Concrete forms, or formwork or shuttering, are temporary structures used to support freshly poured concrete until it hardens and gains enough strength to support itself. They are typically made of wood and are used to create the desired shape and dimensions of the concrete element being formed, such as walls, columns, beams, and slabs.
Wooden forms are usually constructed on the site using standard lumber, plywood sheets, or timber and are assembled and anchored in place before the concrete is poured. Once the concrete has cured and achieved the required strength, the forms are removed, and the resulting concrete element retains the shape and dimensions of the formwork.
How to Build Wooden Concrete Frames?
Plan the Project:
- Start by checking the planning permissions for the project to undertake. For this, you can check with the local authorities and obtain the necessary permits to undertake the project if required.
- Determine the load-bearing capacity of the structure, the type of concrete being used, and any design requirements. Once done with that, ensure the concrete structure’s appropriate size, shape, and location.
Note: You can also consult a structural engineer or contractor to ensure the project is properly planned. This is especially required if you’re doing this for the first time and are going to put a lot of investment into the project.
Gather Materials and Tools:
- Acquire the necessary materials and tools once the project is planned. This typically includes wooden boards, hardware such as screws and nails, a saw, a drill, a level, and a measuring tape.
- The most important thing in this phase is selecting an appropriate-sized wooden board according to the site and concrete slab requirements.
Note: Usually, a 4 x 1-inch wooden board is preferred for building a 4-inch concrete slab structure. But if you want a thicker slab, you require a thicker board or sheathing.
Prepare the Site:
- Clear the site of any debris or obstacles, such as rocks or tree roots, that could interfere with the construction process. Level the site using a shovel or other tool, ensuring the ground is even and free of large bumps or depressions.
- Compact the soil using a compactor or other heavy equipment to prevent settling and ensure a stable foundation. Moreover, install any necessary drainage systems, such as pipes or gravel, to ensure proper drainage and prevent water build-up.
- Mark the perimeter of the construction site using stakes or other markers to ensure that the wooden frame is properly positioned.
Cut the Wooden Boards:
- Once you have taken the site’s measurement and decided on the slab size, carefully measure the wood pieces accordingly, and mark them with stakes.
- Use the saw to trim the boards to the appropriate length and width.
Note: Ensure the boards are cut accurately to prevent gaps or unevenness in the finished product.
Assemble & Place the Frame:
- Piece together the wooden boards to form the frame.
- Carefully screw or nail the boards together at the corners to ensure the wooden board is attached appropriately to prevent concrete leakage.
- Ensure the frame is square and level to prevent any issues during concrete pouring.
- You can also provide additional support to the wooden structure by adding braces if you think that structure may not be able to carry the concrete load.
- Position the frame where the concrete will be poured.
Pour & Set the Concrete:
- Fill the frame with concrete to the desired level. Ensure to do this slowly and consistently to avoid damage and lay it evenly.
- Once the concrete is poured, level out the concrete surface with a trowel or other appropriate tool.
Remove the Wooden Frame:
Concrete typically begins to set within 30 minutes to 2 hours after it is mixed, depending on the type of cement used. In 24-48 hours, it becomes safe to walk on. But the concrete should cure for at least 28 days for most applications to achieve maximum strength.
- After 24-48 hours, when the concrete is bearing your weight, disassemble and remove the wooden frame.
- Do this carefully to prevent any damage to the concrete structure.
- Remove the hardware used to secure the frame.
Frequently Asked Questions
Can You Frame Concrete with Wood?
Yes, concrete frames are the most commonly used material for concrete framing. They provide strength, durability, fire resistance, and the ability to withstand heavy loads and seismic activity.
What Is the Best Wood for Framing Concrete?
Spruce Pine Fir (SPF) timbers are considered the best wood for concrete framing due to their strength, stability, and ease of use. They can support heavy loads without bending, are less likely to warp or shrink, and are easy to work with.
What Wood Size to Use for Concrete Forms?
For concrete slabs up to 4 inches thick, sheathing boards of at least 1 x 4 inches are required. But, load-bearing slabs like driveways will require 2- x 6-inch boards to provide additional support.