By Joel Scully · Published 2026-10-20

Roofing Codes Explained: What the Building Code Requires for a New Roof

Quick answer: The roofing code for most Texas homes is the International Residential Code (IRC) chapter 9, as adopted and amended by your city. It sets minimum slopes by material, underlayment and flashing rules, fastening requirements, wind ratings and conditions restricting roof recovers. Check your city's adopted edition before reroofing.

Key takeaways

• Residential roofs in Texas cities follow the IRC, adopted edition by edition with local amendments.
• The code covers slope, underlayment, drip edge, flashing, fasteners, wind resistance, ventilation and recover limits.
• A new roof cannot go over two existing layers; tear-off is required at that point.
• Manufacturer installation instructions are effectively part of the code, because the IRC requires products to be installed per those instructions.
• Look up your city's adopted codes page or call its permit office to confirm what applies to your address.

What are roofing codes and who sets them?

Roofing codes are the minimum construction rules a roof must meet to be legal and safe. In the United States, the model codes are written by the International Code Council (ICC). Cities and counties then adopt them, often with amendments, which turns them into local law.

For houses, the relevant model is the International Residential Code. For commercial and larger multifamily buildings, it is the International Building Code, with energy requirements in the International Energy Conservation Code. Texas law makes the IRC the residential code for municipalities, and cities choose which edition to enforce. That is why the importance of knowing your roof municipality codes is practical, not academic: the details your roof must meet depend on what your city adopted.

Codes set minimums. Manufacturers' instructions, warranty requirements and good practice often go further.

IRC chapter 9: the roof code requirements that matter most

IRC chapter 9 covers roof assemblies and rooftop structures. The topics that shape almost every residential reroof are:

Ventilation of the attic sits in the IRC chapter on roof-ceiling construction rather than chapter 9, but it matters just as much to a reroof. Vented and unvented attic assemblies have different requirements; confirm which applies before changing roof ventilation.

Roof replacement requirements under the code

Roof replacement requirements focus on what may stay and what must go. Under the IRC reroofing rules:

• No recover over two layers. If the house already has two or more layers, tear-off to the deck is required.
• No recover over damaged roofs. A new covering may not go over a roof that is water-soaked or deteriorated enough to be an inadequate base.
• Existing material matters. Recover rules include material-specific provisions and exceptions. Have the designer identify the applicable section and approved assembly rather than assume all roof types follow the same rule.
• Flashing may be reused only if sound. Existing flashing, edgings and vents can stay only if they are in good condition; otherwise they are replaced.
• Decking must be solid. Damaged sheathing found during tear-off should be replaced before underlayment.

Many roofers tear off even when a recover is technically allowed, because it exposes the deck for inspection and lets new underlayment and flashing go down correctly. Our guide to roof replacement in Austin explains how a tear-off project runs.

Pitched roof building regulations: slope, underlayment and flashing

Pitched roof building regulations hinge on slope, because slope decides which materials and underlayment rules apply. Asphalt shingles have a minimum permitted slope and additional low-slope underlayment requirements. Tile and metal systems have their own limits. Identify the exact product and adopted code provision before choosing the assembly; a generic slope chart is not an installation specification. Our roof replacement planning page explains the service process.

Flashing is where codes and real-world leaks meet. The code expects:

• step flashing where a sloped roof meets a sidewall, one piece per shingle course;
• counter-flashing or cricket details at chimneys, with a cricket on the high side of wider chimneys;
• valley lining appropriate to the valley type, open or closed;
• flashing at every penetration, such as plumbing vents and skylights.

Have the contractor identify which flashing will be replaced and justify any reuse from its condition and the approved detail.

How to access your municipality's roof codes

How to access roof municipality codes, in practice:

1. Confirm your jurisdiction. Inside city limits, in a city's extraterritorial jurisdiction, or in unincorporated county land.
2. Find the adopted codes page. Most Texas cities publish a page listing the adopted IRC edition and amendments, usually under building inspections or development services. In Austin, that is the City of Austin Development Services Department.
3. Read the amendments. Local amendments may change wind, energy or reroof provisions. They are usually published as ordinances.
4. Read the model code. The ICC posts the model code text online for public viewing.
5. Call the permit office. Give your address and ask which edition applies to a residential reroof and whether a permit and inspection are required.

