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Metal roofing in Bethesda, MD: what the county historic guidelines say and leave out
For a Bethesda property on the county historic list, the roofs section of the design guidelines is the document that matters for metal. It names one metal by type, says nothing about metal shingles, tile-profile panels, copper, zinc or coatings, and points readers to National Park Service briefs for the rest. This page reads those documents side by side with the Maryland code text, and marks every gap.
- 2 places where the roofs section names metal
- 0 mentions of copper, zinc or coatings in that section
- 115 mph wind speed in the county design table
What section 5.0 says about metal
The Historic Preservation Commission’s design guidelines are the county’s plain-language reference for exterior work on listed properties. Roofs get their own section, 5.0, on printed pages 63 and 64 of Chapter 3. Metal shows up twice. The first is a list of traditional roof materials. The second is a photo caption.
“A metal seam roof is a traditional roof material”
Caption, section 5.0 Roofs, Chapter 3, Montgomery County Historic Preservation Commission design guidelines- Traditional list
- Slate, wood shingle, standing seam metal and tiles, with asphalt shingles added for 20th century buildings. Metal appears as one type, standing seam.
- 5.1 and 5.3
- Keep the original roof form, the roof angle as seen from the street, the roof detailing and the eave depth. None of this names a material, but a panel profile changes how a roof reads from the street.
- 5.2
- Maintenance and cleaning come first. Look for breaks or holes and check the flashing for open seams, which is the one place the section speaks to metal construction details.
- 5.4
- Preserve original roof materials. Material in good condition should not be removed, and similar material replaces it only when necessary.
- 5.5
- Replacement should convey a scale and texture like those used traditionally. It says “Replacement in-kind is encouraged,” with new material matching the original in scale, color and texture as closely as possible.
Two definitions sit behind those lines. The Purpose chapter says in-kind replacement must “exactly match the old in design, color, texture, and materials.” Chapter 3, on page 48, softens that for one case: where the original is beyond repair and original materials are not feasible, a substitute that closely resembles the original in design, color, texture and other visual qualities may be considered.
What the guidelines leave out
A word search of the three chapters stored for this page finds “metal” in section 5.0, in a line about security bars and in a line about fences. The roofs section gives a reader no product-level answer. The table sets what is named against what is not.
Named in section 5.0
- Standing seam metal, as a traditional material
- A metal seam roof, in a caption, as worth preserving
- Flashing and open seams, as maintenance checks
- In-kind replacement, as encouraged
Not named in section 5.0
- Metal shingles and tile-profile panels
- Copper, zinc, terne or galvanized steel
- Paint, finish or coating systems
- Seam spacing, fasteners or panel width
Section 5.0 refers readers to National Park Service Preservation Briefs 4, 19, 29 and 30 through Appendix pages APP-2 and 3. The appendix was not opened for this page. Brief 4, Roofing for Historic Buildings, was, and the next section uses it.
The silence neither forbids nor clears a metal product. The guidelines also say design review applies only to actions an owner starts, and that HAWP questions go to the Historic Preservation Section. Our Bethesda roofing guide covers who is on the county historic list and which towns may review work first.
Four metal products, three documents
National Park Service Brief 4 and the Maryland code text fill part of what the county guidelines leave open.
| Product | County guidelines, 5.0 | NPS Brief 4 | Maryland code text, chapter 9 |
|---|---|---|---|
| Metal shingles | Not named | Tin shingles were often embossed to imitate wood or tile | Solid or closely fitted deck, not below 3 in 12, wind-tested |
| Tile-profile panels | Tiles named as a traditional material, with no metal version | Galvanized sheet-metal shingles imitated pantiles into the 20th century | No tile-profile category; falls under panels or shingles |
| Copper | Not named | Listed among historic sheet metals; touching iron can corrode | Minimum 16 oz per square foot for sheets; 12 oz for preformed shingles |
| Zinc | Not named | Came into use in the 1820s and was never widely used here | Minimum thickness 0.027 inch for zinc covering |
Sources: guidelines Chapter 3 section 5.0; National Park Service Preservation Brief 4; MBPS Residential Code 2021 chapter 9 as published by UpCodes, Table R905.10.3(1) and sections R905.4 and R905.10. County amendments to the code were not read.
Metal shingles and tile-profile panels
Brief 4 carries a photo caption about “Galvanized sheet-metal shingles imitating the appearance of pantiles,” and says tile and embossed metal shingles can be made by makers of related products. That is history, not approval. The code text sets the technical frame: shingles go on a solid or closely fitted deck unless made for spaced sheathing, are not installed below 3 in 12, and must be wind-tested to one of four named standards. Whether a modern profile counts as in-kind for a listed building is not answered in any of the three documents.
Copper and zinc
Brief 4 names “lead, copper, zinc, tin plate, terne plate, and galvanized iron” as the common historic sheet metals. It adds that copper and iron in direct contact set up galvanic corrosion, with steel nails in copper sheets as its example. The code text turns that into a fastener rule for copper roofs and a weight or thickness floor for each metal. The code also lists copper sheets of at least 16 ounces per square foot over combustible decks among Class A assemblies.
Where the county’s own numbers come in
The county’s design criteria sheet, dated August 13, 2026, lists a 115 mph wind speed, a ground snow load of 30 psf and ice barrier underlayment as required. The code text says ice barriers, where required, follow section R905.1.2, which reaches a metal shingle scope. On wind, our reading is that 115 mph falls in the code table’s 116 mph row, where an ASTM D3161 class A, D or F label is listed.
Coatings and fasteners in the code text
Coatings are the one topic where the code text is more detailed than either preservation document. It sets floors, not rankings.
