Where Oregon R327 is adopted, a small deck of nominal 2-inch lumber can skip the R327.3.5 walking-surface menu. The exception is walking surfaces of decks, porches, and balconies not greater than 200 square feet where the surface is that lumber (amendment PDF). It is not an underfloor skip. It is not a wall skip. It is not a composite-brand pass.
You are measuring the deck boards and the area. Two inches nominal, two hundred square feet or less. The inspector will measure both.
DET-004’s height bands live on the 12-foot rule and on decking. This page is only the lumber exception. Do not write the 30-inch to 12-foot band onto R327.3.4.4.
Why it matters
Builders hear “2x is allowed.” The sentence has an area cap. A 400 square foot 2x deck in the walking-surface band is still in the R327.3.5 menu. Embers still sit in the board gaps and at the ledger. See deck ledger and the wall.
How the exception sits
Object
Does 200 sq ft / 2x lumber finish it?
Walking surface in the 30-inch to 12-foot band
Yes, if both limits are true
Walking surface 12 feet or more up
R327.3.5 does not use that band. Confirm with the official
Underfloor
No. Enclose to grade or protect. No 12-foot out
Stairs
County FAQ. BCD exemption. Not this exception
Wall covering at the ledger
No
Composite “2x look”
The exception names lumber
The paths
1. Use the exception. Nominal 2-inch lumber. Area not greater than 200 square feet. Write both numbers on the drawing.
2. Stay on the menu.ASTM E2632, ignition-resistant, exterior FRT, noncombustible, or the E2632 paths that also need the wall covering to be noncombustible or ignition-resistant. See decking.
3. Still do the underside. R327.3.4.4. Mesh, if used, is vertical to grade. See the under-deck mesh finding.
4. Trex is not this exception. Presenters said Trex does not meet testing requirements. See the Trex finding.
What people mix up
2x of any area.
Using the exception as an underside pass.
Composite stock as lumber.
Stairs as walking surface.
How to check
Measure area. Two hundred square feet or less, or you are on the menu.
Confirm nominal 2-inch lumber, not a look-alike.
Look under the deck. Enclose or protect.
Put the exception sentence on the drawings if you use it.
Limits
This page does not spec species or fasteners. FireApproved is not the AHJ. Seminar slides are event testimony.
No. The exception is walking surfaces not greater than 200 square feet where the surface is constructed of nominal 2-inch lumber. Larger walking surfaces in the 30-inch to 12-foot band follow the R327.3.5 menu.
Does the exception cover the underside?
No. R327.3.4.4 still requires enclose-to-grade or a protected underside. There is no 12-foot out on that section. Stairs are a BCD exemption in the county FAQ, not this exception.
Does composite 2x-looking stock qualify?
The exception names nominal 2-inch lumber. Presenters said Trex does not meet the testing requirements. That is event testimony about the menu, not a rewrite of the lumber exception. See the Trex finding.