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PVC roofing in Oakton, VA: the storm record, the county design values and what a PVC sheet is made of
NOAA files 17 storm rows under the label Oakton, and none of their narratives mentions a roof. This page counts those rows by month and by what they describe, sets them beside the wind and snow values Fairfax County prints, then turns to the material: the PVC sheet standard says the sheet must be reinforced, and a federal guide specification explains how reinforced, fleece-backed and felt-backed sheets and thickness figures are written. Where a source is silent, the page says so.
- 17 NOAA rows labelled Oakton, 2016 to 2026: 9 wind, 5 flood, 2 hail, 1 flash flood
- Fairfax County lists 115 mph ultimate wind speed for residential
- ASTM D4434 scope: the sheet shall contain reinforcing fibers or fabrics
The 17 rows, counted by month
The NOAA Storm Events Database files its rows by a place label typed by a forecast office. Filtering the Virginia detail files for 2016 through June 2026 to the Fairfax County zone and the begin location Oakton returns 17 rows. The table splits them by the month they began.
| Event type | Feb | May | Jun | Jul | Aug | Nov | Total |
|---|---|---|---|---|---|---|---|
| Thunderstorm wind | 1 | 3 | 0 | 2 | 2 | 1 | 9 |
| Flood | 0 | 1 | 1 | 0 | 3 | 0 | 5 |
| Hail | 0 | 1 | 0 | 0 | 1 | 0 | 2 |
| Flash flood | 0 | 0 | 1 | 0 | 0 | 0 | 1 |
| All rows | 1 | 5 | 2 | 2 | 6 | 1 | 17 |
Source: NOAA NCEI Storm Events Database, Virginia detail files for 2016 to 2026 (file versions dated March to September 2026), county zone Fairfax, begin location Oakton, counted October 24, 2026. The nine wind rows fall on seven distinct dates, three of them on May 23, 2019. Months with no row are left out.
May and August hold 11 of the 17 rows. No row begins in January, March, April, September, October or December, which says only that NOAA filed none under this label in these files.
What the narratives name
Cutting the same 17 rows by what the text says gives a different picture from the type column. Every one of the nine wind narratives names fallen trees or branches. On May 23, 2019 a row reports trees snapped off behind a residence, and a row for August 11, 2021 has a tree coming down onto a car.
Of the six water rows, five name roads: a lane on Pickett Road, Route 50 at VA-123, Fairfax Boulevard near Oak Street, Hunter Mill Road and Chain Bridge Road. The sixth, from May 31, 2018, reports several inches of water on the first floor of an apartment building.
The row for July 2, 2019 is filed under Oakton but describes the Old Lee Hills and Country Club Hills neighborhoods in the City of Fairfax. The flood row for Route 50 at VA-123 on August 15, 2019 says the road is in the city of Fairfax. A label is a pointer, not a boundary.
County design values beside the gusts
Fairfax County Land Development Services prints a Local Design Load Criteria table on its Codes and Standards page. Oakton has no municipal government, so this is the county table and not a town one.
NOAA records wind in knots and marks these nine rows as estimated gusts. The 70 knot row converts to about 81 mph. The county figure is a design speed for a risk category, not a measured gust, so this page does not subtract one from the other. The county also notes that its 25 psf snow figure holds only if the design team uses the 2021 Virginia code figures and ASCE 7-16.
For a PVC roof the numbers matter in two places. The code requires adhered or mechanically attached single-ply systems to be tested to FM 4474, UL 580 or UL 1897, and the federal guide specification asks for FM-tested uplift ratings backed by engineer-sealed calculations if the system is not rated. It explains that an FM 1-90 rating correlates to a maximum calculated uplift of 45 psf, because the rating includes a factor of 2. Ask who calculated the load.
Reinforced, fleece-backed, felt-backed: three different layers
The federal Unified Facilities Guide Specification 07 54 19, issued August 2023 for reinforced PVC roofing, separates three terms that a quote can blur. It is written for federal designers, so it is a reference for questions and not a Virginia rule.
Reinforced
Fibers or scrim inside the sheet. The guide says adhered and mechanically fastened PVC systems must use reinforced membrane, always, and allows an exception only for prefabricated detail flashings supplied by the system manufacturer.
Fleece-backed
A fabric layer on the underside, allowed in certain adhered applications where the adhesive is an applied compound or spray foam, or over lightweight cellular insulating concrete. The thickness it names does not include the fleece.
Felt-backed
A different backing, called for where the sheet would otherwise lie directly on concrete or another hard surface that may damage it. The guide says not to place non-felt-backed sheet on concrete.
Cold and green roofs
A designer note requires reinforced membrane on vegetative roofs and in cold climate locations.
A quote that says only PVC has not told you which of these applies to the deck sheet, which to the flashings, and what the roof deck is. The guide names a concrete deck and a lightweight insulating concrete deck in different backing conditions, so the deck is part of the answer.
What the PVC sheet standard covers
ASTM D4434 is the sheet standard that both the residential and the commercial Virginia code texts name for PVC. The live ASTM page refused an automated request and was not bypassed, so this page uses an archived copy of the 2015 edition dated June 5, 2023. The current edition was not opened.
"The sheet shall contain reinforcing fibers or reinforcing fabrics."
ASTM D4434/D4434M-15, scope 1.1 (archived copy of the ASTM page)That sentence is the PVC-specific point. Its scope covers only reinforced sheet. The abstract lists what the sheet is tested for:
- Thickness. Overall thickness, and thickness over the scrim, are separate measurements.
- Strength. Tensile strength at break, breaking strength and elongation at break.
- Seams and tearing. Seam strength, tear resistance and tearing strength.
