How to Hire an Architect in St. Louis: When the Law Requires One

Revised August 16, 2026

Imagine it’s a Saturday morning and you’re standing in a back yard with a tape measure and a rough idea. The house went up before your grandparents were born — a brick four-square in Affton, a bungalow in Florissant. Push the kitchen out twelve feet. Take down the wall by the stairs. Put a bedroom on the sun porch.

Maybe you’re in Kirkwood and the addition has to clear a setback nobody mentioned at closing. Maybe you bought a storefront in Belleville and want the back half turned into two apartments. Maybe you’re in Maryland Heights and your contractor has a guy who does plans, cheap, and you can’t tell if that’s a bargain.

Here’s the fork. Some of that work legally requires a licensed architect and some of it flatly doesn’t, and the line sits in statute in both Missouri and Illinois. Work out which side you’re on before you hand anyone a deposit. It changes who you hire, what you pay, and whether the permit counter sends you home.

When does Missouri law actually require a licensed architect?

Missouri exempts a short list of small private buildings and requires a licensed architect for the rest. So can you draw your own house plans without an architect? Under RSMo 327.101, an unlicensed person may render architectural services for a dwelling house, a flat or apartment holding no more than two families, a farm building, or any one building serving no more than nine people, under two thousand square feet, and not part of another structure.

Read that carefully. In the version effective August 28, 2021, the conditions stack: nine people or fewer and under two thousand square feet and freestanding. A 2,400-square-foot storefront build-out fails it, however few people work inside.

A second condition gets missed entirely. The exemption only holds if the unlicensed designer states on the drawings, specifications and reports that the person is not a licensed architect. Plans with no seal and no such note are a red flag. Three- and four-family buildings get a narrower break: remodeling and repair only, where the work does not affect architectural or engineering safety features.

State law is a floor. The Missouri board’s Reference Manual for Building Officials says a municipality may use requirements more stringent than the state’s, so your permit counter is the real authority. Two provisions add teeth: RSMo 327.461 makes a contract for architectural services unenforceable by an unlicensed, non-exempt person, and RSMo 327.077 allows civil penalties up to $5,000 per offense.

What changes on the Illinois side of the river?

Illinois exempts less. Section 3 of the Illinois Architecture Practice Act of 1989 (225 ILCS 305/3) says the Act does not apply to farm buildings outside municipal limits, detached single-family homes on a single lot, wood-framed two-family homes on a single lot no more than two stories and a basement, and interior design that does not involve life safety or structural changes.

The words wood-framed do a lot of work. A masonry two-flat in Belleville, Alton or Granite City sits outside that exemption, while the same building in south St. Louis falls inside Missouri’s, which has no construction-type test. That one word is the sharpest practical difference between the two states for a small owner.

Illinois also snaps the exemption shut when a building changes jobs. The IDFPR code enforcement manual gives the example directly: a farm building that becomes a commercial machine shop is no longer exempt. Interior alterations creating life safety or structural changes are covered too, and a local ordinance can require an architect anyway. Enforcement is not administrative-only — a first offense is a Class A misdemeanor, later offenses are Class 4 felonies, and IDFPR fines run up to $10,000 per offense.

Architect, draftsperson or design-build contractor — which do you need?

Is there a cheaper alternative to an architect? On an exempt project, yes. A draftsperson can legally draw an exempt project in either state, and for a straightforward single-family remodel that is often the right and cheaper answer. Once a project falls outside the exemption, the drawings need a licensed architect’s seal, and experience does not substitute for the license.

Design-build muddies this. The checkable version: in Illinois, a design-build entity may not offer professional design services unless it is registered with IDFPR as a Professional Design Firm — or it independently contracts with an Illinois-licensed design professional, gives the client a written disclosure naming that professional when services are offered, keeps them in direct supervision of the design, and replaces them within 30 days if they leave. That disclosure is yours to ask for.

Missouri differs on firms. Under RSMo 327.401 a corporation offering architectural services must hold a certificate of authority from the board, and the person in charge of the architectural work must be licensed. Verify both: the individual and the entity.

