Here's what matters: The right lumber and decking for your dock comes down to budget, maintenance, weight, and how you use the dock. Pressure-treated lumber is the affordable workhorse for framing and decking. Marine-grade plastic (like SunWalk) and composite boards cost more up front but cut the upkeep. Cedar and hardwoods sit in the middle providing sturdy solutions but typically are expensive with more required maintenance.
Framing vs. Decking: Two Different Jobs
Framing is the skeleton; outer frame, joists, and stringers. It has to stay strong, square, and straight under wet conditions and foot traffic. Decking is the surface you walk on. It takes the sun, the rain, and the bare feet.
You can mix them. A lot of DIY builds use pressure-treated 2x6 framing with SunWalk or composite decking on top. Our DIY Dock Kits are designed around 2x6 (or 2x8) pressure-treated framing. You buy the lumber and decking locally, or grab SunWalk panels from us.
Framing Lumber Options
1. Pressure-Treated Southern Yellow Pine
This is the default for most freshwater floating docks. Preservatives are forced into the wood so it resists rot and insects. Ground-contact rated stock is what you want for dock frames; it is built for wet, hard-to-replace locations.
Pros:
- Affordable and available at almost every lumber yard and big-box store.
- Strong enough for most residential live load when used as 2x6 or 2x8 at 16" on-center (Needs may vary with decking).
- Easy to cut, drill, and fasten with standard tools.
- What our DIY kits are designed around (Substitutions are acceptable and common but be sure to account for any weight differences).
Cons:
- Moisture content from the yard. Pressure treated lumber isn't what it once was. Weights and quality can vary drastically from batch to batch.
- Can warp or splinter over time if left unfinished.
- Considered aesthetically inferior to cedar or hardwood by many.
Best for: Almost every freshwater DIY kit dock. Start here unless you have a specific reason not to.
Important Note: Not all pressure-treated pine is the same. The difference is how much preservative is in the wood and what conditions it is rated for.
- Standard pressure-treated lumber (often labeled for above-ground or general outdoor use) is fine for fences and dry decks, but it is not the best choice for a dock frame that stays wet and is hard to replace.
- Ground-contact pressure-treated is the everyday option for freshwater docks. It is treated to hold a higher amount of preservative than above-ground stock.
- Marine-grade is the next step up. In real terms, that usually means a heavier treatment (often UC4B or similar) made for continuous wet exposure, saltwater splash, or critical members you do not want to rebuild.
- True saltwater immersion stock (UC5) goes further and is meant for piles and bulkheads in the ocean. It is more than most freshwater floating docks need. The practical rule: for a typical fresh water application, ground-contact pressure-treated pine is the right default. Step up to marine-grade if you are in brackish water, take a lot of spray, or want the extra durability.
2. Cedar (Western Red Cedar)
Cedar is light, works easily, and has natural rot resistance in the heartwood. It is popular for decks and outdoor furniture.
Pros:
- Produces a minor bump to buoyancy efficiency as it is lighter than treated pine.
- Provides a natural look and smell.
- Works with standard tools and does not require special fasteners the way copper-treated wood does.
- Less chemical treatment; sometimes local entities require chemical free lumber for marine applications.
Cons:
- More expensive; typically 2-3X more expensive than Southern Yellow Pine depending on market conditions.
- Softer and weaker than Southern Yellow Pine of the same size.
- Availability can be challenging in some regions. True heartwood grade is not always easy to find.
- Still needs maintenance in marine environments.
Best for: Builders who want a lighter, chemical-free frame and are willing to size up or accept a softer feel underfoot. More common for decking or trim than structural joists on a floating dock.
3. Cypress
Common on Southern waterfronts. Heartwood handles wet/dry cycles well and has a distinctive look.
Pros:
- Good natural durability in wet environments when you get true heartwood
- Local and familiar in the Southern regions.
- Can provide more competitive pricing than Southern Yellow Pine depending on market conditions and regional availability.
Cons:
- Availability and price vary a lot by region.
- Sapwood is not the same product as old heartwood. Confirm with the lumber yard what you are actually buying.
- Heavier than treated pine for approximately the same strength.
Best for: Regional builds where cypress is plentiful and you want a traditional Southern look. Confirm grade and weight before you commit.
4. Hardwoods (White Oak, Ipe, and Others)
White oak has a long history in boats and lock gates. Tropical hardwoods like ipe are more common as decking than as framing.
