PROPER STAINING OF A DECK

Here you see that the stain on the deck that was applied some years ago was peeling and the deck boards were cracked.  Power washing did not do a sufficient job of surface preparation.  The industrial strength belt sander (Ryobi, ~$99) was brought in to sand the loose paint and mildewed wood off and get down to solid wood.  I filled in all of the cracks with Elmer's Carpenter's Wood filler.  It took me 16 Fluid Ounces to finish the job.
Although the pine board looked ok, I soon found that it was rotted and inhabited by ants.  I cut the plank, careful not to cut the supporting beam and worked it out from under the siding without damaging it.  Note the extent of the rot.
I cut the rotted plank back to where the pine was sound.  Cut the plank with a jig saw at a 45 degree angle so it can be spliced with the patch.  Note the board nailed in place to assure a straight cut.  I used pressure treated wood for this patch.  Four foot lengths were available at Home Depot at a discount price.
Here the better side of the pressure treated plank was cut at the complementary angle.  Nail the guide board in place temporarily to get a nice, straight cut.  Taper the other end on top with the belt sander so you can snugly insert it back under the siding.  Use a hammer to drive it home.
Once you get the plank cut to the proper length you prop it up with your hammer and apply the Wood Filler to the open ends.  Screw the patch in place with two Phillips 7X1-th" exterior screws at a 45º angle.  You will have to pre-drill holes for these screws.
A drill can be used to probe for rotted wood.  In this case, the rot went on for a considerable distance.  This board had to be replaced as above.  Altogether I had to replace 12 feet of the original pine with pressure treated planks.  BTW, the planks are 2X6 inches.
Here is the finished replacement which was completed with one 8-foot-long 2X6 pressure treated plank. I did not have to splice the plank as was done with the replacement described above.  The plank was secured with 3 inch galvanized exterior deck screws.  Whenever a loose nail was found it was replaced with a 3" deck screw.  I almost used up a 1 pound box of exterior deck screws for this job.
Two knot holes had rotted out and these were drilled with a 2-th inch hole saw to a depth of about ¼ inch.  Here is the patch, a 2 inch diameter disk cut from a cedar board   The patch was held in place with Elmer's Wood Filler which dries hard in 2 hours.  Then the patch was sanded flat with the belt sander..
Swabbed down the deck with the recommended Behr Multi-Surface Cleaner applied with a stiff bristle brush.  The hypochlorite will remove any remaining loose paint, mildew, and mold growing on the wood.  Allow to stay in contact with the wood for at least 1 minute and rinse with a power spray.  The canvas is now ready for you to take your brush in hand.  I purchased the best quality Behr Deck Fence, & Siding wood stain from Home Depot.  Their #317 is very close to the gray of our decks. 
The finished work of art!  This stain is guaranteed for 4 years.  The deck furniture was badly infested with mould and algae which was removed with the Behr Multi-Surface Cleaner that was left over.  They looked like new.
Baby, let's play!  This satisfying deck project was completed in four days and the stain applied 24 hours before the rains came in.  The grand baby had a great time in the pool on our flawless new deck.

Why did I do this?  Well, the deck was severely peeling and rotted and this unit was not scheduled for painting this year.  After so many years exposed to the elements the deck needed a really deep preparation to get it right.  Power spraying is not sufficient to remove years of neglect.