Research by DoINeedAPermit Research Team · Updated May 2026
The Short Answer
Any attached deck requires a permit in De Pere. The only exemption—a freestanding ground-level deck under 200 sq ft and under 30 inches high—is almost never built attached to a house. Plan on a permit, a footing depth of 48 inches minimum (to clear Wisconsin's frost line), and a 2–3 week plan review.
De Pere sits in climate zone 6A with a 48-inch frost depth—the deepest requirement in the state—which shapes every deck decision here. The City of De Pere Building Department enforces the Wisconsin Building Code (which tracks the 2023 IBC/IRC), and unlike some neighboring towns, De Pere applies that frost depth strictly to all footings, including deck posts. The city's plan-review process is in-person at City Hall; there is no self-service online permit portal for decks (you submit plans and applications by hand or mail). Attached decks are NEVER exempt—even a tiny 8x10 platform bolted to your house requires a permit, because attachment to the home triggers structural review under IRC R507. The 48-inch frost requirement is the wild card: standard deck footings in most of Wisconsin can go 42 inches, but De Pere's soil (glacial till with frost-heave clay pockets) has historically shifted shallow footings, and the city has codified 48 inches as the minimum. This drives up material cost and labor, and it's something to confirm with the building department before you price the job.
What happens if you skip the permit (and you needed one)
- Stop-work orders from the City of De Pere can cost $500–$1,500 in fines, plus you'll have to un-build the deck and re-permit it, paying double permit fees (typically $300–$800 total).
- Insurance claims on deck collapses are denied if the structure was unpermitted; a 2,000 lb snow load collapse injuring someone can expose you to liability of $50,000–$500,000+.
- Wisconsin's Residential Real Property Disclosure (RRPD) form requires you to declare unpermitted work; selling a house with an undisclosed deck kills the deal or tanks the price by $10,000–$30,000.
- Mortgage lenders and refinance appraisers will flag an unpermitted deck and may refuse to lend or require removal before closing.
De Pere attached deck permits — the key details
The 48-inch frost depth is real; don't take a shortcut. De Pere's Building Department has a written standard on this, and the inspector will measure your post holes. If you're excavating in winter or early spring and the ground is frozen, the inspector may waive the first inspection until thaw, but the hole must still reach 48 inches below grade. If your site has clay and is wet (common in De Pere, especially near the Fox River valley), the frost depth requirement can trap water around the post; use a sonotube (cardboard post form) and extend it above the top of the hole to keep water out of the hole until the concrete is poured. Sand or crushed stone at the bottom of the hole helps with drainage. Post materials are usually pressure-treated (PT) lumber rated UC4B (above-ground contact) or UC4A (ground contact); PT lumber is wet when you build, so it'll shrink as it dries—some builders use PT ground posts and then switch to cedar or composite above ground. This is fine, but the transition detail needs to be on your plans. If you're using composite decking (Trex, etc.), the rim joist under it must still be PT or cedar (not regular framing lumber), and the posts must be PT rated for the application. Handrails on stairs must be 1 1/4 inches to 2 inches in diameter (round) or 1 1/4 to 1 1/2 inches (square), graspable; balusters (the vertical infill pieces) must be spaced no more than 4 inches apart. These are IRC R312 requirements, and De Pere's inspector checks them at final.
