Maryland Roofing Code Requirements for Homeowners & Real Estate
Maryland roofing code is layered: federal IRC (2021 or 2024 depending on county) plus Maryland Building Performance Standards (MBPS) amendments plus county-specific requirements. Every residential re-roof in Maryland needs a permit, an MHIC-licensed contractor (#137491 for JDH), code-compliant ventilation per IRC R806, and at minimum Class D wind resistance under ASTM D7158. Coastal counties default to Class H (150 mph).
Maryland does not have a single statewide residential roofing code. Instead, the Maryland Department of Labor requires every jurisdiction in the state to use the same edition of the International Residential Code (IRC), modified by Maryland Building Performance Standards (MBPS), with additional county-specific amendments on top. The result is a three-layer code framework where the IRC sets the federal baseline, MBPS adds Maryland adjustments, and each county adds its own permit requirements. This guide walks Maryland homeowners and contractors through how that framework actually applies on a residential re-roof: the four IRC chapters (R905, R806, R902, R903) that touch every job, the ASTM D7158 wind resistance specs that vary by county, ice-and-water shield rules, MHIC licensing requirements, and the permit + inspection process for the five Southern Maryland counties JDH serves.
The Maryland roofing code framework, chapter by chapter, county by county
Read these in order. They are the same seven conversations a HAAG-certified inspector has with a homeowner at the kitchen table before any contract gets signed or any shingle gets ordered.
Maryland's three-layer code framework (and why all three matter)
Maryland roofing code is not one document. It is three layers, and a contractor has to comply with all three or the work fails inspection.
Layer 1 - International Residential Code (IRC)
The federal baseline. The IRC 2021 is the version most Maryland jurisdictions reference as of 2026; some are transitioning to IRC 2024. Defines residential construction standards including roof coverings (Chapter 9), roof drainage (Chapter 15), and energy efficiency (Chapter 11). Published by the International Code Council.
Layer 2 - Maryland Building Performance Standards (MBPS)
Maryland-specific amendments to the IRC, adopted statewide and administered by the Maryland Department of Labor Building Codes Administration. MBPS requires every Maryland jurisdiction to use the same edition of the building codes (so a contractor working in Calvert County and one working in Anne Arundel are governed by the same IRC edition + amendments). State-level amendments cover climate-specific items like ice-and-water shield extents and seismic adjustments.
Layer 3 - County and municipal code
Each Maryland county (and Baltimore City) adds its own permit requirements, inspection schedule, contractor licensing verification, and sometimes additional amendments. Calvert County requires its own permit. Baltimore County recently adopted Bill 49-24 effective September 2024 (replacing the older Bill 40-15). When state and county disagree, the county takes precedence in practice.
The four IRC chapters every Maryland residential roof job touches
Most Maryland residential roof replacements engage exactly four chapters of the IRC. Compliance with all four is what an inspector signs off on at final inspection.
IRC R905 - Roof Coverings
Material-specific install standards. Asphalt shingles, metal panels, slate, tile, and concrete tile each have their own subsections. Defines minimum slope (2:12 for asphalt), underlayment requirements, fastening patterns, and references ASTM D3462 for shingle quality and ASTM D7158 for wind resistance. Most code violations JDH documents in inspections trace back to R905 fastening or underlayment.
IRC R806 - Roof Ventilation
Attic ventilation. Minimum 1 sq ft of net free vent area per 150 sq ft of attic floor space (1:150 ratio), balanced between intake (soffit vents) and exhaust (ridge or gable vents). Can drop to 1:300 with a vapor retarder on the warm side of insulation. Most manufacturer warranties still require the 1:150 ratio regardless. Ventilation non-compliance is the single most common code violation JDH documents.
IRC R902 - Roof Decks + Sheathing
Roof deck material, thickness, and attachment requirements. Acceptable plywood (CDX) and OSB grades. Fastener type and spacing tables. Critical for wind-uplift resistance, especially in coastal-adjacent counties. Standard residential decking is 7/16-inch OSB or 1/2-inch CDX plywood; 5/8-inch is required in some load conditions.
IRC R903 - Roof Drainage
Roof-to-wall flashing minimum 4 inches in both directions. Valley flashing requirements. Penetration boots. Ice-and-water shield from the eave to at least 24 inches inside the exterior wall line (climate zones 4A and 5A, which is all of Maryland per DOE climate zone definitions). Some counties require shield over the entire roof in specific conditions.
