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Hardscaping, Patios & Retaining Walls in Minneapolis-St. Paul, MN

Quick answer

Hardscaping adds patios, walkways, steps and retaining walls. In the Twin Cities, durability comes down to frost: deep excavation, a thick compacted aggregate base and good drainage keep freeze-thaw cycles from heaving pavers or pushing walls. Walls over four feet, or walls holding back a driveway or slope, generally need a permit and often engineering.

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Hardscape in Minneapolis and St. Paul has one big enemy: frost. Water that gets into the base under a patio or behind a wall freezes, expands and lifts things, then lets them settle back unevenly when it thaws. The difference between a patio that is still flat after 20 Minnesota winters and one that heaves in three is mostly underneath the surface you see.

Common projects

  • Paver patios and walkways over a compacted aggregate base
  • Natural stone patios and steps, such as flagstone or limestone slabs
  • Segmental retaining walls built from interlocking concrete block
  • Steps and landings on sloped lots, including lake and river bluff properties
  • Fire pits, seat walls and outdoor kitchens

Building for freeze and thaw

Minnesota's building code sets frost footing depth at 3-1/2 feet in the metro counties, which tells you how deep the ground can freeze. Most paver patios aren't built on frost footings. Instead they rely on drainage: excavating below the topsoil, a thick layer of compacted, free-draining aggregate, and a slight slope so water leaves instead of soaking in. Heavier clay soils hold water and need a deeper base or added drainage, while sandy soils drain well but still need proper compaction. Ask any contractor how deep they excavate, what base material they use and how they compact it in lifts.

Retaining walls

A wall holds back soil that gets heavier when wet and pushes harder when frozen. A durable wall typically has:

  • A compacted gravel leveling pad with the first course partly buried
  • Free-draining gravel behind the block and a perforated drain pipe at the base with an outlet
  • Geogrid reinforcement for taller walls, per the block maker or an engineer
  • A setback so the wall leans slightly into the slope

Under the Minnesota State Building Code, a retaining wall not over four feet tall, measured from the bottom of the footing to the top of the wall, is generally exempt from a building permit unless it supports a surcharge such as a driveway, a structure or a slope above it. Cities can still apply zoning, grading, shoreland or watershed rules, so check with your city's permit office before work starts.

Lakes, wetlands and watersheds

Many Twin Cities lots sit near a lake, creek, wetland or the Mississippi and Minnesota river bluffs. Adding a large patio increases runoff, and work near shorelines or bluffs may need city or watershed district review. Ask early if your lot is near water.

Licensing and utilities

Minnesota has no separate landscape contractor license. A company that contracts with homeowners for work in more than one of the state's residential "special skill" categories, such as excavation and grading plus masonry and concrete, generally needs a residential contractor license from the Department of Labor and Industry, which you can check on DLI's license lookup. Whatever the license situation, ask for a certificate of insurance. Before excavation, the contractor should contact Gopher State One Call (811).

Comparing quotes

Compare excavation depth, base thickness, edge restraint, joint sand, drainage details, product lines and warranty, not just the total. Low bids often save money on the base. For more detail, see our guide to patios and retaining walls that survive Minnesota frost.

Have a project in mind? Request a hardscape company and share photos of the space.

See how it works

How a French drain carries water away from a yard. Press the buttons to run each step and see what happens inside. Made with Colorfigures ·
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Frequently asked questions

Do I need a permit for a retaining wall in Minnesota?

Under the state building code, walls not over four feet from the bottom of the footing to the top are generally exempt unless they support a surcharge such as a driveway or slope. Your city can still have zoning, shoreland or grading rules, so check locally.

Why do patios heave in Minnesota?

Water trapped in the base or soil freezes and expands. Heaving usually means the base was too thin, poorly compacted or poorly drained, especially over heavier soils.

Does a hardscape contractor need a license in Minnesota?

There's no separate landscape license. A company contracting with homeowners for work in more than one residential special skill category, such as excavation plus masonry and concrete, generally needs a residential contractor license from the Department of Labor and Industry. Check DLI's license lookup and ask for insurance.

Sources and further reading

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