What Is “Form Lumber” And How Is It Used In Construction Projects?

What Is “Form Lumber” And How Is It Used In Construction Projects?

In construction, form lumber are planks or beams of wood used to hold concrete in place while it dries. By arranging the lumber in artful ways, builders can give concrete a wide assortment of shapes, dimensions, and surface textures even though the substance is hard to work. Once the concrete has been poured onto form lumber and allowed to dry, construction workers remove the lumber, leaving just the molded concrete in place. To ensure the concrete can support loads in addition to its weight, builders also often incorporate tie anchors, shores, and other devices in the construction process.

What Types of Form Lumber Are There?

Plywood is a popular form lumber because of its smoothness, which leads to glossy concrete, and its stiffness, which allows it to remain in place while the concrete is poured over it. Typically, plywood is also light and features a large surface area per panel, making it easy to remove once the concrete has been poured. Plywood form lumber comes in many varieties. BBOES plywood, for example, comes from fir trees and features a sanded, oiled surface ideal for smooth concrete finishes and quick stripping. Like many types of formwork plywood, BBOES is highly durable and reusable.

Medium and High Density Overlay types of form plywood provide the stability needed to pour the concrete while allowing for the addition of an outside layer to achieve a precise finish. In particular, High Density Overlay is good for a glossy concrete surface, and it can be stripped and reused over 10 times. Finland Form, another type of form lumber, comes from Eastern Europe and is popular for its lightness and customizable sizing.

Form Lumber: The Application Process

Form lumber is tricky. If the boards aren’t arranged in a strong frame, they can collapse and even kill construction workers once the concrete is poured over them. Therefore, builders follow strict protocols when setting up form lumber, including ones to ensure the lumber holds up in case of accidental overloading. Responsible builders also wait until the concrete is completely dry before removing the lumber, as premature removal can lead to a dangerous collapse.

When setting up form lumber, workers pick complementary boards, inspect them for grime or imperfections, and fasten them together at the joints to form an elaborate frame, double-checking periodically to ensure the system won’t wobble or allow leakage during the pouring process. Once the frame is complete, the construction crew pours the concrete over it with delicacy. Then they wait for the concrete to dry and remove the boards piece by piece, storing them for the next project.


When choosing form lumber, builders must take into account the cost of the lumber, as it can be expensive to replace if the pouring doesn’t go well. Lumber framework is among the costliest stages of construction, so reusability is a key criterion when choosing form lumber. In addition, builders tend to avoid dry lumber, as it saps moisture from the concrete during the drying process and thereby weakens it. However, builders can apply special coatings to dry lumber to avoid this problem. Finally, weight is a major factor when choosing form lumber. The lighter the lumber, the cheaper and easier it is to remove. Lighter lumber is also less apt to hurt workers if the frame buckles during construction.

Form lumber is the skeleton of any concrete construction project. Because it influences the shape and texture of the finished building more than any other material in the construction process, form lumber is perhaps the most important part of concrete architecture.

Security Building Supplies in Tulsa, OK provides commercial grade rebar, lumber, fabrication for footing steel, form lumber and quick response service for many of the commercial contractors in Tulsa and surrounding areas.

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