Looking for a crawl space contractor in Alton, IL? Describe your project once and up to five crawl space contractors who work in Alton and Madison County get back to you with a quote. It's free and there is no obligation.
Alton is home to about 24,967 people (2024 Census Bureau estimate), a shrinking community (−2.8% since 2020). With 1,593 people per sq mi, it is a suburban area. Humid summers and homes built over vented crawl spaces make moisture problems common here.
Alton at a glance
- Population (Census Bureau estimate, 2024)
- 24,967 (−2.8% since 2020)
- Rank in Illinois
- 89th of 1,294 cities and towns
- Land area
- 16 sq mi
- Population density
- 1,593 people per sq mi (suburban)
- Type
- City (Alton city)
- Main county
- Madison County
What to check before hiring in Alton
- Water first: standing water needs drainage before a vapor barrier.
- Wood damage: ask for a moisture reading and an assessment of joists and sills.
- Humidity control: check what dehumidifier or air supply is included and its maintenance.
- Price drivers: footprint, height, debris removal, drainage and repairs.
Useful official resources
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U.S. Department of Energy: Energy Saver
Official information and guidance.
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EPA: mold
Official information and guidance.
Services available in Alton
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Crawl space encapsulation
Heavy vapor barrier on the floor and walls, sealed vents and a dehumidifier or conditioned air.
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Crawl space drainage and joist repair
Drainage, sump pump, joist or support repairs before or with encapsulation.
Frequently asked questions in Alton
How much does crawl space encapsulation cost in Alton, IL?
It depends on the size of the crawl space, its condition and the equipment. Describe it: contractors who serve Alton reply with a quote.
How long does it take?
Often two to four days for a typical house.
Does it need maintenance?
Yes: the dehumidifier and any sump pump need regular checks.
Which crawl space contractors will contact me?
Up to five independent crawl space contractors who serve Alton and the surrounding area, chosen for the service you need. Your details are shared only with your consent.
Source: U.S. Census Bureau, Population Estimates Program (Vintage 2024) and Gazetteer Files (public domain), imported on 10/31/2026. Figures describe the incorporated place or county as published; they are shown for information only.