Pressure-Treated Pine or Composite? What Actually Decides It in Peachtree City

The pine-versus-composite argument is usually had at the wrong level. People compare a sample board in a showroom, look at the price difference, and decide on feel. The variables that actually determine which material outperforms the other on a given Fayette County lot are exposure, frame condition, joist spacing, and an honest answer about how much of your own time you are willing to spend maintaining a horizontal wood surface in a climate that gives it 50.43 inches of rain a year across 115 days, 44 days at 90 degrees or hotter, and an annual average morning relative humidity of 81 percent.

This page works through the technical differences that matter here, in the order they matter. It also covers the part almost nobody accounts for in Peachtree City specifically: the tree permit and HOA architectural review that sit in front of the build, and what they do to a schedule. Nothing on this page is a sales argument for the more expensive material. Pressure-treated southern yellow pine is an excellent deck material in Georgia when it is specified and maintained correctly, and it is the right answer on a large share of the decks we build.

What this climate actually does to a deck surface

The published record for the Atlanta area, which is the nearest long-run station to Peachtree City, describes conditions that are harder on horizontal wood than most people assume. Normal annual precipitation is 50.43 inches, spread across 115 days a year with measurable rain. There are 44 days at a maximum of 90 degrees or higher and a July normal daily maximum of 90.1. Average relative humidity runs 81 percent in the morning and 55 percent in the afternoon across the year. That combination - wet, then hot, then wet again, repeated all summer - is the specific stressor. Wood swells and shrinks with each cycle, and it is the dimensional movement rather than the water alone that opens checks in the surface and works fasteners loose.

Ultraviolet exposure is the second half. UV breaks down lignin at the wood surface, which is the actual mechanism behind that silver-gray color on an unfinished deck. The gray layer is degraded wood fiber a fraction of a millimeter deep, and it is why an unprotected board feels furry and takes stain unevenly. It also explains why the sunny half of a deck loses its finish long before the shaded half. In a city with as much mature canopy as Peachtree City, two decks on the same street can be on completely different maintenance schedules purely because of what is growing over them. Any general rule about how often to refinish is really a rule about exposure.

What the stamp on pressure-treated pine actually tells you

Pressure-treated lumber is not one product. The end tag carries an AWPA use category, and that category is the specification that matters. For deck components, UC3B is the minimum for above-ground exterior use with uncoated, poor water runoff - deck boards, joists and beams that stay above ground, and railing. UC4A is the minimum for ground contact, which covers structural posts and any joist or beam that will be in contact with the ground. Using a UC3B post in the dirt is the single most common material specification error in residential deck work, and it fails from the bottom up over about a decade. Modern treatments are typically micronized copper azole or alkaline copper quat rather than the CCA that older decks were built with, which changed the chemistry but not the use-category logic.

Two practical consequences follow from the treatment. The first is fasteners: copper-based preservatives are corrosive to ordinary steel, so hardware and fasteners in contact with treated lumber have to be hot-dip galvanized to the appropriate standard or stainless, and joist hangers have to carry a matching coating. Mixing an ungalvanized screw into a treated joist is a joint that will fail at the fastener long before the wood gives up. The second is moisture: most treated southern yellow pine arrives saturated from the treatment cylinder and has to dry down before it will accept a penetrating finish. Georgia's own deck details are written for southern pine No. 2 under wet service conditions, at 40 pounds per square foot live load and 10 pounds dead. Cut ends have to be field-treated with an approved preservative, because the cut exposes untreated heartwood the cylinder never reached.

What composite is now, and where it still fails

Modern composite decking is a wood-flour and polymer core with a hard polymer cap on the surface and, in better products, all four sides. The uncapped boards that gave composite a bad reputation fifteen years ago are largely gone from the market, and the reason matters: the failure was not the polymer, it was the exposed wood flour in the core taking on moisture and feeding surface mildew. A four-sided cap solves that. A three-sided cap leaves the bottom edge open, which is a real distinction on a deck sitting close to damp Piedmont clay and largely irrelevant on a second-story deck with airflow underneath. Cellular PVC removes the wood content entirely, runs cooler, weighs less, and costs more.

Where composite still needs respect is heat and movement. A dark board in direct sun on one of Atlanta's 44 annual days over 90 degrees gets meaningfully hotter than a light one, hotter than wood, and hot enough that color selection on a west-facing deck is an engineering decision rather than a decorating one. Composite also moves more with temperature along its length than wood does, which is why every manufacturer publishes end-gap and side-gap tables keyed to the temperature at installation. Cutting to those tables is not a nicety. And mildew is not eliminated, only relocated - what grows on a capped composite deck in a canopy-heavy neighborhood is growing in the pollen and leaf tannin film on the surface, not in the board, and it washes off with soap and water once a year.

The frame is the decision nobody thinks they are making

Whichever surface you choose, it is being carried by a frame, and the frame constrains the choice more than the showroom does. Most capped composite boards want joists at 16 inches on center for a perpendicular layout and 12 inches on center for a 45-degree diagonal, with stair treads generally at 12 inches regardless. Wood decking is more forgiving. A lot of pine decks built in this county in the 1980s and 1990s are framed at 24 inches on center, which means a straight composite re-deck on that frame is not a swap - it is a swap plus sistered joists, and that changes the price per square foot enough to change the decision. Anyone quoting a composite re-deck without measuring joist spacing has not looked.

The connections matter more than the boards. The ledger has to be a minimum nominal 2x8, through-bolted with half-inch bolts and washers into a 2-inch nominal band joist or an LVL rim bearing on a sill plate, and it cannot go onto brick, masonry or stone veneer, a cantilevered floor overhang or open-web trusses. Georgia's 2026 amendment to Section R507.9.1.3 spells out the predrill: a half-inch hole through the ledger and sheathing, and a five-sixteenths to three-eighths hole through the band joist. Above it, continuous flashing with a drip edge in copper set with copper nails, stainless, galvanized steel or UV-resistant plastic. Footings bear at least 12 inches below grade, and any footing within five feet of the house foundation has to bear at the same elevation as that foundation. Get those right and either surface lasts. Get them wrong and the surface is irrelevant.

What the tree permit and your HOA do to the schedule

In Peachtree City the paperwork is a real part of the project timeline, and it runs in front of the build rather than alongside it. The city requires a removal permit for understory trees 8 inches DBH or greater and canopy trees 18 inches or greater. Specimen thresholds are stricter - hardwoods at 20 inches, softwoods and sweetgums at 24 - and a specimen tree can only be removed if it is dead, dying or diseased, an immediate hazard to safety or property, located in a construction area approved by a building permit, or the owner contributes $20 per caliper inch DBH to the city's Tree Fund. Every lot must retain at least two trees. Pruning, limbing and raising need no permit as long as the tree survives it, and trees in city greenbelts and environmental protection areas cannot be removed at all. The application wants a tree list with species and measurements, a property schematic, photographs of each tree with the measurement visible, and HOA authorization where applicable.

The design approval, by contrast, usually is not a city matter at all. Peachtree City's Architectural Standards review, conducted by the Planning Commission, applies within 500 feet of a major thoroughfare and covers exterior modifications down to repainting and re-roofing - but single-family properties are exempt from it. What governs the look of a residential deck here is the village or neighborhood HOA architectural committee, and those meet on their own calendars, which is where projects lose weeks. Sequence it properly and none of this is painful: HOA packet and tree permit first, city building permit second, which Peachtree City reviews in three to five business days for residential work, then build. Sequence it backwards and a two-week deck becomes a two-month deck without a single extra board being cut.