a sinkhole occurs.  Additionally, if you know how to spot the signs, you will be able to catch it before it becomes a serious problem. We recently completed a major sinkhole repair project in Largo, and we learned a lot! Here are a few things you should know about sinkholes.

WHY A SINKHOLE OCCURS

A sinkhole is a hole in the ground which occurs when rock near the surface of the earth is dissolved by water.

There are usually two conditions necessary to create a sinkhole:

• If the near-surface rock of the area is made of limestone, which dissolves easily; and
• If the area gets a lot of rain.

While sinkholes are usually triggered by adding weight above a cavity, such as after a period of heavy or prolonged rain or after building large structures over affected areas, it can also be caused by periods of drought. When the water table under the earth goes down, this creates pockets of air in caves under the earth, which can collapse if they’re no longer supported.

In Florida, it is common for sand to sink down and fill the cavities caused by sinkholes, which is why you will start to see settling issues. Most Construction Contractors and experienced Home Inspectors can recognize the signs of a sinkhole.

SIGNS OF A SINKHOLE

All houses have some settling issues, so even if you have one or two of the items on this list, it does not mean you have a sinkhole. However, if you are experiencing a number of these indications, you should seek professional evaluation as soon as possible.

• Cracks in walls and floors
• Doors and windows that don’t properly close
• Separation between walls and ceiling or floors
• Cracked grout between tile, or cracked tiles
• Muddy well water
• Previously buried items outside becoming exposed as the ground sinks
• There will be a circular pattern of ground cracks around the sinking area
• Small ponds might start to form on your property after a good rainfall
• Slumping or falling trees or fence posts
• Plants will start to wilt and die as vital water is drawn away from the roots due to the sinkhole
• Sudden drainage of a pond
• A foundation that slants
• Sinkholes in the neighborhood
• Presence of strange insects in the home like centipedes or slugs
• An earthy smell inside the home after it rains

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Above are some examples of interior and exterior cracks indicating a sinkhole on our clients’ home. 

HOW TO REPAIR A SINKHOLE

Depending on the severity of the issue, a sinkhole can be repaired, even if it is right under the foundation of your home. I say this because this is exactly what just occurred to one of our clients! We were initially hired to do a home remodel, but the sinkhole was soon discovered and an insurance claim was immediately filed. Here is what we did to repair the sinkhole before proceeding with the home remodel:

1. The first step was to inject a chemical grouting into the ground using a series of injection tubes that were inserted around the perimeter of the house, many of them angled under the structure. The tubes had holes in them which allowed the grout (a concrete substance) to seep into the ground beneath the house, the purpose being to reinforce the soil under the foundation. The tubes were then removed.

Sink Hole
Concrete truck pumping the grout

 

Sinkhole
Pumping the grout into the injection tubes.

2. The next step was to wait until the concrete grouting hardened.

3. Once the concrete had set, a special machine was brought in to drive long pin piers into the ground using a smooth, even pressure. The piers were inserted around the perimeter of the house, and also through holes we made in the floor and foundation of the house. The piers reached all the way to bedrock, and the top of each pier was secured to the house using a bracket. Essentially we were propping the foundation of the house up against the bedrock.

                 

Sinkhole
Hole and bracket outside the house for the pin piers.

4. Every step of the sinkhole handling was done under the supervision of a specialty engineer, who was on site every day to ensure it was properly done.

Once the remedy was completed and we completed an eight-week wait period, we were able to proceed with the home remodel. The clients are now moving in and are delighted with their new home! Not only is it beautiful, the clients can rest easy knowing their home is safe and secure for all the years to come.

 

Nelson Construction and Renovations, a family business founded in 2006, is a design-build company that specializes in high-end remodels, home additions, and custom homes. With our headquarters in Clearwater, Florida, we serve homeowners all over Pinellas and Hillsborough Counties. We are an award-winning member of the National Association of the Remodeling Industry and have an A+ rating with the Better Business Bureau.  

Creative Commons Attribution: Permission is granted to re-post this article in its entirety with credit to Nelson Construction and a clickable link back to this page.