House Grail is reader-supported. When you buy via links on our site, we may earn an affiliate commission at no cost to you. Learn more.

How To Treat Rough Cut Lumber For Outdoor Use (4 Easy Steps)

lumber on shelves

Rough-cut lumber is an excellent option for someone looking to cut down on the price when buying lumber in bulk. Of course, with the lower price, this type of wood has some downsides. It lacks finish and is not as resistant to water and other elements, so you will need to treat it. Once you do the necessary treatment, you can use it outdoors the same way you use commercial wood.

If you’re wondering how to treat lumber for outdoor use, we’re here to help! We’ve developed a step-by-step guide for treating rough-cut lumber for outdoor use below.

divider 4

Before you begin

There are some important things to consider before you begin. You should use protective gloves, goggles, and a mask when treating the rough-cut wood. Also, it’s best to process the wood in a well-ventilated area or do it outside because there may be some toxic fumes.

1. Sand the wood

First of all, since the wood is rough-cut, you will need to sand it. It’s best to use an electric sander to achieve a good look and do the job faster. Use 100 grit or 120 grit sandpaper on the power sander. Of course, you can use regular sandpaper, but that will take far more time and effort. This step is essential because you can jeopardize the rest of the process if you don’t sand the wood properly. So, take your time with this part of the project, and be as thorough as possible.

person sanding lumbers
Image Credit: ABO PHOTOGRAPHY, Shutterstock

2. Clean it up

Once you’ve sanded all your rough-cut lumber, you will need to clean it. Sanding creates a lot of dust, and since the lumber is rough-cut, it might have dirt and dust stuck on it. Take a clean, slightly damp cloth to clean the wood. You can also use a pressure washer if you’re doing the job outside. The important thing is to leave the wood to dry properly before you proceed to the next step.

3. Stain the wood

After cleaning, you can now stain the lumber. For this part of the project, it’s best to use a paintbrush and to have a cloth nearby to wipe off any excess stain. There are plenty of different stain options on the market so you can choose a wood stain of your preference. Still, since you’re treating the wood for outdoor use, it might be best to choose a water-resistant stain for the best effect. Apply one coat of stain, and allow it to dry out, preferably by leaving it for several hours. To be on the safe side, repeat this step and add a second coat.

4. Apply wood varnish

Last but not least, you should apply wood varnish to the lumber. Wood varnish is used to prevent scratches and abrasions. It will also make the wood more water-resistant, which will benefit outdoor usage. Once you finish, allow the varnish to dry and sand the wood one more time. Apply two more coats of varnish, and you have completed the treatment.

person varnishing lumber
Image Credit:, Shutterstock

Other Methods of Treating Rough Cut Lumber for Outdoor Use

Other than the steps we mentioned above, there are several other methods people use to treat rough-cut wood. These are some of the most common ones:

1. Outdoor Wood Sealers

Outdoor wood sealers are easy to apply, and they will make your rough-cut lumber last much longer when used outside. These are commonly a combination of oils and chemicals that provide the wood with mildew and UV protection. The main goal of using a wood sealer is to keep the wood dry, which will prolong its lifespan and make it more durable. It’s best to use wood sealers on rough-cut lumber you will use for decks, fences, wooden exteriors, or gazebos.

2. Exterior Paint

Another easy way to treat rough-cut wood for outdoor use is to apply exterior paint onto the wood. Just choose a water-resistant paint and paint over the lumber. Using exterior paint might not be an option for people who still want to preserve the wooden look, though. It works best for outdoor furniture, but you can use it for other outdoor wood projects too.

3. Wood Oils

If you’re looking for an easy solution to treating rough-cut lumber, think about using wood oils. It’s a natural way to protect the wood and prevent decay and rotting. It will provide you with a natural look once you finish, and it will be weather resistant. Although this is a good option, it might not be enough for outdoor usage, so it’s best to mix this method with wood sealers for the best results. If you just use wood oils, the wood will need regular maintenance to keep everything in shape.

4. Epoxy

If you’re looking for the best option to protect rough-cut lumber from water damage, choose epoxy. It’s a polymer that is exceptionally resistant to any liquids. When you apply epoxy to rough-cut lumber you can be sure it’s water-resistant, and therefore it will have a longer lifespan. We recommend using a layer of wood oils and then the epoxy, since epoxy is not UV resistant. The only downside to using epoxy is that once you apply it to the wood, you should wait several days or longer for everything to set completely.

Which wood is the best for outdoor use?

Depending on what kind of project you have in mind, you can use various types of wood outdoor. Both softwoods and hardwoods can be used outside, although hardwoods are more durable. These are our wood recommendations for outdoor usage:

  • Cedar
  • Pine
  • Teak
  • Redwood
  • Cypress
  • Oak

Of course, there are plenty of other options depending on what you want to achieve. Make sure to familiarize yourself with all wood options and know their pros and cons before you make a purchase.

How long will rough-cut lumber last outside?

Rough-cut lumber is very weather-resistant, and it will have a shorter lifespan than commercial wood. Still, rough-cut lumber can last anywhere from 5 to 50 years outside, depending on the conditions. You can always treat the wood by using some of the methods we mentioned to prolong its lifespan. When rough-cut lumber is treated, you can expect it to last at least twice more as usual.

Image Credit: antmoreton, Pixabay

How do you keep your rough-cut lumber from rotting?

To stop rough-cut lumber from rotting, you need to treat it properly. The treatment needs to be UV and water-resistant, and anything from wood vanishes, sealers, oils, or epoxy will work just fine.

Can you use rough-cut lumber to build a deck?

You can use rough-cut lumber to build a deck without any issues. As mentioned throughout the article, you should treat it first. That’s not a must, but if you want your deck to last, you shouldn’t skip that part. Rough-cut wood should always be treated to get the best out of it and increase its durability. Depending on what you want to achieve in the end, you can go for several different treatment options.

Is rough-cut lumber expensive?

Rough-cut wood is affordable, which is why many people use it for their outdoor projects. You will have to treat it, but the final price will be lower than buying commercial wood, even with those costs. So, if you haven’t tried using rough-cut lumber for your outdoor projects, it might be an excellent time to begin and save some money.

divider 7


Rough-cut lumber is a great, inexpensive option for outdoor projects. It has to be treated for outdoor use, but once you read this article, you should have no issues with treating it properly. So, take your time, finish the treatment process, and enjoy your new project while spending far less money on materials.

Featured Image Credit: JueWorn, Shutterstock

Related posts

OUR categories

Project ideas

Hand & power tools