Anyone Can Design a Missouri House: When St. Louis Projects Need an Architect
Revised October 22, 2026
Can you draw your own house plans without an architect?
In Missouri, usually yes for a home. RSMo 327.101 lets an unlicensed person design a dwelling house, or a flat with no more than two families, as long as every drawing states the designer is not a licensed architect. Other small buildings qualify only if they hold nine people or fewer, stay under 2,000 square feet and stand alone. In Illinois, a detached single-family home or a wood-frame two-family qualifies; anything else may need a licensed architect.
Keep reading ↓Missouri lets anyone design your house, as long as one sentence is on the plans. The tape measure snaps back into its case with a crack that bounces off the brick. Twelve feet. That’s how far you want to push the kitchen out the back of an old bungalow in Affton, and you’re standing in wet grass at dusk wondering whose name has to be on the drawings.
Here’s the answer most people never hear. On the Missouri side, the law that licenses architects lets anyone design a house, as long as one sentence appears on the plans. Cross the river into Illinois and the same two-family flat can need a licensed architect for one reason: what its walls are made of.
That’s the fork, and it decides who you hire, what you pay and whether the permit counter slides your plans back across the desk. Find out which side you’re on before you hand anyone a deposit.
Can you draw your own house plans without an architect?
In Missouri, usually yes for a home. RSMo 327.101 lets an unlicensed person design a dwelling house, or a flat with no more than two families, as long as every drawing states the designer is not a licensed architect. Other small buildings qualify only if they hold nine people or fewer, stay under 2,000 square feet and stand alone. In Illinois, a detached single-family home or a wood-frame two-family qualifies; anything else may need a licensed architect.
The one sentence that makes Missouri plans legal
Read the statute and the surprise is how little it asks of a homeowner. Under RSMo 327.101, a person who isn’t a licensed architect may render architectural services for a dwelling house, or for a multiple family dwelling, flat or apartment containing not more than two families. The condition is printed right in the law: the drawings, specifications and other documents have to state that the person is not a licensed architect.
So when your contractor’s “plans guy” hands you a roll of drawings, unroll them on the kitchen table and look at the title block. No seal and no such statement is your first red flag. It costs you thirty seconds and a cup of coffee going cold.
Everything else gets a much tighter test. A non-residential building escapes only if it provides for the employment, assembly, housing, sleeping or eating of not more than nine persons, contains less than two thousand square feet, and is not part of another building. All three at once. Turn the back half of a storefront into a 2,400-square-foot space and that test fails, however few people work inside.
Three- and four-family buildings get a narrower break: an unlicensed person may handle remodeling or repairing only when the work does not affect architectural or engineering safety features. If you own a south city four-family, ask that question before anyone moves a wall.
The teeth are real. Under RSMo 327.461, a contract for architectural services with someone who needed a license and didn’t have one is unenforceable by that person. And under RSMo 327.077, the state board can seek civil penalties of up to five thousand dollars for each offense, where each day of a continued violation counts as a separate offense, up to twenty-five thousand dollars.
Why a brick two-flat is different across the river
Illinois writes it differently. Section 3 of the Illinois Architecture Practice Act exempts farm buildings, the construction, remodeling or repairing of a detached single-family residence on a single lot, and a two-family residence of wood frame construction on a single lot, not more than two stories and basement in height.
Two words do the work. Run your hand along the soft old brick of a two-flat in Belleville, Alton or Granite City and you’re touching the reason it falls outside that exemption. The same brick two-flat on a south St. Louis street sits inside Missouri’s rule for a flat containing not more than two families. For a small landlord, that’s the sharpest practical difference between the two states.
If the drawings do need a licensed architect, the seal is the proof. Missouri law requires each architect to have a personal seal and to affix it to all final technical submissions, drawings and specifications included. A stamp is a person putting their license on the line, not a decoration.
What the City of St. Louis permit counter will ask for
Whoever draws it, the plans still have to get through City Hall. The city’s Building Division asks for the project address, project plans, a letter of authorization if you’re not the owner of record, and a $25 application fee per application. If you apply in person, bring five copies of the plans, and know that only check or cash is accepted at the counter.
Then the math. Above $3,000 of estimated construction cost, the city charges the $25 application fee plus $10 per thousand dollars of estimated cost. So a $60,000 kitchen addition runs $25 plus $600, or $625 in permit fees, and every dollar paid to the city for a building permit is non-refundable. Get the drawings right the first time, before you ever file.
That’s also why the cheapest plans can be the most expensive. A set that gets bounced costs you weeks of a torn-up kitchen, the microwave on the dining room floor, and a contractor who moved on to his next job.
Architect, draftsperson or design-build?
On an exempt house project, an unlicensed designer such as a draftsperson can legally draw your plans, and for a straightforward remodel that is often the right, cheaper hire. Once a project falls outside the exemption, you need a licensed architect, and Missouri requires that architect to seal the final drawings. Thinking of drawing them yourself? Here’s what Missouri lets a homeowner draw without an architect.
