Ask around about Thompson’s WaterSeal and you’ll get two completely different answers. Half of people swear by it. The other half will tell you it weathered off their deck before the first winter was out.
Both are usually telling the truth, because almost everything that goes wrong with this product happens before the can is even open.
Which Can Are You Holding?
Find the opacity on the label. That decides your dry time, your coverage, and how long before you’re out there doing it again.
Product | Coverage | Dry time | Deck guarantee |
Clear | 200 to 400 sq ft/gal | 48 to 72 hours | None published |
Transparent | 150 to 400 sq ft/gal | 2 to 4 hours | 4 years |
Semi-Transparent | 150 to 400 sq ft/gal | 2 to 4 hours | 5 years |
Solid Color | 150 to 400 sq ft/gal | 2 to 4 hours | 6 years |
Notice how the guarantee climbs with the pigment. Pigment is the only thing standing between your boards and a July afternoon, which is why Clear, the one most people picture when they hear the name, is also the one you’ll redo most often.
Clear is the odd one out in other ways too. It cleans off tools with solvent instead of soap and water, and the label carries combustible and vapor warnings the tinted versions don’t.
Thompson’s is what we reach for on most wood decks around Omaha, and the choice between those four comes down to how much of the grain you want to see against how long you want to go between coats.
All four are on Thompson’s wood sealer page.
Does It Even Need Sealing Yet?
Sprinkle water on a few spots and watch. Soaks in and darkens within five seconds, you’re ready but if it beads up and sits there, your old finish is still working.
Try it in a few places, because the shaded corner will still be beading long after the middle has given up.
Getting the Deck Ready
There are three levels to this, and which one you need depends on what’s on the boards now:
- Power wash. Enough for dirt, mildew, and pollen on bare or lightly weathered wood. A deck cleaner does the rest.
- Power sanding. Once the old finish is ground into the grain, washing alone won't lift it, and sanding gets you back to clean wood faster than another round of chemicals.
- Stripping. Reserved for a coating that has genuinely failed and has to come off completely. Stripper goes on with a watering can rather than a sprayer, and anything you strip needs a brightener behind it, since strippers run alkaline and darken some woods on the way through.
That’s the same ladder we work up on customer decks, starting with the wash and only escalating when the deck makes us.
The Weather Rules That Catch People Out
- The wood has to be dry. Just cleaned it, or it rained Tuesday? Give it a full 48 hours.
- Temperature holds for two days. Surface and air above 50°F while you work and for 48 hours after. A 70-degree Saturday followed by a 44-degree night hands you a tacky deck.
- No rain in the 24-hour forecast. Check again the morning you plan to start.
- New pressure-treated lumber waits 30 days. A deck built last weekend isn't ready.
- Nothing goes over paint or a recent stain.
Add it up and your window here is narrower than it looks, which quietly rules out most of April and a good stretch of September.
Sprayer, Brush, or Pad?
A pump-up sprayer is far and away the fastest way to get product onto the boards but on its own, it will let you down.
The reason is simple enough: a sprayer lays product on top of a board, while back-brushing actually drives it in. Thompson’s recommends following the sprayer with a pad, brush, or roller, and skipping that second pass is what produces the blotchy finish that shows up two days later.
The pad on a long pole is the underrated tool here. It keeps you upright, and by board forty your knees will have opinions.
Doing the Work
- Test the color on a hidden board and let it dry all the way. Wet and dry look nothing alike.
- Cover plants and furniture, and tape where the deck meets siding.
- Stir well. If you bought more than one can of a tinted product, pour them together first, because two cans of the same color aren’t always the same color.
- Start with railings, so you aren’t walking over fresh boards to reach them later.
- Work a few boards at a time, keeping the wet edge moving. Let it dry before you get back to it and the lap mark is permanent.
- One thin coat. Spread or wipe anything you’ve laid on heavy before it sets.
How Many Coats?
One.
All four products list a single recommended coat, and that isn’t a minimum they expect you to build on. A second coat exists purely for color, and on the tinted products it has to go on within four hours of when you started.
Clear is stricter still. Over-applying it is listed right on the label as a cause of the oily, tacky surface that then has to be scrubbed back off with degreaser.
If deeper color is what you’re actually after, staining is the better conversation.
How Much Will You Need?
Length times width for the floor. Add roughly a quarter for railings, since spindles carry more surface than your eye credits them with. Count stairs separately, then divide by the low end of the coverage range.
A 16 by 20 deck comes to 320 square feet, call it 400 with railings, which at 150 square feet per gallon puts you at three gallons.
Buy to the optimistic number and you’ll run dry with six boards left.
The Cost to Have It Done Professionally
We seal decks across the Omaha metro as a standalone service, so you don’t have to bundle it into a full restoration to get it done.
