St. Louis County is a large and diverse area that includes everything from dense suburban neighborhoods to wooded lots and rural-style properties. Because "St. Louis County" covers so many different communities and housing types, homeowners need contractors who can adapt to varied foundation types, well water or municipal water, septic or sewer, and homes ranging from mid-century ranches to newly built subdivisions.

STL Home Pros helps St. Louis County homeowners find local contractors across this wide service area. Whether you live near Creve Coeur, Florissant, Kirkwood, or an unincorporated pocket, our directory includes pros who understand county building codes, soil conditions, and the specific challenges of your neighborhood.

Housing stock and what it means for service needs

•Mid-century ranches and split-levels are widespread throughout the county, many with original mechanical systems and aging plumbing.
•Newer subdivisions in West and South County feature modern construction, high-efficiency HVAC, PEX plumbing, and poured-wall foundations.
•Rural and estate properties may rely on well water, septic systems, and larger lots with unique drainage and foundation conditions.

Common HVAC, plumbing, and foundation issues in St. Louis County

•Clay soil movement affects homes across the county, causing foundation cracks, sticky doors, and uneven floors.
•Hard water is common in many municipal and well-water supplies, shortening water heater life and clogging fixtures.
•Aging HVAC systems in 40- to 60-year-old homes often need replacement rather than repeated emergency repairs.

What to look for when hiring a contractor

•Contractors should be familiar with St. Louis County building codes and permit requirements for your specific township or municipality.
•Well and septic properties need plumbers with specialized expertise beyond standard municipal systems.
•Foundation pros should evaluate drainage, soil type, and vegetation before recommending repair methods.

Permit and code considerations

St. Louis County building codes apply across unincorporated areas and many municipalities. Permit requirements vary by township, but most HVAC replacements, water heater installations, plumbing modifications, and foundation repairs require permits. Your contractor should verify local requirements.

Seasonal maintenance tips

•Spring: Inspect foundations, clean gutters, and service air conditioners before summer demand surges.
•Summer: Monitor indoor humidity and run dehumidifiers in basements and crawl spaces as needed.
•Fall: Schedule furnace tune-ups and replace filters before the heating season.
•Winter: Protect wellheads, pressure tanks, exterior plumbing, and hose bibs during severe cold.

St. Louis County home facts at a glance

Jurisdiction: St. Louis County includes roughly 90 municipalities plus unincorporated areas. Permitting and contractor licensing depend on exactly where the property sits — the county covers unincorporated areas, while many municipalities run their own programs.
Housing profile: Post-war ranches and split-levels dominate the inner suburbs, with larger 1970s–1990s homes farther west. Many homes are at the age where sewer laterals, water heaters, and HVAC systems are all due for attention.
Water supply: Most of the county is served by Missouri American Water. The supply is mineral-rich; softeners and routine water heater flushing are common.
Sewer service: The Metropolitan St. Louis Sewer District (MSD) serves the county. Homeowners own the lateral to the main — a camera inspection is a smart step before buying any older county home.
Permits: For unincorporated areas, St. Louis County Public Works issues permits. If the property is inside a municipality (Kirkwood, Florissant, Creve Coeur, and so on), that city’s requirements apply instead.

Official local resources

Verify permits, flood zones, and utility details directly with these official sources:

Frequently Asked Questions

How do I know whether the county or a city issues my permit?

Check your address against the municipality list on the county website. If your home is inside an incorporated city, that city’s building department handles permits. Unincorporated addresses go through St. Louis County Public Works.

Does St. Louis County license contractors?

The county maintains licensing requirements for several trades in unincorporated areas, and many municipalities run their own programs. Always ask for the license number and verify it with the issuing jurisdiction before hiring.

Why do so many county homes need sewer lateral work?

Much of the county’s housing is 50–70 years old, and original clay laterals are reaching the end of their service life. Root intrusion is the most common failure. A camera inspection before purchase or when drains slow is far cheaper than an emergency excavation.