Madisonville lots along the Tchefuncte River offer the water views and shade that make a deck worth building, and a lot near the water may also sit in a mapped flood zone. Before you pick a deck height or a board, a flood zone lot in Madisonville raises questions a dry inland lot never does. You’ll want to know your zone, whether the deck needs a permit, how much fill the town allows, and how an attached deck counts under federal flood rules.
This guide is general information drawn from the Town of Madisonville’s code, St. Tammany Parish, and FEMA guidance. It isn’t a floodplain determination for your property, so confirm your zone and the requirements for your address with the town and your floodplain administrator before design starts.
Key takeaways
- St. Tammany Parish points owners to a flood zone lookup by address and to the parish floodplain administrator for flood zone and flood history questions.
- Madisonville’s code requires a building permit before construction, with an exemption for detached decks under 200 square feet and no more than 30 inches above grade.
- The town’s code limits fill for driveways and patios to 6 inches above natural grade, and fill beneath a structure to 12 inches.
- FEMA’s substantial improvement guidance counts attached decks and porches in the cost of improvements to a building.
- In coastal high hazard areas, FEMA says an attached deck’s lowest horizontal structural member must be at or above the base flood elevation.
How do you find your Madisonville lot’s flood zone?
Start with the map, not a guess. St. Tammany Parish’s flood information page invites owners to “find your property’s flood zone” by searching an address, and it tells them to “contact the Parish Floodplain Administrator for flood zone, anticipated flood depth, flood history, or other flood related hazards.” For an address inside town limits, also ask the Town of Madisonville who handles floodplain review, since the town keeps its own code.
Two facts from that lookup drive most of what follows: whether the lot sits in a special flood hazard area, and the base flood elevation (BFE) where one applies. Get both in hand before anyone draws a deck.
Does a deck need a permit in Madisonville?
Section 10-11 of the Madisonville Code says “no person shall commence any construction within the town without obtaining a building permit,” then lists a handful of exceptions. One covers “decks being less than 200 square feet in area and not more than 30 inches above grade which are not attached to a structure.”
That exemption is narrow. An attached deck doesn’t fit it, and neither does a detached deck that’s larger or higher than those limits. On a flood zone lot, raise your floodplain questions when you apply, so they shape the design instead of arriving at the end. Our Madisonville decks page explains how we set footings for the soil on the lot.
How Madisonville’s fill limits shape a deck or patio
Fill is where Madisonville’s code gets specific. The town’s definition of construction fill allows fill placed no more than 12 inches above natural grade beneath a structure, and it states that “fill for driveways and patios can be no more than six inches above natural grade.”
That limit matters when you compare a raised deck with a slab patio. A ground-level patio on a low lot can only be built up a few inches with fill under the town’s code, while a framed deck stands on posts and footings and doesn’t rely on fill to gain height. It’s one reason we often steer riverside lots where the ground rolls toward the water toward a deck, as our Madisonville service area page describes. If a patio still fits your plans, our Madisonville custom patios page and our comparison of concrete vs. pavers cover the surface choices.
Outside town limits, St. Tammany Parish’s development code sets its own fill rules. It states that “net fill shall be strictly prohibited in any critical drainage area and on any lot or parcel 90 feet or less in width,” with exceptions spelled out in the code, so an unincorporated lot needs the parish’s answer, not the town’s.
Flood zone rules that affect an attached Madisonville deck
Two federal flood rules come up with attached decks. The first is substantial improvement. Under 44 CFR 59.1, a substantial improvement is any improvement to a structure “the cost of which equals or exceeds 50 percent of the market value of the structure” before construction starts. FEMA’s Substantial Improvement/Substantial Damage Desk Reference lists “attached decks and porches” among the costs that must be counted and excludes “detached accessory structures (e.g., garages, sheds, and gazebos).” An attached deck added alongside other work on an older home adds to that total.
The same reference says “enclosing a deck that is below the BFE to change it to livable space should be treated as an addition.” If you picture screening or glassing in the deck someday, raise that with the floodplain administrator before you build, and see our guide to enclosing a patio in the New Orleans metro for how enclosures are classified.
The second rule applies in coastal high hazard areas. FEMA’s Technical Bulletin 5 says that “if structurally attached to a structure, the bottom of the lowest horizontal structural member of the deck or porch must be at or above the BFE,” and a deck lying partly below the BFE must be structurally independent from the structure and its foundation system. Check your map before assuming this one applies. Federal rules are also a floor: the regulations say more restrictive state or community floodplain rules “are encouraged and shall take precedence.”
Choosing deck materials for a flood zone lot
FEMA’s Technical Bulletin 2 defines flood damage-resistant materials as “any building product [material, component, or system] capable of withstanding direct and prolonged contact with floodwater without sustaining significant damage.” On a lot where part of the framing may sit below the BFE, ask which framing and decking materials qualify before you pick a board by its looks.
We build Madisonville decks on pressure-treated framing with decking choices that run from treated lumber to composite boards, fastened with hardware rated for outdoor exposure. Our post on how climate affects decking material choice covers the humidity side. A riverside deck also has to dry out after heavy rain or high water, so airflow under the framing matters as much as the boards on top. The Atlantic hurricane season runs June 1 to November 30, according to the National Hurricane Center, and our hurricane season patio prep guide covers storm steps for outdoor structures.
Questions to settle before you choose a deck height
- What flood zone is the lot in, and what is the base flood elevation?
- Is the address inside Madisonville town limits or in unincorporated St. Tammany Parish?
- Will the deck attach to the house, and could it count toward substantial improvement along with other planned work?
- Does any part of the plan add fill, such as a slab at the foot of the stairs?
- Will the project call for a new elevation certificate? FEMA’s elevation certificate FAQ says that if modifications have been made to the building or its adjacent grade, a new certificate should be generated.
- Might you want to enclose the deck later?
Frequently asked questions
Do I need a permit for a small deck in Madisonville?
Madisonville’s code exempts decks under 200 square feet that are no more than 30 inches above grade and not attached to a structure. A deck outside any of those limits needs a building permit, so check with the town before you build.
Can I raise my yard with fill before adding a patio?
Inside town limits, Madisonville’s code says fill for driveways and patios can be no more than 6 inches above natural grade. In unincorporated St. Tammany Parish, the development code prohibits net fill in critical drainage areas and on lots 90 feet or less in width, with exceptions spelled out in the code. Ask the town or parish before you haul in dirt.
Does an attached deck count toward substantial improvement?
FEMA’s Substantial Improvement/Substantial Damage Desk Reference lists attached decks and porches among the costs that must be counted. Your community’s floodplain administrator makes the determination for your project.
Can I screen in my deck later?
FEMA’s desk reference says enclosing a deck below the BFE to make it livable space should be treated as an addition. Talk with the floodplain administrator before you plan an enclosure, and ideally before you build the deck.
Planning a deck on a Madisonville lot near the water? We’ll walk the site with you to see how the ground and water move, then put the design and permit steps in writing. Call (504) 285-2659 or reach out through our contact page to set up a walkthrough.
