This post was updated on February 19, 2024
Applying Polyurethane Wood Deck
Welcome to DeckStainHelp.com, the internet’s number one reference for all things wood deck restoration related. As before, we do not recommend the use of polyurethane stains on outdoor decks. We always appreciate your comments and questions, so feel free to leave one below.
Should I Apply Polyurethane to a Deck?
Selecting a deck stain or sealer is a vital step when finishing your deck or when your deck is in need of being recoated. Wood decks are exposed to severe weather conditions and need to be protected with the correct type of wood sealant.
Peeling Deck Varnish
The best choice for finishing a wood deck is to use an exterior wood stain. A semi-transparent penetrating stain will provide adequate water and sun protection. This type of deck stain will enhance the natural beauty of the wood increasing its appearance.
When refinishing a deck, do not use a urethane, varnish, or polyurethane coating that films on top of the wood, creating a “shiny” finish. These types of finishes are mainly used for indoor applications and break down easily when exposed to the elements. Rain and harsh UV rays will cause polyurethane to fail quickly, which will subject the wood to weathering. The polyurethane will blister and peel on exterior wood. This will create a nightmare to fix where heavy sanding will be involved in the removal. If you want a clear or natural look to your deck, consider a deep penetrating (non-filming) clear deck sealer or better yet a semi-transparent deck stain in a natural tone.
Peeling Polyurethane Deck
When looking for the right deck stain you will find a large variety of colors. Finding a color like Natural, Cedar, or Redwood in a semi-transparent stain will not hide the wood grain as a solid stain or paint would. This can give your deck the natural look you desire while still giving the wood moisture and UV protection.
Do some research on your deck’s type of wood. Search for colors that will give you the final results you want. Do not apply polyurethane to a deck or it may jeopardize the deck’s beauty and longevity. The outdoor elements are too harsh for polyurethane making it a bad choice for exterior deck use. Keep your deck maintained with the proper choice of deck stain and it will be there for you to enjoy for many years ahead.
Please Ask Any Questions Below
Deck Stain Help & Questions
Stain Reviews & Comparisons
I have a newly built deck, the wood is not treated but I would like to treat it, really don’t want a stain but I want to seal it and finish coat, what’s recommended!
See here about new wood:
https://www.deckstainhelp.com/how-long-should-you-wait-to-stain-a-new-deck/
You must stain it for UV protection:
https://www.deckstainhelp.com/will-a-clear-sealer-prevent-graying-on-deck/
I applied Dura Seal Polyurethane Satin finish on my outside deck and after being exposed to the winter season elements the coating is peeling. What should I use to strip it off and what coating would you recommend applying to this out door pressure treated wood deck?
Use this to strip it: https://www.deckstainhelp.com/rad-paintstrip-paint-solid-stain-stripping-gel-review/
Use a penetrating stain after so it does not peel. https://www.deckstainhelp.com/the-5-best-deck-stain-reviews-and-ratings/
We installed wolmanized-type treated 2×6 decking two years ago. It is splitting more than I expected, even though we keep it stained. One deck expert says to fill the splits with flexible polyurethane caulk before sealing, but you seam to frown on that suggestion. We can’t replace the decking, and every winter in thee Puget Sound area it will obviously get worse. What do you recommend?
Splits and cracks are normal for exterior wood decking and are not an issue. Just leave as is.
We built a redwood deck last year in higher elevation Colorado and it gets lots of sun. We were told not to use anything because we would have to redo every year. But the wood has started to splinter. What would be long a lasting finish? We are too old to do every year. Thank you!
Clean and brighten for prep and then use a penetrating semi-transparent stain. Look at Restore A Deck or TWP 1500 Series.
Why do cruise ships use gloss varnish on all the rails..extreme exposure in that situation..
regards
RON CUTLER
For aesthetic appearance and to prevent splinters. If you watch them or ask them, it is constant maintenance and they recoat the rails numerous times per year due to failure and peeling. If you do this to a horizontal deck, you will ruin the wood.
The patio deck was painted with latex paint by the previous owner. We’ve sanded it off in preparation for applying primer & oil paint. The owner liked the sanded down version better than the paint options & said stain it & varnish it. So we stained it & was prepping to varnish it with Spar Varnish but Alas the internet is sending forboding anti-varnish vibes. ( It’s Tuesday night & we want this thing dry & not smelling like varnish by Saturday noon).
What would you do?
I’ve been advised to put linseed oil on it all instead, to avoid the chance of varnish still being tacky or smelly by Saturday. This would make the whole thing quite dark & dark was not meant to be dark
Should we give up & paint it with solid oil paint ontop of the stain?
