How to choose hardware and lumber for home projects

Start by matching the material to the job

Hardware and lumber work best when they are selected as one assembly, not as separate items on a shopping list. A good board can fail early if it is held with the wrong screw, and a strong connector cannot make up for lumber that is undersized, too wet, poorly graded, or not treated for the exposure. For most home projects, start with four questions: is the wood structural or decorative, will it stay dry or get wet, will it touch soil or concrete, and does a local building code or project plan specify the material?

This guide focuses on practical buying checks for common framing, repair, deck, fence, shelving, and exterior projects. The recommendations align with public guidance from NIST, the American Wood Protection Association, the International Code Council, the American Wood Council, the U.S. Environmental Protection Agency, and recognized lumber grading organizations such as WWPA and SFPA. For more material selection articles, visit the Buying Guides section.

• Interior dry projects: Untreated kiln-dried lumber and standard interior hardware are usually appropriate when the assembly is nonstructural and protected from moisture.
• Structural framing: Use the lumber species, grade, size, and fasteners specified by the plan, span table, or local code.
• Exterior above-ground work: Consider decay-resistant or preservative-treated lumber, along with corrosion-resistant fasteners.
• Ground contact or hard-to-replace parts: Choose treated lumber with the correct use category and hardware rated for preservative-treated wood.

Read lumber sizes, grades, and stamps before you load the cart

Lumber buying is easier when you separate the trade name from the installed size and structural grade. NIST explains that a common name such as 2×4 is a nominal size, meaning it is an approximate trade designation rather than the final dressed dimension. A standard surfaced dry 2×4 commonly measures about 1 1/2 in. by 3 1/2 in. after drying and planing. That difference matters when you are fitting shelves into a tight opening, replacing a board in an existing frame, or calculating clearances for trim and panels.

Nominal size is not the installed size

Before buying, measure the space where the board will actually be installed and compare it with the actual dimensions on the rack label or supplier listing. This is especially important when new lumber is being tied into older framing, because older structures may contain boards that do not match modern surfaced sizes. If the project requires a tight fit, do not rely on the nominal name alone.

Grade stamps carry important information

Most softwood structural lumber is marked with a grade stamp. Under the American Lumber Standard system, a typical stamp identifies the grading agency, mill, grade, species or species group, and seasoning condition. Common moisture designations include S-Dry or KD19 for lumber surfaced or kiln dried to a maximum moisture content of 19 percent, MC15 or KD15 for a maximum of 15 percent, and S-Grn for unseasoned lumber over 19 percent at the time of surfacing.

Grade is not just a label. Select Structural and No. 1 grades have tighter limits on strength-reducing defects than lower grades. No. 2 is common in many framing applications, but it is not a universal substitute. Stud grade is intended for vertical stud use, while appearance boards are often selected for visible faces rather than structural strength. If a plan calls for No. 2 Southern Pine, Douglas Fir-Larch, or another specific grade and species group, do not replace it with a better-looking board unless you confirm that the substitute meets the structural requirement.

Choose treated lumber by exposure, not by color alone

Pressure-treated lumber is not a single product. Treatment levels and preservatives are selected for specific exposure conditions. The American Wood Protection Association Use Category System is the clearest way to read those conditions. UC1 is for interior dry conditions. UC2 covers interior damp conditions. UC3B is used for above-ground exterior exposure where the wood can dry between wetting cycles. UC4A is for ground contact general use and also covers some above-ground situations with ground-contact hazards, such as poor ventilation, frequent wetting, or components that are difficult to replace. UC4B is used for heavier-duty ground contact and critical applications.

For the buyer, the important step is to read the end tag. A green or brown color does not prove the correct treatment category, and some modern treated products are not strongly colored. The end tag should identify the treatment standard, use category, preservative, retention information, and inspection agency. If the lumber will become a fence post, deck support, sill near masonry, or another part that stays wet, look for the category required for that exposure instead of assuming above-ground treated lumber is enough.

Cut ends and drilled holes also need attention because they expose inner wood that may not have the same protection. Many treated-wood guidelines recommend field treatment of cuts in exterior or ground-contact applications with a preservative suitable for the original treatment system. Also keep the EPA safety point in mind: preservative-treated wood should not be burned in a residential setting. The EPA also records that manufacturers voluntarily discontinued most residential uses of CCA-treated wood after December 2003, so extra caution is sensible when handling old reclaimed treated lumber from decks, playgrounds, or landscape structures.

Match fasteners and connectors to the lumber

The costliest hardware mistake is often a compatibility problem: using a metal that does not suit the wood, treatment, or exposure. Moisture, preservative chemicals, salt air, and dissimilar metals can all accelerate corrosion. The 2021 International Residential Code section R317.3.1 states that fasteners, nuts, and washers for preservative-treated wood are to be hot-dipped zinc-coated galvanized steel, stainless steel, silicon bronze, or copper, with stainless steel required for staples. It also directs connector coatings to follow the connector manufacturer’s recommendations, or a minimum G185 galvanized coating where recommendations are absent.

