Looking for an addition contractor in Olathe, KS? Describe your project once and up to three addition contractors who work in Olathe and Johnson County get back to you with a quote. It's free and there is no obligation.
Olathe is home to about 149,035 people (2024 Census Bureau estimate), a growing community (+5.5% since 2020). With 2,314 people per sq mi, it is a suburban area. Growing families here often add space instead of moving.
Olathe at a glance
- Population (Census Bureau estimate, 2024)
- 149,035 (+5.5% since 2020)
- Rank in Kansas
- 4th of 625 cities and towns
- Land area
- 64 sq mi
- Population density
- 2,314 people per sq mi (suburban)
- Type
- City (Olathe city)
- Main county
- Johnson County
What to check before hiring in Olathe
- Zoning: check Olathe's setbacks, lot coverage and height limits first.
- License and permit: in Kansas, additions are built by licensed contractors under a permit.
- Structure: second stories need an engineer to check the existing house.
- Price drivers: size, foundation, roof tie-in, plumbing and finishes.
Useful official resources
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ICC: International Code Council
Official information and guidance.
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NAHB
Official information and guidance.
Services available in Olathe
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Room addition
Ground-floor addition with foundation, framing, roof and finishes.
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Second-story addition
New floor over the existing house, with structural engineering.
Frequently asked questions in Olathe
How much does an addition cost in Olathe, KS?
It depends on size, foundation and finishes. Describe your project: contractors who serve Olathe reply with a quote.
How long does it take?
Often a few months, plus design and permits.
Does an addition raise property taxes?
Usually, since it increases the assessed value.
Which addition contractors will contact me?
Up to three independent addition contractors who serve Olathe 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.