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I recently cleaned my deck using Behr deck cleaner and want to re-stain it before the winter. Do you recommend sanding the entire deck, or just the affected areas where the stain has come off?
I was thinking of renting a belt sander for the day just to get the rough spots and re-stain with the same stain. There's a tub of it left over from the previous owner.
I wouldn't belt sand any outdoor deck, especially with a commercial belt sander that your talking about. More damage will ensue. Take the $60.00 you'll spend on the rental and buy a Makita Palm Sander. It takes a 1/4 sheet of sandpaper to load onto the pad to sand. Buy some 80 grit sheets and some 120 grit sheets. Grab a beer and get down on your knees and feel for rough spots, sand lightly with the 80 grit on all the rough spots on the deck. The electric sander will make light work of sanding the deck without going to far. Then swap out for the 120 grit and hit all the spots again and your ready to stain/seal once you do your clean-up.. that size deck may take you 2 -3 hours total, good luck.
For a deck that has already been stained it would be better to use chemicals and a pressure washer than sanding.
For a new deck, you can use a pressure washer or you can sand it. Honestly, I have tried large floor sanders and they don't do a good job. Deck boards often are cupped and warped, if even slightly and you won't be able to sand the whole thing easily.
I also would not bother with a belt sander.
For new unstained deck boards, I use a Random Orbital Sander. It would be easier (and better) to do before you install the boards. Otherwise, I'd get on my hands and knees. One board at a time. With a good sander and paper this goes pretty quick.
I use 60-80 grit sandpaper.
A little late but at least others will find this.
Firstly I must add that I restore decks for a living where the outdoor elements are notorious for harsh UV rays and wide variations in moisture exposure.
The deck above from the original poster has a failed acrylic based oil - sanding will give you that results as strippers will cost a small fortune and still leave some coating behind so sand away.
I recommend starting with a drum sander and start with a 40 grit which will rip it all up with its first attempt - 1 belt should last around 30 sqm. Once you have given the deck a once over with the 40 hit the deck again with a 80 grit - 1 belt per 30 Sqm will be fine.
Lastly get me decking cleaner which is really just oxalic acid / wet down your deck that spread the acid and let it sit for 20 mins before hosing off or with the help of a high pressure cleaner no stronger than 1000 psi.
Let rest for 24 hours and then seal with your offered protective coating.
Don't be scared of the belt sanders start with a 80 to have practice for 10 mins then back to business
If you can only find a hand held orbital sander buy yourself me knee pads and get your abrasives from floor sanding supplier and buy discs made from zirconia they are blue in colour and last for ages...
Another tip get a wire brush and clean your pads as you go as this all save you lots of money..... same principles apply startth you rough 40 grit and finish with 80..... trust me go the walk behind belt or drum sander and just do edges with your hand held orbital.
At a minimum, all the horizontal surfaces should be prepared. My method of choice has always been to use a pressure washer and wood cleaner. If it is particularly bad you can take a firm nylon bristled broom/scrubber and help work it in. Once the cleaner has been on for a few minutes (check the label) pressure wash the deck clean, it is the easiest and frankly most effective way to get rid of the old stuff and ensure a well prepared surface for the new coating.
Only use a pressure washer on a low setting with a wide fan. If used incorrectly or with too much pressure you can tear up the wood effectively ruining the boards requiring they be replaced.
You need to let it dry completely before applying new stain. For reference as others have mentioned...don't sand a deck.
Sometimes if you're staining the same color you can avoid sanding the whole thing. If you're staining though you want to be aware that some stains get darker with layers. So if you have a spot with no stain it will look different than the spot next to it. You can lighten this by "pre-staining" or sanding everything as close to bare wood as possible. Sometimes you can power wash or scrape the wood to the point where you can stain. The recommendations for semi-solid stains are excellent. When I've used these products they go on well and last some time. To prevent this in the future keep up with the stain of the deck and reapply before it gets too bad and you have to scrape and sand a lot.
You can buy a liquid stripper that is formulated to remove old deck stain. Rent a pressure washer from the hardware store. Use a pump sprayer to spray the stripper, and use a stiff nylon brush on a pole to loosen the old stain. Pressure wash until the deck is clean. It should only take a few hours. Allow it to dry for one week before staining.
DO NOT SAND A DECK!
Use a semi-solid oil-based stain like Cabot's. Apply only one coat. The semi-solid stain will cover a few imperfections, and will look great when you are done! Re-stain about every 4 years, or when the stain no longer repels water.
