Yes. For common residential roof coverings, roofing underlayment is generally required under the residential code in effect in Marietta, although the material and installation method depend on the roof covering, slope, deck, wind-design provisions, manufacturer instructions, and any applicable exception. Confirm the current project requirements with the permitting authority for the property's actual jurisdiction before installation.
Relevant services
The direct code answer for a typical Marietta home
The 2024 International Residential Code with Georgia Amendments governs common one- and two-family residential work in Georgia as of January 1, 2026. Its roof-covering provisions state that underlayment is required for asphalt shingles and several other listed coverings. The code also requires roof assemblies to follow the applicable chapter provisions and the manufacturer's installation instructions.
That general answer is only the starting point for a project. The correct product, number of layers, fastening pattern, overlap, and special membrane details can change with covering type, roof slope, deck configuration, and wind-design provisions. Commercial buildings and some other structures may fall under a different code path. A contractor should verify the actual project rather than applying one detail to every roof.
Why jurisdiction must be confirmed before quoting code
A Marietta mailing address does not necessarily mean the property is inside the City of Marietta. The City's homeowner-permit page explains that a property in Tax District 4 is within City limits, while Tax District 9 is in unincorporated Cobb County. Other nearby addresses may fall under another city. The authority having jurisdiction controls permitting and inspection for that address.
This distinction matters because homeowners and contractors should direct permit and interpretation questions to the correct office. State minimum codes create the foundation, while the local authority administers the project and may have approved local provisions or documentation requirements. Confirm jurisdiction early, especially when a proposal uses Marietta as a general service-area label rather than a legal boundary.
What roofing underlayment does
Underlayment is the layer installed over roof decking and beneath the primary roof covering. It is part of the water-shedding assembly, but it is not intended to make incomplete roofing a permanent finished roof. It provides secondary protection and a compatible base while shingles, metal, tile, or another approved covering performs as the exposed surface.
Underlayment should not be confused with roof decking, leak-barrier membrane, insulation, or an interior vapor retarder. Those materials have different functions. A complete proposal should name what will be placed directly over the deck and identify any self-adhering membrane or other special treatment at valleys, penetrations, eaves, or roof transitions when the design or scope calls for it.
The roof covering determines the applicable rule
- Asphalt shingles have underlayment requirements and separate provisions for slope, sheathing, flashing, drip edge, and wind resistance.
- Clay and concrete tile, metal roof shingles, slate, wood shingles, and wood shakes each follow their applicable roof-covering sections.
- Metal roof panels have their own slope and installation rules; the code's general underlayment language includes a limited exception for structural metal panels that do not require a substrate or underlayment.
- Low-slope assemblies such as modified bitumen, single-ply, or built-up roofing are not detailed as though they were ordinary asphalt-shingle roofs.
- Manufacturer instructions remain part of the installation standard and may require a specific compatible layer or preparation for the selected system.
Roof slope changes the underlayment method
For asphalt shingles, the code distinguishes lower slopes from steeper slopes and does not permit shingles below the stated minimum slope. In the standard application path, roofs from 2:12 up to 4:12 receive a more protective underlayment application than roofs at 4:12 or greater. The current table also includes methods tied to wind-design conditions.
A porch, rear addition, shed roof, or dormer may have a different slope than the main house. That is why the contractor should measure each roof area rather than assume the same shingle and underlayment detail works everywhere. When the slope or assembly is uncertain, the permitting authority, approved plans, product instructions, and any required design professional should resolve it before materials are installed.
Code minimum and a proposed roof system are not identical questions
Code establishes minimum construction requirements. A manufacturer may require specific components or installation details for its product and warranty, and a contractor may propose an upgrade when it is compatible and appropriate. Homeowners should ask which parts of the proposal are code-required, manufacturer-required, or elective scope improvements rather than treating all three categories as interchangeable.
Synthetic underlayment is common in current roof proposals, but the word synthetic by itself does not prove compliance. The material should be identified and installed for the applicable assembly. Likewise, a self-adhering membrane in a valley is not automatically a substitute for every other layer on every roof. Compatibility, approved use, fastening, laps, and product instructions matter.
Rhino's Marietta roofing company overview describes full roof-system scopes that address underlayment, flashing, ventilation, deck condition, permits, and documentation rather than treating shingles as the whole project.
Underlayment should be evaluated after tear-off
A proper replacement scope must account for what happens to the existing covering and underlayment. The current residential code generally calls for roof replacement to remove existing roof-covering layers down to the deck, subject to stated exceptions. Tear-off makes it possible to evaluate sheathing and install the new assembly on a known surface.
If deteriorated decking, adhered membrane, or an unusual existing assembly appears, the crew should not improvise silently. The contractor should document the condition and determine the code-compliant, manufacturer-compatible next step. Concealed conditions are also why a written proposal should explain how additional deck or detail work will be authorized and priced.
Permits and inspections should be addressed in writing
The City of Marietta states that permits are required for new construction and certain alterations and directs homeowners to verify with its permitting staff when they are unsure. The City's homeowner page also says a permit is required when an owner or contractor intends to construct, enlarge, alter, or repair a building or structure. Project-specific interpretation belongs to the correct local office.
Ask the roofing contractor to state who will confirm the permit, who will apply when one is required, what inspections apply, and how approval will be documented. Do not rely on a broad statement that roofing never needs a permit or that every job follows the same process. Jurisdiction, work type, building type, and scope determine the answer.
How to review underlayment in a roofing proposal
- Confirm the property jurisdiction and the code path used for the building and project type.
- Ask for the underlayment manufacturer and product rather than a generic phrase such as premium synthetic.
- Verify that the proposed roof covering, deck, slope, and underlayment are compatible under code and manufacturer instructions.
- Identify whether valleys, penetrations, eaves, or transitions receive a distinct self-adhering membrane or flashing treatment.
- Ask how laps, fastening, temporary weather exposure, damaged material, and mid-project rain are handled.
- Make sure the written scope explains tear-off, deck inspection, concealed damage, drip edge, flashing, ventilation, permit handling, and final cleanup.
Common underlayment misunderstandings
Underlayment does not correct rotten or structurally inadequate decking. It does not replace step flashing, chimney counterflashing, pipe boots, valley details, or correctly installed roof covering. Adding a premium membrane while leaving a failed water-entry detail unresolved can still produce a leak. The assembly succeeds when its connected parts are designed and installed together.
More material is not automatically better if it creates incompatibility, traps moisture in an unintended assembly, or departs from approved instructions. Conversely, leaving the product and method unspecified makes it difficult to evaluate the quote. A knowledgeable contractor should be able to explain why the proposed layer fits the roof without overselling it as a cure for every roofing problem.
How homeowners can verify the current rule
Start with the property's jurisdiction, then use the local building department and current Georgia code resources. Bring the roof covering, slope, building type, and project scope when asking a question; a general request about underlayment may not give the reviewer enough information. If engineered plans or a specialized assembly are involved, follow the approved documents and professional direction for that project.
Codes and local procedures change, so a guide should never substitute for the authority administering the permit. The sources below support this article as of August 12, 2026. Confirm again before construction, especially if the project is scheduled later or if the property is outside City limits.
The bottom line on Marietta roof underlayment
Underlayment is generally required for the common residential roof coverings identified by the current code, including asphalt shingles. The correct installation is project-specific. A complete roofing scope should identify jurisdiction, covering, slope, deck, underlayment product and method, flashing, manufacturer instructions, and permit responsibility so the homeowner can see how compliance is being addressed.