1) DETERMINATIONS: Can you get by with water-blast and re-seal, or does it need to be sanded or even repaired.
a. Determine the condition of the deck. If sanding is needed or if it can effectively be water-blasted. If there are major areas that need to be stripped because they are in the shade and the sealer hasn’t broken down. To be sanded, the wood needs to be fairly level, firm and never painted. Nails may need to be pounded in first.
b. Has it been Urethaned? If so, strippers don’t really work well. It will need to be sanded.
c. Is the wood dark and need to be brightened up with an acid wash? If there are areas that need to be stripped, it will have to be acid washed, as the stripper is alkaline and will darken the wood.
d. If the stain is very dark, it is hard going lighter. If there are variations in the color, as in repairs with newer wood, an opaque stain may be in order.
e. Determine the physical area of the deck and ensure there are no problems with plants, fish ponds or other features that may need to be protected.
f. How nice do you want it? If you want it really nice and uniform, sanding may be in order if possible, but is more time consuming.
2) MATERIALS: Make a materials list to ensure you have the equipment and materials you need. Pick up others as needed and deliver to the job site. Use mainly 36 grit sandpaper. Have or get a good 7” 40 grit flap disk for the grinder to do the edges with. Also palm sander sheets and sanding belts for belt sander, if needed. Is there anything that need protection from chemicals, sawdust or stain, get plastic or tarps. Get a flat applicator with lambs wool and extension. You will need some old rags, towels or heavy duty shop towels to wipe off the excess. A few old towels works the best. One gallon of Cabot Australian Timber Oil covers about 600 square feet of Ipe’. Old dry redwood may only do 200 square feet.
3) LOGISTICS: Move any furniture or potted plants out of the working area so that it can be easily cleaned as needed. Bring in your equipment, tools and any materials.
4) IF SANDING:
a. Rent out a drum floor sander for Ipe’, hardwood or redwood that has Urathane or a lot of thick build-up. For other redwood, a vibrating floor sander is usually better as the drum sander can eat into the soft redwood pretty fast, but is faster. Use mainly 36 grit sandpaper, maybe a couple 20s to take down high spots, get plenty of each (8-10) and take back what you don’t need. Have or get a good 7” 40 grit flap disk for the grinder or an edger to do the edges with. Also palm sander is good to finish off any rough spots from the edger.
b. Sand the main flatwork of the deck with the floor sander. If low spots are not sanding out easily, use the grinder with flap disk to sand out low spots and go over with floor sander.
c. Sand edges, steps and railing with the grinder with flap disk, and if rough, finish off with belt or palm sander.
5) IF WATER-BLASTING:
a. Rent or get a 2400 -3500 PSI pressure washer.
b. Blast the deck once over making sure you don’t get the tip too close to the wood to damage it. The higher PSI machine you use, the further you can hold it away, and the faster you can do a large area.
c. If stripping, apply the stripper to the areas that the blaster didn’t get, usually the protected areas that haven’t been broken down by the sun. It may need to be scraped, or water-blasted off. If stripped, it will have to be acid washed, as the stripper will darken the wood.
d. If acid washing, apply the acid wash (deck cleaner) splashing out directly from the bottle, and immediately spreading out with a push broom with plastic bristles in order to fully cover the area. Let it sit for a few minutes, but don’t allow to dry before it is water-blasted off. Do one or two hundred square feet at a time until the deck is done and do any bad areas a second or third time to get as even as possible
e. Let the deck dry a day or two. One hot afternoon may be enough, but the dryer it is, the more the sealer will suck into the wood.
6) SEAL THE DECK: The sealer can be applied in various ways. If it is a new deck, the spaces between the boards will probably have to be brushed first. On older decks it is not as apparent, as the old stain is usually in the cracks and is dark in color, but it may be a situation, depending on the color, like if it is a dark stain and the spaces look light. If this is the case, a sprayer may be best used to spray the cracks as well as the flat-work, but you will get more waste. Most oil based sealers you have to wipe off the excess, so you don’t want to over-apply. The best method I found for this is to use a flat applicator on a broom handle with a lamb’s wool pad. Don’t get much on it and just drag it squeegeeing the excess off. Just do 3-400 square feet, and then take two rags, one under each foot, and slide your feet down two boards to squeegee-off the excess sealer before it gets tacky, which is about 30 minutes on a hot day. If it is a hot day and especially if you are using a stain with a lot of pigment in it, you may have to just do a board at a time so you don’t get lap marks.
7) CLEAN-UP: The area should be totally cleaned up, all refuse removed and any messes or mistakes corrected. Hose off the applicator pads, they may be able to be used again. Any oily rags should be put in water, as they can spontaneously combust, especially if balled up.
Courtesy of ExteriorSpecialtyConstruction.com. Contact Us in the L. A. area for a free estimate.