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Metal roofing in Annandale, VA: exposed-fastener panels and who signs for them
Lapped metal panels with screws through the face are simple to describe and easy to get wrong in the details: how tight the screws are, what the washers do, and how the metal moves in the sun. Annandale adds a question of its own, because the people who decide about a roof differ sharply between its houses and its apartment buildings. This page puts the Census counts first, then the neutral rules for fastening and movement.
- 3 in 12 is the code minimum slope for lapped metal without lap sealant
- 2,500 RPM is the most an MCA bulletin allows when screwing panels to framing
- 4,494 Annandale homes (31.0%) are in buildings of 5 or more units
Who decides about a metal roof in Annandale
The first question about an exposed-fastener metal roof is not the metal. It is whose roof it is. Annandale is a Census-designated place inside Fairfax County, and its housing splits into very different groups. The counts below come from the American Community Survey 2024 five-year estimates (2020 to 2024). They are estimates with margins of error, so treat them as sizes, not exact tallies.
Owner-occupied homes
Of 9,087 owner households, 6,025 live in detached houses and 1,926 in attached homes such as townhouses. That is 87.5% of owners. For these, the owner signs the contract, but a townhouse association may set roof rules, so check its documents first.
Renters in larger buildings
Of 4,804 renter households, 3,154 (65.7%) live in buildings of 5 or more units. A tenant in these buildings does not choose a roof. The decision sits with the owner or a manager, and for condo buildings with the association.
Only 988 owner households live in buildings of 5 or more units, the group where a condo board would vote on a roof. The tables say nothing about which roofs are metal. They do not show roof material at all, so this page asserts nothing about what any Annandale building wears. The Annandale roofing guide covers the year-built bands and the county permit rows.
What an exposed-fastener panel is
The Metal Construction Association (MCA) describes corrugated and tile-look metal roofs as attached with exposed fasteners directly through the panels, with panels overlapping or interlocking at side and end laps. Standing-seam systems instead use hidden clips or fastening flanges. The difference shapes everything below: a screwed-down roof has many holes in the face of the panels, and each one depends on a washer.
The MCA adds that architectural steep-slope panels always need a solid substrate such as plywood. Virginia's code says metal panel roofing goes on solid or spaced sheathing unless the product is designed for spaced supports.
A slope of 3 in 12 rises 3 inches over 12 inches of run. Anything flatter needs lap sealant or a different product, which matters on any low-slope area. The flat roof page covers those roofs.
Screws, washers and spacing
- The code points to the maker. Panels are secured under the roof chapter and the manufacturer's installation instructions. Without instructions, the code names galvanized fasteners for steel roofs and copper-family or 300-series stainless for copper roofs. Stainless is accepted on metal roofs.
- The code gives no spacing figure. The attachment section prints no screw spacing. Spacing therefore lives in the product's own instructions, and a quote that states a number should name its source.
- The washer does the sealing. The MCA says fasteners must be set so the EPDM sealing washer performs. It points to the fastener maker for how tight, and does not give a torque or a turn count.
- The tool matters. The MCA recommends screw guns with an adjustable clutch or depth-sensing nosepiece, advises against impact drivers, and sets 2,500 RPM as the ceiling when fastening panels to framing.
An overdriven screw damages the EPDM sealing washer, which "could potentially be the source of water leaks."
Metal Construction Association, technical bulletin on fastening tools (version 3, April 2024)The bulletin also says overdriven fasteners can restrict thermal movement and cause the waviness called oil canning. That links this section to the next one.
Expansion and contraction
- MorningCool panels are at their shortest. Fasteners and edge details hold them in place.
- Sunny afternoonThe MCA says surface temperature can be more than 100 degrees higher than the air, so the panel lengthens, mostly along its run.
- EveningThe panel contracts. The cycle repeats every day, and across the seasons.
The same MCA bulletin says fasteners, clips and perimeter connections should be designed and installed to allow the movement that is expected. When flashing at an edge, or a second fixing point, holds the panel, the result can show as waves in the flat of the panel. It also notes that waves from heat can come and go in a day, that thicker metal is less likely to wave, and that no installer can guarantee total prevention.
For an exposed-fastener panel, the practical point is where the fixing sits. Ask whether screws go through the flat or the rib, and how the panel is held at the eave and the ridge. The bulletin does not give hole sizes or slot lengths for roofs, so that detail comes from the product instructions.
Questions and a written scope
- What is the measured slope of each roof plane, and which minimum does the quote use?
- Is lap sealant used, and which instruction sheet calls for it?
- Which fastener metal and washer type, and what tool and clutch setting?
- Where do the screws sit, and how is panel movement allowed at eaves, ridges and flashings?
- What is under the metal, and is the deck solid?
- For a condo or townhouse: has the association approved the work in writing?
For Fairfax County permits and the state exemption, the Annandale guide holds the detail. Our metal roofing page covers standing seam and shingles, the materials page compares systems, and roof replacement and services describe the work. Book a phone consultation to talk through an Annandale metal roof: call (571) 397-6072 or use the consultation page. Have the address, the building type and what you can see ready.
Where the figures come from
All opened October 19, 2026. The Virginia Residential Code text was read from a public copy of the Virginia edition.
- Virginia Residential Code 2021, chapter 9 (sections R905.10.1, R905.10.2, R905.10.4)
- Metal Construction Association: steep slope metal roofing
- MCA technical bulletin: Proper Tools for Fastening Metal Panels (April 2024)
- MCA technical bulletin: Oil Canning in Metal Roof and Metal Wall Systems (July 2023)
- U.S. Census Bureau ACS 2024 5-year, tables B25024, B25032, B25034, via Census Reporter
Questions people ask
What slope does a lapped exposed-fastener metal roof need in Virginia?
The 2021 Virginia Residential Code sets 3 units vertical in 12 horizontal for lapped, nonsoldered-seam metal roofs without applied lap sealant, and one half unit in 12 where lap sealant is applied under the manufacturer's instructions. Measure each roof plane and ask the quote to state the slope against that minimum.
Does the Virginia code say how far apart the screws go?
The section on metal panel attachment says panels are secured under that chapter and the manufacturer's installation instructions. It prints no spacing figure of its own. If your quote lists a spacing, ask which instruction sheet it comes from.
Why do the washers matter on a screwed-down panel?
The Metal Construction Association says the fastener must be installed so the EPDM sealing washer performs, and that an overdriven screw damages the washer and could be a source of leaks. Its bulletin sends readers to the fastener maker for tightening guidance.
Can a crew use an impact driver on metal panels?
The Metal Construction Association bulletin on fastening tools does not recommend impact drivers for roof or wall panels. It cites broken screws, chipped paint, stripped threads on stainless screws and damaged washers. Ask what tool the crew uses.
Do metal panels expand and contract enough to matter?
The Metal Construction Association says exposed panel surfaces can run more than 100 degrees warmer than the air and that fasteners, clips and edge connections should allow the movement. Panels held back at flashings or edges can show waves.
Will the Census numbers tell me who approves my Annandale roof?
No. The Census counts homes by building size and by owner or renter, but it does not show who holds the roof. Your deed, lease or association documents say that. The counts only show how many homes sit in each situation.
Is screwed-down metal the same as a standing-seam roof?
No. The Metal Construction Association describes standing seam as fastened with hidden clips or flanges, and exposed-fastener products as attached directly through the panels. The code also sets a different minimum slope for each.
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.