What happens if you skip the permit (and you needed one)
- Stop-work order issued by the city carries a $500 fine, plus you must pull the permit retroactively and pay double the base permit fee ($800–$1,600 total on an otherwise $400 permit).
- Home inspection or refinance triggers title search; unpermitted work discovered, lender refuses to close or requires licensed contractor tear-out and re-do ($3,000–$8,000).
- Insurance denial on water damage or injury: if a guest slips in your unpermitted finished basement and sues, claim is denied because the space was not code-compliant.
- Selling the home requires disclosure of unpermitted work on Michigan Transfer Disclosure Statement; buyer negotiates $5,000–$15,000 credit, or deal falls apart.
Ann Arbor basement finishing permits — the key details
Ann Arbor Building Department requires a permit for any basement project that creates habitable space — a bedroom, bathroom, family room, office, or any room with plumbing or HVAC service. The threshold is governed by Michigan Building Code Section 202 (definition of 'habitable space': a room or enclosed space designed for living, sleeping, cooking, or dining). Exempt work includes unfinished storage areas, utility shelves, paint, flooring over an existing slab with no new electrical circuits or plumbing, and mechanical chase work that does not enclose living space. The permit application requires architectural drawings showing floor plan, framing, window locations, egress windows (if a bedroom), ceiling heights, and electrical/plumbing riser diagrams. Plan review in Ann Arbor typically takes 3–4 weeks; the reviewer checks IRC R310 (egress), R305 (ceiling height), R314 (smoke/CO alarms), E3902.4 (AFCI circuits), and Michigan Energy Code radon-readiness. Most first submissions receive at least one round of comments — commonly missing egress windows, radon ductwork, or ceiling-height documentation.
Egress is the single most critical code requirement for any basement bedroom. IRC R310.1 mandates a second means of escape (egress) for every habitable basement room where sleeping is intended. In Ann Arbor, this means an exterior window or door meeting minimum dimensions: 5.7 square feet of glass (3.3 sq. ft. minimum, but 5.7 is the practical standard to avoid builder argument), sill height no more than 44 inches from floor, and a direct path to grade or a window well that meets code. Many existing homes have single windows that fail these criteria. If your basement window is a fixed 2x2 ft single-hung above the rim joist, it does not meet code; you must install a new egress window ($2,500–$5,000 installed, including wall framing and window well). Ann Arbor's plan reviewer will flag a bedroom without egress on the first submission, and you cannot proceed to framing inspection without resolution. No variance or exception is granted for egress in occupied basements; it is a life-safety item.
Ceiling height is the second-most-common reason for permit rejection in Ann Arbor. IRC R305.1 requires 7 feet measured from floor to the lowest ceiling member (beam, duct, or structural). In existing basements with shallow rim joists, a 6'8" finished ceiling is the bare minimum allowed if you can position the drywall directly under a beam and still maintain 6'8' clear. Many reviewers in Ann Arbor require a 7-foot ceiling for any habitable space; if your existing basement has joists at 6'10" clear, you can finish to 6'8" with a dropped soffit. If the clear height is 6'6" or less, the space cannot be habitable, and you must plan it as storage, mechanical, or unfinished utility. Measure your rim-joist-to-joist distance now; if it's under 6'10", talk to the city or a structural engineer before investing in design.
Moisture and radon are two critical non-structural issues that will block permit approval or lead to expensive retrofit. Michigan Building Code requires radon-mitigation-ready construction in all basement spaces: a 3-inch or 4-inch PVC duct stubbed up from the sub-slab, running within the insulation or exterior wall to the roof, left capped for future activation. Ann Arbor's plan reviewer will require this on all basement applications; if your drawings do not show radon ductwork, you will receive a comment. Cost to rough in: $300–$600. Moisture is equally critical: if you have a history of water intrusion, efflorescence, or dampness, the plan reviewer may require a perimeter drain, sump pump, vapor barrier, or certified moisture test before approval. The 42-inch frost depth in Ann Arbor means that basement walls below grade are in contact with groundwater during spring thaw and after heavy rain. Do not assume your basement is dry; if you have never had water issues, the code still requires a continuous vapor barrier (6-mil polyethylene or better) over the slab before flooring. If you have had water, expect the city to require a subsurface drain, sump pump with a cover, and/or a sealed-sump ejector pit if installing a bathroom.
