Menards Treated Lumber: Which Grade to Buy (UC3B vs UC4A)

Menards treated lumber only works if the end tag matches the job: UC3B for decking and railings above ground, UC4A for posts, ledgers and garden boxes. Shelf labels like Ground Contact are retail wording, but the AWPA use category printed on the tag decides how long the board lasts. Here is which category each part of a project needs, how to read the tag, and how to compare prices fairly.

Types Of Treated Wood Available At Menards

Treated lumber is described two ways: the grade name on the shelf sign or product listing, and the AWPA use category stamped on the end tag. Menards listing titles that appeared in a web search on October 1, 2026 use grade words such as Above Ground, Ground Contact and Critical Structural. We could not open menards.com pages to confirm current stock or sizes, so check your own store. The grade words are marketing tiers. The end tag is the part you can hold up against a code or a project plan.

How to Read the End Tag

According to the Western Wood Preservers Institute guide to AWPA use categories, the tag lists the treating company, the preservative, the retention in pounds per cubic foot (pcf), the AWPA standard, the exposure, and the inspection agency. WWPI's own example reads CA-C, .06 pcf, Above Ground, AWPA U1, UC3B.

• Preservative: ACQ (alkaline copper quaternary) and CA (copper azole) are the two copper systems in WWPI's tables, and each has its own retention numbers.
• Retention: a higher pcf means more preservative in the wood, which is why one grade costs more than another.
• Use category: UC3B is above ground and exposed, UC4A is ground contact for general use, and UC4B is ground contact for heavy duty or critical parts.

For the full category definitions and a second retailer's lumber aisle, see our Lowe's pressure treated lumber guide. If you want sizes and landscape timbers, our Menards pressure treated lumber sizes guide covers those. This page stays on one question: which grade to put in your cart.

Structural posts need 0.40 pcf of ACQ or 0.15 pcf of copper azole (UC4A), while decking boards need only 0.15 pcf of ACQ or 0.06 pcf of copper azole (UC3B). Source: AWPA 2020 Book of Standards, Table 3-1, via the Western Wood Preservers Institute

Menards Treated Lumber Prices by Dimension

We do not print Menards shelf prices here. Menards.com blocked our automated check on October 1, 2026, and prices change by store and by week, so any dollar figure would be a guess. What you can calculate exactly is how much wood each board gives you, which is what makes two different sizes comparable.

Board feet equal thickness in inches times width in inches times length in feet, divided by 12, using the nominal size. Divide the shelf price by that number to get price per board foot.

Size	Length	Board feet per piece
2×4	8 ft	5.33
2×4	12 ft	8.00
2×6	8 ft	8.00
2×6	12 ft	12.00
2×8	12 ft	16.00
4×4	8 ft	10.67
4×4	12 ft	16.00
6×6	8 ft	24.00
6×6	12 ft	36.00

Here is a worked example with made-up shelf prices, not Menards prices. A 4x4x8 at $9.00 works out to $0.84 per board foot, and a 2x6x8 at $6.00 works out to $0.75. The 2×6 is cheaper per board foot, but you cannot swap it for a post, so use price per board foot to compare boards for the same job, and use the use category to decide whether a board is allowed in the job at all.

Always compare the same category and preservative. A UC3B board and a UC4A board of the same size are different products, and the cheaper one is only a bargain if it is the right one for where it goes.

4×4 Pressure Treated Lumber at Menards

Most 4x4s end up as posts, and posts are where treatment mistakes cost the most because the bottom of a post sits in wet soil. Whether the sign says Ground Contact or Critical Structural, buy by the tag: UC4A or higher for anything in or near the ground.

Ground Contact vs. Critical Structural 4×4

Use category	AWPA exposure	ACQ retention	Copper azole retention	Parts WWPI lists
UC3B	Above ground, exposed	0.15 pcf	0.06 pcf	Decking, railings, fence pickets
UC4A	Ground contact, general use	0.40 pcf	0.15 pcf	Structural posts, sawn fence posts, ledgers, garden boxes, landscape walls
UC4B	Ground contact, heavy duty	0.60 pcf	0.31 pcf	Permanent wood foundations

Here is the common mix-up. Critical Structural sounds like the grade for deck posts, but the AWPA table in the WWPI guide lists structural deck posts at UC4A and saves UC4B for permanent wood foundations. A 4×4 stamped UC4B exceeds the UC4A requirement, so it is acceptable for a deck post, but you do not need to hunt for it. Your local building department has the final word on what your deck requires.

What to Build with Menards 4×4 Treated Posts

• Deck posts: UC4A or higher, because WWPI lists structural posts at UC4A.
• Fence posts: sawn fence posts are listed at UC4A, whether they are set in concrete or soil.
• Raised garden bed corners: WWPI lists garden boxes at UC4A, and the preserved-wood industry FAQ at treatedwood.com says treated wood labeled for ground contact can be used for raised beds for edible plants.
• Landscape walls: UC4A as well.

Our ground contact pressure treated wood guide goes further on what ground contact exposure really means.

