Trying to fill Fir Floor Gap

[ThisGuy5280]

My 100 year-old fir floor has a wide gap in one section. I have tried different fillers, but eventually they crack and even fall out.
This photo doesn't really show how deep the crack is.
Is there a product that will work for something like this? I have tried Elmer's and Minwax,
Thanks.

 

[Tile Tom]

Have any extra material? Or some you can borrow from a closet?

If so I would just replace the board.

 

[ThisGuy5280]

I'll look into that. Thanks.

 

[DarisMulkin]

Where the filler falls out, if you can get under the floor scab another board over the gap and refill.

 

[ThisGuy5280]

Have any extra material? Or some you can borrow from a closet?

If so I would just replace the board.

I found that a closet has the same flooring. The finish is different, of course, as it hasn't been sanded and coated in years - if ever. How do I use that wood? Do I sand it, collect the dust, and then make it into filler?

 

[Tile Tom]

I was thinking more about pulling a plank from the closet and using it to replace the damaged plank...

You could make your own filler with fine saw dust and a little tite bond. I personally don't have any experience doing that but I know a couple guys on here that have talked about doing that.

Maybe they could chime in on how well it works?

 

[C.J.]

That’s a big chunk to fill. I wonder if that chunk is the top half of the groove side that split off. If you have movement between the boards then the putty will want to break up. If it’s seasonal movement then it will just take a little longer to break up. Could you fill it with epoxy? Or a hot stick burn in? I’ve seen rope used to fill gaps (This Old House). I had a spot like that at my old house and I just left it the way it was, sucked out any dirt that collected when I vacuumed.