I found some serious rotting under 2 boards of our balcony/deck. I guess I need to replace the board.
I'm not sure how this rotting developed, and how can I prevent it happen again. Rain can fall on the edge board, but not this one.
Other than that board, there are also two problems I need to address:
2. One side joist have lots of peeled off paint, nails pop out, also some cracks
I'm thinking removing the paint, sand it, add some 3M bondo rotted wood filler, paint it.
Maybe also add some deck screws? Should I add a sister joist?
3. The boards that on the outer side have lots of cracks and paints peeled off.
Should I remove the paint, sand and stain them again, or maybe just replace the boards?
Do I need to stain the under side too?
The one on the edge have most cracks, but the fence is bolted to it so I'm not sure if I can replace it. Can I just use rotted wood filler to treat it?
And here is the whole album with more pictures
https://www.flickr.com/photos/dracodoc/albums/72157714808563623
Thanks!

I'm not sure how this rotting developed, and how can I prevent it happen again. Rain can fall on the edge board, but not this one.
Other than that board, there are also two problems I need to address:
2. One side joist have lots of peeled off paint, nails pop out, also some cracks


I'm thinking removing the paint, sand it, add some 3M bondo rotted wood filler, paint it.
Maybe also add some deck screws? Should I add a sister joist?
3. The boards that on the outer side have lots of cracks and paints peeled off.


Should I remove the paint, sand and stain them again, or maybe just replace the boards?
Do I need to stain the under side too?
The one on the edge have most cracks, but the fence is bolted to it so I'm not sure if I can replace it. Can I just use rotted wood filler to treat it?

And here is the whole album with more pictures
https://www.flickr.com/photos/dracodoc/albums/72157714808563623
Thanks!