Deck Framing Options Compared
The boards are what you see, but the framing underneath decides how long a deck lasts. Here is how the four common framing materials compare.
Why the frame matters
Most decks are framed with pressure-treated lumber, even when the deck boards are a long-life composite. A treated-lumber frame can wear out long before the deck boards on top of it, especially in wet spots and humid climates where water is not kept off the joists. When the frame goes, the boards come off with it.
The four options
| Material | Moisture & rot | Corrosion | Working it |
|---|---|---|---|
| Pressure-treated lumber | Absorbs water; can warp, split and rot over time | Treatment chemicals call for corrosion-rated fasteners | Familiar tools and methods |
| Steel | Does not rot | Protective coating; cut ends and holes need touch-up | Metal-cutting tools and system-specific brackets |
| Aluminum | Does not rot | Can corrode near saltwater and where it touches other metals | Metal-cutting tools and system-specific parts |
| VORO structural composite | No wood fiber; 0.6% max water absorption in 24 hours | No steel in the member to rust | Cut and handled with common job-site tools |
Where VORO fits
VORO is a structural composite framing system: joists, beams and posts made from fiberglass composite. It is aimed at builders who want a frame that keeps up with long-life deck boards, such as composite, PVC and other high-end boards.
- Moisture: 0.6% maximum water absorption in 24 hours in manufacturer testing.
- Fire: flame spread index 25 maximum (Class A), self-extinguishing per ASTM D-635, UL 94 V-0.
- Weight: density of 0.07 lb per cubic inch.
- Sizes: 2x4, 2x6, 2x8, 2x10 and 2x12 profiles, plus 4x4 and 6x6. See the technical specs.
- Spans: joist, beam and post tables are on the VORO span tables page.
Choosing
Every option has a place. Treated lumber has the lowest upfront cost. Metal framing is strong but expensive, and it corrodes. Structural composite sits between them: built for long life, worked much like wood. Compare the total cost over the life of the deck, not just the price of the material, and check what your local code and building official accept for your project.
More guides: Fiberglass Deck Joists, Explained · Deck Framing for Coastal & Humid Climates · Become a VORO Dealer · VORO Installation Basics
This guide is general information, not engineering advice or a warranty. Product values are typical results from manufacturer testing. Structural work should be designed or reviewed by a licensed professional and must meet local building codes.