In practical buying terms, plain bright nails, drywall screws, and indoor wood screws belong indoors and away from treated lumber. For decks, fences, exterior stairs, sill plates, and other wet-service applications, choose packaging that specifically says the fastener is approved or recommended for the lumber treatment and exposure. In coastal environments or other corrosive locations, stainless steel is often the safer choice, especially where the manufacturer or code requires it.

Do not mix connector systems casually. A joist hanger is rated with specific nails or approved structural screws, not with whichever screw is closest on the shelf. A deck screw may be excellent for holding deck boards down, but that does not make it a substitute for a hanger nail, lag screw, through-bolt, or engineered structural screw. When hardware has a load rating, that rating depends on the exact fastener type, diameter, length, and installation pattern.

Inspect boards and hardware before checkout

Even when the label is correct, the individual pieces still need a quick inspection. Pull each board and sight down its length from both ends. Some crown is normal in framing lumber, but severe bow, twist, cup, or crook can create installation problems and waste. For framing, place the crown consistently according to the builder’s practice. For shelves, trim, furniture-like projects, or deck boards, flatter and straighter stock is usually worth the extra sorting time. See also: Fasteners.

• Look for splits and checks: Small checks can be normal as wood dries, but deep splits near fastener locations reduce performance and appearance.
• Watch large knots at edges: Knots near edges or bearing points can interfere with fastening and cutting.
• Check wane: Wane is missing wood or bark along an edge. It may be allowed within a grade, but it can be a problem where full bearing or appearance is needed.
• Compare moisture feel and weight: Very wet boards may shrink more after installation. For interior trim or panel-like work, allow material to acclimate before final fitting.
• Buy hardware in the same system: Match screws, nails, washers, bolts, anchors, and connectors by coating and material. Avoid mixing stainless and galvanized parts in the same wet connection unless the manufacturer allows it.

Storage before installation also matters. Keep lumber off the ground, support it evenly, and protect it from standing water. For appearance work, sticker and acclimate boards in the space where they will be installed when possible. For treated lumber, follow supplier guidance on spacing and finishing, because boards installed wet may shrink as they dry.

Plan quantities, cuts, and substitutions before shopping

A useful buying list is more than a board count. Start with a simple cut plan and identify the longest required pieces first. Long clear lengths are harder to substitute than short blocking pieces. Add a reasonable waste allowance for cuts, defects, and sorting, especially for visible work. For sheet goods, map cuts before buying so grain direction, finished faces, and panel seams land where you want them.

For hardwood or specialty boards sold by the board foot, the standard formula is thickness in inches multiplied by width in inches multiplied by length in feet, divided by 12. For dimensional softwood sold by piece, use the store’s listed nominal size but design around actual size. For hardware, count every connection, then add the correct nuts, washers, anchors, driver bits, and specialty fasteners. Running out of approved hanger nails or washers halfway through an assembly often leads to poor substitutions.

When an item is out of stock, substitute by performance rather than appearance or price alone. A longer board may be acceptable if it can be cut down, but a lower grade, different species, thinner connector, shorter screw, or different coating may change the strength or durability of the assembly. If the project is structural, check the plan, local code office, engineer, or manufacturer instructions before substituting.

Common mistakes that increase cost or shorten service life

• Buying the cheapest board without reading the stamp: Low price is not helpful if the grade, species, or moisture condition is wrong for the job.
• Ignoring actual dimensions: Nominal sizes can create layout errors, especially in repair work and built-ins.
• Using above-ground treated lumber where ground contact is needed: Exposure category is a durability requirement, not a cosmetic label.
• Using indoor screws outside: Interior screws can corrode, stain wood, or lose holding capacity in wet service.
• Replacing connector nails with random screws: Rated connectors depend on specified fasteners.
• Skipping end-cut treatment on exterior treated wood: Fresh cuts can expose less-protected wood fiber.
• Storing lumber directly on soil or concrete before installation: Moisture pickup and staining can start before the project begins.

Frequently asked questions

Is a 2×4 really 2 inches by 4 inches?

No. In modern surfaced softwood lumber, 2×4 is a nominal trade size. A common actual size is about 1 1/2 in. by 3 1/2 in. Always check actual dimensions when fit matters.

Can regular screws be used with pressure-treated lumber?

Regular interior screws should not be used for pressure-treated lumber in wet or exterior service. Choose fasteners labeled for treated wood and the expected exposure, such as hot-dip galvanized or stainless steel where appropriate.

What is the difference between above-ground and ground-contact treated lumber?

Above-ground treated lumber is intended for exposure where the wood can dry and is not in contact with soil or similar hazards. Ground-contact lumber is treated for more severe moisture and decay risk, including posts, supports, and hard-to-replace parts.

Should hardware or lumber be bought first?

Decide the design first, then buy the lumber and hardware together. The board size, treatment, species, and exposure determine which nails, screws, bolts, anchors, and connectors are appropriate.

Does color prove that lumber is pressure treated?

No. Color is not a reliable specification. Read the end tag or product documentation for the treatment standard, use category, preservative, and approved applications.