UpCodes: Maryland IRC Chapter 9 viewerMaterial and ASTM specifications for code-compliant residential roofing
Code-compliant roofing materials in Maryland must meet specific ASTM standards. The product label or technical data sheet confirms compliance; ASTM-noncompliant material on a residential install is a code violation regardless of how the shingle looks.
Asphalt shingles - ASTM D3462 or D3018
ASTM D3462 sets the baseline residential shingle quality standard: tensile strength, tear strength, granule retention, and fire resistance. Owens Corning Duration and similar premium architectural shingles meet or exceed D3462 by a wide margin; basic 3-tab products meet the baseline. Any asphalt shingle installed in Maryland that does not meet D3462 is a code violation.
Wind resistance - ASTM D7158
ASTM D7158 classifies shingles by wind resistance: Class D (60 mph), Class G (110 mph), Class H (150 mph). IRC R905 in Maryland accepts Class D as a minimum for most inland counties. Coastal and bay-adjacent counties (Calvert, St. Mary's, parts of Charles, parts of Anne Arundel, the entire Eastern Shore) should default to Class H per FEMA P-804 wind retrofit guidance. JDH installs Class H as default on all Southern Maryland coastal-adjacent installs.
Underlayment - synthetic preferred, felt accepted
Code accepts either ASTM D226 felt or synthetic underlayment meeting equivalent specifications. JDH defaults to synthetic on all installs (better tear resistance, longer UV exposure tolerance during the install window, lighter weight). Ice-and-water shield (self-adhered membrane meeting ASTM D1970) is required at eaves and valleys.
Metal panels - manufacturer spec + IRC R905.10
Standing-seam and screw-down metal panels must meet manufacturer install specifications PLUS the IRC R905.10 panel requirements. Galvalume or galvanized steel substrate. Minimum panel thickness. Fastener type and torque specifications. Most metal panel failures in Maryland trace to install errors at panel joints rather than material failure.
ENERGY STAR: residential roofing material specsWind and snow load requirements vary by Maryland county
Maryland's wind and snow load requirements are not uniform across the state. Coastal and bay-adjacent counties have stricter wind resistance requirements; western Maryland has higher snow load requirements. The IRC tables in R301 define the specific values; counties may add stricter local requirements.
Wind exposure categories
The IRC classifies sites by wind exposure category (B, C, or D) based on surrounding terrain. Most Maryland residential sites are Category B (urban, suburban, wooded). Coastal sites with open water exposure are Category D, which requires substantially stronger wind resistance. Bay-adjacent counties have mixed exposure.
Typical wind ratings by Maryland county
- Calvert + St. Mary's (bay-adjacent peninsula): Class H (150 mph) recommended for all asphalt shingle installs. FEMA P-804 applies.
- Anne Arundel (bay + ocean influence): Class H for waterfront, Class G (110 mph) for inland.
- Charles (mixed bay + inland): Class G or H depending on specific site.
- Prince George's (inland): Class G typical, Class D acceptable for low-exposure sites.
- Western Maryland (Frederick, Washington, Garrett): Class D or G; snow load takes precedence over wind in many designs.
Snow load requirements
Residential roof snow loads in Maryland range from approximately 20 psf (Eastern Shore + Southern MD) to 30+ psf (Western MD mountains). The IRC R301.2(5) ground snow load map specifies values; structural design accounts for the difference between ground snow and design roof load. Most residential decking and rafter sizing handles 20-30 psf without issue; truss-built structures may have specific load assumptions on file with the county.
Hail resistance - optional UL 2218 Class 4
Not a Maryland code requirement, but increasingly required by insurance carriers in MD for storm coverage. UL 2218 Class 4 impact-rated shingles often qualify for premium discounts on homeowner policies. Owens Corning and similar manufacturers offer Class 4 options on their premium product lines.
NWS Storm Events Database: historical wind + hail by MD countyMaryland licensing and permit requirements for residential roofing
Maryland requires both state-level contractor licensing AND county-level permits for residential roof work. Skipping either is illegal and creates immediate problems at warranty claim, insurance renewal, or property sale.
MHIC license - state level, required for residential
The Maryland Home Improvement Commission (MHIC) licenses residential roofing contractors. JDH's MHIC license is #137491, continuously active since 1986. Any contractor working on a Maryland residential roof without an MHIC license is operating illegally - the homeowner has no recourse through the state if work goes bad, and the install may be uninsurable.