Treat this as a roof municipality code lookup guide you can reuse for any city. For permit-specific questions, see our explainer on roof replacement planning.

New Texas roofing codes: how to stay updated

The ICC publishes new model code editions every three years. Texas cities adopt them on their own timelines, so "new Texas roofing codes" usually means a city moving to a newer IRC edition with fresh amendments, rather than a statewide change.

How to stay updated on roofing codes:

• Watch your city's building department announcements and council agendas for code adoption.
• Read the ICC's summaries of changes between editions.
• Check manufacturers' updated installation instructions, which can change independently of the code.
• Ask contractors which edition they are building to on your project.

For roofing contractors, staying current also means following industry guidance from groups such as NRCA and reading each manufacturer's technical bulletins. Roofing codes for contractors are not just about passing inspection; they define the baseline that warranty and insurance reviewers will compare the work against.

Ensuring roofing code compliance on your project

Ensuring roofing codes compliance on your project comes down to a few checks you can make as a homeowner:

• Ask, in writing, whether a permit is required and who obtains it.
• Confirm the contract specifies tear-off or recover, underlayment type, drip edge, new flashing and ventilation work.
• Ask what the crew does if it finds damaged decking, and how that is priced.
• Make sure the shingles' wind rating suits your area and the manufacturer's installation instructions are followed.
• Keep the permit record, final inspection and product documentation.

Our homeowner guide covers more planning questions, and the roof installation page describes how new roofs are built from the deck up.

Austin: check the current rule rather than a statewide shortcut

The City of Austin technical-code page lists its adopted codes and amendments. The city’s permit exemptions include some roof-covering replacements that do not adversely affect the structure, with an exception for certain Wildland-Urban Interface replacements. Exemption from a permit does not exempt the work from code compliance.

Use the 2024 IRC roof-assemblies chapter as a model-code reference only after identifying the edition and amendments applicable to the property. Ask the permit office to resolve unfamiliar assemblies or disputed interpretations before work begins. Keep that determination with the proposal.

Count existing coverings before specifying a recover

ICC’s reroofing explanation identifies the model-code restriction on recovering over two or more existing coverings. Apply the locally adopted edition and its exceptions; a contractor should identify that basis in the proposal rather than rely on a generic layer-count rule.

Frequently asked questions

Which building code applies to roofs in Texas?

For one- and two-family homes, Texas cities use the International Residential Code (IRC), with chapter 9 covering roof assemblies. Each city adopts a specific edition and may add local amendments, so the rules in Austin can differ in detail from those in Round Rock or Georgetown. Commercial buildings fall under the International Building Code instead.

Does the code limit how many roof layers I can have?

Yes, roof-covering count is one condition in the recover rules, but the count alone does not establish eligibility. Existing moisture, deterioration, roof material and the proposed assembly also matter. Ask the contractor to identify the reroofing provision in the locally adopted edition and explain why the existing roof qualifies or must be removed.

How do I find my city's roofing code?

Visit your city's building or development services website and look for the adopted codes page, which lists the IRC edition and local amendments. The International Code Council publishes the model codes online, and many cities post amendments as ordinances. If the website is unclear, call the permit office with your address and ask which edition applies.

Do roofing codes change?

Yes. The International Code Council updates the model codes on a three-year cycle, and cities adopt new editions on their own schedules, sometimes skipping one. Changes can affect underlayment, drip edge, ventilation or wind requirements. The code in force when your permit is issued is generally the one your roof must meet.

Get a code-aware inspection

Texas Professional Roofing offers a free, no-obligation roof inspection with photo documentation. Discuss inspection access and what may remain concealed until work begins. Call (512) 910-4110 to book.