Three De Pere deck (attached to house) scenarios
Scenario A
12x16 attached pressure-treated deck, 18 inches above grade, no stairs, Northside neighborhood
You're building a modest single-story platform off your back door: 12 feet wide, 16 feet deep (192 sq ft), bolted to the house's rim joist with lag bolts and a ledger board, sitting on four 6x6 posts that rest on concrete footings. The deck is 18 inches above the ground (a one-step rise from your back door threshold), and you're using pressure-treated 2x8 joists, 2x10 rim board, and PT 5/4 decking. Because it's attached and less than 30 inches high, the frost depth rule is your main constraint: each post hole must be 48 inches deep (12 inches deeper than you'd dig in most of the state). Digging in De Pere's clay-till soil is slow; budget 8–10 hours of labor and a backhoe rental ($150–$250 for the day) just to excavate. The footing pre-pour inspection is your first gate: the building inspector visits the site, measures the hole depth with a tape or probe, and marks the form-work 'approved' or 'rejected.' If the frost line hasn't receded enough (in early spring), the inspector may delay the footing pour and re-inspect when frost is out. Ledger flashing is critical: you'll install 1/2-inch galvanized flashing between the ledger and the house rim joist, bolted every 16 inches with 1/2-inch lag bolts and 2x8 backing plates. The plan must show this detail; the city will not approve without it. Expect to submit plans (two copies, legible, with footing detail, ledger flashing, guardrail height, and stair landing dimensions if applicable) to the City of De Pere Building Department in person or by mail. Plan review is 3–7 days if plans are complete; if anything is missing, you're asked to revise and resubmit (adding 1–2 weeks). Once approved, you receive a permit card to post on-site. Three inspections follow: footing pre-pour (before concrete), framing (after posts and beams), and final (after railings and stairs). Timeline from permit issuance to final sign-off is 4–6 weeks if you're diligent with scheduling. Total permit fee is $200–$350 (roughly 2% of a $15,000–$17,500 project valuation). Material cost runs $4,000–$6,000 (footings, posts, beams, joists, decking, fasteners); labor is $2,000–$4,000 (excavation, framing, decking); permit and inspections add $300–$500. Total out-of-pocket: $6,500–$10,500.
Attached deck | 48-inch frost depth (non-negotiable) | Ledger flashing detail required | 4-post footing pre-pour inspection | Owner-builder allowed | Permit fee $200–$350 | Plan review 3–7 days | Total project cost $6,500–$10,500 | Final inspection within 6 weeks
Scenario B
20x20 composite deck, 36 inches high, with stairs and railing, near historic downtown overlay
You're ambitious: a large elevated deck with composite decking, stairs, and a view. 20 feet by 20 feet (400 sq ft), 36 inches above grade (sits on 4-foot posts), using Trex composite decking, pressure-treated rim and joists, and eight 6x6 posts on footings. Because it's over 30 inches high, IRC R312 guardrail and R311.7 stair requirements kick in: guardrails must be 36 inches tall (measured from the deck surface to the top rail), balusters no more than 4 inches apart, and stairs must have treads of 7–11 inches deep and risers of 7–11 inches tall, with a landing at the door threshold and at the bottom of the stairs (both landings 36 inches deep minimum). This is a 'structural review' permit—the building department wants detailed plans: footing detail showing 48-inch depth, ledger flashing, post-to-beam connections (bolted or lag-bolted), joist spacing, stair stringers with tread/riser dimensions, guardrail height and baluster spacing. Composite decking is allowed (it's not wood, so it won't rot), but De Pere's building code still requires a PT rim board and PT joists underneath (composite decking alone isn't structural). If your property is in or near the historic downtown overlay (common in De Pere near Broadway and Nicolet), the city's planning or historic preservation board may also want to weigh in on deck appearance (color, style, etc.); this is separate from the building permit but adds 1–2 weeks to the timeline. Submit plans to City Hall (two copies, one for your file, one stamped by the city). Plan review takes 5–10 days because the city needs to check footing depth, ledger detail, stair geometry, guardrail height, and post-to-beam connections. Expect one round of minor revisions (missing a dimension, unclear stringer detail, etc.); resubmit and get final approval within 3–5 days. Inspections are four-stage: footing pre-pour (48-inch depth), post-setting (posts plumb and on footings), framing (beams and joists secured), and final (stairs, railings, decking). Each inspection is scheduled 1–3 days out. Total timeline: 6–10 weeks from initial submission to final sign-off. Permit fee is $350–$500 (2% of a $17,500–$25,000 valuation). Material cost for composite decking, PT framing, footing concrete, and hardware: $8,000–$12,000; labor: $3,500–$6,000; permit and inspections: $400–$600. Total: $12,000–$18,500.
