wrote in message :

The previous owner of my house built a cheap wooden deck with the
cheapest pressure treated wood possible. That was maybe two years ago
and he didn't stain or paint the deck.


In reality, you should never have to do anything to pressure treated. It may
not be pretty, but it will hold up for a long time with no additional
treatment.

When I stain the deck last
year, I noticed some good cracks along the grain line so I stained the
whole deck thinking it'll hold up to the elements.

Very typical. Looks crappy, but not a structural concern. I have some of
my deck like that and it is 20 years old.

This year, I notice even larger cracks and some surfaces are starting
to flak.

Typical, unfortunately.


What should I do to preserve the deck? I am thinking of getting some
fillers and restain the deck. Do I need to seal this surface at the
end with a clear coat? I don't think so because it's outdoor. But
the stain doesn't seem to be able to seal the large cracks though.

Fillers will probably do more harm than good. By clear coat, if you mean a
polyurethane, NO, that will not help. Avoid Thompson's stuff also. Stain
does not hold up more than a couple of years on horizontal surfaces.

If you can't stand the appearance, as long as the rest of the deck is
structurally sound, you can replace the top with better quality woods like
mahogany or ipe. Not cheap, but better looking and longer lasting,
especially with a coat of Penofin oil. Ipe was 2.09 a linear foot a coupe
of years ago when I looked.