Different trade entirely — concrete work decides how the whole thing sits.

How do architects charge, and what does each method cover?

Three structures dominate: a percentage of construction cost, an hourly rate, and a fixed fee. Percentage is the common one for full-service work. Architect Bob Borson, writing at Life of an Architect, puts most percentage-based residential firms in the 8 to 15 percent range of construction cost. Iowa firm Neumann Monson publishes 9 percent on a $20 million commercial project.

One detail changes how a percentage behaves. The AIA’s B101-2017 owner-architect agreement calculates progress payments against the owner’s budget for the cost of the work rather than the final construction cost, so the fee stops sliding every time a bid comes back high.

Hourly is the honest structure for the fuzzy front end — feasibility, zoning, a historic review nobody can scope yet. Fixed fee buys predictability and gets renegotiated when scope moves. How much does an architect cost for a small project? Proportionally more. Smaller projects carry higher percentages for a reason that is not greed: a 400-square-foot addition still needs every joint and header drawn.

What are the five phases, and which one do clients try to skip?

AIA B101-2017 splits basic services into five phases: schematic design, design development, construction documents, procurement (bidding or negotiation), and construction. That last one, construction administration, is the phase clients try hardest to cut — and the one that costs most to lose.

Schematic design sets size, shape and the relationships between rooms. Design development picks systems, structure and real materials, and pulls in the structural, mechanical and electrical consultants. Construction documents turn that into the drawings and specifications a contractor prices and a plan reviewer stamps. Procurement is bidding. Construction administration is the architect on site: visits, answers to contractor questions, submittal review, payment certification.

Firms publish their splits. Neumann Monson lists schematic design at 20 percent of the fee, design development 20 percent, contract documents 30 to 35 percent, bidding 5 percent, contract administration 25 to 30 percent. Cutting that last line looks like a quarter off the design budget. What it buys is a job site where the contractor reads the drawings alone, substitutions go unremarked, and when a change order lands nobody is there to say whether it came from a hidden field condition or the drawings themselves.

How do you verify a Missouri or Illinois architect’s license?

Both states run a free public license search that answers in about a minute. Missouri’s Division of Professional Registration hosts a licensee search at pr.mo.gov; the board is reachable at 573-751-0047. Illinois uses the IDFPR License Look Up, where architect licenses carry the 001 prefix.

Missouri licenses renew every two years by December 31 — odd years if first issued in an odd year, even years if even (20 CSR 2030-11.010). Each cycle takes 24 continuing education units, at least 16 in health, safety and welfare. RSMo 327.411 requires the seal on all final technical submissions and makes the licensee personally responsible for what sits under it.

On an Illinois set, read the seal. It has to carry the licensee’s name, the license number and the words “Licensed Architect, State of Illinois,” with the signature, the current date and the license expiration date, on the first sheet of a bound set. A retired or inactive licensee cannot seal drawings at all.

What do St. Louis historic districts and tax credits change?

In a City of St. Louis local historic district, exterior work is reviewed against that district’s own ordinance standards before a permit issues, which makes prior experience a real hiring criterion. The Cultural Resources Office performs more than 3,000 reviews a year, from large developments to small home repairs, and each district has its own standards written with neighborhood residents. Larger projects go to the Preservation Board. Demolition runs a separate track: in the city’s Preservation Review Districts, every demolition application is referred to that office and no permit issues without its approval. In Belleville, exterior work in the three local districts — Old Belleville, Hexenbuckel and Oakland — needs a certificate of appropriateness.

Then the money, where the states split hardest. The federal 20 percent rehabilitation credit applies only to certified historic structures in income-producing use; the National Park Service states plainly that owner-occupied residential properties do not qualify. Missouri’s state credit does cover owner-occupied homes: 25 percent of qualified rehabilitation expenditures, or 35 percent outside St. Louis City and Kansas City where no low-income housing credits are involved, with a $250,000 project cap on owner-occupied residential and a requirement that qualifying costs exceed 50 percent of the property’s basis. Illinois offers 25 percent capped at $3 million per project, income-producing use only.

