This post was updated on July 2, 2024
Hi, I am Scott Paul, a leading exterior restoration contractor and business owner with over 30 years of experience in exterior wood coatings. See here for more info about me.
Clear Sealer or Poly over a Deck Stain?
If you have ever considered using a polyurethane coat to give your outdoor wood deck a smooth appearance, read this article and consider the potential repercussions. As always, I appreciate your input, so feel free to leave a comment below.
Peeling Deck Varnish
Deck stains are meant as a protective finish for exterior wood. They contain special UV shielding pigments and mildewcide to ward off mold and mildew and keep the wood from fading. Other sealers or clear finishes will not adhere well to a deck stain and may result in the topcoat failing prematurely. The clear sealer or polyurethane will likely peel and flake off the deck stain.
Clear Sealer Over Deck Stain
Unlike paint, stains, and sealers are not necessarily designed to adhere to each other. Most are designed to penetrate the wood or at least adhere to the bare wood in the case of film-forming stains. Applying a clear sealer over a deck stain is never a good idea. It won’t help the deck stain or give any added protection more than it already is. Clear sealers have no pigment and, therefore, provide zero UV protection. The same goes for polyurethane.
Peeling Polyurethane Deck
Shiny Deck Stain
If you are looking for a more shiny finish on your exterior wood surface, it is best to choose a deck stain that will give you the appearance you are looking for. Applying a clear sealer or polyurethane over a deck stain will cause more problems than it is worth. If you want a clear finish, you can strip off any old stain and start fresh with bare wood. Then, you can apply a clear sealer if that is the look you are going for. Remember that you won’t get any UV protection from a clear sealer, only water protection.
Polyurethane Peels on Exterior Wood
In addition, applying polyurethane over a deck stain will make it nearly impossible to maintain the deck down the road. As the deck stain begins to fail underneath the polyurethane, it won’t be possible to clean and recoat it without first stripping or power sanding off all the polyurethane.
Peeling Polyurethane Exterior Wood
Questions on Sealing over a Deck Stain?
So, can you apply a clear sealer or polyurethane over a deck stain? It is not recommended and should be avoided if possible. Feel free to ask me any clarifying questions below.
I have a deck that has previously been stained (2 years ago) with Benjamin Moore semi transparent deck stain. I recently power washed it and scrubbed it with vinegar and baking soda and then power washed it again. I like the color and don’t want to add more stain. Can I use Olympic transparent sealer on it?
Did you remove all of the old BM stain?
No. It was one coat and it has faded over two years and with the washing.
No, I didn’t.
You must remove all when switching stain brands. Post some pics for advice on how to remove it fully.
I screwed up and uses exterior acrylic stain on an inside project. Can I put some sort of polyurethane top coat over it and not risk damage?
It will most likely not work.
I have stained my redwood deck with semi-transparent stain 2 month ago, The stained doesn’t look good and also there is constantly footprint or dirt mark . It get instantly dirty. Is there a sealer that I can apply to avoid or minimize the footprint? Or do I need to redo the stain process and choose different stain and color?
No, you cannot apply a sealer or coating over a deck stain. It would peel if you tried.
So basically your recommendation is that there is NO coating to put over deck stain for additional protection against say pet poop or urine?
Correct, it does not work.
Could I put a stain sealer over top of the stain I have already put down? Like the #1 brand you recommend?
You cannot apply a sealer over a deck stain. It will peel if you did this.
I stained my cedar deck with Ready Seal 510. After a year the deck has sustained a lot of scratches, scrapes and wear. Is there a way to make the cedar decking more resistant to scratches, like a Poly coating or something else?
No. It would peel if you did this.
I want to stain and protect my barn that was recently built. It is rough cut pine It has been weathering since June. Do I have to do the whole cleaning and brightening process? Would love to spare the extra work. I planned on using a penetrating oil based semi transparent stain. What product works best on vertical wood? Any opinions on Ready Seal 510 Exterior? Much thanks!
Yes, clean and brighten all wood. Ready Seal is a very poor stain. Use one of these brands:
https://www.deckstainhelp.com/best-semi-transparent-deck-stain-reviews/
I have solid Acacia steps with an anodized clear satin finish (exterior, little to no sun with occasional light rain) that are generally in excellent condition, but after 2 years, I have a couple of very minor scrapes and I would like to recoat them with something just as bullet proof without having to take them all the way down to bare wood. Any ideas? Also in another few months, I will be putting down a deck made of red cedar with a clear penetrating oil – any ideas for a protective coating/sealer to go over that oil would be appreciated too. Thanks!
You cannot apply a different coating over your current coating. Use the same as before and make sure to follow their prep directions.
You cannot apply a sealer over a clear deck oil. In addition, you need a deck stain, not a clear oil for UV protection.
https://www.deckstainhelp.com/will-a-clear-sealer-prevent-graying-on-deck/
I want to faux paint my covered deck. I would use a solid deck paint and then apply glaze and wipe it down to resemble wood grain. I will need to put on a clear topcoat. What product do you recommend?
I have done this technique on wood garage doors with great success. Just not sure about a good sealer you can walk on for the deck.
Don’t do this. It will peel on an exterior deck and create a huge mess for you to fix. The main reason is you can never top coat over a deck stain.
We had a front porch installed last end of September early October. It’s all yellow pine . I want to apply a sealer. The one guy I talked to told me to wait about 3 months before I stained it . I guess to let it weather. Now it’s June. I am in Chicago and it has been very hot. I spray it down to cool down the porch and put life back into the wood . We have direct sunlight from 12:30/1:00 pm until 8:00 or so. My question is what kind of clear sealer can I use. And what else should I do to prep the wood before sealing.
You cannot apply a clear sealer and have UV protection:
https://www.deckstainhelp.com/will-a-clear-sealer-prevent-graying-on-deck/
It must be tinted. Use one of these brands:
https://www.deckstainhelp.com/best-semi-transparent-deck-stain-reviews/
Clean and brighten for prep.