What Materials Are Needed to Build a Deck?

Ask ten people what a deck is made of and ten will name the boards. That answer covers about a fifth of the bill. Deck building materials run from the concrete in the ground to the guardrail at the edge, and the ones that decide how long the structure lasts are almost all invisible in the finished deck.

What follows is a working list rather than a catalog. It covers the materials for building a deck layer by layer, what each one does, and where the choice matters. Decks & Balcony builds and rebuilds decks across Northern California, and the pattern holds on backyard structures and apartment communities alike. The budget goes to the surface. The failures start underneath.

A Deck Building Materials List, From the Ground Up

Every structure draws on the same short list of materials for building a deck, whether it is a ground-level platform or a third-floor walkway. The order matters. Each layer protects the one below it.

1. Concrete footings or piers, sized for the soil and the load above them.
2. Metal post bases that hold timber clear of the concrete instead of letting it sit in standing water.
3. Posts and beams in pressure-treated lumber, rated for ground contact wherever they meet soil or concrete.
4. A ledger board and its flashing, where the deck attaches to the building.
5. Joists, rim joists, and blocking, with tape or flashing over every joist top.
6. Connectors and fasteners: hangers, hold-downs, bolts, and screws rated for treated lumber.
7. The decking surface, in wood, composite, PVC, or thermally modified timber.
8. Guardrails, stair stringers, treads, and graspable handrails.
9. Waterproofing and drainage, wherever the deck covers something below it.

Nine lines, and one of them is where almost every project conversation starts. Building materials for decks get compared on the surface, because the surface is the part anyone can photograph. It is also the cheapest layer to replace later, which is the reverse of how most budgets get built. The list is the same on every deck we build, and a backyard build and a forty-unit walkway draw from it identically.

The Half You Stop Seeing

The most consequential material for building a deck is metal. A deck is held together by hardware nobody will look at again once the boards are down. That hardware has to match the wood it sits in. Preservative-treated lumber corrodes plain steel, so screws, nails, bolts, washers, and connectors need to be hot-dipped galvanized, stainless steel, silicon bronze, or copper. Within reach of coastal air, stainless stops being an upgrade and becomes the specification.

Treatment level is the second invisible decision. Lumber is the one item among building materials for decks that comes in retention grades. Anything meeting soil or concrete needs a ground-contact grade, and joists and beams above grade use a lighter one. Get that backward and nothing looks wrong for six or seven years. Then a post base gets pulled during an inspection and the bottom of the post is gone.

Connectors are the other half of that decision. Joist hangers get sized to the joist they carry, not to whatever the truck had on it. Post caps, bases, and lateral hold-down devices go where the drawings call for them. Mixing metals across a connection is worth avoiding, since dissimilar metals corrode faster in a wet assembly.

Flashing and joist tape finish the invisible list. Water coming off the boards has to leave the ledger and the joist tops, because sitting there is what rots a frame. Flashing at the building and tape across the framing are what prevent it. The materials needed to build a deck that reaches thirty years are, by cost, close to trivial. Tape, flashing, metal post bases, rated hardware. All four are cheap on installation day and expensive later, because adding them means taking the structure apart.

Wood Deck Building Materials

Framing is wood on nearly every deck, and the material to build a deck frame is nearly always pressure-treated. In California that usually means hem-fir or Douglas fir, incised with rows of small slits because both species resist preservative on their own. Surfaces are where the species question opens up. Pressure-treated boards sit at the budget end, and redwood and cedar heartwood bring natural decay resistance and color. Dense hardwood handles traffic. Thermally modified timber suits owners who want wood that moves less. All of them weather, and all go gray if nothing is put back on them.

There is no single best material for building a deck, only one that suits the exposure, the traffic, and the maintenance program that will actually happen. Wood surfaces carry a real recurring cost: strip, sand, and re-stain on a cycle, plus board repairs as checks and splits open. Cedar and redwood also stain around the wrong fasteners, one more argument for stainless.

California weather makes that cycle harder than the brochures suggest. Winter rain soaks the boards, and summer sun bleaches and cracks the finish. Coastal fog keeps the framing damp long after the surface dries. A wood deck build is often the right answer. It works where somebody owns the refinishing schedule.