A design-build contractor can feel like the easy answer: one phone number, one truck in the driveway, one person to blame. That can work well on an exempt house. On a building that needs a licensed architect, ask who is actually drawing the plans and whose seal will be on them, and get that name in writing before the first payment. The question takes ten seconds. The answer tells you whether the bid in your hand is a design-build bid or just a build bid with drawings to be figured out later.
How architects charge matters too. Architect Bob Borson, writing at Life of an Architect, says percentage-of-construction fees vary by firm but generally fall in the 8% to 15% range. Hourly is the honest structure for the fuzzy front end, when nobody can scope a zoning question yet; a fixed fee buys predictability and gets renegotiated when the scope moves.
If the designer works through a company, check the company too. Missouri requires a corporation or company that practices architecture to obtain a certificate of authority from the state board for each profession named in its articles. A slick website and a truck wrap are not that certificate.
Five questions to ask before you sign anything
The first meeting usually happens at your kitchen table, with the old floor plan spread out and a coffee mug holding down one curling corner. Watch how they listen. A good designer walks the house before talking price, opens the basement door to look at the joists, and asks what bothers you about the place at 7 a.m. on a weekday. Then put these on the table:
- Does my project fall inside the exemption? Make them say which part of the law they’re relying on, out loud.
- Who stamps the drawings, and can I see that license? If the answer is “nobody,” the plans should say the designer is not a licensed architect.
- How is the fee built? Percentage, hourly or fixed, and what triggers a change.
- What happens if the permit reviewer sends comments back? Revisions should be in the price, not a surprise invoice.
- Will you visit during construction? Drawings answer most questions; the ones they don’t answer show up with a framing crew standing around waiting.
After you file, the city routes the plans to whichever staff and agencies the project calls for, and that depends on the specifics of the project itself. A designer who has walked plans through City Hall before will tell you who is likely to comment, and that knowledge is worth more than a slightly lower fee.
A different trade, same addition: the concrete work under it decides whether that new kitchen floor stays level.
How to check a license in a minute
In Missouri, call the state board that licenses architects at 573-751-0047, or start from its page on pr.mo.gov. In Illinois, architects are licensed by IDFPR, and its site has a License Look Up. Check the person, then check that the name on the search matches the name on the seal.
- Exempt Missouri house plans: look for the statement that the designer is not a licensed architect.
- Anything outside the exemption: look for a licensed architect’s seal on the final drawings.
- City of St. Louis permit: five copies in person, $25 to file, the rest when the permit is ready.
More for a project like this:
Not sure whether your project needs a seal? Ask two professionals the same question. Browse architects across the St. Louis metro on St Louis Near Me Directory, hand both the same one-page description of the work, and compare what each includes.
If you run an architecture or drafting practice that takes the small jobs, this part is for you. Homeowners standing in their back yards with a tape measure are searching for you tonight; a St Louis Near Me Directory listing helps turn them into customers. See how it works → Hiring a drafter? Post the role on our jobs board.
Frequently asked questions
Is there a cheaper alternative to an architect?
When the project is exempt, yes: in Missouri, an unlicensed designer such as a draftsperson may design a dwelling house or a flat of up to two families, provided the drawings state that the person is not a licensed architect. In Illinois, the exemption covers a detached single-family home on a single lot. Outside those lines there is no legal shortcut: final drawings need a licensed architect’s seal.
What is the average fee for an architect?
For full-service work priced as a percentage of construction, architect Bob Borson says fees vary by firm but generally fall in the 8% to 15% range. Hourly billing is common for early feasibility and zoning questions, and fixed fees show up once the scope settles. Ask every firm which method it uses and what phases the fee covers.
How much does an architect cost for a small project?
Small jobs are often quoted hourly or as a flat fee rather than a percentage, because a small addition still needs every wall and header drawn. Get the scope in writing first. And budget the city’s side too: in the City of St. Louis, work over $3,000 pays a $25 application fee plus $10 per thousand dollars of estimated cost.
Is AI replacing architects?
Not where the law is concerned. Software can sketch a floor plan, but Missouri requires each architect to have a personal seal and affix it to all final technical submissions, and a seal belongs to a licensed person, not a program. For a project outside the exemption, a licensed human still has to put a name on it.
What is the correct order to renovate a house?
Plans and permits first, then demolition, structure, the rough-in trades, inspections, insulation and drywall, and finishes last. In the City of St. Louis, the building permit application is where you’ll be asked about any associated plumbing, electrical or mechanical permits, so line those trades up before you file.
What is the 30% rule for renovations?
It’s a budgeting rule of thumb, not a law or a code: keep a renovation’s cost to a modest share of the home’s value so you don’t over-improve for the street. What decides whether you need an architect is the building type, not the budget.
How do I check whether an architect is licensed in Missouri or Illinois?
In Missouri, call the state board that licenses architects at 573-751-0047. In Illinois, architects are licensed by IDFPR, and its site has a License Look Up. Then match the name on the license to the name on the seal.
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