When embarking on a woodworking or construction project, understanding lumber dimensions is critical for success. At Ipe Woods USA, we specialize in providing premium Ipe wood—a durable, tropical hardwood ideal for decking, siding, and outdoor projects. However, the difference between nominal and actual lumber sizes, alongside other sizing conventions, can be confusing. This comprehensive guide will help you navigate Ipe wood dimensions and make informed decisions for your next project.
Nominal vs. Actual Lumber Sizes: Why the Difference Exists
Lumber is typically sold using nominal dimensions, which are the sizes assigned to a piece of wood before it is fully processed. However, the actual dimensions—the measurements you’ll get when you measure the board—are smaller due to the milling, drying, and surfacing processes. For Ipe wood, which is often kiln-dried and surfaced for precision, these differences are standardized but still important to understand:
| Nominal Size | Actual Size |
|---|---|
| 1″ x 6″ | 3/4″ x 5-1/2″ |
| 5/4″ x 6″ | 1″ x 5-1/2″ |
| 2″ x 4″ | 1-1/2″ x 3-1/2″ |
| 2″ x 6″ | 1-1/2″ x 5-1/2″ |
| 2″ x 8″ | 1-1/2″ x 7-1/4″ |
| 4″ x 4″ | 3-1/2″ x 3-1/2″ |
| 6″ x 6″ | 5-1/2″ x 5-1/2″ |
For additional sizes that are available and more information visit our page on Ipe Wood Sizes.
These differences can affect everything from structural calculations to how pieces fit together in your design. For example, if you’re building a deck with 1″ x 6″ Ipe boards, you’ll actually be working with 3/4″ x 5-1/2″ boards, which could impact spacing and load-bearing considerations.
Specialty Lumber Sizing with Ipe Wood
Beyond standard dimensional lumber, Ipe wood is commonly used in specialty applications such as decking, siding, and structural beams. These products have their own sizing conventions:
- Decking and Patio Planks: Ipe decking is often sold in a nominal 5/4″ x 6″ size (actual: 1″ x 5-1/2″). This thickness provides a balance of strength and aesthetics, ideal for outdoor flooring. Ipe decking may also come in 1″ x 4″ (actual: 3/4″ x 3-1/2″) for narrower profiles or custom designs.
- Siding and Cladding: Ipe siding typically ranges from 1″ x 4″ to 1″ x 8″ nominal sizes, with actual dimensions following the same reductions as above. The durability of Ipe makes it a popular choice for exterior cladding, resisting weathering and insects naturally.
- Glue-Laminated Beams (Glulam): While less common with Ipe due to its high cost, glulam beams made from tropical hardwoods follow similar nominal-to-actual sizing rules as dimensional lumber. Common sizes might range from 3-1/8″ x 5-1/8″ to larger beams like 3-1/8″ x 24″.
- Engineered Wood Products: Unlike solid Ipe, engineered products like laminated veneer lumber (LVL) or parallel strand lumber (PSL) are rarely made from Ipe but can be used in conjunction with it. These products are manufactured to precise dimensions, so their listed sizes are typically their actual sizes.
When working with Ipe wood specifically, keep in mind its extreme density (nearly three times harder than oak) can affect milling precision. Always confirm actual dimensions with your supplier to ensure accuracy.
Standard Lumber Lengths for Ipe Wood
Ipe lumber is typically available in lengths ranging from 6 feet to 20 feet, with increments of 2 feet (e.g., 6′, 8′, 10′, 12′, etc.). At Ipe Woods USA, we often stock lengths up to 20 feet, though longer lengths (up to 24 feet) may be available upon special order. Minor variations in length can occur due to milling tolerances, so it’s wise to measure your stock upon delivery.
For larger projects, such as expansive decks or pergolas, you may need to join shorter lengths of Ipe. In such cases, using stainless steel fasteners or hidden fastening systems ensures a seamless appearance and prevents corrosion due to Ipe’s high tannin content.