Which Treated Lumber for Which Part

This table lists each application from WWPI's guide with the use category it assigns, so you can match each part of a build to a tag before you load the cart.

Part	Minimum use category (WWPI)
Decking boards	UC3B
Railings	UC3B
Fence pickets and rails	UC3A or UC3B
Joists and beams above ground	UC3B or UC4A
Stairs	UC3B or UC4A
Ledger board	UC4A
Structural posts	UC4A
Sawn fence posts	UC4A
Garden box and landscape wall	UC4A
Permanent wood foundation	UC4B

When Above-Ground Lumber Must Be Ground Contact

This is the part most buyers miss. WWPI's note says sawn parts that are physically above ground must still be treated to UC4A or higher in these cases:

• Soil, plants, leaf litter or other debris can build up against the part.
• The structure or nearby plants block air from circulating under the deck and between deck boards.
• The part sits less than 6 inches above final grade on permeable material such as treated wood or concrete.
• The part touches non-durable untreated wood, or older construction showing decay.
• The part gets wet often, such as on a dock or beside a watering system.
• The project is in a tropical climate.

So a low deck whose joists hang 4 inches above the dirt is not a UC3B job just because nothing is buried. It needs UC4A joists and beams.

Before You Build: Drying, Fasteners, Cut Ends and Safety

How Long to Wait Before Staining

Treated lumber is usually sold wet. The treatedwood.com FAQ says it is typically ready to finish about 60 days after installation, and that you can test by dropping water on it: if the water soaks in readily, the wood is ready. Trust the water test over a fixed number of weeks.

Fasteners That Survive Copper

Copper preservatives are corrosive to most metals. The same FAQ calls for hot-dipped galvanized fasteners rated G-185 or stainless steel, and warns against electro-galvanized, G-90 and G-60 hardware. Our Menards deck screws guide covers screw length and coatings.

Cut Ends and Drilled Holes

Cutting a treated board exposes wood the preservative did not fully reach. The FAQ recommends a brush-on preservative on field cuts and drilled holes, and names copper naphthenate. Our guide to sealing cut ends of pressure treated wood walks through it.

Handling, Burning and Disposal

Wear gloves, eye protection and a dust mask when cutting, sawing or sanding treated wood. Do not burn scraps: the FAQ warns that burning concentrates the preservative components in the ash, and the EPA page on chromated arsenicals also advises against it. See our burning treated wood guide for specifics. The EPA says manufacturers voluntarily stopped making CCA-treated wood for homeowner uses in December 2003 and does not require removing older structures. It adds that treated wood can usually go out with ordinary trash, subject to local rules, and should not be reused as mulch.

Frequently Asked Questions

What Is Treated Wood At Menards?

Treated wood at Menards is lumber that has had a preservative driven into it under pressure to resist rot and insects. Listings use grade words like Above Ground, Ground Contact and Critical Structural, but the AWPA use category on the end tag is what tells you where the board can safely go.

How Long Does Treated Wood Last?

No single number applies. Lifespan depends on the use category, the exposure and the care it gets. The most avoidable cause of early failure is using a lower category than the exposure calls for, such as UC3B lumber in soil, where AWPA requires UC4A or higher.

Is Treated Wood Safe For Gardens?

Treated wood labeled for ground contact can be used for raised beds for edible plants, according to the treatedwood.com FAQ. WWPI lists garden boxes at UC4A. Older CCA-treated wood was discontinued for homeowner use in December 2003 per the EPA, so avoid reusing old CCA boards in a vegetable bed.

Can I Paint Or Stain Treated Wood?

Yes, but wait until it is dry. The treatedwood.com FAQ says treated wood is typically ready for finishing about 60 days after installation. Drop water on the surface: if it soaks in readily, the board is ready for stain, sealer or exterior paint.

What sizes of treated lumber does Menards carry?

Stock changes by store, and we could not open menards.com pages to verify current sizes, so check the product listing and your local store before you drive over. For a size-by-size rundown, see our Menards pressure treated lumber sizes guide.

How do I know if Menards treated lumber is dry enough to stain?

Use the water test. Sprinkle a few drops on the board. If they bead up, wait longer. If they soak in readily, it is ready. The treatedwood.com FAQ puts typical drying at about 60 days after installation.

Is Menards treated lumber the same quality as Home Depot?

Quality is set by the tag, not the store. Compare the preservative, retention in pcf and use category on the end tag of each board. Two boards stamped UC4A with the same preservative and retention are equivalent for a post, whichever store sold them.

Can I use Menards treated 2x4s for deck framing?

Often yes, if the tag matches the part. WWPI lists joists and beams above ground at UC3B or UC4A, and requires UC4A when the part is less than 6 inches above grade, has no airflow beneath it, or collects debris. Check the tag and your local code.

Conclusion

Buy Menards treated lumber by the end tag. Use UC3B for decking, railings and above-ground boards with good airflow, and UC4A for posts, ledgers, garden boxes and anything low, wet or buried. Price per board foot tells you what a board costs. The use category tells you whether it is the right board.