Large timber is a defining element in pergolas, covered outdoor structures, and exposed architectural framing. When those sections split along the face, the connections weaken while the finishes fail to hold. As a result, the structure will appear as a quality problem on first inspection. Boxed heart cedar is the most common material in that size range, and it's prone to exactly that outcome. Meanwhile, Douglas fir beams specified as Free of Heart Center (FOHC) are built to avoid this issue.
The difference comes down to the pith. As the juvenile core dries more slowly than the surrounding wood, internal stress builds and pushes outward. The FOHC specification removes the pith entirely from the cross-section. The timber dries more uniformly, and the conditions that produce deep splitting now have far less room to develop.
What "Free of Heart Center" Actually Means in the Mill
Every log has a pith: the soft, juvenile core that forms first as the tree grows. In a boxed heart beam, that core sits at or near the center of the finished timber. As the piece dries from the outside in, the outer fibers shrink while the pith stays wet. The mismatch drives the radial cracking that runs from the surface toward the center.
FOHC specifications require the removal of the pith from the finished cross-section. The sawyer positions the cuts to produce pieces coming from the more mature and stable outer wood. Because the moisture gradient is more consistent without the pith, the timber dries in a more controlled way. Compared to boxed heart material, checking in Douglas fir beams becomes significantly reduced. Note, however, that some surface checking in large timbers is a normal part of seasoning and rarely affects structural integrity. In contrast, the deep, face-to-face splitting that occurs in larger boxed heart sections presents a real problem. Checking affects both appearance and, in certain connection zones, performance.
Why Douglas Fir Beams Hold Up Where Cedar Doesn't
Douglas fir is one of the most specified structural species in North America. It's dimensionally stable, holds fasteners well, and offers a high strength-to-weight ratio across a wide range of load conditions. The USDA Forest Products Laboratory identifies it as the single most important lumber species in the United States. Its applications span dimensional lumber, heavy timber framing, and engineered construction.
FOHC grading reinforces those properties with a more consistent drying profile. The result is a beam that performs predictably in service and resists moisture-driven movement. Surfaces stay cleaner on exposed applications like pergolas, covered patios, and outdoor living structures.
The species also accepts surface treatment well. Lee Roy Jordan Lumber Company carries FOHC Douglas fir in its timber inventory. Our milling services at the Hillsboro, TX remanufacturing plant can surface timbers to a smooth finish on request.
The Splitting Problem with Boxed Heart Cedar
Another popular large timber is Western Red Cedar, which is widely used for good reason. It's lightweight, appealing, and naturally resistant to decay. However, at dimensions of 8×8 or above, cedar timbers are almost always sawn to include the boxed heart. This results in lumber prone to pronounced splitting as it dries.
Thankfully, FOHC Douglas fir beams don't have that limitation, as the wood comes from larger-diameter logs. This makes producing FOHC material at structural sizes easier and more practical. The beam dries more evenly, and the deep splitting that boxed heart cedar develops is greatly reduced.
It's worth knowing that some surface checking in large timbers is normal and doesn't affect structural integrity. The problem with boxed heart cedar isn't seasoning checks, which stop short of the opposite face. It's the true splits that pass all the way through, and these are what the FOHC specifications are designed to prevent.
Specifying FOHC Douglas Fir Beams for Your Next Project
Lee Roy Jordan Lumber Company carries structural timbers in sizes up to 12" x 20" and lengths up to 40’. This range covers most architectural and construction applications across the Dallas area. Our in-house milling services mean that surfacing is available upon request.
Douglas fir beams' strength, dimensional stability, and consistent drying behavior make them a reliable counter to the cracking that boxed heart cedar produces in larger sections. If splitting and checking on large timber jobs has been a recurring headache, it's worth having a conversation about FOHC before your next order. Contact us and we’ll be glad to help you match the right lumber grade and size for your next project.