This is in tropical rainforest. There is a lot of humidity. There is a roof over this deck. Outside of the roof, we are in the top 20 places in the world for highest ammount of rainfall
You cannot add linseed on it. That will be a mess. Never use a varnish. You can sand to remove the incorrect stain and then use a proper deck stain or you can paint over it.
My deck was recently power washed and stained. I have an exterior spar urethane I wish to apply to the railing. Is this advisable. It is a clear gloss
No, it will peel and blister if you use it.
Varnish is a popular coating for boats, rather than poly, for its weather resistance, whereas poly is touted as an interior finish lacking exactly the wearability in outdoors . So I’m left wondering why all those boat owners and various detailing contractors can be so foolish! Huh!
They do it for appearance and it is constant maintenance as it does peel and blister. But, if you do not believe me, go ahead and apply it to your deck and see what happens :).
There is a reason that no deck stain manufacturer offers a “varnish” type finish in their product lines.
Hi, I have recently stripped and sanded a huge deck that is 5 years old. It has direct sunlight about 8 hours/day. Live in OK- so we have all 4 seasons- often multiple times of the year! I love the color of my deck right now- the rustic blondes, mixed with the browns and weathered worn lived-on look. I am looking everywhere trying to figure out a way to just put a clear sealant to protect from UV and weather- but I don’t want to change the color, and I want to keep the Flat/Matte look of the wood. Any type of semi-transparent stain is going to change the color. (I’ve tried many attempts). I have researched water-based Polyurethane to keep the color the same, that’s as close as I can find. Any suggestions???
It is not possible for a clear to give protection. It must be tinted and that means your color will be altered or enhanced. Poly will not prevent UV and will peel.
I painted my deck with glidden porch and floor paint. I want to seal it so the paint does not chip off. Can you please tell me a specific sealer I can use on it?
You cannot evet apply a sealer over a deck stain or paint. It will peel.
What sealant can I use on my 100 year old covered porch that has been stripped. I want something that will scrub off and not need a stripper. In the past used double deck natural, and scrubbed it with bleach each spring. It all came off and I recoated it each year. It always looked wonderful. Then 3yrs.ago my husband bought Bher deck natural stain. It wasn’t bad at first. By the 3rd year it was off in some places and really spotty looking. I’m in the process of stripping it using Bher deck stripper. WHAT A MESS. It’s very hard, the stripper works slow and is needing 2 or 3 applications and heavy scrubbing with a stiff brush and pressure washer. I have a very large porch that swings out in a circle at one end. So far it’s taken 7hrs to do a 5×8 area. What a nightmare!! Is there a type of oil I could use. Please help, thanks
You need a penetrating semi-transparent stain. See this for suggestions: https://www.deckstainhelp.com/the-5-best-deck-stain-reviews-and-ratings/
Older deck; I have three zones of decking hell within a 10′ X 24′ porch. Only 33% exposed NOW that carport roof repaired. Was effectively 66% exposed prior. Guy used a brown poly/oil (found the can in shop) and it is shot in “exposed”, looks “ok” in “not exposed”. I own a pressure washer and am about ready to “hit” it. So, three levels of “mucked-up coming and going”. Am imagining I will need to drum sand entire, but trying to avoid. Recommendation? I see no proof my pictures are posting, but if you will use email provided, I could send pictures. The deck was NOT properly “spaced” between boards and multiple other “what was he thinking(s)”. Carport supports “sit” on top of deck,so total “redo” with composite or other brings a world of structural shenanigans. Only option is “prep and re-seal”.
Pictures would not post if file sizes are too large. We do not work through emails, only in comment areas. You will have to sand off a poly. See this for tips: https://www.deckstainhelp.com/how-to-sand-your-wood-deck/
My deck was previously painted. I did a light sanding, then power washed, allowed to dry thoroughly and then put my first coat of deck paint on. Same color. Same deck paint. But the deck has a a slight tackiness to it. Have I done something wrong? What should I do now?
Let it cure out for a week or two. Hopefully, it goes away. If not, you will have to sand it down ad start over.
Would putting an oil based second coat over the latex first coat work without having to wait? Or is there a clear coat I can use to seal the paint?
No. Adding anything on top would result in peeling and making it even harder to fix.
Thank you
Why use latex on a deck?
I have a covered porch that has minimal exposure to the elements (just the steps and perimiter.) It is made of good quality wood decking material that has held up extremely well for 15 years. I restained it with a gel stain that has some glaze in it. It looks great and I wonder about adding a top coat to keep it looking that way. Something that will give general protection like an interior floor but is ok to use outside?
Nope, it will peel and your gel stain is not designed for outside so that will not work well either. It has no UV protection from graying so it will fade quickly and probably peel on the outside exposed edges. Basically, you can never use interior products on exterior wood.
