How to Build Basic Concrete Forms

What Can I Use for Concrete Forms?

You can use these materials to build concrete forms. 

• Wood is the most cost-effective and popular material for concrete forms. Properly built wooden forms are lightweight, flexible and durable. When choosing the wood for concrete forms, select straight, flat lumber with minimal knots.
• Resin-bonded plywood sheets can be attached to timber frames to create large, inexpensive concrete forms, but they are less durable.
• Fiberglass concrete forms are best for projects with curved surfaces, though they are expensive and often need to be custom ordered.
• Steel concrete forms are heavier and more expensive, but can be reused and offer savings in the long run.

Concrete forms may account for a significant amount of a job’s expenses, so reusing formwork can save money, especially on jobs that require pouring multiple concrete slabs of equal size.

Basic concrete forms must have the following qualities to be effective:

• Joints strong enough to prevent leaks
• Rigid structure that withstands the weight of the concrete without bending or breaking
• Design that can be easily reinforced with horizontal or vertical bracing

Construction costs for concrete slabs vary, but average $6 per square foot. The cost of a 30x30 concrete slab is estimated at approximately $5,400. 

Pro Tip: Wood forms can absorb water from the concrete mix. To reduce warping, treat the concrete-facing side of the wood with a sealant.