Concrete Foundations in Chicago, IL

Foundation work is the part of a project with the least room for improvisation. It is inspected, it is engineered, and everything above it depends on it being right. We pour footings, foundation walls, garage slabs and addition foundations across Chicago and the suburbs.

This is also where the freeze line matters more than anywhere else. Footings in Cook County have to bear below the frost depth, or the whole structure rides up and down with the seasons.

Footings and frost depth

Footings have to sit below the frost line so seasonal freezing cannot lift them. In the Chicago area that depth is set by code and it is deeper than most homeowners expect. A footing poured shallow will heave, and a heaved footing cracks everything above it.

Footing width and reinforcement follow the load above and the soil below. We work to the engineered drawings where there are any, and where there are not, we work to code minimums rather than guesses.

Foundation walls

Poured walls are formed, reinforced and poured in a single monolithic lift wherever the pour allows it. A cold joint in the middle of a foundation wall is a future water path.

Damp-proofing and drainage go on before backfill: membrane or coating on the exterior, drain tile at the footing, stone around it, and backfill that does not just dump clay straight against the new wall.

Garage slabs and pads

Garage slabs take vehicle load, they get salt dragged onto them all winter, and they have to drain toward the door rather than toward the back wall. We pitch them, reinforce them and set the apron so the transition to the alley works.

Detached garages in the Chicago alleys have their own set of constraints: alley access, existing pad removal, and neighboring structures inches from the line.

Addition and new-build foundations

An addition foundation has to tie into the existing house without transferring movement into it. That means matching bearing depth, doweling where appropriate, and paying attention to how the new footing loads soil that has already been consolidated by the old one.

We coordinate with the inspection schedule so footings are open when the inspector arrives and covered as soon as they pass, rather than sitting open through a rainstorm.

How we run a concrete foundations job

1. Review plans and permitsDrawings, engineering where it exists, and what the municipality requires before anything is dug.
2. ExcavateTo bearing depth, with spoil managed on a site that often has no room for it.
3. Form and reinforceFootings formed and rebar set to the drawings. Inspection before the pour where required.
4. Pour footingsPlaced and consolidated. Keyways or dowels set for the walls.
5. Form and pour wallsWall forms set, reinforced, poured in a single lift wherever possible.
6. Waterproof and backfillDamp-proofing, drain tile and stone before backfill goes in.

What affects the price

• Linear feet of wall and cubic yards of concrete
• Excavation depth and how spoil gets off a tight site
• Reinforcement per the drawings
• Access for concrete trucks or whether the pour has to be pumped
• Permits and inspection scheduling
• Waterproofing and drain tile scope

What we check before quoting

An estimate that arrives without anyone looking at the site is a guess. These are the things that move the number, and the reason we come out.

• Access. Whether a truck can back up to the work or everything moves by buggy, pump and wheelbarrow. On a Chicago city lot this can double the labor on its own.
• What is underneath. If the existing base was never compacted, it has to come out. Pouring over failed base buys a couple of seasons at most.
• Drainage. Where water goes now and where it needs to go. Downspouts, grade and yard drainage all feed into this.
• Public way. Aprons and sidewalk sections sit on city property, need a permit, and have to meet municipal specification.
• Load. What the finished work actually carries, which sets thickness and reinforcement.
• Disposal. Concrete is priced out by weight. An honest quote includes the haul and the tipping fees instead of adding them later.

Caring for new concrete

The first year decides the next twenty. Keep vehicles off new slabs for about a week and foot traffic off until the following day. Do not use de-icing salt on new concrete through its first winter, and seal it before the second. Keep downspouts discharging onto grass or a splash block rather than onto the slab, and put something underneath anything heavy that sits in one spot so it does not trap moisture there. Hairline shrinkage cracks are normal and not a defect; cracks with vertical displacement between the two sides are telling you something moved underneath, and those are worth a call.

Why concrete fails in Chicago

Chicago is one of the hardest climates in the country on concrete. The freeze-thaw cycle runs from November into March, de-icing salt goes down on every driveway and public walk, and the clay soil underneath holds water instead of draining it. Concrete that survives here is air-entrained, poured on a compacted stone base, pitched so water leaves, jointed on a proper grid, and kept away from salt through its first winter.

• Freeze-thaw scaling. Water gets into the surface, freezes, and lifts the top layer off in flakes. It comes from too much water in the mix, finishing while bleed water is still on the slab, or skipping the air entrainment Illinois exterior concrete needs.
• Road salt damage. De-icing salt accelerates surface scaling badly. New concrete should not see salt through its first winter and should be sealed before the second.
• Slabs poured on bad base. Most cracked driveways in the older neighborhoods were poured straight on disturbed clay with no compacted stone under them.
• Control joints cut late or shallow. Concrete is going to crack. Joints decide where. Cut at the wrong depth or a day late and the slab picks its own line across the middle.

Concrete foundations across Chicagoland

We handle concrete foundations throughout the city and the suburbs. A lot of this work happens in Chicago, Oak Park and Naperville, and we cover Evanston and Avondale regularly too. Every area we serve has its own page with the local detail.

Related work: Concrete driveways, Concrete patios and Sidewalks & walkways. See all services or the full service area.

Concrete foundations FAQ