Treated wood, composite or durable lumber for a deck, and what to do about an old CCA deck

Updated November 10, 2026 · KeystoneProGuide editorial team

Which materials can a deck be built from?

Under the building code Pennsylvania adopts, a wood-framed deck's structure must be No. 2 grade or better lumber that is either preservative-treated to the code's standard or an approved, naturally durable species, and protected against termites where the code requires it. Deck boards, stair treads, guards and handrails can also be plastic composite, if they meet the ASTM D7032 standard and are labelled. The code allows other materials, such as glass and metal, as alternates, and decks of materials it does not prescribe must be designed under its general structural rules.

Note what the composite standard covers: boards, treads, guards and handrails. The code's composite rules do not cover the posts, beams and joists, which fall under the lumber rules.

What should you look for on treated lumber?

Its label, and where it is used. The code says all preservative-treated wood in contact with the ground must be labelled for that use, so lumber sold for above-ground use should not be buried or set in soil. Where treated members are cut, notched or drilled, the cut surfaces must be treated as well. The ledger that attaches the deck to the house must be pressure-treated Southern pine, incised treated hem-fir, or an approved naturally durable species.

The fasteners matter as much as the wood. Nails, bolts, lag screws and metal connectors on a deck must meet the code's corrosion table, which calls for hot-dipped galvanized coatings to set classes or alternatives such as stainless steel, silicon bronze or copper, and ledger fasteners must be hot-dipped galvanized or stainless. Ask what the fasteners are, as well as what the wood is.

What does the composite label mean?

That the board has been tested to ASTM D7032, the standard the code cites for plastic composite deck boards, stair treads, guards and handrails. The code requires the boards, or their packaging, to bear a label showing compliance. Composite guards are also covered by the code's guard section, which sets the same 36-inch height and 4-inch opening limits as for wood, and sends exterior plastic composite guards to a further section of the code on composites.

What does each cost?

The national cost surveys give materials and labor separately. HomeAdvisor lists pressure-treated wood at $2 to $5 per square foot for materials, against $12 to $22 for premium composites or fiberglass, with labor at $15 to $35 per square foot either way. Fixr's $14,000 average assumes a 320-square-foot composite deck with railings, and its low figure of $1,500 is for a 100-square-foot deck of pressure-treated pine. Fixr's deck page was last updated in January 2023; HomeAdvisor's in June 2026. Neither publishes a Pennsylvania figure.

What about an older deck built before 2004?

It may be built from wood treated with chromated arsenicals, CCA among them. The EPA says such wood was used in residential decks and playsets until manufacturers stopped making it for homeowner uses in December 2003. Its position on these decks is measured:

• The EPA does not require existing CCA structures, or the soil around them, to be removed.
• It did not find health risks of concern for the general public; the risks of concern it identified were for workers in wood treatment plants.
• For an older deck, it says applying a penetrating protective coating, such as an oil- or water-based stain, on a regular basis may reduce the leaching of chemicals.

If you are replacing an old deck, the EPA's handling advice applies. Wear goggles and a dust mask when sawing CCA-treated wood, wash your hands after handling it, and do not burn it, or any other treated wood, at home, because of the smoke and ash. Households can usually dispose of it with ordinary trash, but state and local governments may have their own instructions, and it should not be reused as mulch. Ask your contractor how the old deck will be cut up and disposed of, and include that in the contract.

What are the alternatives the EPA lists?

For new work, the EPA names wood treated with other EPA-approved preservatives, wood-alternative and composite materials, and species of wood that resist pests. That list lines up with the code's three routes: treated lumber, naturally durable lumber, and labelled composite.

How do materials affect upkeep and inspection?

The deck trade association's consumer checklist asks owners to look for decaying materials and corroding fasteners, among other things, which applies to wood and composite decks alike; it says the checklist does not replace a professional inspection. Whatever the boards are made of, the checklist's points about fasteners and decay apply to the framing underneath.

Does the material change the permit?

No. The permit line is set by the deck's height and whether it is covered: an uncovered deck whose floor is no more than 30 inches above grade needs no permit under the state regulation, whatever it is made of, unless a local ordinance says otherwise. The structural rules in is your deck safe apply to every material. Prices in context are in the cost guide, and builders are listed on the exterior remodeling directory page.

Sources

1. Chapter 5 Floors, 2021 International Residential Code, International Code Council
2. Chapter 3 Building Planning, 2021 International Residential Code, International Code Council
3. Chromated Arsenicals (CCA), U.S. Environmental Protection Agency
4. How Much Does It Cost to Build a Deck in 2025?, HomeAdvisor
5. How much does it cost to build a deck?, Fixr
6. NADRA.org Urges Homeowners to Prioritize Deck Safety with Check Your Deck Campaign, North American Deck and Railing Association (NADRA)
7. 34 Pa. Code 403.62. Permit requirements and exemptions., Commonwealth of Pennsylvania (Pennsylvania Code)