County permit - required for replacement, sometimes for repair
Every Maryland county requires a building permit for a full roof replacement. Repair permit thresholds vary: Baltimore County requires a permit when 50 percent or more of the deck is replaced. Some counties have specific surface-area thresholds. Permit fees range from approximately $75 to $400 depending on county and project value. Calvert County publishes specific requirements on its code requirements page.
Required inspections - typically 2 or 3 per install
Most Maryland counties require: (1) deck inspection after tear-off and before underlayment; (2) optional in-progress inspection; (3) final inspection after completion. Inspector verifies fastening pattern, flashing installation, underlayment coverage, ventilation compliance. JDH coordinates all inspections; the homeowner receives the inspection result documentation with the warranty package.
Insurance + COI requirements
Maryland requires roofing contractors to carry general liability and workers compensation insurance. JDH carries $8 million in combined coverage. Certificate of insurance (COI) is provided with every estimate. OSHA residential construction safety standards apply on every job. A contractor unable to produce a current COI is operating outside Maryland law.
MD Attorney General: home improvement consumer rightsCounty-by-County Permit + Code Reference (Southern MD)
Permit office, portal, IRC edition adopted, and key county-specific code amendments for the 5 Southern Maryland counties JDH serves. Always confirm current requirements with the county before signing a roofing contract.
| County | Permit office | IRC edition | Wind class default | Key amendments |
|---|---|---|---|---|
| Calvert (JDH HQ) | Calvert County Code | IRC 2021 + MBPS | Class H (150 mph) - bay-adjacent | Chesapeake Bay Critical Area review for waterfront sites; standard permit fees |
| St. Mary's | St. Mary's County Land Use & Growth Management | IRC 2021 + MBPS | Class H (150 mph) - bay + ocean adjacent | Critical Area review for waterfront; Pax River-adjacent rules for some sites |
| Charles | Charles County Planning & Growth Management | IRC 2021 + MBPS | Class G (110 mph) inland, Class H bay-adjacent | Standard permit fees; deck inspection typically required |
| Anne Arundel | Anne Arundel County Department of Inspections & Permits | IRC 2021 + MBPS | Class H for waterfront, Class G inland | Annapolis Historic District: additional review required |
| Prince George's | Prince George's County Department of Permitting, Inspections & Enforcement | IRC 2021 + MBPS | Class G (110 mph) | May require ice-and-water shield over entire roof surface in some conditions |
| Baltimore County | Baltimore County Building | IRC 2021 + MBPS (Bill 49-24, eff. Sep 2024) | Class G typical | Permit required for repair if 50%+ of deck is being replaced |
County-specific requirements change as jurisdictions adopt new IRC editions and update local amendments. Always confirm current requirements directly with the county permit office. JDH coordinates all permits and inspections on every install in the counties above. For VA counties JDH serves, see the Virginia DPOR contractor lookup and the Virginia Uniform Statewide Building Code.
How to Pull a Residential Roof Permit in Maryland
A six-step process for a Maryland homeowner or contractor to pull the required residential roof replacement permit in any of the Southern Maryland counties JDH serves. JDH handles all of this on every install.
Identify the correct county permit office
Maryland roof permits are county-issued, not state-issued. Use the county-by-county table on this page to find the permit office that has jurisdiction over the property. JDH-served counties: Calvert, St. Mary's, Charles, Anne Arundel, Prince George's.
Confirm the adopted IRC edition for your county
Most Maryland counties reference 2021 IRC with MBPS amendments as of 2026. Some are transitioning to 2024 IRC. The exact edition determines the specific requirements that apply. Call or check the county permit office portal.
Prepare the permit application
Required attachments typically include: contractor MHIC license number, scope of work (replacement vs repair vs roof-over), material specification sheets, manufacturer install instructions, and proof of insurance (general liability + workers comp). JDH handles all of this on every job.
Submit and pay the permit fee
Most Maryland counties accept online submission. Permit fees range from approximately $75 to $400 depending on county and project value. Some counties charge a flat fee for residential re-roofs under a specified value threshold.
Schedule the required inspections
Typical inspection points: deck inspection (after tear-off, before underlayment), in-progress inspection (during install), final inspection (after completion). Some counties require all three; some only deck + final. Inspector arrives within the county's standard scheduling window.
Receive the final certificate and file it
After the final inspection passes, the county issues a certificate of completion. Keep this with the property records. It is required when the home is later sold (real estate disclosure) and can be required by insurance carriers at policy renewal. JDH provides a copy of the certificate to the homeowner along with the warranty package.
