Why Does Outdoor Concrete Sink?

Void in concrete sidewalk

Soil washout can result in empty space beneath your concrete slab, unable to support it. This can lead to cracks and sinking over time.

Concrete is heavy! When the soils underneath a concrete slab are unable to support its weight, the slab will sink.

If part of the concrete slab is supported by soils and other sections are not, the unsupported pieces may crack away from the other section and result in unlevel concrete.

Quality 1st Basement Systems can inspect the condition of your concrete slab during an on-site estimate. Call us today to schedule a free quote in Philadelphia, Freehold, Edison and surrounding areas.

Customer Reviews

View All Reviews

full starfull starfull starfull starfull star
By Michael D. from Piscataway, NJ
full starfull starfull starfull starfull star
By Jeff K. from East Brunswick, NJ
full starfull starfull starfull starhalf star
By Craig from East Brunswick, NJ
full starfull starfull starfull starfull star
By Phil S. from Jackson, NJ
full starfull starfull starfull starfull star
By Chris S. from Middletown, NJ

Primary causes of sinking outdoor concrete

  1. Soil Shrinkage, Compaction & Settling

    A hoofprint in the mud, showing compacting soils

    Different types of soil have different load-bearing capacities. When a soil's load-bearing capacity is exceeded, the soil will compact and settle.

    It's also possible for the soil beneath a slab to settle and compact of its own accord. Soil that contains large amounts of clay and/or silt will shrink substantially when it gets dry.

    As the soil compacts underneath a concrete slab, the unsupported slab will sink as well, usually cracking in one or more spots.


  1. Washout Of Soils

    Water washing away mud and sediment in rainy weather.

    The soil that is underneath your driveway, patio or concrete steps may not necessarily remain there to provide adequate support for the concrete element.

    As water moves underneath your concrete slabs, it can wash away the soil that's supporting the weight of the concrete. As this happens, it creates a void, or empty space, underneath. Over time, with nothing to support it, your concrete slab can begin to sink or cave in.

Want a fast solution? Learn more about our PolyLevel® installation in New Jersey & Pennsylvania

The good news is that you don't have to live with sunken concrete anymore! Check out our before and after photo gallery to illustrate what PolyLevel® concrete lifting can do for your property!

We would be happy to provide you a free evaluation and cost estimate for PolyLevel® concrete repair in Sicklerville, Jersey City, Paterson, Newark, Woodbridge, Brick, Clementon and the nearby areas.

Greater Monmouth Chamber of Commerce
Staten Island Chamber of Commerce
Township of Aberdeen
National Foundation Repair Association Member
2018 Angies List Super Service Award
Best Place to Work 2018
HomeAdvisor Association

our service area

We serve the following areas

PennsylvaniaNew Jersey Our Locations:

Quality 1st Basement Systems
359 Route 35 South
Cliffwood, NJ 07721
1-732-719-3079


Quality 1st Basement Systems
2750 Morris Rd
Lansdale, PA 19446
1-267-376-9955


Quality 1st Basement Systems
450 N. Main St.
Woodstown, NJ 08098
Unable to process this phone number
Quality 1st Basement Systems service area
Service Area
Free Quote