Ideas for filling in plywood defects before vinyl goes down?

[1lhorn]

The exterior grade plywood that I bought to redo my floors has some defects that I'd like to fill in since I think they might otherwise show through after the Nautolex goes down.

The MariDeck youtube video recommends that joint compound can be used (sparingly). I'm not sure I can think of a less water resistant method of filling in the knot holes etc. I suppose under Nautolex and covered with epoxy it should be Ok but I just wanted to see if there were any other ideas.

My dad thought about mixing a copious amount of sawdust with epoxy into a putty or mud like consistency and using that.

Bondo also makes a product called "wood filler." It sounds like it would hold up better to walking on than joint compound. Can be painted and says it's water resistant. I'd cover it with epoxy any way. This seems like it might be the way to go. It's inexpensive (relatively), dries fast, can be painted over, sanded, is water resistant and is more "structural" than joint compound.

Any other ideas?

 

[Johnny]

I personally am a big fan of Bondo.

compare the prices of Bondo Auto Body Filler at your auto parts store
and Bondo Wood Filler at the big box store. (you can probably do that on line)
They are one and the same. (the fillers may be a little different)
Then, using Bondo, you will have patches that will never fail under your vinyl.

Try to stay within the prescribed ratio of the filler/hardener mix as you can.
In the hot weather, a little too much hardener will set up faster than you can
use it - thus results in wasted material (money).

I don't use "epoxy" in large projects because of the cost factor.
If you have some "Polyester Resin" (fiberglass) on hand, that is awesome to mix
with sawdust as a filler also.
Depending on how big your defects are and how many you have, epoxy in the syringe
double barrel hobby type will work just fine.
Just mix your liquids well BEFORE you add your sawdust.

Photos as you go is nice to see

 

[lckstckn2smknbrls]

There's a product called "Rock Hard" I've used it outdoors to fill in woodpecker damaged siding before staining.
Most hardware stores will have it, it's a powder you mix with water.

 

[duckfish]

I definitely need to find this Rockhard product. Woodpeckers are making swiss cheese out of my cedar siding. Never had a problem till the %$#& stinkbug invasion began about 5 years ago.

To the OP, sawdust in your 2 part epoxy will certainly work. I use it for wood boat building projects. The added benefit is you already have the epoxy and you know there won't be any bonding issues with your epoxy sealing and the filler.

It works best if you use very fine saw dust. I keep a container filled with what is captured in my belt sander dust bag. If you don't have that available just steal your wife's flour sifter and keep the finer stuff from sifting (just don't let her catch you. I made that mistake, once [-X ) For what you are doing I like to mix it thinner, about ketchup consistency, so it is self-leveling. Helps cut down on sanding effort before applying your epoxy for waterproofing.

You can also buy Cabosil (silica dust) to use as an epoxy thickener but saw dust will work fine here. I only use the Cabosil when mixing the epoxy for gluing purposes.

 

[rscottp]

I would go with bondo, it's not waterproof but should be fine if sealed and covered with vinyl. I would shy away from the "rock hard", if its what I think it is I think it will crack.

 

[Johnny]

yes, Rock Putty is a great product - if used INDOORS.
small exterior holes can be filled with Rock Putty if painted over.
Do your homework prior to using it anywhere outside.
https://waterputty.com/repairs/precautions/
https://waterputty.com/faq/

 

[Tallpine]

+1 for Bondo.

 

[DaleH]

Best deal on epoxy is that by Raka, www.raka.com, as I can buy 1/2-gallon kits for $50 or less and get it in 2-3 days. It has totally replaced West Systems for me and the boatyards I work with and there's no need for expen$ive epoxy pumps.

 

[Hanr3]

Wood Filler.

 

[huntersdad]

You probably could use what flooring folks use to fill in imperfections before they apply vinyl as well, lowes or Home Depot should have what you need. Just ask someone in the flooring department.