Why Inspection Findings Matter
A JDH HAAG Master Certified walkthrough of the PCC Method (Problem, Cause, Consequence) on a Southern Maryland roof. The same documentation a manufacturer needs to honor (or deny) a warranty claim.
From the JDH Remodeling channel · PCC Method on a real Southern Maryland roof.
Not sure your current install meets Maryland code?
JDH's HAAG-certified inspection documents every code-relevant finding: ventilation calculation against IRC R806 spec, fastening pattern, flashing dimensions, ice-and-water shield coverage, decking condition. Free 60-90 minute on-roof inspection with photo and video report. We pull permits and coordinate inspections on every install we recommend.
Maryland Roofing Code FAQ
Do I need a permit to replace my roof in Maryland?+
Almost always yes. Every Maryland county requires a building permit for a full roof replacement, and most also require permits for repair work that exceeds a specified threshold (commonly 50 percent of the deck or 25 percent of the surface). A permit-free re-roof is rare and almost always indicates a contractor cutting corners. JDH pulls every permit required by the county where the work happens and provides the permit number to the homeowner before work starts.
Do roofers have to be licensed in Maryland?+
Yes, for residential work. Maryland does not have a statewide general contractor license, but residential roofing falls under the Home Improvement Commission (MHIC) which DOES require a state license. JDH's MHIC license is #137491, verifiable at the Maryland Department of Labor electronic licensing search. Any contractor working on a Maryland home roof without an MHIC license is operating illegally.
What is the 25 percent rule in Maryland roofing?+
The 25 percent rule is an industry guideline (not a Maryland code requirement) that recommends full replacement when 25 percent or more of the roof's surface area needs repair. JDH applies a slightly stricter 35 percent threshold internally: if repair would cost 35 percent or more of full replacement, we recommend replacement. Below 35 percent, we repair. Some Maryland counties additionally require a permit when more than a specified percentage of deck or surface is being replaced - check the county-specific table on this page.
Which version of the International Residential Code does Maryland follow?+
As of 2026, most Maryland jurisdictions reference the 2021 IRC with Maryland Building Performance Standards (MBPS) amendments. Some counties are transitioning to the 2024 IRC. The MBPS framework requires every Maryland jurisdiction to use the same edition of the building codes, but counties phase in updates at different speeds. Always confirm the adopted edition with the specific county permit office where the work will happen before signing a contract.
What wind rating do Maryland residential shingles need to meet?+
Maryland’s residential roof wind requirements depend on the county. Most inland counties accept Class D (60 mph) or Class G (110 mph) under ASTM D7158. Coastal and bay-adjacent counties (Calvert, St. Mary's, Anne Arundel, parts of Charles, and the Eastern Shore) should default to Class H (150 mph), and FEMA P-804 recommends Class H or better for any coastal residential construction. JDH installs Class H as the default on all Southern Maryland coastal-adjacent installs; the upcharge is small relative to the storm protection delta.
What attic ventilation does Maryland code require for residential roofs?+
IRC Section R806 (adopted by MBPS) requires attic ventilation of at least 1 square foot of net free vent area per 150 square feet of attic floor space, balanced between intake (soffit) and exhaust (ridge or gable). The ratio can drop to 1:300 if the ventilation is balanced and a vapor retarder is installed on the warm side of the insulation. Most manufacturer warranties (Owens Corning, GAF, etc.) require the 1:150 standard regardless. Ventilation non-compliance is the single most common code violation JDH documents on inspections.
Is ice-and-water shield required by Maryland code?+
Yes, under IRC R905 for any area subject to ice damming, which in practice is all of Maryland north of about Calvert County and including most of the Eastern Shore. The shield must extend from the eave edge to a point at least 24 inches inside the exterior wall line of the building. Some counties (Prince George's notably) require ice-and-water shield over the entire roof surface in certain conditions. The shield is one of the most-overlooked code requirements on lower-cost re-roofs.
Can I roof-over my existing shingles in Maryland?+
Most Maryland counties allow one roof-over (installing new shingles directly over one existing layer), but it voids most manufacturer warranties, makes future inspection difficult, and shortens the new roof's lifespan substantially. JDH does not recommend roof-overs and almost never performs them. The contractor savings on a roof-over (about 15 to 25 percent) is rarely worth the homeowner cost over the 25 year lifespan. Many counties (including all of Southern Maryland) require additional inspections if two existing layers are present before re-roofing.
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