Composite Deck Building Materials and PVC

Composite deck building materials are wood flour bound in polymer, usually with a capped outer layer for stain and fade resistance. PVC is fully synthetic, with no wood content. Both remove the sanding and staining cycle permanently. On a property refinishing decks every few seasons, that is the entire point. Neither one changes the structure below. Neither one exempts a deck from SB 721 or SB 326, because the joists, beams, and ledger under that surface are still wood.

Two installation rules decide whether the surface performs. Knowing how to build a deck with composite materials starts with span. Composite is less stiff in bending than the wood it replaces, so it needs closer joist spacing. Sixteen inches on center is common for perpendicular boards, and diagonal layouts need closer again.

Composite also moves with temperature, so end gaps and butt gaps get set for the temperature on installation day rather than by eye. Choosing Trex as a deck building material, or any composite line, means building a composite deck frame-first. A frame laid out for wood flexes the boards until they crack, and the warranty goes too.

One line is missing from that table on purpose: fire. Inside a mapped fire hazard severity zone the surface has to meet ignition-resistance standards, which rules out plain lumber and narrows the composite deck building materials that qualify. That check happens at plan review, so it belongs in the material decision.

Railings, Stairs, and Anything Over Occupied Space

Guardrails are their own material category. The deck building material options there run from timber and powder-coated aluminum to steel, cable, and glass, and each brings its own posts, infill, and hardware. On commercial and multifamily property the guard reaches 42 inches, with openings that reject a 4-inch sphere. Composite pickets and rails are permitted for guard components meeting ASTM D7032, up to that same 42-inch limit. Older railings fail inspections on height and baluster spacing more often than on rot. The post connection at the rim joist matters as much as the infill. That connection is what has to resist a 200-pound load applied at the top rail.

Stairs consume more material per foot than any other part of a deck. Stringers, treads, risers, closed sides, and a graspable handrail all get counted separately. Treads are normally matched to the decking so the run does not read as an afterthought. Traction deserves thought on composite and hardwood treads, because a shaded stair in a wet winter is where people slip.

The materials to build a deck over parking, storage, or a unit belong to a different category. At that point the deck is a roof. The assembly needs a sloped substrate, a membrane or coating, edge metal, and sealed penetrations. The water also needs somewhere to go. Deck waterproofing systems carry manufacturer warranties in the ten to twenty-five year range. They hold only when the details around them are built to the same standard.

Construction type can settle the framing material before anyone picks a board. Type I and II buildings are noncombustible by classification, and their decks and exterior stairs are held to that standard. Fire-retardant-treated wood is permitted at three stories or less. That is where alternative deck building materials reach the drawings, usually steel framing under the walking surface instead of treated lumber. Worth asking early: it changes the entire material schedule.

Choosing Between the Options

A useful deck building materials comparison does not start with looks, or even with price. It starts with who maintains the deck, on what schedule, and out of whose budget. A cedar surface at a self-managed HOA with no reserve line for refinishing is one proposition. The same boards at a house where the owner enjoys the work are another. Where an annual maintenance plan exists, wood stays viable far longer.

Past that, the deck building material options narrow fast once a few questions get answered:

• Exposure: coastal salt air, Central Valley heat and UV, or shade that stays damp all winter.
• Traffic: an amenity deck, a shared walkway, or a balcony used by one household.
• What sits below the structure, since anything over occupied space needs a waterproofed assembly.
• Compliance obligations, including SB 721 or SB 326 cycles and the 42-inch guardrail standard.
• Fire zone limits on surface material, where the parcel is mapped.
• How a board gets replaced later, which is where hidden fasteners and face screws differ most.
• Consistency across a portfolio, since matched material makes the next repair simpler.

Cost belongs at the end of that list rather than the start. The material cost to build a deck per sq ft is the figure everyone asks for first. It is also the least comparable number here, because published rates cover boards and labor. They leave out re-joisting a frame, joist protection, ledger repair, railings, and stairs. On a rebuild those are frequently the larger half. Compare quotes on scope.

Get a Material Schedule Tied to Your Structure

The honest version of this conversation happens on site, with somebody probing the framing instead of pointing at a sample board. We will tell you the best materials to build a deck on your property. That holds even when the answer is the cheaper one, which on a sound frame is often a new surface rather than a rebuild. It costs us margin regularly, and it is why managers call D&B back.

An on-site assessment gets you a written scope and a deck building material list for your structure. Framing, hardware, protection, surface, railings, stairs, and waterproofing where the structure needs it. Request a free on-site assessment and a licensed contractor follows up the same business day. The quote is itemized, with no obligation.