We have a large-ish two level deck that needs cleaning, sanding, sealing. Anyone have any suggestions on the best methods/products to use?
Also a section of one of the floor boards has rotted through. I have no idea how to fix that and I have to little ones that could end up with a leg dangling through.

Hey mom, any chance you could tell us the wood species or if it is pressure treated lumber. Most wooden decks can be sprayer with a wood cleaner pre sold in the big home centers. Allow to soak and then pressure wash with a good washer but stay under 2500psi since more pressure would start tearing up the wood. We almost never sand decks unless there is a bad board.

I have no idea what kind of wood it is. I used a pressure washer on it last year (before I read all about how too much pressure can cause damage) hence the need for sanding.

I'm afraid sanding want fix stuff like that, treated wood, and I'm guessing that's what you have, doesn't sand like wood you'd find in your house would sand. As for cleaning it, you can buy deck wash, and use a gerneral purpose spray tip for the pressure washer

Hey mom, on your other insulation question I had typo, I meant a 2" hole not a 2' hole in the wall. My bad.

No problem ballengerb. Whether it's a 2 foot or 2 inch hole, it's not a project I can tackle right now. But thanks so much for the clarification.

Does it have a finish on it now? Pressure washing is highly effective in cleaning wood, but it takes a lot of practice to do it right--and the correct "chemical help." Sodium Hydroxide to strip and Oxalic Acid or Phosphoric Acid to neutralize and brighten. Replacement of the rotten planks is the only solution to the rotten wood.

It has a semi-transparent stain/sealer on it now. It looks aweful and I suspect the sealer is third rate as the water has never really beaded up on it like I think it should when it's well protected. So is there a product that's better than another or any products with the chemicals you mentioned are fine? I am planning to just use a clear Thompson's water sealer this time. Is this a good product? Please say yes because my dad gave me 6 gallons of it so I don't think I'd have to buy any more.
Do we need to replace the entire plank with the rotten spot or is there a way to cut out the bad portion. The boards are quite lengthy, probably about 14 feet.
Also, the posts for the railing are (I'm guessing) about 4'X4' and are splitting vertically with the grain of the wood. Is there a way to maintain the structural integrity of the wood once it starts splitting? Should we put some sort of wood filler in the cracks before we seal them?

January has come and gone and you are ready to get back at it, good for you mom. Not all Thompson's stuff is good. Please give us the exact wording on the can, the whole name. Is it Advanced or wood sealer plus wood protector?

It just says "Clear Multi-Surface Waterproofer" It says it beads, waterproofs, and allows wood to gray naturally.
You're going to tell me it's no good now aren't you?

I am truly sorry mom but that's the one that brought some shame to Thompsons. Please, please do not use it, you would regret it I swear. Advanced and Waterproofer plus wood protector and both far superior, the latter can come in tinted shade for about $68 for a 5 gallon drum. Deck Protection Guide - ThompsonsWaterSeal.com

Well now that sounds just about right. So I was reading that with Thompsons Waterseal Advanced wood protectors you can apply it to damp wood 2-4 hours after cleaning. Have you tried this? Putting a sealer on wet wood just seems to go against logic.

Advanced is about Thompson's best and most expensive, about $20 per gal and yes its great. I'm still using their previous flag ship product water proffer plus wood protector because I got a great deal and bulk, $68 for 6 gallons. I will swicth to Advanced when this supply runs out. You can spray it on with a graden sprayer, its water based so clean up is easy and that's why you can apply it to wet wood, its 95% water.

You're always so helpful. Thanks so much.

Best wishes on your efforts here mom, you are doing more than most folks so we love you.

Well I'm thinking about doing a lot anyway. Getting down to the actual doing is a bit more difficult. I did get the little screened in porch washed and was a little disappointed to see that the deck wash bleached out the brown of the wood quite a bit. But it's clean and hopefully soon I'll get to sealing it. Then I just the decking around the porch, the stairs going up and the top deck and railing. Oh yeah, and then there's getting the house painted, the insulation blown in, the interior painted, the landscaping... I'll stop now because my head is starting to hurt.
But thanks again for all your help. I would have used a bad sealer again and found myself right back here in another year.
On a happy note, I did dig out all the grout that should have been caulked in the kids' bathroom because as you predicted it start to crack. So that is caulked and that bathroom is finished. One project down!