- Aging. Heat aging, low temperature bend, and cracking and crazing after accelerated weathering.
- Movement and water. Linear dimensional change and change in weight after immersion in water.
- Puncture. Static and dynamic puncture resistance.
Section 1.2 puts fire resistance, material compatibility, wind uplift resistance and in-situ shrinkage "beyond the scope". A sheet that meets D4434 is therefore not a wind rating for the roof. The commercial code text adds a link to wind: low-slope coverings that flex with wind must show no significant loss of breaking strength for reinforced membranes after accelerated weathering.
Reading a thickness line
Thickness is the one number on a PVC quote that looks simple. The guide shows why it is not.
General minimum
2.03 mm, or 0.08 inch, reinforced PVC for the sheet. Flashing, penetration flashing and prefabricated pipe seals are listed separately at 1.8 mm, or 0.072 inch.
Heavier sheet
2.4 mm, or 0.096 inch, which the guide says to specify for regular heavy traffic or for regular extreme wind that can carry airborne debris. It may be adhered or mechanically fastened.
- Ask what the figure measures. ASTM D4434 tests overall thickness and thickness over the scrim as separate properties. The figure on a quote should say which.
- Ask whether the backing is counted. The guide states that its minimum is exclusive of the backing on fleece-backed sheet.
- Ask where the label governs. The guide says that notwithstanding the ASTM standards, the labeled minimum thickness it names applies. The product label is the evidence.
- Ask about the flashing line. Flashing has its own figure in the guide. A single number for the whole roof can hide a thinner or prefabricated detail piece.
- Connect it to the weather. The Oakton wind rows name falling trees, and the hail rows give 1.00 and 1.75 inches. The guide ties the heavier sheet to airborne debris and says a glass mat or moisture resistant gypsum board over insulation can improve wind, impact and hail resistance. The commercial code text points to impact tests under ASTM D3746, D4272 or the FM 4470 foot traffic test. None of these sources says a given thickness survives a given hailstone.
Questions before signing a PVC scope
- Is the sheet reinforced, and does the product data sheet say it meets ASTM D4434 and which type?
- Is the sheet fleece-backed or felt-backed, and what deck and adhesive does the manufacturer pair it with?
- Does the thickness figure include or exclude the backing, and is it overall or over the scrim?
- What is the flashing thickness, and which flashings are prefabricated by the manufacturer?
- Which FM, UL or ANSI test label covers the whole assembly, and who calculated the uplift load?
- What does Fairfax County Land Development Services say about the permit class for the area? The permit lists and the historic overlay checks are on the Oakton roofing guide.
- If an association governs the building, has its architectural review approved the work in writing?
Read the general PVC roofing page, the roofing materials, flat roof and commercial roofing overviews and the services list. Book a phone consultation to talk through an Oakton PVC roof, and keep the Oakton hub beside it for permits, overlays and association rules.
Documents and archived copies opened October 24, 2026
- NOAA NCEI Storm Events Database, yearly detail files and the format document.
- Fairfax County Land Development Services, Codes and Standards, local design load criteria.
- UFGS 07 54 19, Polyvinyl-Chloride Roofing, August 2023.
- ASTM D4434/D4434M-15 abstract and scope, archived copy dated June 5, 2023.
- 2021 International Building Code chapter 15, Virginia listing on UpCodes and 2021 Residential Code chapter 9. These are third-party copies of the base model codes and may not show Virginia amendments.
Questions people ask
How many NOAA storm events are labelled Oakton?
Seventeen between 2016 and June 2026 in the Fairfax County files: nine thunderstorm wind rows on seven dates, five flood rows, two hail rows and one flash flood row. The label is a reference point in NOAA data, and one of the wind rows describes neighborhoods in the City of Fairfax.
Do the Oakton storm rows mention roof damage?
No. The word roof appears in none of the 17 event or episode narratives. The wind rows name fallen trees and branches, the water rows name closed roads and one apartment building with water on its first floor, and the hail rows give a size. Absence from a narrative is not proof that no roof was hurt.
What wind speed does Fairfax County print for a residential roof design?
Its Codes and Standards page lists an ultimate wind speed of 115 mph for Risk Category II and residential buildings, 105 mph for Risk Category I and 120 mph for Risk Category III. NOAA records estimated gusts at a point, so the two numbers are not directly comparable. Ask the building official or an engineer how they apply to a roof.
Does ASTM D4434 require PVC roofing sheet to be reinforced?
Its scope says the sheet shall contain reinforcing fibers or reinforcing fabrics. An archived copy of the 2015 edition was read for this page, and the current edition was not opened. The standard also states that wind uplift resistance and fire resistance of the finished roof are beyond its scope.
What does fleece-backed PVC mean?
It is a PVC sheet with a fabric layer on the underside, used where the sheet is adhered with an applied compound or spray foam adhesive or to lightweight cellular insulating concrete, according to a federal guide specification. The same document says the minimum thickness it names does not include the fleece.
Is a thicker PVC sheet required in Oakton?
No document read for this page says so. The federal guide specification names 0.08 inch as its general minimum and 0.096 inch for regular heavy traffic or regular extreme wind with airborne debris. It is written for federal buildings, so use it as a list of questions, not as an Oakton rule.
Does a PVC quote need to say whether thickness includes the backing?
It is worth asking. The guide specification states that its thickness is exclusive of the backing on fleece-backed sheet, and ASTM D4434 tests both overall thickness and thickness over the scrim. A figure with no label leaves open which one is meant.
What should I have ready before a phone consultation about an Oakton PVC roof?
Have the street address, the building type, the slope or drainage of the flat area, any association approval rules and what you can see from the ground. Book a phone consultation to talk through which checks on this page apply to your roof.
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.