Seal Cedar Deck for a Durable & Better Finish (Important!)

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Should You Seal a Cedar Deck?

A cedar deck finish is very appealing aesthetically, because of its color, which can range from light honey to rich russet. The pleasant, fragrant aroma only adds to the appeal. Cedar secretes natural preservative oils which resists insects and rotting. So, why should you seal a cedar deck?

You must seal your cedar deck once a year, preferably in fall, to enhance its weatherability and increase its durability. 

Without a sealer, the cedar deck finish will

• Fade to a dull gray color
• Get scratched easily
• Encourage fungus growth
• Not be stain resistant
• Get damaged by ice melt or dog pee

Cedar, used for making decks, is classified as a softwood. Softwoods are porous and hygroscopic. They will absorb moisture readily. This also means that they can stain easily.

Porosity is useful as cedar can easily be stained to a desired color. On the flip side, cedar will get permanent stains from red wine or tomato ketchup. Sealing cedar will block the pores and make your cedar deck a lot more stain resistant.

Cedar decks tend to trap moisture and are therefore susceptible to mold, mildew & fungus growth. You must seal to protect your cedar deck from rain and humidity.

Cedar decks get nicked & scratched quite easily because it is a softwood. By sealing your cedar deck you will be able to retain the finish and minimize scratches from deck furniture or dog’s claws.

Sealing a cedar deck will block the pores, extend its life and help retain the finish.

What Happens If You Don’t Seal Cedar?

A cedar deck will last 15 – 20 years, but only if it is regularly cleaned, maintained and sealed. You should reseal your cedar deck, once a year, preferably in late fall to winterize it and to retain its finish for many years.

If you don’t seal your cedar deck regularly your deck will have several problems. Some of these are:

Fading & Loss of Color

A cedar deck looks beautiful when it is new, especially if it has been stained. The sealer protects the stain and the natural color of cedar from the harsh UV radiation from the sun.

If you do not seal your cedar deck regularly, ideally once a year, cedar will lose its original natural color and turn a dull gray. The cedar deck loses its original gloss too, if it is not sealed.

Scuffs & Scratches

Cedar decks get scuffed & scratched pretty easily. The hardness of a wood is a measure of the resistance to denting & wear. This is measured on the Janka Hardness Scale.

The Janka Hardness Score for Western Red Cedar, used as decking is just 350. (Eastern Red Cedar used for making cabinets scores 900).

You need to seal your cedar deck to protect it from scratches from deck furniture and foot traffic.

Mold, Mildew & Fungus Growth

Mold spores, a kind of fungi, are in the air, everywhere, all the time. All they need is to find a spot on the cedar deck that is moist. Wood is made up of cellulose, which is food for the fungi. Add moisture & some shade and mold, mildew & fungi will thrive.

Cedar, being a softwood, is quite porous & hygroscopic. It will absorb water from rain or high humidity conditions. Only sealing your cedar deck will prevent it from absorbing & retaining moisture and resisting fungus growth.

Food & Beverage Stains

A deck is the “go to” place for alfresco dining or just relaxing with a glass of wine. Once in a while there will be spills. Cedar decks absorb the spills very quickly as they are so porous.

Surface spills can usually be removed quite easily with a napkin or a wet mop. However, stains that penetrate are extremely difficult to get rid of. By sealing your cedar deck you will prevent the stains from penetrating.

Damage from Ice Melt & Dog Urine

Do you live in an area that gets really cold in winter? Is your deck is covered in snow often?. You may, as most people do, use a salt based ice melt to hasten the process of getting rid of the snow.

This is not good for your cedar deck finish. Water, rich in salt, penetrates the porous cedar. When the deck dries, the salt within cedar crystallizes, pushes the fibers apart and gives the deck a “fuzzy” appearance.

The deck may also start showing signs of cracking & warping.

Dog pee can damage your cedar deck in a similar way. Dog urine contains uric acid, which is acidic. Uric acid can burn the tannins in cedar resulting in black spots.

Moreover, once uric acid penetrates cedar, dries & crystallizes, it creates the pungent, obnoxious dog pee odor. It is not easy to get rid of the dog pee smell that has got embedded in the cedar deck.

What Is the Best Sealer for a Cedar Deck?

For a new cedar deck that is in the color that you want, you do not need to use a stain. Just use a good quality waterproof sealer that is UV resistant.

Thompson’s Water Seal is the right sealer for a new cedar deck. Its key features are:

• Waterproofer – prevents water damage
• UV Resistant – prevents fading
• Mold & Mildew Resistant

However, if you are resealing an existing cedar deck then you should use a product that is a combination of a stain & a sealer. It will bring back the natural color without having to stain and then seal in two operations.

Thompson’s Water Seal Semi Transparent Waterproofing Stain, Woodland Cedar, could be a good option for you. 

How Do You Seal a Cedar Deck?

Here is how to seal a new cedar deck:

• Wait for a month after installing the deck before sealing
• Use a waterproof or water repellent wood sealer. 
• Wash & sand the deck before applying the wood sealer
• Wood sealer can be applied just like paint using a brush, roller or spray
• Apply 2 coats, with a gap of 24 hours between coats, in case of a new deck.

Here is how to reseal an existing cedar deck:

• Sweep the deck to remove dust & debris
• Repair cracks & chips. Hammer in any protruding nails
• Pressure wash the deck to remove any traces of the old stain
• Clean the deck with a Thompson’s Water Seal 3 in 1 Wood Cleaner to
  • remove stains from dirt, mildew, algae & fungus
  • eliminate tannin & rust stains
  • brighten & restores wood’s natural beauty
• Sand areas that still have some of the stubborn old stain
• Apply the combination stain+sealer using a staining pad

Thank you very much for reading the post. I do hope you found it informative and helpful.