Metal-coated steel
Table R905.10.3(2) lists minimum corrosion resistance for galvanized, aluminum-zinc alloy-coated, aluminum alloy-coated and aluminum-coated steel by standard and coating class.
Prepainted steel
The same table names a paint standard and says paint systems go over steel that already carries one of those metallic coatings.
Terne and lead-coated copper
Table R905.10.3(1) lists terne as field painted where applicable under the maker’s instructions, and lead-coated copper by its own standard.
Fasteners
Where the maker gives no instructions, galvanized fasteners for steel roofs and copper-family or 300-series stainless for copper roofs. Stainless is acceptable on metal roofs.
Brief 4 adds a preservation view of the same issue. Iron rusts unless plated or painted, and the brief says plating lasts only while the coating stays intact. It also says lead-coated copper, terne-coated steel and aluminum and zinc-coated steel can stand in for tin, terne plate, zinc or lead.
Lines to put in a Bethesda metal quote
- The metal: steel with its coating class, aluminum, copper with its weight, or zinc with its thickness.
- The profile: standing seam, lapped panel, metal shingle or tile-profile panel, with the slope measured on site.
- The deck and underlayment, including the ice barrier line the county table calls for.
- The wind test and label for shingles, or the maker’s installation instructions for panels.
- Fastener metal, so copper and steel never touch through a nail or clip.
- The finish: prepainted, field painted, or natural, with who maintains it.
- Any written reply from the Historic Preservation Office or DPS that the work relies on.
Roofers of Arlington installs, repairs and replaces roofs, including flat and metal systems. Book a phone consultation to talk through a Bethesda metal roof. See the general metal roofing guide, roofing materials, roof replacement and services pages, and the Bethesda guide for the Maryland license and permit path.
The order to ask in
- Find out if the property is listed. The county guide ties historic review to the Master Plan for Historic Preservation or the Locational Atlas. If it is not listed, the guidelines in this page are background, not rules for your roof.
- Describe the roof you have. Material, slope, seam spacing if metal, flashing and eave depth are what sections 5.1 to 5.5 turn on.
- Name the product you are considering. Give the Historic Preservation Office the profile, finish and metal, since the guidelines do not tell you whether it fits.
- Settle the permit lane with DPS. Roof covering only is on the no-permit list, with the code still applying, and a HAWP comes before a building permit where one is needed.
- Check any association or town. The county does not enforce covenants, and some nearby municipalities review work separately.
Documents read, with dates
Every source was opened on October 19, 2026. UpCodes publishes the Maryland code text; the ICC site returned an access error, and the county amendments were not read.
- Historic Preservation Commission design guidelines, Chapter 3, General Rehabilitation, and Chapter 1, Purpose
- National Park Service Preservation Brief 4, Roofing for Historic Buildings
- MBPS Residential Code 2021, Chapter 9 Roof Assemblies, as published by UpCodes
- Montgomery County DPS: Master List of Building Codes and Standards, which names the 2021 International Residential Code, effective December 10, 2024
- Montgomery County DPS: Climatic and Geographic Design Criteria (dated August 13, 2026)
- Montgomery County DPS: Home Improvements and Montgomery Planning: Historic Area Work Permits
Questions people ask
Do Montgomery County historic guidelines ban or allow metal roofs?
Neither. Section 5.0 lists standing seam metal among traditional roof materials and says replacement in-kind is encouraged. It does not rank metal against other coverings or name a product that is off limits. Whether a given panel counts as in-kind for your building is a question for the Historic Preservation Office.
My Bethesda house already has a standing seam roof. What do the guidelines say about it?
A caption in section 5.0 calls a metal seam roof a traditional material that should be preserved and maintained. Guideline 5.4 adds that roof material in good condition should not be removed. Brief 4 from the National Park Service says the spacing of seams affects a building’s scale, so replacement seams should match the original dimensions where they are visible.
Do the guidelines say anything about copper or zinc roofs?
Not in the roofs section or the other chapters stored for this page. Copper and zinc appear in National Park Service Brief 4, which lists them among the sheet metals found on historic buildings, and in the Maryland code text, which sets a minimum weight for copper and a minimum thickness for zinc.
Is a metal shingle that imitates slate or tile treated as a substitute material?
The guidelines do not say. Their substitute-material test, on page 48, asks that a substitute closely resemble the original in design, color, texture and other visual qualities, and applies only where the original is beyond repair. Brief 4 notes that metal shingles imitating pantiles are themselves part of roofing history, so ask the office how it reads your case.
What is the lowest slope for metal shingles in the Maryland code text?
Section R905.4.2 of the 2021 residential code as published for Maryland bars metal roof shingles below 3 units vertical in 12 horizontal. Panels differ: lapped panels without sealant need the same 3 in 12, while standing seam is listed down to one quarter in 12. Measure your slope before choosing a product.
What wind label should metal shingles carry in Bethesda?
The county’s design table lists 115 mph. In the code’s table for metal shingles tested to ASTM D3161, our reading puts that in the 116 mph row, where class A, D or F is listed. The code also lets shingles be tested to FM 4474, UL 580 or UL 1897. Ask DPS to confirm the row for your address.
Does a metal roof replacement need a permit in Bethesda?
The county’s home improvement page lists roof covering only among work that most likely needs no permit, and the code still applies. On a property listed for historic preservation, the guide says a historic area work permit may come first. Call the Department of Permitting Services with your scope before ordering panels.
Does paint or coating matter on a steel metal roof?
The code text requires metal-coated steel to meet listed corrosion standards, and prepainted steel to follow a paint standard applied over those coatings. Brief 4 says iron-based roofing rusts once plating wears through unless the surface is kept painted. None of the sources gives a service life, so ask the roofer to name the coating system in writing.
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.