PONTOON DECKS - Wood-Aluminum-Composite
3/4" Marine Grade Decking versus Ordinary 3/4" Plywood
7 PLY, CCA Treated, top side is sanded with any voids filled and sanded.
Usually 3 or 5 ply, ACQ treated, knots or voids visible on both sides.
WHATS THE DIFFERENCE BETWEEN CCA AND ACQ DECKING? About ten years ago the EPA dictated that lumber yards could no longer sell CCA treated plywood without a special permit. CCA treating involves the use of arsenic in the treating process and the government was concerned about unused pieces of scraps. The marine industry was granted an exemption with the understanding that wood would not be cut and would be used in whole sheets. Marine grade decking is also kiln dried, it lays flat. Marine grade decking has the individual layers of plywood (usually 7) glued together with waterproof glue. Any voids, knotholes, etc. in the top side are filled and sanded flat.
Most modern lumberyard plywood is treated using the ACQ method. This method uses copper sulfate to retard rot in the wood. Although some large lumber suppliers especially in lake regions do stock CCA. There are several drawbacks with the FDA approved ACQ treated plywood. It warps easily because the ply's are glued together with non waterproof glue. The copper sulfite used to treat the wood leeches out and can dissolve adhesives as well as the backing of some carpets.
CCA “marine grade” decking can be hard to find and you should be prepared to pay probably as much as $25 more per sheet. But most boats only take 4-5 sheets and the extra $125. you’ll spend versus ordinary lumber yard 3/4” decking will save you re-decking in a few years
Tongue & Groove Marine Decking
Some boat builders used a tongue and groove method to fit the
individual deck boards together. The benefit was that it helped
prevent water from working up between deck seams. The difficult
was that even in a production setting with special tools to pull the tongue and groove together, it sometimes didn’t fit tightly. Modern pontoon manufacturers generally don’t use tongue and groove decking, but the rebuilder may see it and want to replace the old deck the same as original. Since there is no one using it in new boat manufacturing, it is difficult to find in the aftermarket.
8' Wide-8' 1/2"-10' Wide Marine Decking
Crest and JC Pontoons started experimenting with 8’6” wide decking in the late 1990’s. The idea was that the extra 6” difference allowed for larger more spacious seating floor plans. By about 2012 the industry adopted 8’6” wide as the standard. In 2015 a couple brands experimented with 10’ wide pontoons. Because of transportation difficulties, 10’ probably won’t become common. Rebuilders must be careful when buying material for late model rebuilds. It's difficult to spot the difference between an 8’ or 8’6” deck. You should always measure the width of a re-deck before ordering components. Especially if the older boat is a Crest or JC.
Adhesive (Glue) and Laying the Flooring
The majority of problems in rebuilding can be traced to glue. Getting the wrong kind, not using enough or not compressing the glue into the back of the floor covering. Get any of these wrong and the 14-20 hours you spent redecking will have to be redone.
Prepare the surface– When rebuilding you may often be able to use the old wood. 50 year warranty wood was introduced about 1985. Many of the boats being re-carpeted may not need new decking. But, don’t be surprised if a paid rebuilder refuses to recarpet without putting down a new deck.
This is off an 8 year old pontoon. The old carpet pulled up easily but pulled the top layer of plywood. These holes need to be filled and sanded before new carpet can be laid.
Sometimes the old carpet pulls up easily. Clean the old deck with a steel brush or light sanding and you’re ready to put down new carpet. Other times pieces of backing stick to the wood or chucks of wood tear up if they're stuck to the carpet. It takes time to scrape off the chunks of backing and glue or fill pieces of wood torn from the deck. When labor is charged by the hour it might be easier to replace the decking. If you're doing it yourself you might spend an afternoon and rent a belt sander to save a few hundred dollars. The floor must be clear of residue, flat and smooth to accept new glue.
Marine Grade CCA Treated Wood Decking (XL-50 PTP-50) Because marine grade decking is kiln dried and the top is sanded with imperfections filled you generally have less difficulty with the glue. Several companies sell Slocum (sometimes labeled Tennessee) 776 Marine Carpet/Vinyl Adhesive. It’s water based, not much odor. It's thick so that you spread it with a trowel, designed for outdoors applications. There are dozens of other types, again watch for Outdoor Use, Water Soluble and Thick. Some carpet companies; Syntec, Lancer, etc. offer glue labeled for their carpet. Some large companies also have glue labeled with their brand. It’s generally all the same but you do get some piece of mind buying the glue that is recommended by the carpet company.
You’ll learn a lot about your supplier from the price of glue. These range from $24 to $39 per gallon.
Lumber Yard ACQ Decking
There are situations where people just aren't going to pay for the good decking. When you buy the wood, try and get some guidance from the salesman. ACQ wood is "wet", and you need a special glue to adhere it to the decking. For information, search - Adhesive bonding of wood treated with ACQ and copper azole preservatives.
Marine Grade carpet will usually adhere to aluminum decks with ordinary (Water soluble) adhesives.
Vinyl Flooring will NOT adhere to aluminum decks. Something about the floor covering can not breathe for the adhesive to dry. I can’t explain it and we’ve warrantied vinyl floors on aluminum decks with special adhesives from three different companies, we just couldn’t get it to adhere.
Putting Down the Glue & How Much Because we recommend “thick” glue we suggest using a 1/16” notched trowel to apply adhesive to the decking. 1/8” wouldn’t be a problem. When glue is applied to a deck in this manner, one gallon will cover an area about 8’ x 9’. Thus two gallons will do most 16’-20’ decks, three gallons for a 24’ deck.
While we like a trowel, we recognize that others have different methods. Most boat builders use a spray glue, spraying the floor and then the back of the flooring as they roll it down. Working from the front to back, or vice versa. Most rebuilders don’t have a glue pot and heavy duty commercial sprayers. Some rebuilders use a thin glue and apply it with a paint roller and while they seem happy with this method I question if you're actually getting enough glue on the deck and carpet. The important point is don’t be cheap with the glue, it’s probably the least expensive component of the re-deck.
Compress the glue into the back of the carpet. If you just unroll the flooring on top of the lines of glue, you’ll get adhesion along the top of the ridges. If you roll or compress the lines of glue into the back of the carpet you’ll get thorough adhesion. Pressure will flatten the ridges of glue. This is perhaps the most important step in preparing new flooring over a deck.
A lawn roller
Stomp the glue into the carpet
A commercial carpet roller