TPO Roofs in Great Falls, VA: What NOAA's Storm Record Shows
The federal Storm Events Database holds 48 reports under the name Great Falls for Fairfax County. Trees, wires, hail sizes and water on roads fill them. This page reads the list for what a flat TPO section would be asked to handle.
June 1996 to July 2025
that name a roof
The record
What does NOAA file under the name Great Falls?
We read NOAA's bulk Storm Events files on 2026-10-16 and kept the Fairfax County rows whose reference place is Great Falls. That label is a reference point, not a boundary: where NOAA gives a distance, it runs from 0.39 to 4.11 miles out. One storm can produce several rows.
- Wind: 35 rows
Thunderstorm wind reports. Thirty-one carry an estimated gust between 39 and 65 knots, NOAA's unit. Thirty-two of the narratives mention a tree.
- Hail: 5 rows
Sizes from 0.75 to 1.75 inches, on four separate dates between 1997 and 2019. None of the narratives describes damage.
- Water: 8 rows
Flood and flash flood reports: closed roads, a submerged vehicle and a swiftwater rescue.
- Roofs: 0 rows
No narrative names a roof or shingles. One mentions a residence: three large trees down at a house on Milstead Road, with nothing said about the house.
Four rows in full
Which reports are worth reading line by line?
- April 26, 2019
An NWS storm survey estimates a 65-knot gust, the highest on this list. Trees came down near Chesapeake Drive, between Arnon Chapel Road and Beach Mill Road, and one took two power poles with it.
- June 2, 2019
Two hail reports from the same afternoon: quarter size (1.00 inch) and golf ball size (1.75 inches).
- June 19, 2025
An estimated 61-knot gust. Large trees came down along Georgetown Pike near Ellsworth Avenue and Old Dominion Drive, and on Towlston, Swinks Mill, Old Dominion and Spring Hill roads.
- July 19, 2025
Flash flood rows: one to two feet of water across Georgetown Pike near Miller Avenue, and a swiftwater rescue on Old Dominion Road. Roads, not roofs.
Thirty-one of the 40 days fall in June, July or August
That is when reports were entered under this label, not a forecast. Rows filed for the whole county are outside the count, so this is a narrow slice.
From the list to the roof
What would a flat TPO section make of each kind of row?
Wind and fallen trees
- What the list gives
- Estimated gusts up to 65 knots and many trees on wires and roads. No row says wind lifted a roof.
- What it becomes
- The model building code asks that fully adhered or mechanically attached single-ply systems be tested to FM 4474, UL 580 or UL 1897. Ask which one applies to the proposed system and have it written into the scope.
- What we cannot say
- How a gust estimated at a roadside becomes force at a roof edge. That is design work, not a database field.
Hail
- What the list gives
- Five size reports and no damage description.
- What it becomes
- For low-slope coverings the code names impact test methods (ASTM D3746, ASTM D4272 or the foot-traffic test in FM 4470). It prints no hail size. Our reading: get any hail claim in writing, with the test named.
- What we cannot say
- Whether any of the five reports left a mark on a roof. None says so.
Trees, debris and drains
- What the list gives
- Trees in nearly every wind narrative.
- What it becomes
- A single-ply trade association says low-slope roofs should be inspected at least twice a year and after any major storm, with debris removed and drains kept open.
- What we cannot say
- Where leaves and limbs would collect on your roof. That depends on your trees and your drains.
A 2024 trade bulletin, two Phoenix roofs, and its own limit
The Western States Roofing Contractors Association reported crazing and cracking on some aged TPO membranes after lab work on two roofs in Phoenix. It adds that the study “is not an assessment of all TPO membranes.” Phoenix is not Great Falls, so we pass it on as a reason to ask for the product data sheet and to keep seams and edges on the inspection list, not as a finding about this town.
For the written scope
Before a TPO section goes on, what should the paperwork name?
- The uplift testFM 4474, UL 580 or UL 1897, whichever the system was tested to.
- The membrane data sheetThe document that names the product, instead of a colour or a nickname.
- Edges and corners in plain wordsHow the sheet is held and finished where wind meets it first.
- Drains and debrisWho clears them, and when, after a storm like the ones above.
- Seam checksHow welds are inspected before the crew leaves.
- The county's answerLand Development Services, 703-222-0801, for your exact scope.
The county's permit list names shingle replacement as work without a building permit and roof repairs as work with one; commercial covering under 100 square feet is exempt. No membrane appears on either list.
Questions
Reading the NOAA list for a TPO roof
Does the database say storms damaged Great Falls roofs?
Not in the 48 rows we read. The narratives talk about trees, power lines, hail sizes and flooded roads. That describes the text, not proof that no roof was hit.
Why say “under the name Great Falls” and not “in Great Falls”?
NOAA's field names the town from which a distance is measured. Where a distance is given it reaches 4.11 miles, so a row can sit outside the community.
Is that five hail reports a hail rate?
No. It is five entries on four dates between 1997 and 2019. A list of reports is not a frequency, and we draw no forecast from it.
What does a 65-knot gust mean for a roof?
NOAA records wind in knots and marks this one as an estimate from a storm survey. The row describes trees and poles, not forces on any roof.
Does the county name TPO anywhere?
The permit pages we read name no membrane. Ask Land Development Services about your scope.
Who should look at a flat section after a storm?
The single-ply association's maintenance advice is to consult the contractor that installed the roof or a Registered Roof Consultant if questions arise.
Nearby pages: the Great Falls hub, EPDM roofs in Great Falls, PVC roofs in Great Falls, metal roofs in Great Falls, TPO roofs in McLean and TPO roofs in Reston. General reading: TPO roofing in Northern Virginia and the flat roof guide.
Sources used
Checked 2026-10-16: NOAA NCEI Storm Events bulk files with the bulk file format guide; Fairfax County, when a permit is required; SPRI frequently asked questions; the WSRCA TPO bulletin, 2024. Test names from the 2021 International Building Code, Chapter 15, opened 2026-10-11.
Talk through the next step
Bring the flat section and the street
Tell us the street, what the flat part sits on, and which trees lean over it.
9220 Topaz St, Fairfax, VA 22031
Mon to Fri 7 AM to 8:30 PM, Sat 7 AM to 8 PM, closed Sunday