Why it’s best to replace, not repair, damaged composite deck boards

Q: Our deck was installed in 2007 with EverGrain composite. (We chose the redwood color.) One of the planks is deteriorating. Replacing the whole plank is one option, but we’d have to take apart the whole deck — something we’d like to avoid. Is there a material we can use to fill this area so it’s protected from further damage, and perhaps a stain so it blends with the color of the rest of the deck?

A: EverGrain and other composite decking boards are made primarily from wood flour and plastic. Unfortunately, that plastic component is why there is no suitable filler.

Envision Outdoor Living Products, which makes EverGrain and other lines of composite decking, had nothing to recommend. A representative who handles warranty issues for the company told me that they don’t make anything to fill these types of cracks and that they don’t recommend products they haven’t tested themselves.

A customer service representative for DAP (dap.com), which makes an array of patch products, said nothing in its line would stick reliably to composite decking. Some websites suggest using Bondo auto-body filler. But a woman with Bondo’s manufacturer, 3M, who answers questions about that product and other 3M fillers for vehicles and marine vessels said she knows of none suitable for use on composite decking. “Bondo would peel off,” she said.

MoistureShield (moistureshield.com), another composite decking manufacturer, warns in its cleaning and care guidelines to avoid filling deep scratches with putty or wood fillers: “These materials will not adhere to composite decking due to the plastic content.”

There are options for cleaning vintage Trex composite decking

Some manufacturers do sell products for repairing composite decks, such as the DeScratch composite decking repair kit, which comes in various colors ($7.98 at Home Depot). But the manufacturer says this filler is just for minor scratches and dents — and only on “capped” composite decking. Capped decking, which came out about two years after your deck was installed, has a core similar to your decking, but it’s encased in a plastic cap to shield the wood in the composite core from becoming stained and harboring fungi that can cause rot and mildew.

EverGrain, like other traditional composite decking, is not capped. It consists of the same material throughout. Unlike other uncapped composite products, though, it is compression-molded to eliminate air bubbles, rather than extruded. Ironically, if your issue were light scratches, this type of composite decking would be an advantage: Instead of buying a kit to hide the scratches, you could just wait 12 to 16 weeks, and they would probably fade enough to blend in, according to MoistureShield.

The picture you sent shows damage that’s more than a few minor scratches. Even though there isn’t a way to plug the holes with filler, you don’t need to live with an ugly deck. You say replacing the damaged board would mean dismantling the entire deck. It’s unclear why you have decided that, but perhaps it’s because you don’t see any nail or screw heads and thus have concluded that the decking is held in place with hidden fasteners that can’t be loosened with the boards in place.

This conclusion might not be correct. EverGrain makes the redwood color only in square-edge boards. These don’t work with the hidden fasteners the company sells or with many other manufacturers’ hidden fasteners, which are designed for boards with grooves along their edges. Instead, for square-edge boards, manufacturers often recommend using screws topped by plugs that are color-matched to the composite material.

Inspect the boards where they intersect with the framing underneath. You should be able to see through the cracks to determine whether a fastener is there or whether screws through the top surface are capped. Or there may be angled screws with the heads sunk into the sides of the boards, near the top.

If you find plugs, try prying them out of the damaged board with a tool such as the Husky precision pick and probe set ($9.97 for four pieces at Home Depot). If that doesn’t work, carefully drill out the caps, using a bit that is slightly narrower. Go in only a short distance; stop when you hit the screw head. Use a pick or probe to get out the remnants. Then remove the screws and free the board.

If you see clips between the boards, or if you aren’t able to determine how the boards are fastened, you or someone you hire can use a circular saw to cut lengthwise through the damaged board with two parallel cuts that are far enough from the edges so the blade doesn’t hit metal fasteners. (Some are plastic, which eliminates this concern.) Once the middle of the board is free, lift it out. Then, with a small pry bar, push the two remaining pieces up from the fasteners. Freeing the middle first gives you better leverage and prevents damage to boards on either side.

Once you have the old board out, you’ll probably need to install the replacement with screws through the top. Pre-drill holes and use either stainless-steel screws or deck screws color-matched as closely as possible to the new board. A new EverGrain board in the redwood color will look more vibrant at first, but it should fade. In a year, you may not be able to identify which one it is.

One final point: You say only one board is showing damage, and from the picture you sent, it looks as if the damage is confined to a small enough area that it isn’t (yet) a structural issue. If you search for Tamko EverGrain decking (Tamko is the parent company of Envision), you will find complaints about this product from 2007 specifically. Tamko’s 25-year limited warranty covers replacement costs for five years and only a portion of the material costs after that, but if numerous boards start showing problems, it’s worth contacting the warranty department. No manufacturer wants a recall of its products, and there have been a few huge ones involving manufacturers of other composite deck boards. In 2009, after reports of 37 accidents resulting in 14 injuries, the Consumer Product Safety Commission announced a recall of three lines of composite decking made by Louisiana-Pacific. Composite decking doesn’t usually rot and collapse, but it has happened.

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