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Metal roofing in Silver Spring, MD: what the county documents say, and what they leave out
Montgomery County publishes a historic roof guideline that names standing seam metal, a permit page that lists roof covering as work that most likely needs no permit, and a Maryland residential code that sets flashing and fastener rules. None of them explains how copper, zinc, aluminum and steel behave when they touch or drain onto each other. This page reads each document, says where it is silent, and adds the galvanic compatibility points from the Metal Construction Association.
- 3 documents read: guidelines, permit pages, code
- 0.019 in minimum thickness for metal flashing in the code copy
- Aluminum is not named in the guideline roof chapter
The historic guideline on metal roofs
Montgomery County's Historic Preservation Commission uses a design guideline book for properties on the Master Plan for Historic Preservation. Its roofs section, on pages 63 and 64 of the chapter on general rehabilitation, is the only county document read here that speaks to metal as a look and a tradition rather than as a code product.
"A metal seam roof is a traditional roof material"
Montgomery County Design Guidelines for Historic Sites and Districts, roofs section, caption- Materials named
- Slate, wood shingle, standing seam metal and tiles, plus asphalt shingles for twentieth-century resources. The text says using traditional materials is recommended.
- Replacement rule
- Guideline 5.4 says to preserve original roof materials and replace with similar material only when necessary. Guideline 5.5 says replacement in-kind is encouraged and new material should match the original in scale, color and texture.
- Maintenance
- Guideline 5.2 tells owners to look for breaks or holes and to check the flashing for open seams.
Where the guideline is silent. The roofs section does not name aluminum, copper, zinc or steel as flashing, does not mention fasteners, coatings or galvanic action, and does not say whether a metal roof may replace shingles on a house that never had one. Aluminum appears only in the materials chapter, where it is listed among nonhistoric materials in the context of siding. Read the full chapter, then ask the Historic Preservation Office how it applies to your property.
Permit pages compared
Three offices touch a Silver Spring roof, and each page is short on material. The comparison below shows what the wording covers.
Department of Permitting Services
Its Home Improvements list places "Roof (covering only)" and gutters and downspouts on the list of work that most likely will not need a permit. It adds that the list leaves out municipality and homeowner association rules, and that exempt work must still meet the building code. No roofing material is named.
Montgomery Planning and HPC
The Historic Area Work Permit page lists changes to exterior materials as work that needs a permit, and treats roof repairs and gutters with matching materials and design as ordinary maintenance. A change from one roof material to another is not a matching repair on its face. The Historic Preservation Office is the place to ask.
Takoma Park adds a step. The city says any project that needs a county permit first needs a Municipality Letter, no fee, "not a permit," and that a county Historic Area Work Permit applies in the historic district. Its page does not say whether a covering-only re-roof needs the letter. Silver Spring itself is not a city, so the county pages are the starting point for most addresses. The Silver Spring hub covers who owns the roof in each building type.
Flashing metals and galvanic compatibility
The Metal Construction Association (MCA), a trade association, publishes a technical bulletin on dissimilar metals. It says corrosion needs two conditions at once: metals that are galvanically incompatible, and moisture joining them. Rainwater and snow melt both count as that moisture. On a roof, the other metals are the flashings, fasteners, gutters, vents and rooftop equipment, which is why the choice is a roofing decision and not only a panel decision.
The bulletin also says the problem can happen without contact. Runoff from a more noble metal onto a less noble one can corrode and stain it.
| Pairing in the MCA bulletin | What it says |
|---|---|
| Galvanized nail in an aluminum roof | The zinc coating depletes quickly and the nail begins to red rust. |
| Aluminum nail in a galvanized roof | Poses no problem. |
| Copper with zinc, aluminum or aluminum-zinc coated steel | Extreme caution, including runoff from copper plumbing and HVAC equipment. |
| Copper with lead or stainless steel | Performs well. |
| Rooftop air conditioner condensate onto coated steel | Can be a stronger electrolyte than rainwater. |
| Preservative-treated lumber against metal | Avoid, except with copper and certain stainless steel. |
| Graphite pencil marks on aluminum | Corrosive to aluminum and its alloys. |
Source: MCA Technical Bulletin, Dissimilar Metal Corrosion in Roofing Installations, version 06/22, read October 19, 2026.
The bulletin lists separation barriers such as bituminous membranes or coatings, and says wood blocking and protective pads should not sit on the surface of a coated steel or aluminum roof because they trap moisture. It also notes prepainted roofing is generally not coated to act as that barrier. These are an association's practices, not the county's rules.
What the Maryland code copy covers
The text read here is the UpCodes copy of Chapter 9 of the Maryland Building Performance Standards residential code, 2021 edition, which adopts the International Residential Code with amendments. The ICC site was not opened, so confirm with the county which edition and amendments apply today.
- Flashing section R903.2.1 requires flashing at wall and roof intersections, slope changes and openings, and says metal flashing must be corrosion resistant, at least 0.019 inch thick, the thickness of No. 26 galvanized sheet. It does not pair flashing metal to roof metal.