Pricing tracks how much prep the deck needs rather than the sealing itself:
Scope of work | Cost per sq ft |
Stain and seal | $0.50 to $1.50 |
Power wash, stain and seal | $1.00 to $2.50 |
Power sanding, stain and seal | $2.00 to $4.00 |
Strip, stain and seal | $2.50 to $5.50 |
Railings and handrails | $4.00 to $12.00 |
Look at the spread between the top and bottom row. A deck needing only a wash sits at the cheap end, while one carrying a failed finish that has to come off entirely runs three or four times that for the same square footage.
Which is the real argument for staying ahead of it. Every year you let a finish go past due, you move a rung up that ladder and the next job costs more.
Drying, Foot Traffic, and Furniture
Clear needs 48 hours minimum and can stretch to 72. The tinted three are touchable in around two.
Dry to the touch and ready for real life are different milestones though. Light foot traffic can come back once the surface is genuinely dry, and furniture goes last, because a planter sitting on four small feet while the finish is still hardening leaves four small marks you’ll be looking at for years.
Where DIY Jobs Go Wrong
Most of the decks we get called out to fix failed for one of a handful of reasons, and none of them have anything to do with the product:
- Sealing damp wood. The most common failure by a wide margin.
- Skipping the splash test. Sealing a deck that's still shedding water wastes a weekend.
- Extra coats for good measure. You get tackiness, not durability.
- Spraying without back-brushing. Uneven color, every time.
- Losing the wet edge. Lap marks are permanent once it cures.
- Going over a peeling finish. It keeps peeling and takes your new coat with it.
- Watching the daytime high, ignoring the overnight low.
The pattern underneath all of them is the same. People budget a day for sealing when the job actually needs three, then start cutting corners on the parts that happen before the can opens.
When to Do It Again
The guarantees give you a rough calendar: 4 years on Transparent, 5 on Semi-Transparent, 6 on Solid. Clear carries none, and Thompson’s suggests redoing it annually for the best sun protection.
The splash test beats any calendar, though because a guarantee describes normal conditions, and a west-facing deck baking through a Nebraska August isn’t anywhere near normal conditions.
Those are national figures though, and Nebraska is harder on a deck than most places. In practice we see transparent and semi-transparent finishes wanting attention every 1 to 3 years here, and solid colors holding 3 to 5.
When Sealing Is the Wrong Answer
We’d rather talk you out of a sealing job than take your money for one, and these are the signs that send us in that direction:
- Boards that feel soft or spongy underfoot
- Deep cracking across several boards at once
- Rot at the joist ends or the ledger
- Railings with any give in them
- Posts that move at the base
- Squeaking or movement when you walk across it
That last one matters most, because it means the problem is under the boards.
The good news is that catching it early is cheap. Swapping a few bad boards can run a couple of hundred dollars, while letting it go until the structure is compromised turns into stair rebuilds around $5,000 and full replacements on a small deck closer to $14,000.
Sealing over the early version of that problem buys you one season and adds a step to the repair you were always going to do.
Should You Do It Yourself?
Go for it if the deck is sound, it’s a size you can finish in one dry stretch, and the forecast is cooperating. Plan a full weekend, because cleaning, waiting 48 hours, then applying is a three-day sequence no matter how fast you are.
Hire it out once there’s stripping involved, when boards need replacing first, when the deck is large or elevated with a lot of railing, or when you’ve watched three straight weekends get rained out.
We’ve been staining and sealing wood decks since day one, we handle the whole sequence from wash through final coat, and the work comes with a warranty. Mostly that’s worth knowing if the three-day weather window is the part you can’t make work.
Questions We Get
Is one coat really enough?
Yes. A second is for color only, tinted products only, within four hours of starting.
Can I put it on damp wood?
No. Give it 48 hours after cleaning or rain, since damp wood is what causes that tacky finish.
How long will it last?
Four to six years on the tinted products depending on opacity. Clear has no guarantee and wants doing annually.
Can I seal a brand-new deck?
Not for 30 days, if it’s pressure-treated.
Does it work on composite?
No, wood only. If you’re tired of doing this every few years, that’s usually when people start comparing composite brands.
If you’re not using a pump up garden sprayer, use your piece of cloth or brush directly in the sealant can, and then apply it to the deck surface.
The process may take longer than with a sprayer, but the results will be similar.
Get Eyes on It First
Sealing works beautifully on a deck that’s sound underneath. If you aren’t sure yours is, ten minutes with someone who does this for a living tells you more than any test with a garden hose.
We handle deck sealing across Omaha and will tell you straight whether yours is ready, all you need to do is ring us at (402) 600-0810 or contact us through our website and we’ll come take a look.
Here at DeckBros, we have years of experience in applying sealants and stains on wood decks. If you want a quality sealant application for your deck in Omaha, NE, we can take care of everything for you. Get your free quote today or call now: (402) 369-5724