Wood Deck Construction
in Kansas City

Both are decay-resistant, but for different reasons. Pressure-treated lumber is forced full of preservative at the treating plant, so its resistance comes from the chemical and depends on how much of it the wood holds. Cedar resists decay naturally because of extractives that form in the heartwood as the tree grows. That protection is limited to the heartwood. Oregon State University's checklist of natural durability notes that the sapwood of nearly all species has no natural durability, which is why lighter-colored cedar sapwood doesn't hold up the way the darker heartwood does.

Treated lumber is the usual choice for the structure, and it's also the lower-cost decking. Cedar is chosen mostly for the surfaces people see and touch: decking, railings, stair treads and trim. A common build pairs the two, with a treated frame carrying cedar decking and rails.

Local codes accept either, within limits. Overland Park's deck guidelines, for example, require decks to be built from naturally decay-resistant or pressure-treated lumber, No. 2 grade or better, and require treated wood in contact with the ground to be labeled for that use. Both still need cleaning and a penetrating finish. If you'd rather not refinish a deck at all, our composite deck installation page covers that side of the decision.

Treated lumber isn't one product. Every piece carries an end tag that names the preservative, the retention and the American Wood Protection Association (AWPA) use category it was treated for. Two categories matter on a deck. UC3B is for exterior wood above the ground that can dry out between wettings, and UC4A is for ground contact or comparable exposure. AWPA's guide to residential uses assigns them this way:

Deck boards, railings and stair parts

above ground, UC3B or higher

Posts

ground contact, UC4A or higher

Ledger

ground contact, UC4A or higher

Joists and beams

UC3B or higher, but UC4A when they are difficult to maintain, repair or replace and critical to the structure

AWPA's standard also requires ground-contact treatment for lumber that sits physically above the ground but is exposed to similar conditions. That includes framing installed less than six inches above final grade, framing where leaves, soil or other debris can build up against it, and decks built so low or so enclosed that air can't circulate underneath and between the boards. A low deck close to the yard often meets one of those conditions even though nothing touches the dirt.

Joists and beams are the hardest parts to replace once the decking is on, so framing them with ground-contact lumber is a reasonable choice even when the deck sits well above the yard.

Most treated lumber is still wet from the treating process when it's installed, and wet wood won't absorb a stain. The simple test is to sprinkle water on the boards. If the water beads up, the wood isn't ready. If it soaks in, the boards can take a finish.

There are three main types. Clear water-repellent preservatives contain a mildewcide, limit water absorption and are the easiest to reapply. Colored water-repellent preservatives are lightly tinted and still show most of the grain. Semitransparent stains carry more pigment and last longer, and oil-based versions soak into the wood without forming a layer that can peel. The Forest Products Laboratory puts the service life of a clear water-repellent preservative at about a year on exposed deck surfaces, and pigment extends it because it shields the wood and the mildewcide from sunlight. Railings don't take foot traffic, so paint and solid stains can perform well there even though they're a poor choice for the decking. The same guidance notes that most decks are retired because of cracks and checks that timely finishing could mostly have prevented.

Cleaning comes before every recoat. Deck cleaners and brighteners remove mildew and dirt without adding color, and the Forest Products Laboratory warns that aggressive scrubbing with a caustic cleaner or power washing can strip wood from the surface, especially on softer woods like cedar. For mildew, its guidance calls for household bleach diluted with three parts water and a detergent that doesn't contain ammonia, which reacts with bleach to form a toxic gas. The bleach is rinsed off afterward, and the deck needs at least two warm, windy days to dry before a finish goes on.

A deck is due for a new coat when the finish has worn off in the walking paths, the color has faded to gray, mildew keeps returning or water soaks into the boards instead of beading. Leaves and debris should be cleared regularly, since they hold moisture against the wood and promote mildew.

The North American Deck and Railing Association's Deck Safety Month checklist describes what a yearly inspection covers:

Decay

probe the ledger, posts, joists, boards, railings and stairs with a screwdriver or ice pick. If it sinks in easily, the wood breaks off in a short piece without splinters, or the wood feels soft and spongy, decay may be present.

Flashing

confirm the flashing where the deck meets the house is sound and directing water away from the ledger.

Fasteners

tighten loose fasteners, reset popped nails and replace rusted or corroded fasteners, especially at the ledger.

Railings and stairs

check that railings and handrails are firmly attached and that stringers and risers are secure and not decayed.

Movement

the deck and stairs should look even, without sagging, and shouldn't sway when tested.

Decay showing up in one board or one post is usually a deck repair. Worn-out boards on a frame that passes these checks can be replaced through deck resurfacing.

Two decks of the same size can be priced very differently, because much of the cost is in material and hardware choices a wood deck builder makes below the surface. The main cost factors are:

Species

cedar decking and rails cost more than treated lumber, and many builds mix the two

Lumber ratings

how much of the frame is built from ground-contact lumber, which depends on the deck's height and site

Hardware

stainless steel fasteners and connectors cost more than galvanized ones, and cedar usually calls for stainless

Size, height and shape

taller and larger decks need more posts, footings, framing and stair work

Railings and stairs

the railing style, the length of rail and the number of stair runs

Finishing

whether the first finish is part of the project or applied later, once the lumber has dried

Where a city requires a permit, its fees and inspections are part of the project too. Detailed railing options are covered on our railing installation page.