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Difference Between Pressure Treated And Untreated Rot-Resistant Lumber

All You Need to Know about Pressure Treated Lumber

What is pressure treated lumber and what are its advantages?

Lumber treatment, as the term suggests, is a way of preserving wood from insects and rot. Different methods of treatments are used to preserve wood, one being pressure treatment or PT. Pressure treatment of wood involves the infusing of wood with chemical preservatives. The term “pressure” is from the fact that the treatment is done in a pressurized holding tank. This pressure removes air, replacing it with preservatives. The chemical compounds used to pressure treat lumber are copper-based, copper being a natural biocide.

The greatest benefit of pressure treated lumber is that it is insect and rot resistant. This makes this a good solution for areas that are prone to moisture such as decks, boardwalks, swing sets, picnic tables, landscaping tiles, underwater dock pilings, playgrounds, and poles since rot encourages the growth of fungi, bacteria and other microorganisms. However, it is important to note that the process does not prevent corrosion and weathering and you should, therefore, take other preventive actions to prevent these.

Due to the preservatives used, you should wear NIOSH N95 dust mask, protective goggles, and globes when working with treated lumber. You should also avoid burning the wood and instead dispose of scraps and sawdust in a landfill.

Untreated Softwood Lumber

There are times when you will be able to substitute the untreated softwood with rot resistant lumber. A good example is where you will have contact with cement. In this case, you can sandwich the roofing felt between cement and the untreated lumber. If there are any exposed parts of the untreated softwood, you can cover them up with caulk. Caulk keeps moisture from getting to the untreated lumber thus preventing rot. Alternatively, the untreated lumber can be coated with good quality paint. Doing so will be ideal if you plan on using the softwood outdoors. Oil-based enamel offers the best protection against insect damage and rot.

The three are the types of lumber that you will find from your supplier. When used properly, they can help you meet a wide range of needs. It is important to note that the best choice is one that is based on the environmental demands and your desire for more environmentally friendly materials. The cost of the materials will also have a part to play.

The quality of building materials you end up using will affect your construction. This is why your choice of materials should not be based solely on the cost of the materials but how well the materials will withstand the elements. You should liaise with your supplier to better understand the merits and demerits of all the available options. Don’t choose a material because your friend recommended it but because it will help meet your needs.

The type of lumber you use in construction can make the difference between great outcomes and failure. Prior to contacting a supplier, it is important that you understand your options more so when it comes to pressure and untreated lumber. The purpose of this post is to help you understand your options.

Pressure Treated Lumber

This type of lumber is ideal for contact with the ground or concrete that can wick water. It is treated to prevent insect damage and rot. The pressured lumber is created by placing untreated softwood lumber in vacuum chambers with preservative agents; mostly copper or boron based compounds. The vacuum works by forcing the preservative agents deep into the wood thus ensuring preservatives go all over the wood.

As a result of the added components, pressure treated lumber is bulkier than the untreated lumber. It can be hard to cut. What is more is that it will cost you more than the untreated softwood lumber. However, pressure treated lumber is less expensive than the naturally rot-resistant lumber.

Untreated Rot-Resistant Lumber

There are types of lumber that are rot resistant, naturally. This trait is used as a selling point for families that have kids and animals that tend to chew on wood. The main species with the natural rot resistance include cypress, western cedar, redwood, Pacific yew and black locust. The first three are the most common and the least expensive. All in all, when compared to pressure treated lumber, the untreated lumber is lighter, easy to cut but more expensive.

Types of pressure treated lumber

Treated lumber used in construction is broadly categorized into Borate, Non-Com (non-combustible), and Alkaline Copper Quat (ACQ) and other rot-resistant treatments. Borate is a newer treatment process. The material should be wrapped in a water-tight material during storage. Exposure to the elements during “normal” construction process is allowable. No special fastener is required. ACQ is used for exterior applications, with no special covering precautions necessary. It should be used together with hot dipped galvanized or stainless-steel fasteners. Non-combustible treatments, as the term suggests, give lumber fire resistance. Non-com lumber is not for direct exterior exposure.

Should pressure treated lumber be painted?

It is not recommended that you paint pressure treated lumber because paint will crack and fail to adhere properly because the wood takes months to shrink and re-contract on and off. The treatment used on the wood leaves the wood rather wet, which would cause peeling when painted on. Painting can be done, but it is quite a process and there is no reason to do it.

In any case, pressure-treated lumber should be allowed to dry thoroughly before it is painted or stained. You can test dryness by pouring water on the surface. If the water beads up, then the lumber is too wet, and vice versa.

What are the uses of pressure-treated lumber?

Pressure-treated lumber should be used for outdoor projects – they are not ideal for indoor projects. This is because the chemicals used in pressure treatment are not safe for humans. Pressure treated lumber is used in such applications as decks, underwater dock pilings, pergolas, boardwalks, picnic tables, swing sets, landscaping tiles, and playgrounds.

How does the strength of pressure treated wood compare to that of regular wood?

Pressure-treated lumber is no stronger than regular wood, but it is also not any weaker. The difference between regular and pressure-treated lumber is that the treated wood has greater resistance to the elements and to pests. It, therefore, maintains its integrity not from being stronger, but from being rot resistant.

How much does pressure-treated lumber cost?

At Bernardi Building Supply, we have a wide variety of pressure treated lumber for you to choose from. Although the wood is more expensive compared to regular wood because of the treatment process it has to go through, it is still the more cost-effective option since you will get a longer life. Our pressure treated lumber comes in different sizes and is of the highest quality.

The different grades of pressure treated lumber

We understand that our customers have different uses for pressure treated lumber. This is why the wood comes in different grades. Other than plywood, most treated lumber doesn’t come in a variety of grades. All treated lumber can be used for different types of outdoor applications. Appearance is not an important consideration when selecting pressure treated lumber because the wood will be covered with drywall, trim, or paint anyway. At Bernardi Building Supply, we have our own treated wood, which means better quality and wide availability.

What fasteners should be used with pressure-treated lumber?

We recommend that you use only hot-dipped galvanized or stainless-steel nails, bolts, screws, connectors, and anchors. Most of today’s wood treatments are especially corrosive to aluminum and as such you should use vinyl or copper flashing. Alternatively, wrap the lumber in protective rubberized membranes. Before drilling a screw or a nail, drill a pilot hole. This helps prevent splitting and is particularly important when the fastener is being installed near the end of the board.

Does pressure-treated lumber shrink?

Pressure-treated lumber will shrink to some degree across its width as it dries out. You should, therefore, take this small amount of shrinkage into account when laying fence boards or decking. Note that the lumber will develop cracks after (called “checks”) about 6 to 12 months along the surface of the board. These are part of the normal drying process.