Pros:
- Premium strength and very dense material.
- Long lifespan wet conditions when the right species is used.
- Regarded very high with appearance and aesthetics.
Cons:
- Heavier than Southern Yellow Pine. Changes the buoyancy math and may require additional floatation.
- Often 2-4x more expensive and often difficult to source.
- Harder installation; some species require unique installation methods.
- Overkill for most residential floating docks.
Best for: Custom or high-end builds where the look and longevity justify the cost and weight. Rarely reasonable for residential dock applications.
Decking Options
1. Pressure-Treated Southern Yellow Pine Decking (5/4" or 2")
The classic walking surface. Usually 5/4x6 treated boards run across the joists.
Pros:
- Lowest upfront cost.
- Easy to cut, replace, and match to any layout.
- Classic wood look that can be stained or left to weather.
- Widely available.
Cons:
- Requires regular maintenance such as sealing or staining to fight splinters, checking, and UV fade
- Can get slick with algae if you do not clean it
- Heavier than plastic panels.
- The boards shrink as they dry. Be sure to plan for a gap.
- Our DIY Dock Kits are designed around this lumber.
Best for: Budget builds and anyone who does not mind annual maintenance.
2. Marine-Grade Plastic Decking (SunWalk and Similar)
Don't be fooled by "Plastic Decking", the open-grid SunWalk 90 Series panels are considered the gold standard for decking in the industry. They offer some of the highest performance metrics and can go head to head with just about any decking option.
Pros:
- No rot, mold, or insect issues.
- Low or zero maintenance.
- Lightweight, producing more bang for your buck on floatation.
- Open-grid versions drain water and stay cooler underfoot.
- Slip-resistant texture even when wet.
- Easy to install on 12" or 16" joist spacing.
- Allows more light to hit the water and promotes healthier environments around the dock system.
Cons:
- Higher upfront cost than treated boards.
- Open-grid look is not for everyone aesthetically.
- Color options are limited compared to composite.
Best for: Anyone who wants the dock ready for bare feet and low maintenance. Especially good on swim platforms and high-use docks.
3. Composite Decking (Trex, TimberTech, and Similar)
Wood fibers mixed with recycled plastic. Designed to look like wood without the yearly sanding and sealing.
Pros:
- Low maintenance with no sealing or staining.
- Won’t splinter or rot.
- Wide range of colors and wood-grain textures.
- Long warranties from major brands.
Cons:
- Higher cost than treated lumber.
- Heavier than plastic panels; can affect freeboard on a floating dock.
- Can get hot in full sun (especially darker colors).
- Drainage can be challenging. Often small puddles will build on the decking.
Best for: Builders who want a natural wood look with less upkeep and are okay with the extra weight and cost.
4. Cedar or Hardwood Decking
Cedar, ipe, and other dense woods used as the walking surface instead of treated pine.
Pros:
- Premium appearance.
- Cedar is lighter and more naturally resistant than untreated pine.
- Ipe and similar hardwoods are extremely durable.
Cons:
- More expensive.
- Still needs oil or sealer if you want to keep the color.
- Hardwoods are heavy and hard on saws.
- Can be slippery when wet unless textured or maintained.
Best for: High-end or custom docks where the look is the priority and the budget covers it.
How to Choose
- Lowest cost, you don’t mind maintenance: Ppressure-treated framing and treated 5/4 decking.
- Least maintenance, cool underfoot, light weight: Pressure-treated framing + SunWalk or other marine plastic panels.
- Wood look, low maintenance: Pressure-treated framing + composite decking. Check the extra weight against your freeboard.
- Premium or regional look: Cedar or hardwood for decking (or framing if you size and weight it correctly). Confirm it with us if you are using a kit so the floats still match.
Whatever you pick, keep the outer frame and joists the same depth so the floats sit flat. Heavier decking or thicker framing means more dead load. See How to Assess Your Total Dock Weight if you are stacking on a lot of extras.
Final Thoughts
Most people end up with pressure-treated pine for the frame and decking. That combination is simple, available, and matches how the kits are built. Plastic, cedar, composite, and hardwood are real options when you want a different look or less maintenance; just account for the weight and the cost before you order floats.
👉 Framing lumber comes from your local yard. Decking can too, or you can use SunWalk panels from The Dock Shop. Browse DIY Dock Kits or contact us if you are mixing materials and want the floatation checked.