Electrical and plumbing permits are filed as separate applications but reviewed as part of the same project submission. Any new circuit added to a basement must be Arc-Fault Circuit-Interrupter (AFCI) protected per NEC 210.12; all receptacles in a bathroom must be Ground-Fault Circuit Interrupter (GFCI). If you are adding a bathroom, the plumbing permit includes trap sizing, vent-stack routing, and (if below-grade fixtures are present) an ejector pump with a check valve and sump pit. The ejector pump is not optional if your toilet or shower drains below the rim joist. Plan to rough in a 12-inch-diameter, sump-pit, 18 inches deep, with a sealed 1/2 hp ejector pump and a check valve before drywall. This is a $1,200–$2,000 line item that many homeowners forget until the plumber shows up. Smoke and CO detectors must be interconnected (hardwired, not battery) with the existing home smoke system per IRC R314; the city's electrical inspector will verify this at the rough electrical inspection.
Three Ann Arbor basement finishing scenarios
Radon readiness and Michigan Energy Code — what Ann Arbor requires, what neighbors don't
Michigan's adoption of the 2015 International Energy Conservation Code (IECC) includes radon-mitigation-ready construction for all new and altered basement spaces. Ann Arbor enforces this strictly: the plan reviewer will require a 3-inch or 4-inch PVC duct stubbed from the sub-slab gravel up through the basement wall or interior chase, extending to the roof line, and left capped. The ductwork is not activated (no fan) unless radon testing shows levels above 4 picocuries per liter (pCi/L), which is the EPA action level. However, the infrastructure must be in place before the slab is sealed with flooring, drywall, or epoxy. Many homeowners are surprised by this requirement because it is not in the IRC; it comes from the Michigan-specific Energy Code amendment. Cost to rough in: $300–$600, including labor and materials.
Neighboring jurisdictions like Ypsilanti, Saline, and Plymouth have similar radon requirements, but Ann Arbor's plan reviewers are particularly thorough in checking for it during the first submission. If your architectural plans do not show radon ductwork routing, you will receive a comment, and the project stalls for 1–2 weeks while you revise. To avoid this, include a simple detail on your plan showing the 3-inch PVC stub location (typically in a corner, under a beam, or in an interior wall chase) and its route to the roof. Once the plan is approved with this detail, the contractor can proceed; the ductwork is inspected during rough framing.
If your basement currently has no slab (earthen floor or gravel), radon ductwork is installed directly in the gravel layer and sealed with a 4-6 inch slab poured over it. If your slab is already in place and you are finishing the basement, the ductwork must be cored or sawed through the slab (a $400–$800 extra cost) and connected to subslab gravel below. This is an important discovery during design: ask your contractor if the existing slab has a perimeter gravel layer (visible in any exposed edge); if not, you may face a much costlier retrofit.
Ceiling height, joist depth, and the 6'8" compromise — why Ann Arbor's reviewers are strict
Ann Arbor's climate (Zone 5A/6A) and older housing stock create a persistent ceiling-height challenge. Most basements in pre-1980 Ann Arbor homes were built with 7-foot nominal basement joists (actual clear height 6'8" from finished floor to joist soffit). Modern code (IRC R305.1) requires 7 feet, measured from the finished floor to the lowest ceiling member (beam, duct, soffit). The difference is subtle: if your joist is 6'8" high, you cannot achieve 7 feet of clear height without lowering the finished floor or raising the structure — neither practical. Ann Arbor's plan reviewers have adopted an interpretation that allows 6'8" clear height for habitable spaces if the lowest member is a structural beam (not just ductwork or soffit), and if it is documented in a structural engineer's statement. However, this is not automatic; each review is individual. If the reviewer is conservative, they may reject 6'8" and require you to lower the flooring, use a deeper rim-joist detail, or declare the space as storage/utility only.
To navigate this, measure your existing joists now: from the top of a flat slab to the bottom of the joist. If the dimension is 6'10" or more, you are safe — you can finish to 6'8" with drywall and stay within code. If the dimension is 6'8" or less, you have three options: (1) submit a structural engineer's letter confirming that the joist is the lowest member and 6'8" is acceptable; (2) lower the slab by 4–6 inches (expensive, requires new drainage); or (3) declare the space as non-habitable storage and skip the building permit entirely. Many homeowners choose option 3 for basements with tight ceiling heights, preserving the flexibility to add bathrooms or utilities without triggering a permit. This is legally sound as long as the space is never marketed, deeded, or occupied as a bedroom or living room.
Ann Arbor's specific practice differs slightly from Ypsilanti or Saline, where reviewers may be more lenient on the 6'8" ceiling for older homes. If you are near the border of two municipalities, confirm the local interpretation before finalizing your design. A structural engineer's letter costs $300–$500 and is worth the investment if your ceiling height is marginal; it removes the review guessing game.
Ann Arbor City Hall, 301 E Huron St, Ann Arbor, MI 48104
Phone: (734) 794-6000 ext. 4 | https://www.a2gov.org/government/departments/engineering-services/building-permits
Monday–Friday, 8:00 AM–5:00 PM; counters open 9:00 AM–4:30 PM for permit pickup
Common questions
Do I need a permit to finish my basement as a family room (no bedroom)?