- Fasteners section R905.10.4 says manufacturer instructions come first. Without them, galvanized fasteners for steel roofs, copper-family or 300-series stainless for copper roofs, and stainless acceptable for metal roofs. Aluminum fasteners are not addressed in that sentence.
- Slope section R905.10.2 sets 3 in 12 for lapped seams without sealant, 1/2 in 12 with sealant and 1/4 in 12 for standing seam.
- Recover section R908.3.1 lets complete, separate systems such as standing seam skip removal of the existing roof, while R908.3.1.1 bars recovering slate, clay or cement tile, or a roof with two or more applications.
For the generic profile and slope discussion, see the metal roofing guide, which uses Virginia's code; this page does not apply it to Maryland.
What a written scope should name
Maryland requires a home improvement contract to describe the work and the materials to be used. Because the documents above are silent on pairings, the written scope is where flashing and fastener metals can be settled. Roofers of Arlington installs, repairs and replaces roofs, including metal systems. To talk through a Silver Spring metal roof, book a phone consultation, or see the roof replacement, roof repair and materials pages and services.
- The metal and coating of the panels, and of each flashing, fastener, gutter and vent.
- How any copper item upstream, such as a gutter, pipe or equipment, drains relative to the panels.
- Whether the panel maker has been asked about galvanic compatibility, and the answer in writing.
- Separation barriers at flashing contacts and no wood blocking or pads on coated steel or aluminum.
- Where rooftop equipment condensate will go.
- Which office was asked about permits: county permitting, Historic Preservation Office, Takoma Park, association.
- For a condominium, the council of unit owners' approval, since the council regulates common element replacement.
Nothing here is engineering or legal advice. Ask the county, your association and your engineer.
Documents opened, with dates checked
All opened October 19, 2026.
- Montgomery Planning: Design Guidelines for Historic Sites and Districts
- Montgomery Planning: Historic Area Work Permits
- Montgomery County DPS: Home Improvements
- Montgomery County DPS: Historic Area Permit Process
- City of Takoma Park: Municipality Letters
- Metal Construction Association: Dissimilar Metal Corrosion in Roofing Installations
- UpCodes: MBPS Residential Code 2021, Chapter 9 (third-party copy)
- Maryland Business Regulation 8-501 and Real Property 11-109 (common elements are defined in 11-101)
Back to the Silver Spring roofing hub or all service areas.
Questions people ask
Does Montgomery County's historic guideline allow a metal roof?
The roofs chapter lists standing seam metal among traditional roof materials and calls a metal seam roof a traditional material to be preserved. It encourages replacement in-kind. It does not rule metal in or out for houses that were not originally metal. Ask the Historic Preservation Office before choosing a material for a listed property.
Does a roof covering need a permit in Silver Spring?
The county's Home Improvements list puts "Roof (covering only)" on the list of work that most likely will not need a permit, and says the list leaves out municipality and homeowner association rules. It does not name a material. Ask the Department of Permitting Services about your scope.
Why does flashing metal matter on a metal roof?
The Metal Construction Association says corrosion needs two things: metals that are galvanically incompatible and moisture connecting them. Flashing, fasteners and gutters are the other metals on the roof, so their choice can decide whether a panel is corroded by its neighbors.
Can copper flashing or a copper gutter be used with an aluminum or steel metal roof?
The MCA bulletin says to use extreme caution about electrolytic contact of zinc, aluminum or aluminum-zinc coated steel with copper, and it counts runoff from copper as a risk. Ask the panel manufacturer and your roofer how the details are separated.
Does the Maryland residential code say which fasteners to use on a metal roof?
In the UpCodes copy of the Maryland 2021 residential code, section R905.10.4 sends installers to the manufacturer's instructions first. Only if there are none does it name galvanized fasteners for steel roofs and stainless steel as acceptable. Confirm the edition in force with the county.
Does a metal roof in Takoma Park need anything extra?
The city says work needing a county permit first needs a Municipality Letter, which is not a permit, and a county Historic Area Work Permit if the property is in the historic district. The city page does not say whether a covering-only re-roof needs the letter, so ask the city.
Can a new metal roof go over an existing roof in Maryland?
The code copy lets complete, separate systems such as standing seam, designed to carry loads without the old roof, skip removal of the existing covering. It bars a recover over slate, clay or cement tile and over a roof with two or more layers. Whether your roof qualifies is a question for the county and an engineer.
Who signs for a condominium roof in Silver Spring?
Maryland law gives the council of unit owners power to regulate repair, replacement and modification of common elements. Maryland defines common elements as all of the condominium except the units, and whether a roof falls inside a unit depends on the declaration, so check the declaration and the council's process first. Ask your association for its architectural and reserve documents.
Talk through your roof with Roofers of Arlington
Share the address, what you are seeing on the roof and the decision you need to make. We will tell you what to expect before anything is scheduled.