Before you begin your project, it is important to properly plan and prepare. Proper planning will save time in end, and helps to assure your satisfaction with the end product.
Thickness
For common household projects – driveways, walkways and patios – 4 inches thick should do the trick. You may require a thicker pour should the area see large amounts of traffic.
Base
In the general Portland area we recommend using a ¾ minus crushed gravel compacted base.
Drainage
Industry standard calls for a slope of ¼ inch per foot away from structures. Some projects may be able to use ⅛ inch slope.
Excavation
While taking care to only dig as deep as necessary (keeping an eye out for power lines), ensure you remove tree roots, leaves, wood and any other organic matter in the desired area.
Compaction
To ensure your slab doesn’t settle or vary in thickness, make sure to compact the soil/gravel base in the desired area.
Forming
Take care to stake your forms securely to the ground, while paying close attention to the slope (for proper drainage). 2x4s are perfectly adequate for use as forms, though make sure you have the desired thickness (usually 4″) available at the edges.
Isolation
Install premolded joint material anywhere concrete will come into contact with existing slabs, steps or buildings. The joint most reach the bottom of the slab, and ensures the new slab will be separated from existing structures.
Now that you have your planning down, we suggest you review our Concrete Calculator to determine your exact needs