Here is my issue. I just built a brand new deck. I like so much better the interior stains that you rub off because they pull out the wood grain 100% better that the semi transparent deck stain/sealers out there that you just paint on. My question. If I use the interior stain outside… what can I use to seal it with???
The interior stains will not work on outside wood. No UV protection from oxidation/graying and you cannot ever top coat over a stain with a sealer. It will peel. What you want to do is not possible for exterior wood.
What can I put on top of my natural deck to make it look shiny like a wet look at all times it already has a 10-year clear sealer on it but I want it to to be shiny kind of like a dance floor
You cannot do this. I will blister and peel.
I currently have a painted stain (I think) on our porch that peels every summer. I need to get the current pair/stain off and do what you recommend. Should I just use a paint remover or should I rent a sander and remove it that way? By the way we have a very large porch.
Sand it: https://www.deckstainhelp.com/how-to-sand-your-wood-deck/
If I can apply polyurethane to the wood on my boat and it be fine and exposed to lots of water and outdoor elements, why can’t I put polyurethane to my deck?
It will peel and blister on your deck. Don’t do it unless you want a huge nightmare to fix.
We have decking which has been painted light grey, have no idea what kind of paint. Can you suggest any paint that would look reasonable and survive for a while please?
Paints should never be used on deck and we do not rate them. If you have a solid stain, then look at this: https://www.deckstainhelp.com/what-are-the-best-solid-color-deck-stains/
Hello, we recently stained our newly built deck with a semi- transparent water based stain (Sherwin Williams Super Deck). After only a couple of days, I’m noticing visible scratches from my dogs feet. Is there some sort of top coat we can add that will lessen the wear and tear so quickly?
You can never top coat a deck stain. Nothing will work to fix the problem outside of removing the SW stain by sanding and starting over.
I have a backyard deck, unfortunately, he previous owner re-finished the deck with Sikkens Polyeurathane. Some will say not a good choice because it will blister and peel. The real problem is that the finish is so slippery; that no one dares walk on it when it is wet, or much worse, when it is snow covered. (About six months of the year, here.) I think the only way to make this deck a walkable surface is to remove the Doug fir decking and replace it. Then stain the new wood.
Polyeurathane should be illegal for outside decks!
hate to waste the Doug Fir – what about sanding deck, then apply oil based semi-transparent?
You can do this.
What is the solution? I see discussion of aliphatic polyeurathane but then a comment that it is not intended for exterior use? Of course we could get a floor sander and strip the deck but it’s a big deck, probably a two-day process. Then there’s the issue of the sander planing off the natural texture of the fir planks. One comment recommends applying semi-transparent stain, after sanding, which would be fine, as I have lived with a stained deck. It’s just a huge undertaking. I still think that building codes should prohibit poly-finish on exterior decks.
Sand it all off and then apply a semi-transparent stain that is penetrating. See here for sanding tips: https://www.deckstainhelp.com/how-to-sand-your-wood-deck/
Have you heard of aliphatic polyurethane? Those are impervious to UV radiation, as UV will pass right through it. It won’t prevent what’s underneath from reacting with UV, but as a wear/chemical/water resistant sealant/top coat, it does admirably.
It will not work on exterior wood.
What should I do from this point on
??? No details or pictures.
Hi,
I have a deck made of IPE & PURPLE HART and would love to keep the colors from fading any ideas for a clear finish. full sun!
Thanks
Has to be tinted, not clear for UV protection. See here: https://www.deckstainhelp.com/ipe-exotic-hardwood-stain-review/
I have just replaced the wood on a 20 year old deck that was deteriorating, I did not replace the wood under 2 covered areas. All the wood, both old and new is treated pine. I plan to Stain and seal the deck next spring after the new wood has seasoned some. The old wood has been sealed with Thompson’s Water Seal probably twice over the last 20 years but it was around 10 years ago the last time it was done. The old wood doesn’t get much sun or water and it is just a little gray. Question; what do I need to do to the old wood before staining, I want it to be a dark stain. And will it be possible to get the old wood and the new wood to stain close to the sale color?
The only way to blend new and old wood is to use a solid stain. Clean and brighten all wood for prep with Restore A Deck Kits. Do it all in the Spring. See here: https://www.deckstainhelp.com/staining-a-new-deck/
My deck was built with the poorest quality wood available (I am livid). The wood is already splintering, splitting and in general a total mess. I have gone ahead and treated it hoping to save….something. What would be the best treatment to apply? The quality is so poor that the railing tops are already “flaking” and splintering. If I could clear coat it I would to avoid getting splinters just by resting my hand on the railing. Deck was built in June 2020.
Use a solid stain: https://www.deckstainhelp.com/what-are-the-best-solid-color-deck-stains/