Yes, any finished space intended for living or regular occupancy requires a building permit in Ann Arbor, even without a bedroom. The permit is required because the space becomes 'habitable' under the Michigan Building Code. An unfinished storage area with just shelving does not require a permit, but a finished family room, den, or office does. Plan review takes 3–4 weeks. Permit fee is $300–$500 depending on project valuation.
What is an egress window and why is it mandatory for a basement bedroom?
An egress window is a second means of escape from a bedroom in case of fire or emergency. IRC R310.1 requires it for every basement bedroom. The window must be at least 5.7 square feet of glass area, with a sill height no higher than 44 inches from the floor, and must open directly to grade or a code-compliant window well. Without egress, you cannot legally have a basement bedroom, and the city will not issue a permit. Installing an egress window costs $2,500–$5,000 including the well and wall work.
My basement ceiling is 6'8" clear — can I legally finish it?
Maybe, but it is borderline. IRC R305.1 requires 7 feet for habitable space, but 6'8" is allowed if the lowest member is a structural beam and documented by a structural engineer. Ann Arbor's plan reviewers sometimes require 7 feet; sometimes they accept 6'8" with engineer confirmation. Measure your joist-to-floor height now; if it is 6'10" or more, you are safe. If it is 6'8" or less, budget for a structural engineer's letter ($300–$500) or plan the space as non-habitable storage to avoid rejection.
Do I need a sump pump in my basement?
Only if you are adding a toilet or shower below the rim joist, or if your basement has a documented history of water intrusion. If you are adding a bathroom below grade, an ejector pump with a check valve and sealed sump pit is required by code (NEC/IPC) to pump waste upward to the main drain. If you have no plumbing below grade and no water issues, a sump pump is not required, but a sealed sump pit with a lid is recommended for future drainage (cost: $500–$1,000). The city's plan reviewer may require one if you have efflorescence or moisture history.
What is radon-mitigation-ready construction and why does Ann Arbor require it?
Radon-mitigation-ready means roughing in a 3-inch PVC duct from the subslab gravel up through the basement wall or interior chase to the roof, left capped. The duct is not activated (no fan) unless radon testing shows unsafe levels, but the infrastructure must be in place before flooring or drywall seals the slab. Michigan Energy Code requires this; Ann Arbor enforces it. Cost: $300–$600 to rough in. If you omit it from your plans, the reviewer will comment and delay approval 1–2 weeks.
How long does the permit review take in Ann Arbor?
Plan review typically takes 3–4 weeks from submission to first comment or approval. If the reviewer finds missing details (egress windows, radon ductwork, ceiling-height documentation, moisture mitigation), you will receive comments and must resubmit, adding 1–2 weeks. Once approved, framing and inspections take 2–3 additional weeks. Total timeline from submission to final inspection: 5–8 weeks depending on project complexity and first-submission completeness.
Can I get a variance or exception from the egress window requirement?
No. Egress for bedrooms is a life-safety requirement and is not subject to variance in Michigan or Ann Arbor. If your basement bedroom does not have a compliant egress window, you cannot legally have a bedroom. You must either install an egress window, or declare the room non-habitable (storage, mechanical, closet). There is no middle ground.
Do I need an architect or engineer to draw my basement finishing plans?
For a simple family room or utility space with no structural changes, a detailed sketch or annotated floor plan showing dimensions, ceiling heights, window locations, and electrical/HVAC routes is often sufficient for Ann Arbor's review. However, if you are adding an egress window, altering framing, or have marginal ceiling height, a structural engineer's letter or stamp is recommended (cost: $400–$700). For any bedroom or bathroom addition, an architect or experienced designer is prudent to avoid rejections and rework.
What if my basement has a history of water intrusion? Will it block my permit?
Not automatically, but it will trigger additional requirements. Ann Arbor's plan reviewer may require a perimeter subsurface drain, a new or expanded sump pit, a sealed sump cover, a moisture test (ASTM D4263, ~$200), or a vapor barrier upgrade before approval. These can add $1,500–$3,000 to your project. The bright side: addressing moisture now ensures your finished basement won't have a wet wall or mold problem later. Talk to the city or a waterproofing contractor before design if you have had past water issues.
Is owner-builder work allowed for basement finishing in Ann Arbor?
Yes, owner-builders are allowed in Michigan and Ann Arbor for owner-occupied residences. You can pull the permit yourself and do the work, but you are responsible for code compliance and passing all city inspections. Electrical and plumbing subcontractors (even if you hire them) may still require their own licenses. Most homeowners use a licensed contractor for framing, electrical, and plumbing, and handle finish work (flooring, paint, drywall repair) themselves. Check with the city's permit office for specific owner-builder requirements and bonding.