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Sunken Concrete Slabs

What does sunken concrete look like & what does it mean for my home?

Outside, sunken concrete slabs are easy to identify. They’ll be visibly lower or tilted at uneven angles, posing a tripping hazard around pool areas, garden landscapes, patios, stairways and driveways.

Inside your home, however, sinking concrete slabs are not so obvious.

Within interior environments, such as houses, garages or workspaces, the signs of sinking concrete are shown through structural issues. This is usually due to shifting ground, indicating there might be immense amounts of pressure being placed on your home from the ground up.

Read on to learn how to identify sinking concrete and its causes within your home.

What are the tell-tale signs of sunken concrete?

Floor Drops

If one side of your concrete floor has sunk deeper than the other, it may cause the floor to slant. This creates unwanted drops as you walk, which can be a dangerous trip hazard. If it feels like you’re walking up or down steps when you and your family walk across the floor, it’s likely a floor drop caused by sunken concrete.

Bowing Floor and Door Issues

If the central area of your concrete floor is sunken, your floor will have a noticeable bow. A bowing floor will subtly dip in the middle, forming a concave shape. You can test for this by placing a ball at the edge of the floor. If it rolls towards the centre of the room, you’ve got issues. If floor bows aren’t fixed, internal doors can begin to jam as excess forces are moved around the structure.

Gaps under Skirting Boards

By design, skirting boards are meant to sit flush against the base of your interior walls. If they’re not, something’s wrong. Take note of whether the floors and walls have separated. If your skirting boards have pulled away to reveal gaps underneath the internal walls of your home, then a sunken concrete floor may be the cause.

Floor Drops

If one side of your concrete floor has sunk deeper than the other, it may cause the floor to slant. This creates unwanted drops as you walk, which can be a dangerous trip hazard. If it feels like you’re walking up or down steps when you and your family walk across the floor, it’s likely a floor drop caused by sunken concrete.

Bowing Floor and Door Issues

If the central area of your concrete floor is sunken, your floor will have a noticeable bow. A bowing floor will subtly dip in the middle, forming a concave shape. You can test for this by placing a ball at the edge of the floor. If it rolls towards the centre of the room, you’ve got issues. If floor bows aren’t fixed, internal doors can begin to jam as excess forces are moved around the structure.

Sunken concrete in a home

Gaps under Skirting Boards

By design, skirting boards are meant to sit flush against the base of your interior walls. If they’re not, something’s wrong. Take note of whether the floors and walls have separated. If your skirting boards have pulled away to reveal gaps underneath the internal walls of your home, then a sunken concrete floor may be the cause.

What are the leading causes of sunken concrete?

Stormwater Damage

Flooded or overflowing stormwater drains can be one of the biggest contributors to sunken concrete. Instead of directing water away, flooded drains cause water to pool around your home’s foundations. With nowhere for this water to run off, it soaks into the ground underneath your concrete floors, driveway, stairways, patios and pool areas. This excessive soaking causes soil erosion, eventually leading to your foundations sinking.

Poor Drainage

Similar to stormwater damage, poor drainage can lead to an overflow of water on your property. Instead of this water coming from flooded stormwater drains, though, poor drainage issues result from burst, cracked and/or unconnected pipes in your home.

The malfunctioning pipes leak and pool water into concentrated spots beneath your concrete slabs and floors. This causes the soil to become saturated, weak and unstable, leading straight to sunken concrete.

Poor Compaction of Sub-Soils

Builders have a responsibility to compact sub-soils before constructing a home upon it. This process drives air out from between the soil grains, making the earth more dense and more stable. However, if they’re cutting corners, builders may skip out the soil compaction process to save time. If so, uncompacted soil will be left full of air, which means that when heavy concrete slabs are placed on top, they’ll be bound to sink.

Vibrations

Concrete can also sink due to intense vibrations in the ground. Excavators operating at a nearby construction site, semi-trailers passing by at high speeds, planes taking off and landing at a nearby airport–these situations can all bring on high levels of ground vibration. Over time, these vibrations shake up and aerate the soil, leading to instability and sunken concrete.

Reactive Clay

Reactive clay soil is a dense material that expands under wet conditions and contracts under dry, hot conditions. If your concrete slabs or floors are built upon reactive clay, they’re susceptible to lifting and sunken throughout the year. If your concrete happens to be sunken while the weather is extremely hot and dry, it’s likely your concrete is sitting on reactive clay soil.

Landslip

Landslip is often a natural event caused by the build-up of subterranean water near a slope or embankment. During a landslip event, the ground will shift, which can cause any structure sitting above, including concrete slabs, to be left dangerously exposed.
Flooded aprtment complex

Stormwater Damage

Flooded or overflowing stormwater drains can be one of the biggest contributors to sunken concrete. Instead of directing water away, flooded drains cause water to pool around your home’s foundations. With nowhere for this water to run off, it soaks into the ground underneath your concrete floors, driveway, stairways, patios and pool areas. This excessive soaking causes soil erosion, eventually leading to your foundations sinking.

Clogged gutters

Poor Drainage

Similar to stormwater damage, poor drainage can lead to an overflow of water on your property. Instead of this water coming from flooded stormwater drains, though, poor drainage issues result from burst, cracked and/or unconnected pipes in your home.

The malfunctioning pipes leak and pool water into concentrated spots beneath your concrete slabs and floors. This causes the soil to become saturated, weak and unstable, leading straight to sunken concrete.

Poor Compaction of Sub-Soils

Builders have a responsibility to compact sub-soils before constructing a home upon it. This process drives air out from between the soil grains, making the earth more dense and more stable. However, if they’re cutting corners, builders may skip out the soil compaction process to save time. If so, uncompacted soil will be left full of air, which means that when heavy concrete slabs are placed on top, they’ll be bound to sink.

Vibrations

Concrete can also sink due to intense vibrations in the ground. Excavators operating at a nearby construction site, semi-trailers passing by at high speeds, planes taking off and landing at a nearby airport–these situations can all bring on high levels of ground vibration. Over time, these vibrations shake up and aerate the soil, leading to instability and sunken concrete.

Reactive Clay

Reactive clay soil is a dense material that expands under wet conditions and contracts under dry, hot conditions. If your concrete slabs or floors are built upon reactive clay, they’re susceptible to lifting and sunken throughout the year. If your concrete happens to be sunken while the weather is extremely hot and dry, it’s likely your concrete is sitting on reactive clay soil.

Landslip

Landslip is often a natural event caused by the build-up of subterranean water near a slope or embankment. During a landslip event, the ground will shift, which can cause any structure sitting above, including concrete slabs, to be left dangerously exposed.

Need to stop sunken concrete?

Sunken concrete damages the stability of your home. Our solutions are cost-effective and hassle-free.

Sunken concrete damages the stability of your home. Our solutions are cost-effective and hassle-free.