How to Calculate Board Feet for Ipe Wood
Since Ipe wood is premium and often more expensive than softwoods, calculating the exact amount you need can save costs and reduce waste. Lumber is priced by the board foot—a unit of volume equivalent to a piece 1-inch thick, 12 inches wide, and 12 inches long. Use this formula to calculate board feet:
(Thickness in inches × Width in inches × Length in feet) ÷ 12 = Board Feet
Example with Ipe Decking:
Suppose you’re purchasing nominal 5/4″ x 6″ Ipe decking boards (actual: 1″ x 5-1/2″) in 8-foot lengths:
(1″ × 5.5″ × 8′) ÷ 12 = 3.67 board feet per board
If your deck requires 500 square feet of coverage and you’re using 5/4″ x 6″ boards with a 1/8″ gap between boards, you’ll need to account for the actual width (5.5″) plus the gap (5.625″ total width per board) to determine how many boards and board feet you need. Tools like online board foot calculators can simplify this process—just input your project dimensions and desired Ipe size.
How Ipe Lumber is Manufactured
Understanding the manufacturing process clarifies why nominal and actual sizes differ and highlights the quality of Ipe wood:
- Harvesting and Rough Cutting: Ipe logs are sustainably harvested from South American forests, primarily Brazil. They’re rough-sawn into oversized boards to account for later shrinkage and milling.
- Drying Process: Ipe is typically kiln-dried or air-dried to reduce moisture content to around 12-16%, ideal for outdoor use. This controlled drying minimizes warping and cracking, though the process causes slight shrinkage.
- Planing and Surfacing: Boards are surfaced on all four sides (S4S) to achieve smooth, uniform dimensions. This step reduces the size to the “actual” dimensions listed above. For Ipe, some suppliers offer “E4E” (eased four edges) to prevent splintering, which slightly rounds the edges.
Because Ipe is so dense, the milling process requires specialized equipment, ensuring clean cuts and precise dimensions. However, its natural oils can cause slight variations in finish—something to discuss with your supplier if you need exact tolerances.
Tips for Buying the Right Ipe Lumber Size
Here are expanded tips to help you select the right Ipe wood for your project:
- Account for Shrinkage: Both kiln-dried and air-dried Ipe have minimal shrinkage after installation (typically less than 1% when properly acclimated), but ensuring the wood adjusts to your local climate before installation is key to avoiding gaps or warping over time.
- Kiln-Dried and Air-Dried Lumber: At Ipe Woods USA, we sell both kiln-dried and air-dried Ipe, and both are suitable for outdoor use as long as they are acclimated to your environment before installation. Kiln-dried Ipe is more dimensionally stable and ready for immediate use, while air-dried Ipe offers a more natural drying process and can be slightly more cost-effective. Allow the wood to sit at the installation site for 7–14 days to adjust to local humidity and temperature levels.
- Rough vs. Planed Lumber: Rough-sawn Ipe retains its natural texture and can be custom-milled to your specifications. Planed Ipe (S4S) is smoother and slightly smaller due to milling but easier to work with for beginners. For a rustic look, consider rough-sawn; for sleek modern designs, opt for planed.
- Check for FSC Certification: Since Ipe is a tropical hardwood, ensure your supplier offers Forest Stewardship Council (FSC)-certified lumber to support sustainable forestry practices. At Ipe Woods USA, we prioritize responsibly sourced Ipe.
- Plan for Fasteners: Ipe’s density requires pre-drilling for screws or nails to prevent splitting. Hidden fastening systems (e.g., Ipe Clip) are popular for decking to maintain a clean surface. Factor in these requirements when calculating board spacing and quantities.
Why Choose Ipe Wood?
Ipe is renowned for its unmatched durability, with a Janka hardness rating of 3,680 lbf (pounds-force), compared to red oak’s 1,220 lbf. It’s naturally resistant to fire (Class A rating), insects, and weathering, making it ideal for outdoor applications like decks, pergolas, and siding. While its premium price reflects its quality, understanding sizing ensures you maximize value by ordering precisely what you need.
Shop Ipe Wood with Confidence at Ipe Woods USA
At Ipe Woods USA, we offer premium Ipe lumber in a wide range of sizes for decking, siding, and custom projects. By understanding lumber dimensions and how they apply to Ipe, you can avoid miscalculations and ensure your project runs smoothly. Need help selecting the right size or calculating quantities? Our team is here to assist!