CVS Decks & Docks has issued guidance on lumber treatment categories for freshwater dock construction, following a season in which record low lake levels across Central Florida exposed piling and framing that normally sits underwater.
The company reports that property owners planning waterfront work frequently ask for marine grade lumber on freshwater lakes. The request is based on a reasonable assumption that turns out not to match how treatment standards are actually written.
The American Wood Protection Association maintains a Use Category system, codified in AWPA Standard U1, that classifies treated wood by exposure environment. The marine categories, UC5A through UC5C, are defined for construction in or near salt and brackish water. The hazards those categories address are marine borers, salt kill and tidal action.
None of those conditions exist on a freshwater lake. Ground contact and freshwater exposure fall under Use Category 4, and the distinctions within that category are where the specification decision is made.
UC4A covers general ground contact and includes fence posts, deck posts, joists and beams. UC4B is defined as heavy duty and covers permanent wood foundations, piers and docks. UC4C is defined as extreme duty and covers freshwater pilings and foundation pilings.
A single lake dock can therefore involve more than one category across its own structure. The piling carries the most demanding exposure of any component and is the element most often specified downward.
"People hear marine grade and assume it is the highest standard available, so it must be the safest choice," said Camille Asmar, Co-owner of CVS Decks & Docks. "On a lake it is answering a question nobody asked. The specification that matters is the one covering the part of the structure that goes into the water and stays there."
Fastener selection follows from the same standard rather than being decided separately. Copper based preservative systems used in the higher use categories are corrosive to certain metals. Hot dip galvanized hardware manufactured to the applicable ASTM specifications, or stainless steel in more severe categories, is used in treated wood construction for that reason. Aluminum in direct contact with copper treated lumber is a documented incompatibility.
Treatment retention is the second variable. Retention describes how much preservative remains in the wood after pressure treatment, and the AWPA standards set different minimum retentions for each use category. Two boards can carry the same species and the same dimensions while being treated to different retentions for different service lives.
The AWPA publishes the use category framework and an excerpt of Standard U1 publicly. Treated lumber carries an end tag identifying the use category and the treating standard, which allows a specification to be confirmed at delivery rather than assumed after installation.
Conditions in 2026 have made the question more visible across the region. Central Florida has recorded one of its driest years on record, with Orlando running more than fifteen inches below average rainfall through late July and lake levels well below normal. Sections of piling that have been submerged since installation are currently exposed.
"When the water drops this far, the wood at the waterline is right there to look at," Asmar said. "That is the part of a dock the specification was written for, and it is the part almost nobody has ever seen."
Wood is one path among several. Composite and PVC decking are also used on freshwater docks, and those products are evaluated under a separate framework. ASTM D7032 is the standard governing structural performance of composite and plastic decking, and specific products are assessed against it through third party evaluation reports rather than through use category ratings.
The distinction matters when a structure combines materials. A dock built with composite walking surfaces still rests on a treated frame and treated pilings, which means both frameworks apply to the same project and neither substitutes for the other.
Material selection on a waterfront structure accounts for water type, sun exposure, structural load and expected maintenance. On open water there is no shade from a house or tree canopy, and the walking surface takes reflected light as well as direct sun, which affects surface temperature over the course of a day.
Exposure also differs from a backyard deck in duration rather than intensity alone. A patio deck dries between rains. A dock frame sits in sustained contact with moisture, and the components closest to the waterline cycle through wetting and drying continuously through the year.
Falling water levels have introduced a further consideration for existing structures. A fixed dock built for a typical lake elevation may no longer reach usable depth, and hardware that has been underwater since installation becomes reachable for inspection for the first time in years.
CVS Decks & Docks is a marine construction and outdoor living company serving Central Florida, offering dock construction, repair and maintenance, seawall construction and repair, boat lift installation, decking, pergolas and outdoor kitchens. The company is minority owned and backs completed work with a two year workmanship warranty.
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For more information about CVS Decks & Docks, contact the company here:
CVS Decks & Docks
Camille Asmar
+14075028436
camilleasmar88@gmail.com
2295 S Hiawassee Rd #104-50, Orlando, FL 32835, United States