All of it has to satisfy the Secretary of the Interior’s Standards for Rehabilitation. Missouri’s preservation office warns that work failing the Standards can carry financial consequences at the end of the project. Windows, porches and storefront openings are where that usually bites, and they are the calls an experienced architect makes differently on day one.

What the fee looks like from the architect’s side

A percentage fee has to cover hours nobody bills: site visits before a contract exists, code research, two rounds of a proposal that goes to someone else. The AIA’s 2024 Firm Survey put average pre-tax, pre-bonus profit at 11.5 percent of net service revenue — 9.0 percent at firms billing under $250,000 a year against 14.1 percent at firms over $5 million. Professional liability coverage starts near $1,700 a year for a small practice and runs higher on residential work, carried whether or not the phone rings. NCARB’s 2025 data puts the average road to licensure at 12.9 years. Small jobs hold more decisions per square foot than big ones, which is why many firms set a minimum construction budget, and why construction administration — the phase clients cut first — carries the risk. People search this work by neighborhood, and a complete, current listing is how the firms that take small jobs get found.

Related reading: where the materials come from and permits are a theme here.

Frequently asked questions

Can you draw your own house plans without an architect?

For a house, usually yes on the Missouri side. RSMo 327.101 lets an unlicensed person render architectural services for a dwelling house or a flat holding no more than two families, so a single-family remodel in Affton or Kirkwood can be drawn without an architect — but the drawings have to state that the person who made them is not a licensed architect. Your municipality can require more, so ask the permit counter.

Is there a cheaper alternative to an architect?

Yes, if the project is exempt: a draftsperson. An architect holds a state license, carries professional liability coverage, and can seal drawings a plan reviewer will accept for non-exempt buildings. A draftsperson produces drawings but cannot seal them or use the title architect — in Illinois that title without an active license is a Class A misdemeanor on a first offense. For exempt residential work a good draftsperson is usually the cheaper and sensible hire, and outside the exemption there is no legal alternative.

What is the average fee for an architect?

Most percentage-based residential firms land between 8 and 15 percent of construction cost, per architect Bob Borson at Life of an Architect, with larger commercial work closer to 9 percent. Hourly is common for early feasibility and zoning work; fixed fees appear once scope settles. AIA B101-2017 bases the percentage on the owner’s construction budget, not the final cost.

Can I skip construction administration to save money?

You can, and firms will tell you what you are giving up. Construction administration runs 25 to 30 percent of the fee in published firm breakdowns and covers site visits, contractor questions, submittal review and payment certification. Without it the contractor reads the drawings alone and change-order disputes have no independent voice. Many architects decline to remove it.

How do I check whether an architect is licensed in Missouri or Illinois?

Missouri: use the Division of Professional Registration licensee search at pr.mo.gov, or call the board at 573-751-0047. Illinois: use the IDFPR License Look Up, where architect licenses use the 001 prefix. Check the firm too — Missouri requires a certificate of authority under RSMo 327.401, Illinois a Professional Design Firm registration.

Do I need an architect for work in a St. Louis historic district?

Not automatically, but the review is real. Exterior work in a City of St. Louis local historic district is checked against that district’s ordinance standards by the Cultural Resources Office, which handles more than 3,000 reviews a year; larger projects go to the Preservation Board. Belleville requires a certificate of appropriateness in its three districts.

Does a design-build contractor count as having an architect in Illinois?

Only under conditions you can verify. An Illinois design-build entity must be registered as a Professional Design Firm, or it must independently contract with an Illinois-licensed design professional, hand the client a written disclosure naming that professional, keep them supervising the design, and replace them within 30 days if they leave.

About the Author: The St Louis Near Me Directory Team
Written by a dedicated team of St. Louis locals who live, work, and play right here in the St. Louis metro. Founder Lane Forman and team are committed to building the region’s most trusted directory by verifying listings and connecting local businesses with loyal customers across Missouri and Illinois.

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