Large elevated deck (400 sq ft) | 36 inches above grade | Composite decking allowed (PT rim/joists required) | 8-post footing pre-pour | Stair/landing/guardrail plan review | Possible historic overlay review | Permit fee $350–$500 | 4 inspections required | Plan review 5–10 days | Total project cost $12,000–$18,500
Scenario C
Freestanding 10x12 platform ground-level deck, 20 inches high, suburban lot
You're considering a freestanding deck (not bolted to the house, just sitting on posts in the yard). It's 10 feet by 12 feet (120 sq ft), 20 inches above the ground, four corner posts on concrete footings, no stairs or railings. Under IRC R105.2, freestanding ground-level decks under 200 sq ft and under 30 inches high are exempt from permit. This deck qualifies: it's 120 sq ft (under 200) and 20 inches high (under 30). No permit required. However, the footnotes matter: the deck must be truly freestanding (no ledger bolted to the house—it's just a platform on posts), and De Pere's soil is still subject to frost heave. Even though the city doesn't permit or inspect this deck, you should still follow the 48-inch frost depth rule: dig your post holes 48 inches deep, pour concrete, set posts plumb, bolt or notch the beam to the posts, and decking to the beam. Why? Because a freestanding deck at 20 inches high can tip or shift if the posts move. If you build it shallow and it fails (someone stands on it and it collapses), you're liable for injuries, and your homeowner's insurance may not cover it if they determine it was negligently built. The no-permit route is legal, but it shifts the burden of safe construction entirely to you. De Pere's building inspector won't sign off on this deck, and you won't have a paper trail saying the city approved your footing depth or post sizing. If you sell the house later, the deck won't be on the permit history, and a buyer's inspector might flag it as unpermitted work (even though it was actually exempt). Some buyers don't care; others demand removal or a retroactive permit. To avoid this, consider pulling a permit anyway—it's only $150–$200, and it gives you legal protection and resale clarity. If you skip the permit and build freestanding at 20 inches on shallow footings (say, 30 inches deep), and the posts settle or shift after a harsh winter, you have no recourse and no one to blame but yourself. The exemption is real, but be smart about why you're using it.
Freestanding deck (truly not bolted to house) | Under 200 sq ft | Under 30 inches high | EXEMPT from permit (IRC R105.2) | No building inspection required | BUT: still follow 48-inch frost depth for safety | Shallow footings will shift in De Pere's clay | Consider pulling optional permit for $150–$200 for resale clarity | Total material cost $2,000–$4,000 (no permit fees if exempt)
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The 48-inch frost depth: why De Pere is different from the rest of Wisconsin
If you're excavating a post hole and hit water, don't panic—it's common in De Pere. The water table in the Fox River valley is high, especially in spring and after heavy rain. If your hole fills with water immediately after you dig it, you're hitting perched groundwater or a clay lens that's holding water. To handle this: pump the water out, let the hole dry, and pour concrete before water seeps back in. If the water keeps coming, you may need to install a sump hole (a 4-6 inch diameter gravel pit next to the footing, with a drain pipe running downslope) to shed water away. The building inspector may ask you to do this; it's not expensive (add $50–$100 per post) and it prevents rot. Another option: use a sonotube (a cardboard form) and extend it 6–12 inches above the top of the hole; this keeps groundwater and surface water from getting into the hole or the concrete during the pour. Builders in De Pere who've done many decks swear by sonotubes in clayey soils. Cost is $10–$20 per form, but it saves hassle. Concrete for the footings is standard: 4,000 PSI (pounds per square inch) minimum, 2–3 feet deep (to be well below the frost line). Pour on a dry day if possible; if rain is forecast within 24 hours of your pour, cover the concrete with plastic to shed water while it cures. Concrete takes 7 days to reach design strength; the building inspector may require you to wait 7 days after the pour before setting posts (though 3 days is usually fine in practice).
Plan review and the De Pere Building Department: what to expect
Inspections are scheduled via phone call to the building department; the inspector typically comes within 1–3 business days of your call. Footing pre-pour is the first gate: the inspector measures hole depth (with a tape or depth probe), checks hole diameter (typically 12–18 inches for a 6x6 post), and ensures the hole is below the frost line. The inspector may ask to see the concrete mix design or strength rating; if you're having concrete delivered from a ready-mix plant, bring the batch ticket to the inspection. Once approved, the inspector marks the form 'OK' (usually with chalk or a tag), and you can pour concrete. Framing inspection happens after posts are set, beams are bolted to posts, and joists are attached but before decking goes on. The inspector checks that ledger bolts are spaced 16 inches apart, that post-to-beam connections are secure (bolted or lag-bolted), that joist spacing is per plans, and that everything is level and plumb. Final inspection occurs after decking, railings, and stairs are installed. The inspector checks guardrail height (36 inches, measured from deck surface to top of rail), baluster spacing (no more than 4 inches), stair tread/riser dimensions (7–11 inches each), and stair landing depth (36 inches minimum). If all is well, the inspector signs off 'final' and you're done. No final approval letter is issued; the permit card is stamped 'approved' and filed. Total inspection time is 4–6 weeks from permit issuance, assuming you schedule promptly and don't have delays between stages.
City of De Pere Building Department
411 Green Bay Street, De Pere, WI 54115 (City Hall)
Phone: 920-339-7000 (ask for Building Department or Permit Office)
Monday–Friday, 8 AM to 5 PM (verify locally)
Common questions
Can I build a freestanding deck without a permit in De Pere?
Yes, if it's under 200 sq ft and under 30 inches high (IRC R105.2). However, De Pere's 48-inch frost depth still applies for structural safety. A shallow freestanding deck will shift in winter. To avoid resale complications and liability, consider pulling a $150–$200 permit anyway, even if the work is technically exempt.
Why does De Pere require 48-inch footings when the state code says 42 inches?
De Pere's soil is glacial till with clay lenses that experience frost heave. Decks on 42-inch footings have shifted and rotted historically. The city adopted a local amendment requiring 48 inches to prevent settlement. It costs more to dig and concrete, but it prevents costly repairs 5–10 years down the road.
Do I need an engineer for my deck plans in De Pere?
Not always. Simple 8x12 decks up to 30 inches high typically pass plan review with hand-drawn or contractor-sketched plans. Decks over 30 inches, large spans (16+ feet), or with unusual soil conditions may require a structural engineer's stamp. The building department will tell you if it's needed during plan review.
What's the cost of a deck permit in De Pere?
Permit fees are 1.5–2% of project valuation. A $15,000 deck costs $225–$300; a $20,000 deck costs $300–$400. You estimate valuation (materials plus labor); the city calculates the fee. Payment is made when the permit is issued.
How long does plan review take in De Pere?
3–7 days if plans are complete; 5–14 days if revisions are needed. There is no online portal—you submit in person or by mail to City Hall. If information is missing, you're asked to revise and resubmit, which adds 1–2 weeks per cycle.
Do I need to hire a licensed contractor, or can I build the deck myself?
Owner-builders are allowed in De Pere for owner-occupied homes. You pull the permit in your name, sign owner-builder affidavits, and do the work yourself. You still need plan drawings (to code), still pay permit fees, and still pass three inspections. Many homeowners hire a contractor to handle permits and plan preparation, even if they do some framing themselves.
What happens if I build the deck and skip the permit?
Stop-work orders can trigger $500–$1,500 in fines, plus you'll have to un-build and re-permit. Insurance may deny claims if the deck collapses. Wisconsin's real estate disclosure form requires you to declare unpermitted work, which kills resale value by $10,000–$30,000. Lenders may also refuse to refinance if they discover an unpermitted structure.
Do I need a separate permit for outdoor electrical outlets or a hot tub on the deck?
Yes. Electrical work requires a separate electrical permit from the City of De Pere. Hire a licensed electrician to pull the electrical permit and perform the work. If you're adding a hot tub or outdoor kitchen plumbing, that also requires a separate plumbing permit. These are not included in the deck permit.
Is my deck property-line setback a concern in De Pere?
Yes. Check your lot's setback requirements with De Pere Zoning or Planning (usually 10 feet side setback, 20 feet rear setback for residential lots, but varies by zone). If your deck encroaches on a setback, you'll need a variance from the city's Board of Appeals, which adds 4–8 weeks and $200–$500 to the project. Verify setbacks before you design.
Can I use composite decking on my deck in De Pere?
Yes. Composite (Trex, Timbertech, etc.) is allowed and won't rot. However, the rim board and joists underneath must still be pressure-treated lumber rated for ground contact (PT UC4B or UC4A). Composite decking alone is not structural—it requires PT framing. Plans must show this clearly.
Disclaimer: This guide is based on research conducted in May 2026 using publicly available sources. Always verify current deck (attached to house) permit requirements with the City of De Pere Building Department before starting your project.